Vice President Mike Pence (holding Orion model) receives up close tour of NASA’s Orion EM-1 deep space crew capsule (at right) being manufactured for 1st integrated flight with NASA’s SLS megarocket in 2019; with briefing from KSC Director/astronaut Robert D. Cabana during his July 6, 2017 tour of NASA's Kennedy Space Center - along with acting NASA Administrator Robert M. Lightfoot, Jr., Senator Marco Rubio and Lockheed Martin CEO Marillyn Hewson inside the Neil Armstrong Operations and Checkout Building at KSC. Credit: Ken Kremer/kenkremer.com
Vice President Mike Pence (holding Orion model) receives up close tour of NASA’s Orion EM-1 deep space crew capsule (at right) being manufactured for 1st integrated flight with NASA’s SLS megarocket in 2019; with briefing from KSC Director/astronaut Robert D. Cabana during his July 6, tour of NASA’s Kennedy Space Center – along with acting NASA Administrator Robert M. Lightfoot, Jr., Senator Marco Rubio and Lockheed Martin CEO Marillyn Hewson inside the Neil Armstrong Operations and Checkout Building at KSC. Credit: Ken Kremer/kenkremer.com
KENNEDY SPACE CENTER, FL – Vice President Mike Pence, during a whirlwind visit to NASA’s Kennedy Space Center in Florida, vowed that America would fortify our leadership in space under the Trump Administration with impressive goals by forcefully stating that “our nation will return to the moon, and we will put American boots on the face of Mars.”
“American will once again lead in space for the benefit and security of all of our people and all of the world,” Vice President Mike Pence said during a speech on Thursday, July 6, addressing a huge crowd of more than 500 NASA officials and workers, government dignitaries and space industry leaders gathered inside the cavernous Vehicle Assembly Building at the Kennedy Space Center – where Apollo/Saturn Moon landing rockets and Space Shuttles were assembled for decades in the past and where NASA’s new Space Launch System (SLS) megarocket and Orion deep space crew capsule will be assembled for future human missions to the Moon, Mars and beyond.
Pence pronounced the bold space exploration goals and a reemphasis on NASA’s human spaceflight efforts from his new perch as Chairman of the newly reinstated National Space Council just established under an executive order signed by President Trump.
“We will re-orient America’s space program toward human space exploration and discovery for the benefit of the American people and all of the world.”
Vice President Mike Pence speaks before an audience of NASA leaders, U.S. and Florida government officials, and employees inside the Vehicle Assembly Building at NASA’s Kennedy Space Center in Florida. Pence thanked employees for advancing American leadership in space. Behind the podium is the Orion spacecraft flown on Exploration Flight test-1 in 2014. Credits: NASA/Kim Shiflett
However Pence was short on details and he did not announce any specific plans, timetables or funding during his 25 minute long speech inside the iconic VAB at KSC.
It remains to been seen how the rhetoric will turn to reality and all important funding support.
The Trump Administration actually cut their NASA 2018 budget request by $0.5 Billion to $19.1 Billion compared to the enacted 2017 NASA budget of $19.6 Billion – including cuts to SLS and Orion.
By contrast, the Republican led Congress – with bipartisan support – is working on a 2018 NASA budget of around 19.8 Billion.
“Let us do what our nation has always done since its very founding and beyond: We’ve pushed the boundaries on frontiers, not just of territory, but of knowledge. We’ve blazed new trails, and we’ve astonished the world as we’ve boldly grasped our future without fear.”
“From this ‘Bridge to Space,’ our nation will return to the moon, and we will put American boots on the face of Mars.” Pence declared.
Lined up behind Pence on the podium was the Orion spacecraft flown on Exploration Flight Test-1 (EFT-1) in 2014 flanked by a flown SpaceX cargo Dragon and a mockup of the Boeing CST-100 Starliner crew capsule.
The crewed Dragon and Starliner capsules are being developed by SpaceX and Boeing under NASA contracts as commercial crew vehicles to ferry astronauts to the International Space Station (ISS).
Pence reiterated the Trump Administrations support of the ISS and working with industry to cut the cost of access to space.
Vice President Mike Pence (holding Orion model) tours manufacturing of NASA’s Orion EM-1 crew capsule during July 6 KSC visit – posing with KSC Director/astronaut Robert Cabana, acting NASA Administrator Robert M. Lightfoot, Jr., Senator Marco Rubio, Lockheed Martin CEO Marillyn Hewson and KSC Deputy Director Janet Petro inside the Neil Armstrong Operations and Checkout Building. Credit: Julian Leek
Acting NASA Administrator Robert Lightfoot also welcomed Vice President Pence to KSC and thanked the Trump Administration for its strong support of NASA missions.
“Here, of all places, we can see we’re not looking at an ‘and/or proposition’,” Lightfoot said.
“We need government and commercial entities. We need large companies and small companies. We need international partners and our domestic suppliers. And we need academia to bring that innovation and excitement that they bring to the next workforce that we’re going to use to actually keep going further into space than we ever have before.”
View shows the state of assembly of NASA’s Orion EM-1 deep space crew capsule during inspection tour by Vice President Mike Pence on July 6, 2017 inside the Neil Armstrong Operations and Checkout Building at the Kennedy Space Center. 1st integrated flight with NASA’s SLS megarocket is slated for 2019. Credit: Ken Kremer/kenkremer.com
After the VAB speech, Pence went on an extensive up close inspection tour of KSC facilities led by Kennedy Space Center Director and former shuttle astronaut Robert Cabana, showcasing the SLS and Orion hardware and infrastructure critical for NASA’s plans to send humans on a ‘Journey to Mars’ by the 2030s.
“We are in a great position here at Kennedy, we made our vision a reality; it couldn’t have been done without the passion and energy of our workforce,” said Kennedy Space Center Director Cabana.
“Kennedy is fully established as a multi-user spaceport supporting both government and commercial partners in the space industry. As America’s premier multi-user spaceport, Kennedy continues to make history as it evolves, launching to low-Earth orbit and beyond.”
