Bigelow and ULA are Sending a Habitat to Lunar Orbit by 2022

Bigelow Lunar Outpost. Credit: Bigelow Aerospace
Bigelow Lunar Outpost. Credit: Bigelow Aerospace

Bigelow Aerospace and United Launch Alliance announced on Tuesday that they’ll be sending their own inflatable habitat to lunar orbit by 2022. They’re calling it the Lunar Depot. Part laboratory, part hotel, the habitat will serve as a destination for anyone planning to visit the Moon.

Suddenly the Moon has become all the rage for anyone planning trips to space. Of course, SpaceX noted that their BFR (Big Freaking Rocket) should be capable of sending the BFR spaceship to land on the Moon and return. NASA was instructed by the Trump Administration to set a course for the Moon, before heading off to Mars. The Europeans are considering a lunar village on the surface of the Moon, and the logo for the Chinese Chang’e lunar exploration program has feet on the Moon.

According to a joint press release from ULA and Bigelow, the launch would send the B330 Expandable Module atop a ULA Vulcan 562 rocket, followed by more Vulcan launches to boost the habitat from low Earth orbit to its final lunar destination.

Interior schematic view of Bigelow Aerospace B330 expandable module. Credit: Bigelow Aerospace
Interior schematic view of Bigelow Aerospace B330 expandable module. Credit: Bigelow Aerospace

Bigelow Aerospace has been working on inflatable habitats for years now, sending up their own standalone Genesis 1 spacecraft in 2006. This proved that an inflatable habitat would function in space. It was supposed to last at least 5 years, but it’s still going. This was followed up by Genesis 2 in 2007, which is also still continuing to orbit the Earth. The Bigelow Expandable Activity Module (BEAM) was attached to the International Space Station in April 2016, carried to space aboard a SpaceX Dragon Capsule. Since then, NASA has been testing out its functionality as a module on the station, as well as its strength, radiation protection and how it responds to temperature changes. Earlier this month, NASA announced that the BEAM module was working well, and they’d keep it on the station at least through 2020, reviewing it each year.

The Bigelow B330 is a much larger inflatable habitat. It would be 14 meters long, and 6.7 metres in diameter when fully inflated. Its launch mass will be 20,000 kg, requiring a heavy lift vehicle to carry it out into a lunar orbit. It would have an internal volume of 330 cubic meters. For comparison, the International Space Station has an internal volume of 915 cubic meters, so, about a third of ISS. Pretty impressive for a single launch. Bigelow has yet to actually construct a B330, but they have some in construction, and previously committed to having two ready for 2020.

View of the Vulcan Rocket. Credit: ULA
View of the Vulcan Rocket. Credit: ULA

The Vulcan rocket is the new heavy lift vehicle in development by United Launch Alliance, the collaboration between Boeing and Lockheed Martin. Designed to compete with the newer launch companies, like SpaceX and Blue Origins, the Vulcan will have reusable rocket engines. After the Vulcan lifts off, the engines will detach and parachute back to Earth, caught by helicopters. According to ULA, the engines account for 70% of the cost of a rocket, so by catching them like this, they’ll be able to reuse the engines without the additional weight of fuel, steering and landing systems.

And just like Bigelow, ULA is planning to have their first Vulcan rocket ready for test launch by 2019.

If all goes as planned, a Vulcan 562 rocket would carry the B330 into a low Earth orbit, where it would be inflated, outfitted with equipment and fully tested over the course of a year. Every few months they would send additional supplies and change out the astronaut crew.

Once everything was in working order, another Vulcan rocket would launch carrying an Advanced Cryogenic Evolved Stage (ACES) into low Earth orbit. A second Vulcan ACES would be launched to dock with the first and transfer propellant. The fully fueled ACES would dock with the outpost, and push it out to its final low lunar orbit.

In its final location at the Moon, the Lunar Depot would serve as a destination for NASA’s Orion capsule which is capable of supporting astronauts in deep space. Or it could be visited by SpaceX BFR spaceships, transferring tourists for a space holiday.

The announcement of the Lunar Depot comes right at the point when the Trump Administration is directing its space exploration efforts at the Moon, so the timing is good. Of course, NASA is still working on its Deep Space Gateway, recently announcing that Russia would be contributing modules to the station.

For nearly 50 years human beings haven’t left low Earth orbit, let alone go back to the Moon. Suddenly there are multiple plans to send humans back to various orbiting colonies and ground missions. We’ll have to see how this all shakes out.

Source: ULA/Bigelow Press Release

Where Do Comets Come From? Exploring the Oort Cloud

Where Do Comets Come From? Exploring the Oort Cloud
Where Do Comets Come From? Exploring the Oort Cloud

Before I get into this article, I want to remind everyone that it’s been several decades since I’ve been able to enjoy a bright comet in the night sky. I’ve seen mind blowing auroras, witnessed a total solar eclipse with my own eyeballs, and seen a rocket launch. The Universe needs to deliver this bright comet for me, and it needs to do it soon.

By writing this article now, I will summon it. I will create an article that’ll be hilariously out of date in a few months, when that bright comet shows up.

Like that time we totally discovered a supernova in the Virtual Star Party, by saying there wasn’t a supernova in that galaxy, but there was, and we didn’t get to make the discovery.

Anyway, on to the article. Let’s talk about comets.

Comet C/2014 Q2 Lovejoy, Widefield view, false color. Feb 8, 2015. Credit and copyright: Joseph Brimacombe.
Comet C/2014 Q2 Lovejoy, Widefield view, false color. Feb 8, 2015. Credit and copyright: Joseph Brimacombe.

Comets are awesome. They’re made of gas, dust, rock, and organic materials, smashed together, and existing mostly unchanged since the formation of the Solar System 4.5 billion years ago. Every now and then, some gravitational interaction kicks a comet into an orbit that brings it closer to the Sun.

Because of the increased radiation, the comet’s volatile gas and dust sublimates off the surface, leaving behind a long tail of ice. And this is how we discover them.

In fact, comets are one of the objects in the night sky regularly found by amateurs. And by discovering a comet, you get to have it named after you. Of course many of the comets are named after robotic observatories, just another way the robots are taking human jobs.

The source of comets was originally proposed by Gerard Kuiper in 1951, when he theorized that there must be a vast disk of gas and dust surrounding the Solar System, out beyond the orbit of Pluto.

This “Kuiper Belt”, contains millions of objects, which orbit the Sun, jostling each other with their gravity. These interactions kick these Kuiper Belt comets into orbits that bring them closer to the Sun, where they get their characteristic tails.

Astronomers call these short period comets, since they orbit the Sun relatively often. They’re given names and designations, and astronomers can calculate when the comet will pass near to the Sun and flare up again.

Halley's Comet, as seen by the European Giotto probe. Credit: Halley Multicolor Camera Team, Giotto Project, ESA
Halley’s Comet, as seen by the European Giotto probe. Credit: Halley Multicolor Camera Team, Giotto Project, ESA

The famous Halley’s Comet is a good example, which was known to antiquity, but had its orbit first calculated in 1705 by Edmond Halley. Every 74 to 79 years, Halley’s Comet swings near the Sun, flares up and we get a view of this amazing object. It last passed our area in 1986, and it’s not due to return until 2061. I should be in my third robot body by then.

The long period comets are much more mysterious. These objects come out of nowhere, pass through the inner Solar System or smash into the Sun, and then zip back out into deep space. Now, where do they come from?

The Dutch astronomer Jan Oort calculated that there must be an even vaster cloud of ice even farther out beyond the Kuiper Belt – between 5,000 and 100,000 astronomical units from the Sun. Just a reminder, 1 astronomical unit is the distance from the Earth to the Sun, so we’re talking really really far away.

The layout of the solar system, including the Oort Cloud, on a logarithmic scale. Credit: NASA
The layout of the solar system, including the Oort Cloud, on a logarithmic scale. Credit: NASA

Like, the Voyager 1 spacecraft, which is the most distant and fastest object ever sent out by humanity, will still need about 300 years to reach the edge of the Oort Cloud.