Vice President Mike Pence holds and inspects an Orion capsule heat shield tile with KSC Director/astronaut Robert Cabana during his July 6, 2017 tour/speech at NASA’s Kennedy Space Center – accompanied by acting NASA administrator Robert M. Lightfoot, Jr., Senator Marco Rubio and Lockheed Martin CEO Marillyn Hewson inside the Neil Armstrong Operations and Checkout Building at KSC. Credit: Ken Kremer/kenkremer.com
Pence toured the Neil Armstrong Operations and Checkout Building (O & C) where the Orion deep space capsule is being manufactured for launch in 2019 on the first integrated flight with SLS on the uncrewed EM-1 mission to the Moon and back – as I witnessed for Universe Today.
Vice President Mike Pence tours manufacturing of NASA’s Orion EM-1 crew capsule during July 6, 2017 KSC visit with KSC Director/astronaut Robert Cabana inside the Neil Armstrong Operations and Checkout Building. Credit: Julian Leek
Watch for Ken’s onsite 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.
Orion crew module pressure vessel for NASA’s Exploration Mission-1 (EM-1) is unveiled for the first time on Feb. 3, 2016 after arrival at the agency’s Kennedy Space Center (KSC) in Florida. It is secured for processing in a test stand called the birdcage in the high bay inside the Neil Armstrong Operations and Checkout (O&C) Building at KSC. Launch to the Moon is slated in 2019 atop the SLS rocket. Credit: Ken Kremer/kenkremer.comNASA’s Space Launch System (SLS) blasts off from launch pad 39B at the Kennedy Space Center in this artist rendering showing a view of the liftoff of the Block 1 70-metric-ton (77-ton) crew vehicle configuration. Credit: NASA/MSFC
An artist's conception of a hypervelocity star that has escaped the Milky Way. Credit: NASA
In 2013, the European Space Agency launched the Gaia spacecraft. As the successor to the Hipparcos mission, this space observatory has spent the past three and a half years gathering data on the cosmos. Before it retires sometime next year (though the mission could be extended), this information will be used to construct the largest and most precise 3D astronomical map ever created.
In the course of surveying the cosmos, Gaia has also revealed some very interesting things along the way. For example, after examining the Gaia catalog with a specially-designed artificial neural network, a team of European researchers recently detected six new hypervelocity stars in the Milky Way. And one of these stars is moving so fast that it may eventually leave our galaxy.
Artist’s conception of the Gaia telescope backdropped by a photograph of the Milky Way taken at the European Southern Observatory. Credit: ESA/ATG medialab; background: ESO/S. Brunier
Hypervelocity stars are a rare and fascinating thing. Whereas all stars in the Milky Way are in constant motion, orbiting around the center of our galaxy, some are accelerated to speeds of up to hundreds of kilometers per second. In the past, astronomers have deduced that these fast-moving stars are the result of a close stellar encounter or a supernova explosion of a stellar companion.
And a little over a decade ago, astronomers became aware of a new class of high-speed stars that are believed to have been accelerated from past interactions with the supermassive black hole (Sagittarius A*) that sits at the center of our galaxy. These stars are extremely important to the study of the overall structure of the Milky Way, as they are indicative of the kinds of events and forces that have shaped its history.
As Elena Maria Rossi, from Leiden University in the Netherlands and one of the co-authors on the paper, explained in an ESA press release:
“These are stars that have traveled great distances through the Galaxy but can be traced back to its core – an area so dense and obscured by interstellar gas and dust that it is normally very difficult to observe – so they yield crucial information about the gravitational field of the Milky Way from the centre to its outskirts.“
Artist’s impression of stars speeding through the Galaxy. Credit: ESA
Finding such stars is no easy task, mainly because their velocity makes them extremely difficult to spot in the vast and crowded disk of the Milky Way. As a result, scientists have relied on looking for young, massive stars (2.5 to 4 Solar masses) in the old stellar population of the Galactic. Basically, their young age and high masses are indications that they might not have originated there.
Combined with measurements of their past speeds and paths, this method has confirmed the existence of hypervelocity stars in the past. However, only 20 hypervelocity stars have been spotted to date, and they have all been young and massive in nature. Scientists believe that many more stars of other ages and masses are also being accelerated through the Milky Way, but were previously unable to spot them.
To address this, the European team – led by from Tomasso Marchetti of Leiden University in the Netherlands – began considering how to use Gaia‘s vast dataset to optimize the search for more hypervelocity stars. After testing various methods, they adopted the artificial neural net approach – i.e. using a machine learning algorithm – to search through the star census data Gaia is in the process of gathering.
Beginning in the first half of 2016, the team began developing and training this program to be ready for the first release of Gaia data – which occurred a few months later on Sept. 14th, 2016. As Tommaso Marchetti, a PhD student at Leiden University, described the process:
“In the end, we chose to use an artificial neural network, which is software designed to mimic how our brain works. After proper ‘training’, it can learn how to recognize certain objects or patterns in a huge dataset. In our case, we taught it to spot hypervelocity stars in a stellar catalogue like the one compiled with Gaia.”
Artist’s impression of a hypervelocity star that was detected using the ESO’s Very Large Telescope. Credit: ESO
In addition to a map with the positions of over a billion stars, this first data release included a smaller catalogue with the distances and motions for two million stars. This catalog – which is known as the Tycho-Gaia Astrometric Solution (TGAS) – combined data from both the first year of the Gaia mission and with data from the Hipparcos mission, and is essentially a taste of what’s to come from Gaia.
On the day of the catalog’s release, Marchetti and his team ran their algorithm on the two million stars within the TGAS, which revealed some interesting finds. “In just one hour, the artificial brain had already reduced the dataset to some 20 000 potential high-speed stars, reducing its size to about 1%,” said Rossi. “A further selection including only measurements above a certain precision in distance and motion brought this down to 80 candidate stars.”
The team then examined these 80 stars in more detail, and compared the information about their motions to data from other catalogues. Paired with additional observations, they eventually found six stars which appeared to be moving faster than 360 km/s. One even appeared to be exceeding 500 km/s, which means that it is no longer bound by the gravity of our Milky Way and will eventually leave it altogether.
But perhaps the sot significant aspect of this find is the fact these stars are not particularly massive like the previous 20 that had been discovered, and were comparable in mass to our Sun. In addition, the 5 slower stars are likely to become a focal point of study, as scientists are eager to determine what slowed them down. One possible explanation is that interaction with the galaxy’s dark matter might have been responsible.
Gaia’s first sky map. Credit: ESA/Gaia/DPAC. Credit: A. Moitinho & M. Barros (CENTRA – University of Lisbon), on behalf of DPAC.
Much as the TGAS has been merely an early indication of the vast and valuable data Gaia will eventually provide, this study showcases the kinds of discoveries and research that this data will enable. By with not just 2 million, but a billion stars to study, astronomers are sure to reveal many new and exciting things about the dynamics of our Milky Way and the kinds of forces that have shaped it.
For this purpose, Marchetti and his team are upgrading their program to handle the much larger data set, which is scheduled to be released in April of 2018. This catalog will include distance and motions for over a billion stars, as well as velocities for a specific subset. From this, the team may find that fast-moving stars which are being booted out of the Milky Way are a lot more common than previously thought.
And be sure to enjoy this video that shows the paths of these six newly-discovered fast-moving stars, courtesy of the ESA:
Welcome to another edition of Constellation Friday! Today, in honor of the late and great Tammy Plotner, we take a look at the “Raven” – the Corvus constellation. Enjoy!
In the 2nd century CE, Greek-Egyptian astronomer Claudius Ptolemaeus (aka. Ptolemy) compiled a list of all the then-known 48 constellations. This treatise, known as the Almagest, would be used by medieval European and Islamic scholars for over a thousand years to come, effectively becoming astrological and astronomical canon until the early Modern Age.
One of these constellation is the Corvus constellation, a southern constellation whose name in Latin means “the Raven”. Bordered by the constellations of Virgo, Crater and Hydra, it is visible at latitudes between +60° and -90° and is best seen at culmination during the month of May. Today, it is one of the 88 modern constellations recognized by the International Astronomical Union (IAU).
Name and Meaning:
In classical mythology, Corvus represents the Raven, and is both a charming and sad tale. Legend tells us that the constellation of Crater is the cup of the gods. This cup belonged to the god of the skies himself, the venerable archer-god Apollo. And who holds this cup, dressed in black? The Raven, Corvus.
“Noctua, Corvus, Crater, Sextans Uraniæ, Hydra, Felis, Lupus, Centaurus, Antlia Pneumatica, Argo Navis, and Pyxis Nautica”, plate 32 in Urania’s Mirror, by Sidney Hall. Credit: Library of Congress
The story of a creature sent to fetch water for his master, only to stop to eat figs. Corvus tarried too long, waiting on a fig to ripen. When he realized his mistake, the Raven returned to Apollo with his cup and brought along the serpent Hydra in his claws as well, claiming that the snake prevented him from filling the cup.
Realizing his feathered-friend’s lie, Apollo became angry and tossed the cup (Crater), the snake (Hydra) and the raven (Corvus) into the sky, where they became constellations for all eternity. He further punished the raven by making sure the cup would be out of reach, thus ensuring he would forever be thirsty.
History of Observation:
As with most of the 48 constellations recorded by Ptolemy, the Corvus constellation has roots that go back to ancient Mesopotamia. In the Babylonian star catalogues (dated to ca. 1100 BCE), Corvus was called the Babylonian Raven (MUL.UGA.MUSHEN), which sat on the tail of the Serpent – which was associated with Ningishzida, the Babylonian god of the underworld. This constellation was also sacred to the god of rains and storm (Adad).
By about 500 BCE, this constellation was introduced to the Greeks, along with Crater, Hydra, Aquila and Piscis Austrinus constellations. By the 2nd century CE, they were included by Ptolemy in his Almagest, which would remain the definitive source on astronomy and astrology to Medieval European and Islamic astronomers for many centuries.
In Chinese astronomy, the stars that make up Corvus are located within the Vermilion Bird of the South (Nán Fang Zhu Què). The four main stars depict a chariot (Zhen) while Alpha and Eta mark the linchpins for the wheels, and Zeta represents a coffin (Changsha).
In Indian astronomy, the first five stars in Corvus correspond to the Hast nakshatra – a lunar zodiacal constellation. This is one of is one of the 27 or 28 divisions of the sky, identified by the prominent stars in them, that the Moon passes through during its monthly cycle. While it is Hindu, it is still very similar to the divisions of the ecliptic plane referred to as the zodiac. The Moon takes approximately one day to pass through each nakshatra.
Notable Objects:
This small, box-like asterism has no bright star and consists of 11 stars which are visible to the unaided eye, yet Ptolemy only listed 7! There are 4 main stars and 10 which have Bayer/Flamsteed designations. For unaided eye observers, the Delta, Gamma, Epsilon and Beta (what appears to look like a figure 8, Y, E and B on the map) form an asterism that looks like a “sail”, and when connected seem to point to the bright star Spica.
The brightest star in Corvus is not even its alpha, but is Gamma Corvi. This giant star (which is thought to be a binary system) is located approximately 165 light years from Earth and is also known as Gienah, which comes from the Arabic phrase al-janah al-ghirab al-yaman (“the right wing of the crow”).
Antennae Galaxies – NGC 4038, NGC 4039. Credit: NASA, ESA, and the Hubble Heritage Team (STScI, AURA)-ESA, Hubble Collaboration
The second-brightest star, Beta Corvi, is a yellow-white G-type bright giant that is located about 140 light years from Earth. Its proper name, Kraz, was assigned to it in modern times, but the origin of the name is uncertain. Delta Corvi is a class A0 star in Corvus located approximately 87 light years distant from Earth whose traditional name (Algorab) comes from the Arabic word al-ghuraab – which means “the crow.”
Epsilon Corvi is a K2 III class star that is approximately 303 light-years from Earth. The star’s traditional name, (Minkar) comes from the Arabic word almánxar, which means “the nostril of the crow.” Alpha Corvi, which is only the fifth brightest star in the constellation, is a class F0 dwarf or subdwarf that is only 48.2 light years distant. The star’s traditional name (Alchiba) is derived from the Arabic al hibaa, which means “tent.”