Astronomers think that occasional gravitational nudges in the Oort Cloud cause these long period comets to fall down into the inner Solar System and make their rare appearances. It could take a comet like this hundreds of thousands or even millions of years to complete an orbit around the Sun. I’ll need a few dozen robot bodies for that repeat observation.

Check out this cool picture of Comet C/2017 K2 PANSTARRS, taken by the Hubble Space Telescope. This is a great example of a long-period comet, which is visiting our neighbourhood for the first time in the 4.5 billion-year history of the Solar System.

This is the dimmest, farthest comet ever discovered, first seen when it was out beyond the orbit of Saturn.

This cloud of material around the comet is probably the sublimation of frozen volatile gases, like oxygen, nitrogen, carbon dioxide and carbon monoxide. Astronomers think it started to become active about 4 years ago, and they just discovered it now.

As it gets closer to the Sun and warms up, it’ll become a true comet, when its hard-as-rock water ice structure starts to sublimate and earns its tail.

It should make its closest approach in 2022 when it gets about as close to the Sun as Mars.

And this is why we can’t detect out into the Oort Cloud yet. We can barely detect comets outside the orbit of Saturn, not to mention hundreds of times farther than that.

Our Sun isn’t alone in the Milky Way, obviously. It’s a vast swirling storm of hundreds of billions of stars, and over the tens of thousand of years, other stars come much closer to the Sun than we see today.

The European Space Agency’s Gaia spacecraft recently released one of the most detailed maps of stellar positions and motions, and gave us a much better picture of where our Sun is going, and what it’s going to be interacting with in the future.

In order to interact with the Oort Cloud, astronomers have calculated that a star needs to get within about 6.5 light years before it can interact gravitationally, depending on its mass.

Credit: ESA / Gaia / DPAC / A. Moitinho & M. Barros, CENTRA – University of Lisbon.
Credit: ESA / Gaia / DPAC / A. Moitinho & M. Barros, CENTRA – University of Lisbon.

Based on data gathered by the Gaia spacecraft, astronomers charted out the motions of 300,000 stars in our vicinity of the Milky Way in the next 5 million years or so.

Of those stars, 97 will come within 15 light-years of the Sun, and 16 will get closer than 6.5. The most interesting of these is Gliese 710. In 1.3 million years, it’ll pass less than 2.5 light-years away from the Sun, plunging right through the Oort Cloud.

Gliese 710 has about 60% the mass of the Sun, and it’s going about half the speed that stars normally go as they sweep past the Solar System. Which means that it’s going to stick around for a long time, pushing comets around with its mass, and send showers of comets down into the Solar System.

On average, it seems like a star passes within 15 light-years every 50,000 years or so, jostling up our collection of comets.

This is important, because comet impacts could be a cause of past extinction events on Earth. By tracking the movements of stars in our region, astronomers could try to match up past events with times that stars jostled up the Oort Cloud, and predict future events.

Could we ever reach the Oort Cloud and explore it? A few years ago, a space observatory was proposed that could attempt to observe objects as distant as the Oort Cloud. Known as the Whipple Mission, it would orbit in the Sun-Earth L2 point, and watch the sky with a wide field of view.

It would try to detect transiting events when objects as small as a kilometer across passed in front of a more distant star. In theory, the mission would be capable of spotting these transits out as far as 22,000 astronomical units or nearly half a light year. Unfortunately, it hasn’t gotten past the proposal stage.

How the FOCAL mission would see a terrestrial planet. Credit: Geoffrey A. Landis
How the FOCAL mission would see a terrestrial planet. Credit: Geoffrey A. Landis

Another intriguing idea is known as the FOCAL mission, which involves sending a space telescope out to a distance of 550 astronomical units away from the Sun. At this point, the telescope can use the gravity of the Sun itself as an enormous lens, focusing the light from more distant objects.

Actually, you’d need to go farther. At 550 astronomical units, the sunlight drowns out anything the space telescope might try to see. Instead, it needs to go out to a distance of more than 2,000 astronomical units from Earth, when the light focused by the Sun turns into an Einstein Ring around it.

What could you do with a telescope like this? If an exoplanet were to pass behind the Sun, perfectly lined up, you could resolve features as small as 1 kilometer across on a world 35 light-years away.

A telescope like this gives us a very good reason to learn to travel out and explore the Oort Cloud.

The Gaia spacecraft is still hard at work gathering data, and astronomers are expecting another massive data dump in April, 2018. Over time, the spacecraft will map out the position and movements of a billion stars in the Milky Way.

Comets are awesome, and I’d like to see a visible comet in the night sky, but I’d like them to keep their distance.

Forecast for Titan: Cold, with a Chance of Noxious Ice Clouds

This view of Saturn’s largest moon, Titan, is among the last images the Cassini spacecraft sent to Earth before it plunged into the giant planet’s atmosphere. Credits: NASA/JPL-Caltech/Space Science Institute

During the 13 years and 76 days that the Cassini mission spent around Saturn, the orbiter and its lander (the Huygens probe) revealed a great deal about Saturn and its systems of moons. This is especially true of Titan, Saturn’s largest moon and one of the most mysterious objects in the Solar System. As a result of Cassini’s many flybys, scientists learned a great deal about Titan’s methane lakes, nitrogen-rich atmosphere, and surface features.

Even though Cassini plunged into Saturn’s atmosphere on September 15th, 2017, scientists are still pouring over the things it revealed. For instance, before it ended its mission, Cassini captured an image of a strange cloud floating high above Titan’s south pole, one which is composed of toxic, hybrid ice particles. This discovery is another indication of the complex organic chemistry occurring in Titan’s atmosphere and on it’s surface.

Since this cloud was invisible to the naked eye, it was only observable thanks to Cassini’s Composite Infrared Spectrometer (CIRS). This instrument spotted the cloud at an altitude of about 160 to 210 km (100 to 130 mi), far above the methane rain clouds of Titan’s troposphere. It also covered a large area near the south pole, between 75° and 85° south latitude.

Artist concept of Cassini’s last moments at Saturn. Credit: NASA/JPL.

Using the chemical fingerprint obtained by the CIRS instrument, NASA researchers also conducted laboratory experiments to reconstruct the chemical composition of the cloud. These experiments determined that the cloud was composed of the organic molecules hydrogen cyanide and benzene. These two chemicals appeared to have condensed together to form ice particles, rather than being layered on top of each other.

For those who have spent more than the past decade studying Titan’s atmosphere, this was a rather interesting and unexpected find. As Carrie Anderson, a CIRS co-investigator at NASA’s Goddard Space Flight Center, said in a recent NASA press statement:

“This cloud represents a new chemical formula of ice in Titan’s atmosphere. What’s interesting is that this noxious ice is made of two molecules that condensed together out of a rich mixture of gases at the south pole.”

The presence of this cloud around Titan’s southern pole is also another example of the moon’s global circulation patterns. This involves currents of warm gases being sent from the hemisphere that is experiencing summer to the hemisphere experience winter. This pattern reverse direction when the seasons change, which leads to a buildup of clouds around whichever pole is experiencing winter.

Artist’s impression of Saturn’s moon Titan shows the change in observed atmospheric effects before, during and after equinox in 2009. Credit: NASA

When the Cassini orbiter arrived at Saturn in 20o4, Titan’s northern hemisphere was experiencing winter – which began in 2004. This was evidenced by the buildup of clouds around its north pole, which Cassini spotted during its first encounter with the moon later than same year. Similarly, the same phenomena was taking place around the south pole near the end of Cassini’s mission.

This was consistent with seasonal changes on Titan, which take place roughly every seven Earth years – a year on Titan lasts about 29.5 Earth years. Typically, the clouds that form in Titan’s atmosphere are structured in layers, where different types of gas will condense into icy clouds at different altitudes. Which ones condense is dependent on how much vapor is present and temperatures – which become steadily colder closer to the surface.

However, at times, different types of clouds can form over a range of altitudes, or co-condense with other types of clouds. This certainly appeared to be the case when it came to the large cloud of hydrogen cyanide and benzene that was spotted above the south pole. Evidence of this cloud was derived from three sets of Titan observations made with the CIRS instrument, which took place between July and November of 2015.

The CIRS instrument works by separating infrared light into its constituent colors, and then measures the strengths of these signals at the different wavelengths to determine the presence of chemical signatures. Previously, it was used to identify the presence of hydrogen cyanide ice clouds over the south pole, as well as other toxic chemicals in the moon’s stratosphere.

Artist’s impression of the Cassini orbiter’s Composite Infrared Spectrometer (CIRS). Credit: NASA-JPL

As F. Michael Flasar, the CIRS principal investigator at Goddard, said:

“CIRS acts as a remote-sensing thermometer and as a chemical probe, picking out the heat radiation emitted by individual gases in an atmosphere. And the instrument does it all remotely, while passing by a planet or moon.”

However, when examining the observation data for chemical “fingerprints”, Anderson and her colleagues noticed that the spectral signatures of the icy cloud did not match those of any individual chemical. To address this, the team began conducting laboratory experiments where mixtures of gases were condensed in a chamber that simulated conditions in Titan’s stratosphere.

After testing different pairs of chemicals, they finally found one which matched the infrared signature observed by CIRS. At first, they tried letting one gas condense before the other, but found that the best results were obtained when both gases were introduced and allowed to condense at the same time. To be fair, this was not the first time that Anderson and her colleagues had discovered co-condensed ice in CIRS data.

For example, similar observations were made near the north pole in 2005, about two years after the northern hemisphere experienced its winter solstice. At that time, the icy clouds were detected at a much lower altitude (below 150 km, or 93 mi) and showed chemical fingerprints of hydrogen cyanicide and caynoacetylene – one of the more complex organic molecules in Titan’s atmosphere.

Artist’s impression of the Cassini orbiter entering Saturn’s atmosphere. Credit: NASA/JPL

This difference between this and the latest detection of a hybrid cloud, according to Anderson, comes down to differences in seasonal variations between the north and south poles. Whereas the northern polar cloud observed in 2005 was spotted about two years after the northern winter solstice, the southern cloud Anderson and her team recently examined was spotted two years before the southern winter solstice.

In short, it is possible that the mixture of the gases was slightly different in the two case, and/or that the northern cloud had a chance to warm slightly, thus altering its composition somewhat.  As Anderson explained, these observations were made possible thanks to the many years that the Cassini mission spent around Saturn:

“One of the advantages of Cassini was that we were able to flyby Titan again and again over the course of the thirteen-year mission to see changes over time. This is a big part of the value of a long-term mission.”

Additional studies will certainly be needed to determine the structure of these icy clouds of mixed composition, and Anderson and her team already have some ideas on how they would look. For their money, the researchers expect these clouds to be lumpy and disorderly, rather than well-defined crystals like the single-chemical clouds.

In the coming years, NASA scientists are sure to be spending a great deal of time and energy sorting through all the data obtained by the Cassini mission over the course of its 13-year mission. Who knows what else they will detect before they have exhausted the orbiter’s vast collections of data?

Future Reading: NASA

More Evidence Presented in Defense of Planet 9

Artist's concept of the hypothetical "Planet Nine." Could it have moons? Credit: NASA/JPL-Caltech/Robert Hurt

In January of 2016, astronomers Mike Brown and Konstantin Batygin published the first evidence that there might be another planet in our Solar System. Known as “Planet 9” (“Planet X” to those who reject the controversial 2006 Resolution by the IAU), this hypothetical body was believed to orbit at an extreme distance from our Sun, as evidenced by the fact that certain Trans-Neptunian Objects (TNOs) all seem to be pointing in the same direction.

Since that time, more and more evidence has been produced that show how the presence of Planet 9 affected the evolution of the Solar System, leading it to become as it is today. For example, a recent study by a team of researchers from the University of Michigan has shown how Planet 9 may have kept certain TNOs from being destroyed or ejected from the Solar System over the course of billions of years.

The study, which was recently published in the Astronomical Journal under the title “Evaluating the Dynamical Stability of Outer Solar System Objects in the Presence of Planet Nine“, was led by Juliette Becker, a graduate student with the University of Michigan’s Department of Astronomy. It was supported by Professors David Gerdes and Fred Adams, as well as graduate and undergraduate students from UofM’s Depart of Physics.

Diagram showing how the six most distant known objects in the Solar System with orbits beyond Neptune (TNOs) all mysteriously line up in a single direction. Credit: Caltech/R. Hurt (IPAC)

For the sake of their study, Becker and her colleagues conducted a large set of computer simulations that examined the stability of Trans-Neptunian Objects (TNOs) who’s orbits are believed to have been influenced by Planet 9. In each simulation, the researchers tested a different version of Planet 9 to see if its gravitational influence would result in the Solar System as we know it today.

From this, they uncovered two key findings. First, the simulations showed that Planet 9 may have led to the current Solar System by preventing these TNOs from being destroyed or ejected from the Solar System. Second, the simulations indicated that TNOs can jump between stable orbits, a process they refer to as “resonance hopping”. This would prevent these same TNOs from being thrown out of the Kuiper Belt.

As Becker explained in a University of Michigan press statement:

“From that set of simulations, we found out that there are preferred versions of Planet Nine that make the TNO stay stable for longer, so it basically increases the probability that our solar system exists the way it does. Through these computer simulations, we were able to determine which realization of Planet Nine creates our solar system—the whole caveat here being, if Planet Nine is real.”

Next, Becker and her team examined the TNOs to see if they experienced resonance with Planet 9. This phenomena, which occurs as a result of objects exerting a gravitational influence on each other, causes them to line up in a pattern. What they found was that, on occasion, Neptune will push a TNOs out of its orbital resonance, but does not disturb it enough to send it towards the Sun.

Artist's impression of Planet Nine, blocking out the Milky Way. The Sun is in the distance, with the orbit of Neptune shown as a ring. Credit: ESO/Tomruen/nagualdesign
Artist’s impression of Planet Nine, blocking out the Milky Way. The Sun is in the distance, with the orbit of Neptune shown as a ring. Credit: ESO/Tomruen/nagualdesign

A plausible explanation for this behavior was the gravitational influence of another object, which serves to catch any TNOs and confine them to a different resonance. In addition, the team also considered a newly-discovered TNO that was recently detected by The Dark Energy Survey collaboration – a group of 400 scientist from 26 institutions in seven countries, which includes several members from the University of Michigan.

This object has a high orbital inclination compared to the plane of the Solar System, where it is tilted at 54° relative to the Sun’s ecliptic. After analyzing this new object, Becker and team concluded that the object also experiences resonance hopping, which is consistent with the existence of Planet 9. This, along with other recent studies, are creating a picture where it is harder to imagine the Solar System without Planet 9 than with it.

As Becker explained, all that remains now is to observe Planet 9 directly.”The ultimate goal would be to directly see Planet Nine—to take a telescope, point it at the sky, and see reflected light from the sun bouncing off of Planet Nine,” she said. “Since we haven’t yet been able to find it, despite many people looking, we’re stuck with these kinds of indirect methods.”

Further Reading: University of Michigan, The Astronomical Journal

Stable Lava Tube Could Provide a Potential Human Habitat on the Moon

The Marius Hills Skylight, as observed by the Japanese SELENE/Kaguya research team. Image by: NASA/Goddard/Arizona State University

On October 5th, 2017, Vice President Mike Pence announced the Trump administration’s plan to return astronauts to the Moon. Looking to the long-term, NASA and several other space agencies are also intent on establishing a permanent lunar base there. This base will not only provide opportunities for lunar science, but will facilitate missions to Mars and beyond.