Corvus is also home to many Deep Sky Objects. These include the Antennae Galaxies (NGC 4038/NGC 4039), a pair of interacting galaxies that were first discovered in the late 18th century. These colliding galaxies – which are located 45 million light years from Earth – are currently in the starburst stage, meaning they are experiencing an exceptionally high rate of star forming activity.
There’s also the NGC 4027 barred spiral galaxy, which is located about 83 million light years from Earth. This galaxy is peculiar, in that one of its spiral arm extends further than the other – possibly due to a past collision with another galaxy. Finally, there’s the large planetary nebula known as NGC 4361, which is located at the center of the constellation and resembled a faint elliptical galaxy.
The barred, spiral galaxy known as NGC 4027. Credit : ESO
Finding Corvus:
Let’s start with binoculars and look down at the southern corner, where we will find Alpha Corvi – aka. Alchiba. Alchiba belongs to the spectral class F0 and has apparent magnitude +4.00. This star is suspected of being a spectroscopic binary, although this has not yet been confirmed. Now take a look at Beta Corvi – aka. Kraz. Good old Kraz is approximately 140 light-years away and is a G-type bright giant star whose apparent visual magnitude varies between 2.60 and 2.66.
Head west and look at Epsilon. Although it doesn’t look any further away, spectral class K2 III – Minkar – is 303 light-years from Earth! Need a smile? Then take a look at Gamma, aka. Geinah. How about Delta? Algorab is a spectral class A0 and is about 87 light years from our solar system.
Now get out your telescope as we explore planetary nebula, NGC 4361 (RA 12 24 5 Dec -18 48). At around magnitude 10, this greenish disc is fairly easily spotted with smaller telescopes, but the 13th stellar magnitude central star requires larger aperture to be seen. It has a very symmetrical shape that is similar to a spiral galaxy.
For galaxy fans, have a look at interacting galaxy pair, NGC 4038 and NGC 4039 – the “Ringtail Galaxy” (RA 12 01 53 Dec -18 52-3). This peculiar galaxy (also referred to as the “Antennae Galaxies”) were both discovered by Friedrich Wilhelm Herschel in 1785. Even in relatively small telescopes, you can see two long tails of stars, gas and dust thrown out of the galaxies as a result of the collision that resemble the antennae of an insect.
Map of the Corvus Constellation. Credit: IAU and Sky&Telescope magazine
“The morphology of this object is complex given the highly filamentary structure of the envelope, which is confirmed to possess a low mass. The halo has a high expansion velocity that yields incompatible kinematic and evolutionary ages, unless previous acceleration of the nebular expansion is considered. However, the most remarkable result from the present observations is the detection of a bipolar outflow in NGC 4361, which is unexpected in a PN with a Population II low-mass-core progenitor. It is shown that shocks resulting from the interaction of the bipolar outflow with the outer shell are able to provide an additional heating source in this nebula.”
Most galaxies probably undergo at least one significant collision in their lifetimes. This is likely the future of our Milky Way when it collides with the Andromeda Galaxy. Two supernovae have been discovered in the galaxy: SN 2004GT and SN 2007sr. A recent study finds that these interacting galaxies are closer to the Milky Way than previously thought – at 45 million light-years instead of 65 million light-years. Geez… What’s 20 million light years between friends?
A new study has revealed that Titan's methane lakes could be calm enough for future missions to land there. Credit: bisbos.com
Ever since the Cassini orbiter and the Huygens lander provided us with the first detailed glimpse of Saturn’s moon Titan, scientists have been eager to mount new missions to this mysterious moon. Between its hydrocarbon lakes, its surface dunes, its incredibly dense atmosphere, and the possibility of it having an interior ocean, there is no shortage of things that are worthy of research.
The only question is, what form would this mission take (i.e. aerial drone, submarine, balloon, lander) and where should it set down? According to a new study led by the University of Texas at Austin, Titan’s methane lakes are very calm and do not appear to experience high waves. As such, these seas may be the ideal place for future missions to set down on the moon.
Titan’s three largest lakes and their surrounding areas as seen by the Cassini RADAR instrument. The researchers used the instrument to study waves on the lake surfaces. Credit: Cyril Grima/ The University of Texas at Austin
As Grima explained in a University of Texas press release, this research also shed light on the meteorological activity on Titan:
“There’s a lot of interest in one day sending probes to the lakes, and when that’s done, you want to have a safe landing, and you don’t want a lot of wind. Our study shows that because the waves aren’t very high, the winds are likely low.”
Towards this end, Grima and his colleagues examined radar data obtained by the Cassini mission during Titan’s early summer season. This consisted of measurements of Titan’s northern lakes, which included Ontario Lacus, Ligeia Mare, Punga Mare, and Kraken Mare. The largest of the three, Kraken Mars, is estimated to be larger than the Caspian Sea – i.e. 4,000,000 km² (1,544,409 mi²) vs 3,626,000 km2 (1,400,000 mi²).
With the help of the Cassini RADAR Team and researchers from Cornell University, the Johns Hopkins University Applied Physics Laboratory (JHUAPL), NASA’s Jet Propulsion Laboratory (JPL) and elsewhere, the team applied a technique known as radar statistical reconnaissance. Developed by Grima, this technique relies on radar data to measure the roughness of surfaces in minute detail.
This technique has also been used to measure snow density and the surface roughness of ice in Antarctica and the Arctic. Similarly, NASA has used the technique for the sake of selecting a landing site on Mars for their Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (Insight) lander, which is scheduled to launch next year.
The left image shows a mosaic of images of Titan taken by the Cassini spacecraft in near infrared light. Titan’s polar seas are visible as sunlight glints off of them. The right image is a radar image of Kraken Mare. Credit: NASA Jet Propulsion Laboratory.
From this, Grima and his colleagues determined that waves on these lakes are quite small, reaching only 1 cm in height and 20 cm in length. These findings indicate that these lakes would be a serene enough environment that future probes could make soft landings on them and then begin the task of exploring the surface of the moon. As with all bodies, waves on Titan could be wind-driven, triggered by tidal flows, or the result of rain or debris.