The only question is, where should such a base be built? For many years, NASA, the ESA and other agencies have been exploring the possibility of stable lava tubes as a potential site. According to new study by a team of international scientists, the presence of such a tube has now been confirmed in the Marius Hills region. This location is likely to be the site of future lunar missions, and could even be the site of a future lunar habitat.

In 2009, data provided by the Terrain Camera aboard JAXA’s SELENE spacecraft indicated the presence of three huge pits on the Moon. These pits (aka. “skylights”) were of particular interest since they were seen as possible openings to subsurface lava channels. Since then, the Marius Hills region (where they were found) has been a focal point for astronomers and planetary scientists hoping to confirm the existence of lava tubes.

Artist’s impression of a surface exploration crew investigating a typical, small lava tunnel, to determine if it could serve as a natural shelter for the habitation modules of a Lunar Base. Credit: NASA’s Johnson Space Center

The recent study, titled “Detection of intact lava tubes at Marius Hills on the Moon by SELENE (Kaguya) Lunar Radar Sounder“, recently appeared in the journal Geophysical Research Letters. The team consisted of members from JAXA’s Institute of Space and Astronautical Science (ISAS), Purdue University, the University of Alabama, AstroLabs, the National Astronomical Observatory of Japan (NOAJ) and multiple Japanese Universities.

Together, they examined data from the SELENE mission’s Lunar Radar Sounder (LRS) from locations that were close to the Marius Hills Hole (MHH) to determine if the region hosted stable lava tubes. Such tubes are a remnant from the Moon’s past, when it was still volcanically active. These underground channels are believed to be an ideal location for a lunar colony, and for several reasons.

For starters, their thick roofs would provide natural shielding from solar radiation, cosmic rays, meteoric impacts, and the Moon’s extremes in temperature. These tubes, once enclosed, could also be pressurized to create a breathable environment. As such, finding an entrance to a stable lava tube would the first step towards selecting a possible site for such a colony.

As Junichi Haruyama, a senior researcher at JAXA and one of the co-authors on the study, explained in a University of Purdue press release:

“It’s important to know where and how big lunar lava tubes are if we’re ever going to construct a lunar base. But knowing these things is also important for basic science. We might get new types of rock samples, heat flow data and lunar quake observation data.”

The city of Philadelphia is shown inside a theoretical lunar lava tube. A Purdue University team of researchers explored whether lava tubes more than 1 kilometer wide could remain structurally stable on the moon. Credit: Purdue University/courtesy of David Blair

Granted, the LRS was not specifically designed to detect lava tubes, but to characterize the origins of the Moon and its geologic evolution. For this reason, it did not fly close enough to the Moon to obtain extremely accurate information on the subsurface. Nevertheless, as SELENE passed near the Marius Hills Hole, the instrument picked up a distinctive echo pattern.

This pattern was characterized by a decrease in echo power followed by a large second echo peak. These two echoes correspond to radar reflections from the Moon’s surface, as well as the floor and ceiling of the open lava tube. When they analyzed this pattern, the research team interpreted it is evidence of a tube. They found similar echo patterns at several locations around the hole, which could indicate that there is more than one lava tube in the region.

To confirm their findings, the team also consulted data from NASA’s Gravity Recovery and Interior Laboratory (GRAIL) mission. Consisting of two spacecraft, this collaborative effort collected high-quality data on the Moon’s gravitational field between 2011 and 2012. By using GRAIL data that identified mass deficits under the surface, which are evidence of caverns, the team was able to narrow down their search.

Jay Melosh, a GRAIL co-investigator and Distinguished Professor of Earth, Atmospheric and Planetary Sciences at Purdue University, was also a co-author on the paper. As he explained:

“They knew about the skylight in the Marius Hills, but they didn’t have any idea how far that underground cavity might have gone. Our group at Purdue used the gravity data over that area to infer that the opening was part of a larger system. By using this complimentary technique of radar, they were able to figure out how deep and high the cavities are.”

Arched passages in the main tube show the classic lava tube shape. The floor was the crust on a former lava lake that fell inward as it drained from beneath. Credit: Dave Bunnell/Under Earth Images/Wikipedia Commons

On Earth, stable lava tubes have been found that can extend for dozens of kilometers. To date, the longest and deepest to be discovered is the Kazumura Cave in Hawaii, which is over a kilometer (3,614 feet) deep and 65.5 km (40.7 mi) long. On the Moon, however, lava tubes are much larger, due to the fact that the Moon has only a fraction of the Earth’s gravity (0.1654 g to be exact).

For a lava tube to be detecting using gravity data, it would need to be several kilometers in length and at least one kilometer in height and width. Since the tube in Marius Hills was detectable, it is likely big enough to house a major city. In fact, during a presentation at the 47th Lunar and Planetary Conference, researchers from Purdue University showed GRAIL data that indicated how the tube beneath the MHH could be large enough to house Philadelphia.

This most recent study was also the subject of a presentation at the 48th Lunar and Planetary Conference. Similar evidence of possible stable lava tubes in the Sea of Tranquility was also obtained by the Lunar Reconnaissance Orbiter (LRO) back in 2010. However, this latest combination of radar and gravity data has provided the clearest picture yet of what a stable lava tube looks like.

Similar evidence of lava tubes has also been discovered on Mars, and possible even Mercury. On Mars in particular,  chains of pit craters, broad lava fans, skylights and partially collapsed lava tubes all indicate the presence of stable tubes. Based on this latest study, future mission to the Red Planet (which could include the creation of a habitat) might also entail the investigation of these features.

In fact, lava tubes could become the means through which a human presence is established throughout the Solar System someday!

Further Reading: Purdue University, Geophysical Research Letters

Metal-Eating Bacteria Could Have Left their “Fingerprints” on Mars, Proving it Once Hosted Life

Future missions could determine the presence of past life on Mars by looking for signs of extreme metal-metabolizing bacteria. Credit: NASA.

Today, there are multiple lines of evidence that indicate that during the Noachian period (ca. 4.1 to 3.7 billion years ago), microorganisms could have existed on the surface of Mars. These include evidence of past water flows, rivers and lakebeds, as well as atmospheric models that indicate that Mars once had a denser atmosphere. All of this adds up to Mars having once been a warmer and wetter place than it is today.

However, to date, no evidence has been found that life ever existed on Mars. As a result, scientists have been trying to determine how and where they should look for signs of past life. According to a new study by a team of European researchers, extreme lifeforms that are capable of metabolizing metals could have existed on Mars in the past. The “fingerprints” of their existence could be found by looking at samples of Mars’ red sands.

For the sake of their study, which recently appeared in the scientific journal Frontiers of Microbiology, the team created a “Mars Farm” to see how a form of extreme bacteria might fare in an ancient Martian environment. This environment was characterized by a comparatively thin atmosphere composed of mainly of carbon dioxide, as well as simulated samples of Martian regolith.

Metallosphaera sedula grown on synthetic Martian Regolith. The microbes are specifically stained by Fluorescence-In-Situ-Hybridization (FISH). Credit: Tetyana Milojevic

They then introduced a strain of bacteria known as Metallosphaera sedula, which thrives in hot, acidic environments. In fact, the bacteria’s optimal conditions are those where temperatures reach 347.1 K (74 °C; 165 °F)  and pH levels are 2.0 (between lemon juice and vinegar). Such bacteria are classified as chemolithotrophs, which means that they are able to metabolize inogranic metals – like iron, sulfur and even uranium.

These stains of bacteria were then added to the samples of regolith that were designed to mimic conditions in different locations and historical periods on Mars. First, there was sample MRS07/22, which consisted of a highly-porous type of rock that is rich in silicates and iron compounds. This sample simulated the kinds of sediments found on the surface of Mars.

Then there was P-MRS, a sample that was rich in hydrated minerals, and the sulfate-rich S-MRS sample, which mimic Martian regolith that was created under acidic conditions. Lastly, there was the sample of JSC 1A, which was largely composed of the volcanic rock known as palagonite. With these samples, the team was able to see exactly how the presence of extreme bacteria would leave biosignatures that could be found today.