As a result, these results are calling into question what scientists think about seasonal change on Titan. In the past, it was believed that summer on Titan was the beginning of moon’s windy season. But if this were the case, the results would have indicated higher waves (the result of higher winds). As Alex Hayes, an assistant professor of astronomy at Cornell University and a co-author on the study, explained:
“Cyril’s work is an independent measure of sea roughness and helps to constrain the size and nature of any wind waves. From the results, it looks like we are right near the threshold for wave generation, where patches of the sea are smooth and patches are rough.”
These results are also exciting for scientists who are hoping to plot future missions to Titan, especially by those who are hoping to see a robotic submarine sent to Titan’s to investigate its lakes for possible signs of life. Other mission concepts involve exploring Titan’s interior ocean, its surface, and its atmosphere for the sake of learning more about the moon’s environment, its organic-rich environment and probiotic chemistry.
And who knows? Maybe, just maybe, these missions will find that life in our Solar System is more exotic than we give it credit before, going beyond the carbon-based life that we are familiar with to include the methanogenic.
Observers Kai Getrost and Alex Parker wait to collect 2014 MU69 stellar occultation data in Argentina on June 3, 2017. Several New Horizons team members and collaborators will return to the country on July 17 for this summer's third and final MU69 occultation observation opportunity. (Image credit: Kai Getrost, via NASA)
While the New Horizons spacecraft was heading to Pluto, scientists from the mission used Hubble and other telescopes to try and find out more about the environment their spacecraft would be flying through. No one wanted New Horizons to run into unexpected dust or debris.
And now, as New Horizons prepares to fly past its next target, the Kuiper Belt Object known as 2014 MU69, mission scientists are using every tool at their disposal to examine this object and the surrounding region. The flyby will take place on January 1, 2019.
They’ve already uncovered some surprises.
On June 3, 2017, 2014 MU69 passed in front of a star – in an event called an occultation – providing a two-second glimpse of the object’s shadow.
A diagram of an occultation event, via the International Occultation Timing Association.
More than 50 mission team members and collaborators traveled to South Africa and Argentina to catch the occultation, setting up telescopes to capture the event. They are now looking through more than 100,000 images of the occultation star that can be used to assess the environment around this Kuiper Belt object (KBO). In addition, the Hubble Space Telescope and Gaia, a space observatory of the European Space Agency (ESA) also observed the event.
The team said that while MU69 itself eluded direct detection, the June 3 data provided valuable and unexpected insights that have already helped New Horizons.
“These results are telling us something really interesting,” said New Horizons Principal Investigator Alan Stern, of the Southwest Research Institute. “The fact that we accomplished the occultation observations from every planned observing site but didn’t detect the object itself likely means that either MU69 is highly reflective and smaller than some expected, or it may be a binary or even a swarm of smaller bodies left from the time when the planets in our solar system formed.”
Mission scientist Simon Porter said on Twitter, “The upshot is that MU69 is probably not as big and dark as it could have been, and (more importantly) doesn’t seem to have rings or a dust cloud,” adding later that the “lack of dust was reassuring.”
Again, no one wants to New Horizons to run into any surprising dust or debris.
The team will be observing two more occultation events on July 10 and July 17, and Porter said they should get even better constraints from these next two events.
Projected path of the 2014 MU69 occultation shadow, on July 10 (left) and July 17, 2017. Credit: Larry Wasserman/Lowell Observatory, via NASA.
On July 10, NASA’s airborne Stratospheric Observatory for Infrared Astronomy (SOFIA) will use its 100-inch (2.5-meter) telescope to probe the space around MU69 for debris that might present a hazard to New Horizons as it flies by in 18 months.
On July 17, the Hubble Space Telescope also will check for debris around MU69, while team members set up another ground-based “fence line” of small mobile telescopes along the predicted ground track of the occultation shadow in southern Argentina to try to better constrain, or even determine, the size of MU69.
Initial estimates of MU69’s diameter, based primarily on data taken by the Hubble Space Telescope since the KBO’s discovery in 2014, fall in the 12-25-mile (20-40-kilometer) range. However, the latest data from the June occultation seem to imply it’s at or even below the smallest estimated sizes.
“2014 MU69 is a great choice because it is just the kind of ancient KBO, formed where it orbits now, that the Decadal Survey desired us to fly by,” Stern said back in August 2015 when the target was announced. “Moreover, this KBO costs less fuel to reach [than other candidate targets], leaving more fuel for the flyby, for ancillary science, and greater fuel reserves to protect against the unforeseen.”
You can see the star brightness, predicted shadow path and other tech specs for the July 10 and July 17 occultation events at the embedded links.
SpaceX Falcon 9 blasts off with Intelsat 35e - 4th next gen ‘Epic’ comsat for Intelsat - on July 5, 2017 at 7:37 p.m. EDT from Launch Complex 39A at NASA's Kennedy Space Center in Florida. Credit: Ken Kremer/kenkremer.com
SpaceX Falcon 9 blasts off with Intelsat 35e – 4th next gen ‘Epic’ comsat for Intelsat – on July 5, 2017 at 7:37 p.m. EDT from Launch Complex 39A at NASA’s Kennedy Space Center in Florida. Credit: Ken Kremer/kenkremer.com
The SpaceX Falcon 9 put on a dazzling near dusk display as it roared off historic launch pad 39A on SpaceX’s tenth launch of 2017 Wednesday evening into brilliant blue skies with scarcely a cloud to be seen and delightfully summer weather conditions.
Blastoff of the Falcon 9 carrying the Intelsat 35e communications satellite for commercial high speed broadband provider Intelsat occurred right on time at dinnertime July 5 at 7:38 p.m. EDT, or 2338 UTC from SpaceX’s seaside Launch Complex 39A on NASA’s Kennedy Space Center in Florida.
The thunderous blastoff wowed hordes of spectators gathered along space coast beaches and causeways and local residential neighborhoods from came across the globe to witness and the launch spectacle and many of whom will be users of and benefit from the services offered by Intelsat 35e.
“Tens of millions of customers will be served and be touched by Intelsat 35e,” Intelsat VP for Sales & Marketing Kurt Riegel, told Universe Today in an exclusive interview beside the iconic countdown clock at NASA’s Kennedy Space Center Florida press site.
Launch of expendable SpaceX Falcon 9 with 4th next gen ‘Epic’ DTH comsat for Intelsat at 7:37 p.m. EDT on July 5, 2017 from Launch Complex 39A at NASA’s Kennedy Space Center in Florida – as seen from the countdown clock. Credit: Ken Kremer/kenkremer.com
Wednesday’s liftoff finally took place safely after back to back last moment scrubs on Sunday and Monday (July 2/3) kept Falcon 9 from igniting its engine for the delayed journey to orbit.
Elon Musk told the SpaceX launch and engineering team to stand down over the 4th of July holiday and instead thoroughly investigate the root cause of the pait of launch aborts.
The near scrubs resulted from insidious anomaly not detected after the initial launch abort on Sunday, July 2.
SpaceX Falcon 9 launch of with ‘Epic’ comsat for Intelsat at 7:38 p.m. EDT on July 5, 2017 from Launch Complex 39A at NASA’s Kennedy Space Center in Florida. Credit: Julian Leek
Intelsat 35e will be utilized by copious public, government and commercial clients throughout the Americas, Europe and Africa.
The 23 story tall Falcon 9 lofted Intelsat’s commercial Epic 35e next-generation high throughput satellite to geostationary transfer orbit.
It separated from the Falcon 9 upper stage as planned about a half hour after liftoff.
“The Intelsat 35e satellite separated from the rocket’s upper stage 32 minutes after launch, at 8:10 pm EDT, and signal acquisition has been confirmed,” Intelsat announced post launch..
“This was the SpaceX’s first satellite launch contracted by Intelsat,” Ken Lee, Intelsat’s senior vice president of space systems, told Universe Today in a prelaunch interview on Sunday.
“Intelsat 35e is the fourth in the series of our ‘Epic’ satellites. It will provide the most advanced digital services ever and a global footprint.”
SpaceX Falcon 9 blasts off with Intelsat 35e – 4th next gen ‘Epic’ TV and mobile broadband comsat for Intelsat – on July 5, 2017 at 7:38 p.m. EDT from Launch Complex 39A at NASA’s Kennedy Space Center in Florida. Credit: Ken Kremer/kenkremer.com
SpaceX has now safely and successfully demonstrated an amazing launch pace with 3 rockets propelled aloft in the span of just 12 days from both US coasts. Had Intelsat 35e been launched on Sunday, July 3, it would have established and even faster record pace of 3 launches in just 9 days.
“The successful launch of Intelsat 35e is a major milestone in our business plan for 2017, furthering the footprint and resilience of our Intelsat EpicNG infrastructure,” said Stephen Spengler, Chief Executive Officer, Intelsat, in a statement.
“With each Intelsat EpicNG launch, we advance our vision of creating a global, high performance for our customers that will unlock new growth opportunities in applications including mobility, wireless infrastructure and private data networks. As we further our innovations with respect to ground infrastructure and managed service offerings, like IntelsatOne Flex, we are transforming the role of satellite in the telecommunications landscape.”
Launch of expendable SpaceX Falcon 9 with 4th next gen ‘Epic’ DTH comsat for Intelsat at 7:38 p.m. EDT on July 5, 2017 from Launch Complex 39A at NASA’s Kennedy Space Center in Florida – as seen from the KSC press site. Credit: Ken Kremer/kenkremer.com
The geostationary comsat will provide high performance services in the C- And Ku-bands to customers in North and South America, the Caribbean, as well as the continents of Europe and Africa.
The Ku band service includes a customized high power beam for direct-to-home television (DTH) and data communications services in the Caribbean as well as mobility services in Europe and Africa
The first stage was not recovered for this launch because the massive 6800 kg (13000 lb) Intelsat 35e comsat requires every drop of fuel to get to the desired orbit.
Intelsat 35e marks the tenth SpaceX launch of 2017 – establishing a new single year launch record for SpaceX.
The recent BulgariaSat-1 and Iridium-2 missions counted as the eighth and ninth SpaceX launches of 2017.
Including those last two ocean platform landings, SpaceX has now successfully recovered 13 boosters; 5 by land and 8 by sea, over the past 18 months.
Expendable SpaceX Falcon 9 is seen rising to launch position in this up close view of payload fairing encapsulating Intelsat 35e comsat and is now erected to launch position and poised for liftoff on July 5, 2017 at Launch Complex 39A at NASA’s Kennedy Space Center in Florida. Credit: Ken Kremer/kenkremer.com
Watch for Ken’s onsite Intelsat 35e 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.
Intelsat reps Kurt Riegel, Sr VP Intelsat Sales (c), and Diane VanBeber, VP Intelsat investor relations (l), speak to Ken Kremer/Universe Today (r) about Intelsat35e launch on SpaceX Falcon 9 beside the countdown clock at the Kennedy Space Center Press Site in Florida. Credit: Ken Kremer/kenkremer.com Never used SpaceX Falcon 9 is seen rising to launch position and now stands erect and poised for liftoff Intelsat 35e on July 3, 2017 at Launch Complex 39A at NASA’s Kennedy Space Center in Florida. Credit: Ken Kremer/kenkremer.comArtists concept of Intelsat 35e in geostationary Earth orbit. Credit: IntelsatSpaceX Falcon 9 is poised for liftoff with Intelsat 35e – 4th next gen ‘Epic’ comsat on July 5, 2017 at Launch Complex 39A at NASA’s Kennedy Space Center in Florida. Credit: Ken Kremer/kenkremer.com
An artist's illustration of Pluto. Credit: NASA/New Horizons
Once held to be the outermost planet of the Solar System, Pluto‘s designation was changed by the International Astronomical Union in 2006, owing to the discovery of many new Kuiper Belt Objects that were comparable in size. In spite of this, Pluto remains a source of fascination and a focal point of much scientific interest. And even after the historic flyby conducted by the New Horizons probe in July of 2015, many mysteries remain.