As Tetyana Milojevic – an Elise Richter Fellow with the Extremophiles Group at the University of Vienna and a co-author on the paper – explained in a University of Vienna press release:

“We were able to show that due to its metal oxidizing metabolic activity, when given an access to these Martian regolith simulants, M. sedula actively colonizes them, releases soluble metal ions into the leachate solution and alters their mineral surface leaving behind specific signatures of life, a ‘fingerprint’, so to say.”

Microspheroids containing mostly aluminium and chlorine overgrow the mineral surface of synthetic Mars regolith. These microspheroids can only be observed after cultivation of Metallosphaera sedula Credit: Tetyana Milojevic

The team then examined the samples of regolith to see if they had undergone any bioprocessing, which was possible thanks to the assistance of Veronika Somoza – a chemist from the University of Vienna’s Department of Physiological Chemistry and a co-author on the study. Using an electron microscope, combined with analytical spectroscopy technique, the team sought to determine if metals with the samples had been consumed.

In the end, the sets of microbiological and mineralogical data they obtained showed signs of free soluble metals, which indicated that the bacteria had effectively colonized the regolith samples and metabolized some of the metallic minerals within. As Milojevic indicated:

“The obtained results expand our knowledge of biogeochemical processes of possible life beyond Earth, and provide specific indications for detection of biosignatures on extraterrestrial material – a step further to prove potential extra-terrestrial life.”

In effect, this means that extreme bacteria could have existed on Mars billions of years ago. And thanks to the state of Mars today – with its thin atmosphere and lack of precipitation – the biosignatures they left behind (i.e. traces of free soluble metals) could be preserved within Martian regolith. These biosignatures could therefore be detected by upcoming sample-return missions, such as the Mars 2020 rover.

Biotransformed synthetic Martian Regolith after Metallosphaera sedula cultivation. Credit: Tetyana Milojevic

In addition to pointing the way towards possible indications of past life on Mars, this study is also significant as far as the hunt for life on other planets and star systems is concerned. In the future, when we are able to study extra-solar planets directly, scientists will likely be looking for signs of biominerals. Among other things, these “fingerprints” would be a powerful indicator of the existence of extra-terrestrial life (past or present).

Studies of extreme lifeforms and the role they play in the geological history of Mars and other planets is also helpful in advancing our understanding of how life emerged in the early Solar System. On Earth too, extreme bacteria played an important role in turning the primordial Earth into a habitable environment, and play an important role in geological processes today.

Last, but not least, studies of this nature could also pave the way for biomining, a technique where strains of bacteria extract metals from ores. Such a process could be used for the sake of space exploration and resource exploitation, where colonies of bacteria are sent out to mine asteroids, meteors and other celestial bodies.

Further Reading: University of Vienna, Frontiers in Microbiology

Flowing Water on Mars Likely Cold and Frosty, Says New Study

In the past, glaciers may have existed on the surface of Mars, providing meltwater during the summer to create the features we see today. Credit: NASA/Caltech/JPL/UTA/UA/MSSS/ESA/DLR Eric M. De Jong, Ali Safaeinili, Jason Craig, Mike Stetson, Koji Kuramura, John W. Holt

Thanks to decades of exploration using robotic orbiter missions, landers and rovers, scientists are certain that billions of years ago, liquid water flowed on the surface of Mars. Beyond that, many questions have remained, which include whether or not the waterflow was intermittent or regular. In other words, was Mars truly a “warm and wet” environment billions of years ago, or was it more along the lines of “cold and icy”?

These questions have persisted due to the nature of Mars’ surface and atmosphere, which offer conflicitng answers. According to a new study from Brown University, it appears that both could be the case. Basically, early Mars could have had significant amounts of surface ice which experienced periodic melting, producing enough liquid water to carve out the ancient valleys and lakebeds seen on the planet today.

The study, titled “Late Noachian Icy Highlands Climate Model: Exploring the Possibility of Transient Melting and Fluvial/Lacustrine Activity Through Peak Annual and Seasonal Temperatures“, recently appeared in Icarus. Ashley Palumbo – a Ph.D. student with Brown’s Department of Earth, Environmental and Planetary Science – led the study and was joined by her supervising professor (Jim Head) and Professor Robin Wordsworth of Harvard University’s School of Engineering and Applied Sciences.

Extensive valley networks spidering through the southern highlands of Mars suggest that the planet was once warmer and wetter. Credit: NASA/JPL-Caltech/Arizona State University

For the sake of their study, Palumbo and her colleagues sought to find the bridge between Mars’ geology (which suggests the planet was once warm and wet) and its atmospheric models, which suggest it was cold and icy. As they demonstrated, it’s plausible that during the past, Mars was generally frozen over with glaciers. During peak daily temperatures in the summer, these glaciers would melt at the edges to produce flowing water.

After many years, they concluded, these small deposits of meltwater would have been enough to carve the features observed on the surface today. Most notably, they could have carved the kinds of valley networks that have been observed on Mars southern highlands. As Palumbo explained in a Brown University press release, their study was inspired by similar climate dynamics that take place here on Earth:

“We see this in the Antarctic Dry Valleys, where seasonal temperature variation is sufficient to form and sustain lakes even though mean annual temperature is well below freezing. We wanted to see if something similar might be possible for ancient Mars.”

To determine the link between the atmospheric models and geological evidence, Palumbo and her team began with a state-of-the-art climate model for Mars. This model assumed that 4 billion years ago, the atmosphere was primarily composed of carbon dioxide (as it is today) and that the Sun’s output was much weaker than it is now. From this model, they determined that Mars was generally cold and icy during its earlier days.

Nanedi Valles, a roughly 800-kilometre valley extending southwest-northeast and lying in the region of Xanthe Terra, southwest of Chryse Planitia. Credit: ESA/DLR/FU Berlin (G. Neukum)

However, they also included a number of variables which may have also been present on Mars 4 billion years ago. These include the presence of a thicker atmosphere, which would have allowed for a more significant greenhouse effect. Since scientists cannot agree how dense Mars’ atmosphere was between 4.2 and 3.7 billion years ago, Palumbo and her team ran the models to take into account various plausible levels of atmospheric density.

They also considered variations in Mars’ orbit that could have existed 4 billion years ago, which has also been subject to some guesswork. Here too, they tested a wide range of plausible scenarios, which included differences in axial tilt and different degrees of eccentricity. This would have affected how much sunlight is received by one hemisphere over another and led to more significant seasonal variations in temperature.

In the end, the model produced scenarios in which ice covered regions near the location of the valley networks in the southern highlands. While the planet’s mean annual temperature in these scenarios was well below freezing, it also produced peak summertime temperatures in the region that rose above freezing. The only thing that remained was to demonstrate that the volume of water produced would be enough to carve those valleys.

Luckily, back in 2015, Professor Jim Head and Eliot Rosenberg (an undergraduate with Brown at the time) created a study which estimated the minimum amount of water required to produce the largest of these valleys. Using these estimates, along with other studies that provided estimates of necessary runoff rates and the duration of valley network formation, Palumbo and her colleagues found a model-derived scenario that worked.

Was Mars warm and watery (i.e. a blue planet?) or an ice ball that occasionally experienced melting? Credit: Kevin Gill

Basically, they found that if Mars had an eccentricity of 0.17 (compared to it’s current eccentricity of 0.0934) an axial tilt of 25° (compared to 25.19° today), and an atmospheric pressure of 600 mbar (100 times what it is today) then it would have taken about 33,000 to 1,083,000 years to produce enough meltwater to form the valley networks. But assuming for a circular orbit, an axial tile of 25°, and an atmosphere of 1000 mbar, it would have taken about 21,000 to 550,000 years.