What’s more, ongoing analysis of the NH data has revealed new mysteries. For instance, a recent study by a team of astronomers indicated that a survey by the Chandra X-ray Observatory revealed the presence of some rather strong x-rays emissions coming from Pluto. This was unexpected, and is causing scientists to rethink what they thought they knew about Pluto’s atmosphere and its interaction with solar wind.
In the past, many Solar bodies have been observed emitting x-rays, which were the result of interaction between solar wind and neutral gases (like argon and nitrogen). Such emissions have been detected from planets like Venus and Mars (due to the presence of argon and/or nitrogen in their atmospheres), but also with smaller bodies like comets – which acquire halos due to outgassing.
Artist’s impression of New Horizons’ close encounter with the Pluto–Charon system. Credit: NASA/JHU APL/SwRI/Steve Gribben
Ever since the NH probe conducted its flyby of Pluto in 2015, astronomers have been aware that Pluto has an atmosphere which changes size and density with the seasons. Basically, as the planet reaches perihelion during its 248 year orbital period – a distance of 4,436,820,000 km, 2,756,912,133 mi from the Sun – the atmosphere thickens due to the sublimation of frozen nitrogen and methane on the surface.
The last time Pluto was at perihelion was on September 5th, 1989, which means that it was still experiencing summer when NH made its flyby. While studying Pluto, the probe detected an atmosphere that was primarily composed of nitrogen gas (N²) along with methane (CH4) and carbon dioxide (CO²). Astronomers therefore decided to look for signs of x-ray emissions coming from Pluto’s atmosphere using the Chandra X-ray Observatory.
Prior to the NH mission’s flyby, most models of Pluto’s atmosphere expected it to be quite extended. However, the probe found that the atmosphere was less extended and that its rate of loss was hundreds of times lower than what these models predicted. Therefore, as the team indicated in their study, they expected to find x-ray emissions that were consistent with what the NH flyby observed:
“Given that most pre-encounter models of Pluto’s atmosphere had predicted it to be much more extended, with an estimated loss rate to space of ~1027 to 1028 mol/sec of N² and CH4… we attempted to detect X-ray emission created by [solar wind] neutral gas charge exchange interactions in the low density neutral gas surrounding Pluto,” they wrote.
Images sent by NASA’s New Horizons spacecraft show possible clouds floating over the frozen landscape including the streaky patch at right. Credit: NASA/JHUAPL/SwR
However, after consulting data from the Advanced CCD Imaging Spectrometer (ACIS) aboard Chandra, they found that x-ray emissions coming from Pluto were greater than what this would allow for. In some cases, strong x-ray emissions have been noted coming from other smaller objects in the Solar System, which is due to the scattering of solar x-rays by small dust grains composed of carbon, nitrogen and oxygen.
But the energy distribution they noted with Pluto’s x-rays were not consistent with this explanation. Another possibility that the team offered is that they could be due to some process (or processes) that focus the solar wind near Pluto, which would enhance the effect of its modest atmosphere. As they indicate in their conclusions:
“The observed emission from Pluto is not aurorally driven. If due to scattering, it would have to be sourced by a unique population of nanoscale haze grains composed of C, N, and O atoms in Pluto’s atmosphere resonantly fluorescing under the Sun’s insolation. If driven by charge exchange between [solar wind] minor ions and neutral gas species (mainly CH4) escaping from Pluto, then density enhancement and adjustment of the [solar wind] minor ion relative abundance in the interaction region near Pluto is required versus naïve models.”
For the time being, the true cause of these x-ray emissions is likely to remain a mystery. They also highlight the need for more research when it comes to this distant and most massive of Kuiper Belt Objects. Luckily, the data provided by the NH mission is likely to be poured over for decades, revealing new and interesting things about Pluto, the outer Solar System, and how the most distant worlds from our Sun behave.
The Managed, Reconfigurable, In-space Nodal Assembly (MARINA), developed by MIT graduate students, is designed as a habitable commercially owned module for use in low Earth orbit. Credit: MIT/MARINA team
Looking to the future of space exploration, there really is no question that it will involve a growing human presence in Low Earth Orbit (LEO). This will include not only successors to the International Space Station, but most likely commercial habitats and facilities. These will not only allow for ventures like space tourism, but will also facilitate missions that take us back to the Moon, to Mars, and even beyond.
With this purpose in mind, an interdisciplinary team of MIT graduate students designed a space habitat known as the Managed, Reconfigurable, In-space Nodal Assembly (MARINA). This module would serve as an privately-owned space station that would be occupied by two anchor-tenants for a period of ten years; a luxury hotel that would provide orbital accommodations, and NASA.
For their invention, the team won first prize in the graduate division of the Revolutionary Aerospace Systems Concepts-Academic Linkage Design Competition Forum (RASC-AL), a yearlong graduate-level competition hosted by NASA. This challenge involved designing a commercial module for use in low Earth orbit that could also serve as a Mars transit vehicle in the future.
In the future, LEO will become home to commercial modules (like the Bigelow Aerospace B330 expandable module, shown here), will become a reality. Credit: Bigelow Aerospace
Since 2002, RASC-AL competitions have sought to engage university students and advisors for the purpose of coming up with ideas that could enhancing future NASA missions. For this year’s competition, NASA asked teams to develop human spaceflight concepts that focused on operations in cislunar space – i.e. in, around, and beyond the Moon – that could also facilitate their proposed “Journey to Mars” by the 2030s.
Specifically, they were tasked with finding ways to leverage innovations and new technologies to improve humanity’s ability to work more effectively in microgravity. With this in mind, the themes for this year’s competition ranged from from the design of more efficient subsystems to the development of architectures that support NASA’s goal of extending humanity’s reach into space.
These included new designs for a Lightweight Exercise Suite, Airlock Design, concepts for a Commercially Enabled LEO/Mars Habitable Module, and concepts for a new Logistics Delivery System. As Pat Troutman, the Human Exploration Strategic Analysis lead at NASA’s Langley Research Center, said in a NASA press statement:
“We are carefully examining what it will take to establish a presence beyond low-Earth orbit, where astronauts will build and begin testing the systems needed for challenging missions to distant destinations, including Mars. The 2017 RASC-AL university teams have developed exciting concepts with supporting engineering analysis that may influence how future deep space infrastructure will look and operate.”