The degrees of eccentricity and axial tilt required in these scenarios are well within the range of possible orbits for Mars 4 billion years ago. And as Head indicated, this study could reconcile the atmospheric and geological evidence that has been at odds in the past:

“This work adds a plausible hypothesis to explain the way in which liquid water could have formed on early Mars, in a manner similar to the seasonal melting that produces the streams and lakes we observe during our field work in the Antarctic McMurdo Dry Valleys. We are currently exploring additional candidate warming mechanisms, including volcanism and impact cratering, that might also contribute to melting of a cold and icy early Mars.”

It is also significant in that it demonstrates that Mars climate was subject to variations that also happen regularly here on Earth. This provides yet another indication of how our two plane’s are similar in some ways, and how research of one can help advance our understanding of the other. Last, but not least, it offers some synthesis to a subject that has produced a fair share of disagreement.

The subject of how Mars could have experienced warm, flowing water on its surface – and at a time when the Sun’s output was much weaker than it is today – has remained the subject of much debate. In recent years, researchers have advanced various suggestions as to how the planet could have been warmed, ranging from cirrus clouds to periodic bursts of methane gas from beneath the surface.

While this latest study has not quite settled the debate between the “warm and watery” and the “cold and icy” camps, it does offer compelling evidence that the two may not be mutually exclusive. The study was also the subject of a presentation made at the 48th Lunar and Planetary Science Conference, which took place from March 20th to 24th in The Woodland, Texas.

Further Reading: Brown University, Icarus

Twice Flown SpaceX Booster Sails Proudly into Port Canaveral at Sunrise 3 Days After Sunset Launch and Droneship Landing: Photos

Reflown SpaceX Falcon 9 first stage booster arrives at sunrise atop OCISLY droneship being towed into the mouth of Port Canaveral, FL on Oct. 15, 2017 after successfully launch SES-11 UHDTV comsat to orbit on Oct. 11, 2017. Credit: Ken Kremer/Kenkremer.com
Reflown SpaceX Falcon 9 first stage booster arrives at sunrise atop OCISLY droneship being towed into the mouth of Port Canaveral, FL on Oct. 15, 2017 after successfully launching SES-11 UHDTV comsat to orbit on Oct. 11, 2017. Credit: Ken Kremer/Kenkremer.com

PORT CANAVERAL/KENNEDY SPACE CENTER, FL – The now twice flown SpaceX first stage booster that successfully delivered the SES-11 UHDTV satellite to orbit at sunset Wednesday, Oct 11, sailed proudly back home into Port Canaveral during a beautiful Sunday sunrise, Oct. 15 only three days after it safely landed on a tiny droneship at sea.

The booster arrival also took place just hours after a ULA Atlas launched the covert NROL-52 surveillance satellite for the US National Reconnaissance Office (NRO) – making for a nonstop day of space action on the Florida Space Coast.

The 156-foot-tall Falcon 9 booster accomplished a precision guided rocket assisted touchdown on the football field sized OCISLY droneship platform about 8 minutes after the dinnertime liftoff with the private SES-11/EchoStar 105 communications satellite on Oct. 11 at 6:53 p.m. EDT from seaside Launch Complex 39A at NASA’s Kennedy Space Center in Florida.

The 15 story tall first stage came to rest slightly tilted a few degrees, similar to at least two prior boosters that soft landed upright on OCISLY while prepositioned several hundred miles off shore of the Florida peninsula in the Atlantic Ocean.

The recycled booster was towed into Port Canaveral by a SpaceX contracted tugboat accompanied by a small fleet of pilot ships and support vessels.

The doubly used and doubly successful booster entered the mouth of Port Canaveral around 7:15 a.m. EDT Sunday under dawns delightful twilight I witnessed from Jetty Park and beach together with a few space media colleagues and a small crowd of onlookers with little fanfare.

Reflown SpaceX Falcon 9 first stage booster arrives at sunrise atop OCISLY droneship being towed into the mouth of Port Canaveral, FL on Oct. 15, 2017 after successfully launching SES-11 UHDTV comsat to orbit on Oct. 11, 2017. Credit: Ken Kremer/Kenkremer.com

Over the next hour it was hauled through the narrow channel as numerous vessels large and small and pleasure craft sailed by, likely wondering what they were looking it.

Finally the droneship platform was docked at SpaceX’s spot leased near the two huge shipping cranes dominating the scene across from popular portside restaurants – and also not far from humongous cruise ships dwarfing the booster in size.

The next step was for dock workers to hoist a cap and attach it to the top of the booster. This enabled it to eventually be carefully raised off the barge with a crane by about 1 p.m. and then slowly moved and swung over and affixed onto a restraining pedestal stand on land.

Reflown SpaceX Falcon 9 first stage booster is hoisted off OCISLY droneship after being towed through the channel of Port Canaveral, FL on Oct. 15. It successfully launched SES-11 UHDTV comsat to orbit on Oct. 11, 2017. Credit: Ken Kremer/Kenkremer.com
Reflown SpaceX Falcon 9 first stage booster is hoisted off OCISLY droneship after being towed through the channel of Port Canaveral, FL on Oct. 15. It successfully launched SES-11 UHDTV comsat to orbit on Oct. 11, 2017. Credit: Ken Kremer/Kenkremer.com

By the next evening Monday night, all 4 landing legs were still intact. After they are all detached the booster will be lowered horizontally aided by the cabling attached by the workers and placed on a flab bed transporter and trucked back to the Cape.

SpaceX Falcon 9 SES11 booster standing on a pedestal at night in Port Canaveral, FL, after being craned off the OCISLY droneship upon which it soft landed after Oct. 11, 2017 launch. Credit: Ken Kremer/kenkremer.com

However the impact of developing and reusing ‘used’ rockets is leading to an era when re-flown rockets are offered as a ‘routine service’ rather than the exception.

Rocket reusability is at the heart of the extraordinary vision of billionaire entrepreneur and SpaceX CEO Elon Musk to drastically cut space launch costs and one day build a ‘City on Mars’.

And it represents a ‘major sea change getting closer’ to fruition with each passing day thanks to SpaceX, said SES CTO Martin Halliwell in an exclusive interview with Universe Today, following the stunning sunset blastoff of the SES-11 UHDTV commercial satellite on another ‘flight-proven’ Falcon 9 booster that also re-landed – thus completing another remarkable round of rocket recovery and recycling or ‘launch, land and relaunch!’

“As I’ve said before, I think in a couple years time you won’t even consider whether it’s a preflown rocket or a new rocket or a second time rocket,” SES Chief Technology Officer Martin Halliwell told Universe Today in a one-on-one post launch interview.

“It will just be a flight and you will buy a service to get to orbit – and that will be that!”

“It’s a major sea change,” Halliwell explained. “That’s absolutely true.”

“We’re getting closer to that every day. It’s exactly where we are going. There is no doubt about it.”

Reflown SpaceX Falcon 9 first stage booster is docked near cruise ships after being towed through the channel of Port Canaveral, FL on Oct. 15. It successfully launched SES-11 UHDTV comsat to orbit on Oct. 11, 2017. Credit: Ken Kremer/Kenkremer.com

The launch of EchoStar 105/SES-11 counts as only the third recycled SpaceX Falcon 9 ever to be launched and is the third successful mission with a flight-proven orbital class rocket.

All three ‘flight-proven’ missions have lifted off from Pad 39A this year and all three have relanded.

The Falcon 9 first stage appeared to be in good shape upon its return to Port. I did not observe noticeable significant damage to the outside of the booster skin, grid fins or landing legs. Scorching seemed comparable to the first two reflown boosters.

This booster originally flew on the NASA Dragon CRS-10 resupply mission to the International Space Station in February of this year.

On arrival it was clearly anchored to the OCISLY droneship deck with multiple chains as previously done for droneship landings as well as with what appears to be several gripper arms.

Up close look at the base of the recovered Falcon 9 from SES-11 launch with four landing legs chained to the droneship deck while sailing through Port Canaveral, FL on Oct. 15, 2017. Credit: Ken Kremer/Kenkremer.com

OCISLY, which stands for “Of Course I Still Love You,” had departed Port Canaveral several days ahead of the Oct. 11 launch and was prepositioned in the Atlantic Ocean off the US East coast, just waiting for the boosters 2nd approach and pinpoint propulsive soft landing.

The booster was outfitted with four grid fins and four landing legs to accomplish the pinpoint touchdown on the barge at sea.

The recovered Falcon 9 from SES-11 launch is hoisted off the OCISLY dronseship deck with a crane in this up close view pf the boosters base and placed on a platform for ground processing after sailing through Port Canaveral, FL on Oct. 15, 2017. Credit: Ken Kremer/Kenkremer.com

SES was the first company to ever fly a payload on a ‘flight-proven’ Falcon 9. The SES-10 satellite lifted off successfully this spring on March 30, 2017.

The second reflown booster successfully launched the BulgariaSat-1 a few months later.

NASA is also assessing whether to utilize a reflown booster on upcoming ISS resupply missions – starting with the next flight of the Dragon CRS-13 cargo ship which may liftoff as soon as early December.

Pad 39A has been repurposed by SpaceX from its days as a NASA shuttle launch pad.

Up close look at all four landing legs of the recovered SpaceX Falcon 9 from SES-11 launch as technicians guide the booster onto pedestal for ground processing after sailing through Port Canaveral, FL on Oct. 15, 2017. Credit: Ken Kremer/kenkremer.com

To date SpaceX has accomplished 18 successful landings of a recovered Falcon 9 first stage booster by land and by sea.

SpaceX Falcon 9 recycled rocket lifts off at sunset at 6:53 PM EDT on 11 Oct 2017 carrying SES-11/EchoStar 105 HDTV commercial comsat to geosynchronous transfer orbit from Launch Complex 39A at NASA’s Kennedy Space Center, FL- as seen from the pad perimeter. Credit: Ken Kremer/Kenkremer.com

Watch for Ken’s continuing onsite coverage of SpaceX SES-11, ULA NROL-52 and NASA and space mission reports direct from the Kennedy Space Center and Cape Canaveral Air Force Station, Florida.

Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.

Ken Kremer

Birds tip toe along the Atlantic Ocean shoreline with booster reflection in sand as recycled SpaceX Falcon 9 first stage booster from SES-11 launch sails into Port Canaveral, FL atop droneship on Oct. 15, 2017. Credit: Ken Kremer/Kenkremer.com
Recycled SpaceX Falcon 9 first stage booster from SES-11 launch is towed into mouth of Port Canaveral, FL on Oct. 15, 2017 past Jetty Park pier damaged by Hurricane Irma. Credit: Ken Kremer/Kenkremer.com

Messier 58 – the NGC 4579 Barred Spiral Galaxy

The galaxies of Messier 58, Messier 59, Messier 60, Messier 87, Messier 89 and Messier 90. Credit: Wikisky

Welcome back to Messier Monday! Today, we continue in our tribute to our dear friend, Tammy Plotner, by looking at the barred spiral galaxy, Messier 58.

In the 18th century, while searching the night sky for comets, French astronomer Charles Messier kept noting the presence of fixed, diffuse objects in the night sky. In time, he would come to compile a list of approximately 100 of these objects, with the purpose of making sure that astronomers did not mistake them for comets. However, this list – known as the Messier Catalog – would go on to serve a more important function, becoming one of the first catalogs of Deep Sky Objects.

One of these objects is the intermediate barred spiral galaxy known as Messier 58, which is located approximately 68 million light years away in the Virgo constellation. In addition to being one of just four barred spiral galaxies in the Messier Catalog, it is also one of the brightest galaxies in the Virgo Supercluster. Due to its proximity in the sky to other objects in the Virgo Galaxy Field, it can be seen only with the help of a telescope or a pair of large binoculars.

Description:

This beautiful old barred spiral galaxy located approximately 68 million light-years from Earth. Although it might appear pretty plain, it has some great things going for it… namely an active galactic nucleus. As Marcella Contini indicated in a 2004 study:

“We have modelled the low-luminosity active galactic nuclei (AGN) NGC 4579 by explaining both the continuum and the line spectra observed with different apertures. It was found that the nuclear emission is dominated by an AGN such that the flux from the active centre (AC) is relatively low compared with that of the narrow emission-line region (NLR) of Seyfert galaxies. However, the contribution of a young starburst cannot be neglected, as well as that of shock-dominated clouds with velocities of 100, 300 and 500kms-1. A small contribution from an older starburst with an age of 4.5 Myr, probably located in the external nuclear region, is also found. HII regions appear in the extended regions, where radiation and shock-dominated clouds prevail.

“The continuum SED of NGC 4579 is characterized by the strong flux from an old stellar population. Emissions in the radio range show synchrotron radiation from the base of the jet outflowing from the accretion disc within 0.1 pc from the active centre. Radio emission within intermediate distances is explained by the bremsstrahlung from gas downstream of low-velocity shocks reached by a relatively low radiation flux from the AC. In extended regions the radio emission is synchrotron radiation created by the Fermi mechanism at the shock front. The shocks are created by collision of clouds with the jet. All types of emissions observed at different radius from the centre can be reconciled with the presence of the jet.”

The Messier 58 barred spiral galaxy. Credit: Adam Block/Mount Lemmon SkyCenter/University of Arizona

Yet where is this gas traveling to and why? According to 2014 study by S. Garcia-Burillo (et al):

“We created a complete gravity torque map of the disk of the LINER/Seyfert 1.9 galaxy NGC 4579. We quantify the efficiency of angular momentum transport and search for signatures of secular evolution in the fueling process from r ~ 15 kpc down to the inner r ~ 50 pc around the active galactic nucleus (AGN). The derived gravity torque budget in NGC 4579 shows that inward gas flow is occurring on different spatial scales in the disk. In the outer disk, the decoupling of the spiral allows the gas to efficiently populate the UHR region, and thus produce net gas inflow on intermediate scales. The co rotation barrier seems to be overcome by secular evolution processes. The gas in the inner disk is efficiently funneled by gravity torques down to r ~ 300 pc. Closer to the AGN, gas feels negative torques due to the combined action of the large-scale bar and the inner oval. The two m=2 modes act in concert to produce net gas inflow down to r ~ 50 pc, providing clear smoking gun evidence of inward gas transport on short dynamical timescales.”

What causes inward transport of gases? Why, a massive gravity pull of course. And what could be more gravitational attractive than a black hole! As Eliot Quataert (et al) indicated in their 1999 study:

“M81 and NGC 4579 are two of the few low-luminosity active galactic nuclei which have an estimated mass for the central black hole, detected hard X-ray emission, and detected optical/UV emission. In contrast to the canonical “big blue bump,” both have optical/UV spectra which decrease with increasing frequency in a plot. Barring significant reddening by dust and/or large errors in the black hole mass estimates, the optical/UV spectra of these systems require that the inner edge of a geometrically thin, optically thick, accretion disk lies at roughly 100 Schwarzschild radii. The observed X-ray radiation can be explained by an optically thin, two temperature, advection-dominated accretion flow at smaller radii.”

Galaxy NGC 4579 was captured by the Spitzer Infrared Nearby Galaxy Survey (SINGS) Legacy Project using the Spitzer Space Telescope’s Infrared Array Camera (IRAC). In this image, the red structures are areas where gas and dust are thought to be forming new stars, while the blue light comes from mature stars. This SINGS image is a four-channel, false-color composite, where blue indicates emission at 3.6 microns, green corresponds to 4.5 microns, and red to 5.8 and 8.0 microns. The contribution from starlight (measured at 3.6 microns) in this picture has been subtracted from the 5.8 and 8 micron images to enhance the visibility of the dust features.

Messier 58 (NGC 4579), as imaged by the Spitzer Infrared Nearby Galaxy Survey (SINGS) Legacy Project using the Spitzer Space Telescope’s Infrared Array Camera (IRAC). Credit: NASA/JPL-Caltech/R. Kennicutt (University of Arizona) and the SINGS Team

History of Observation:

When Charles Messier discovered this one on April 15, 1779, I’m sure he didn’t know he was looking back into time when he wrote:

“Very faint nebula discovered in Virgo, almost on the same parallel as Epsilon, 3rd mag. The slightest light for illuminating the micrometer wires makes it disappear. M. Messier reported it on the chart of the Comet of 1779, which is located in the volume of the Academy for the same year.”

Messier 58 may not have been a comet, but it certainly was another distant cousin of our own Milky Way!

Locating Messier 58:

Finding M58 requires a telescope or large binoculars, and lots of patience. Because the Virgo Galaxy field contains so many galaxies which can easily be misidentified, it is sometimes easier to “hop” from one galaxy to the next! In this case, we need to start by locating bright Vindemiatrix (Epsilon Virginis) almost due east of Denebola. Let’s hop four and a half degrees west and a shade north of Epsilon to locate one of the largest elliptical galaxies presently known – M60.

At a little brighter than magnitude 9, this galaxy could be spotted with binoculars, but stick with your telescope. In the same low power field (depending on aperture size) you may also note faint NGC 4647 which only appears to be interacting with M60. Also in the field to the west (the direction of drift) is our next Messier, bright cored elliptical M59. Now we will need to continue about an average eyepiece field of view, or a degree further west of this group to bring you to our “galactic twin”, fainter M58.

The location of M58, in the direction of the Virgo constellation. Credit: IAU

In a smaller telescope, do not expect to see much. What will appear at low power is a tiny egg-shaped patch of contrast change. As aperture increases, so does detail and a bright nucleus will begin to appear as you move into the 4-6″ size range and dark sky locations. As with all galaxies, dark skies are a must!

And here are the quick facts on this object to help you get started:

Object Name: Messier 58
Alternative Designations: M58, NGC 4579
Object Type: SBc Galaxy
Constellation: Virgo
Right Ascension: 12 : 37.7 (h:m)
Declination: +11 : 49 (deg:m)
Distance: 60000 (kly)
Visual Brightness: 9.7 (mag)
Apparent Dimension: 5.5×4.5 (arc min)

We have written many interesting articles about Messier Objects here at Universe Today. Here’s Tammy Plotner’s Introduction to the Messier ObjectsM1 – The Crab Nebula, and David Dickison’s articles on the 2013 and 2014 Messier Marathons.

Be to sure to check out our complete Messier Catalog. And for more information, check out the SEDS Messier Database.

Sources:

Scientists Find Evidence of Extreme Methane Storms On Titan

Titan's atmosphere makes Saturn's largest moon look like a fuzzy orange ball in this natural-color view from the Cassini spacecraft. Cassini captured this image in 2012. Image Credit: NASA/JPL-Caltech/Space Science Institute
According to a study from UCLA, Titan experiences severe methane rainstorms, leading to a the alluvial fans found found in both hemispheres. Credit: NASA/JPL-Caltech/Space Science Institute

Saturn’s largest moon, Titan, is a mysterious place; and the more we learn about it, the more surprises it seems to have in store. Aside from being the only body beyond Earth that has a dense, nitrogen-rich atmosphere, it also has methane lakes on its surface and methane clouds in its atmosphere. This hydrological-cycle, where methane is converted from a liquid to a gas and back again, is very similar to the water cycle here on Earth.

Thanks to the NASA/ESA Cassini-Huygens mission, which concluded on September 15th when the craft crashed into Saturn’s atmosphere, we have learned a great deal about this moon in recent years. The latest find, which was made by a team of UCLA planetary scientists and geologists, has to do with Titan’s methane rain storms. Despite being a rare occurrence, these rainstorms can apparently become rather extreme.

The study which details their findings, titled “Regional Patterns of Extreme Precipitation on Titan Consistent with Observed Alluvial Fan Distribution“, recently appeared in the scientific journal Nature Geoscience. Led by Saun P. Faulk, a graduate student at UCLA’s Department of Earth, Planetary, and Space Sciences, the team conducted simulations of Titan’s rainfall to determine how extreme weather events have shaped the moon’s surface.

Image of Titan’s atmosphere, snapped by the Cassini spacecraft. Credit: NASA/JPL/Space Science Institute

What they found was that the extreme methane rainstorms may imprint the moon’s icy surface in much the same way that extreme rainstorms shape Earth’s rocky surface. On Earth, intense rainstorms play an important role in geological evolution. When rainfall is heavy enough, storms can trigger large flows of water that transport sediment into low lands, where it forms cone-shaped features known as alluvial fans.

During it’s mission, the Cassini orbiter found evidence of similar features on Titan using its radar instrument, which suggested that Titan’s surface could be affected by intense rainfall. While these fans are a new discovery, scientists have been studying the surface of Titan ever since Cassini first reached the Saturn system in 2006. In that time, they have noted several interesting features.

These included the vast sand dunes that dominate Titan’s lower latitudes and the methane lakes and seas that dominate it’s higher latitudes – particularly around the  northern polar region. The seas – Kraken Mare, Ligeia Mare, and Punga Mare – measure hundreds of km across and up to several hundred meters deep, and are fed by branching, river-like channels. There are also many smaller, shallower lakes that have rounded edges and steep walls, and are generally found in flat areas.

In this case, the UCLA scientists found that the alluvial fans are predominantly located between 50 and 80 degrees latitude. This puts them close to the center of the northern and southern hemispheres, though slightly closer to the poles than the equator. To test how Titan’s own rainstorms could cause these features, the UCLA team relied on computer simulations of Titan’s hydrological cycle.

False-color mosaic of Titan’s northern lakes, made from infrared data collected by NASA’s Cassini spacecraft. Credit: NASA

What they found was that while rain mostly accumulates near the poles – where Titan’s major lakes and seas are located – the most intense rainstorms occur near 60 degrees latitude. This corresponds to the region where alluvial fans are most heavily concentrated, and indicates that when Titan does experience rainfall, it is quite extreme – like a seasonal monsoon-like downpour.

As Jonathan Mitchell – a UCLA associate professor of planetary science and a senior author of the study – indicated, this is not dissimilar to some extreme weather events that were recently experienced here on Earth. “The most intense methane storms in our climate model dump at least a foot of rain a day, which comes close to what we saw in Houston from Hurricane Harvey this summer,” he said.

The team also found that on Titan, methane rainstorms are rather rare, occurring less than once per Titan year – which works out to 29 and a half Earth years. But according to Mitchell, who is also the principal investigator of UCLA’s Titan climate modeling research group, this is more often than they were expecting. “I would have thought these would be once-a-millennium events, if even that,” he said. “So this is quite a surprise.”

In the past, climate models of Titan have suggested that liquid methane generally concentrates closer to the poles. But no previous study has investigated how precipitation might cause sediment transport and erosion, or shown how this would account for various features observed on the surface. As a result, this study also suggests that regional variations in surface features could be caused by regional variations in precipitation.

On top of that, this study is an indication that Earth and Titan have even more in common than previously thought. On Earth, contrasts in temperature are what lead to intense seasonal weather events. In North America, tornadoes occur during the early to late Spring, while blizzards occur during the winter. Meanwhile, temperature variations in the Atlantic ocean are what lead to hurricanes forming between the summer and fall.

Similarly, it appears that on Titan, serious variations in temperature and moisture are what triggers extreme weather. When cooler, wetter air from the higher latitudes interacts with warmer, drier air from the lower latitudes, intense rainstorms result. These findings are also significant when it comes to other bodies in our Solar System that  have alluvial fans on them – such as Mars.

In the end, understanding the relationship between precipitation and planetary surfaces could lead to new insights about the impact climate change has on Earth and the other planets. Such knowledge would also go a long way towards helping us mitigate the effects it is having here on Earth, where the changes are only unnatural, but also sudden and very hazardous.

And who knows? Someday, it could even help us to alter the environments on other planets and bodies, thus making them more suitable for long-term human settlement (aka. terraforming)!

Further Reading: UCLA, Nature