Members of the MIT team (from left to right): Caitlin Mueller (faculty advisor), Matthew Moraguez, George Lordos, and Valentina Sumini. Credit: MIT/MARINA team
Led by Matthew Moraguez, a graduate student at MIT’s Department of Aeronautics and Astronautics (AeroAstro) and a member of the Strategic Engineering Research Group (SERG), the MIT team focused on the theme of creating a Commercially Enabled LEO Habitat Module. Their concept, which incorporates lessons that have been learned from the ISS, was designed with the needs of both the private and public space sectors in mind.
“Just like a yacht marina, MARINA can provide all essential services, including safe harbor, reliable power, clean water and air, and efficient logistics and maintenance. This will facilitate design simplicity and savings in construction and operating costs of customer-owned modules. It will also incent customers to lease space inside and outside MARINA’s node modules and make MARINA a self-funded entity that is attractive to investors.”
To meet their goals for the competition , the team came up with a modular design for MARINA that featured several key innovations. These included extensions to the International Docking System Standard (IDSS) interface (used aboard the ISS), modular architecture, and a distribution of subsystem functions throughout these modules. As Moraguez explained, their design will allow for some wide-ranging opportunities.
“Modularized service racks connect any point on MARINA to any other point via the extended IDSS interface,” he said. “This enables companies of all sizes to provide products and services in space to other companies, based on terms determined by the open market. Together these decisions provide scalability, reliability, and efficient technology development benefits to MARINA and NASA.”
Another important benefit comes in the form of cost-savings. According to NASA estimates, the recurring cost of MARINA will be about $360 million per year, which represents a significant reduction over the current costs of maintaining and operating the ISS. In total, it would offer NASA a savings of about $3 billion per year, which is approximately 16% of the agency’s annual budget.
But what is perhaps most interesting about the MARINA concept is the fact that it could serve as the world’s first space hotel. According to Valentina Suminia, a postdoc at MIT who contributed to the architectural concept, the space hotel will be “a luxury Earth-facing eight-room space hotel complete with bar, restaurant, and gym, will make orbital space holidays a reality.”
Other commercial features include serviced berths that would be rented out to accommodate customer-owned modules. This goes for the station’s interior modularized rack space as well, where smaller companies that provide contract services to on-board occupants would be able to rent out space. Would it be too much to ask that it also has robot butlers?
The RASCAL competition began in August of 2016 in Cocoa Beach, Florida, and concluded on June 2nd, 2017. The top overall honors were awarded to the teams from Virginia Tech and the University of Maryland for their space habitat concepts, known as Project Theseus and Ultima Thule, respectively.
The Milky Way is an extremely big place. Measured from end to end, our galaxy in an estimated 100,000 to 180,000 light years (31,000 – 55,000 parsecs) in diameter. And it is extremely well-populated, with an estimated 100 to 400 million stars contained within. And according to recent estimates, it is believed that there are as many as 100 billion planets in the Milky Way. And our galaxy is merely one of trillions within the Universe.
So if we were to break it down, just how much matter would we find out there? Estimating how much there is overall would involve some serious math and incredible figures. But what about a single light year? As the most commonly-used unit for measuring the distances between stars and galaxies, determining how much stuff can be found within a single light year (on average) is a good way to get an idea of how stuff is out there.
Light Year:
Even though the name is a little confusing, you probably already know that a light year is the distance that light travels in the space of a year. Given that the speed of light has been measured to 299,792, 458 m/s (1080 million km/h; 671 million mph), the distance light travels in a single year is quite immense. All told, a single light year works out to 9,460,730,472,580.8 kilometers (5,878,625,373,183.6 mi).
Diagram showing the distance light travels between the Sun and the Earth. Credit: Wikipedia Commons/Brews ohare
So to determine how much stuff is in a light year, we need to take that distance and turn it into a cube, with each side measuring one light year in length. Imagine that giant volume of space (a little challenging for some of us to get our heads around) and imagine just how much “stuff” would be in there. And not just “stuff”, in the sense of dust, gas, stars or planets, either. How much nothing is in there, as in, the empty vacuum of space?
There is an answer, but it all depends on where you put your giant cube. Measure it at the core of the galaxy, and there are stars buzzing around all over the place. Perhaps in the heart of a globular cluster? In a star forming nebula? Or maybe out in the suburbs of the Milky Way? There’s also great voids that exist between galaxies, where there’s almost nothing.
Density of the Milky Way:
There’s no getting around the math in this one. First, let’s figure out an average density for the Milky Way and then go from there. Its about 100,000 to 180,000 light-years across and 1000 light-years thick. According to my buddy and famed astronomer Phil Plait (of Bad Astronomy), the total volume of the Milky Way is about 8 trillion cubic light-years.
And the total mass of the Milky Way is 6 x 1042 kilograms (that’s 6,000 trillion trillion trillion metric tons or 6,610 trillion trillion trillion US tons). Divide those together and you get 8 x 1029 kilograms (800 trillion trillion metric tons or 881.85 trillion trillion US tons) per light year. That’s an 8 followed by 29 zeros. This sounds like a lot, but its actually the equivalent of 0.4 Solar Masses – 40% of the mass of our Sun.
Millions of glowing stars from the brightest part of the Milky Way — a region so dense with stars that barely any dark sky is seen across the picture. Credit: ESO
In other words, on average, across the Milky Way, there’s about 40% the mass of the Sun in every cubic light year. But in an average cubic meter, there’s only about 950 attograms, which is almost one femtogram (a quadrillionth of a gram of matter), which is pretty close to nothing. Compare this to air, which has more than a kilogram of mass per cubic meter.
To be fair, in the densest regions of the Milky Way – like inside globular clusters – you can get densities of stars with 100, or even 1000 times greater than our region of the galaxy. Stars can get as close together as the radius of the Solar System. But out in the vast interstellar gulfs between stars, the density drops significantly. There are only a few hundred individual atoms per cubic meter in interstellar space.
And in the intergalactic voids; the gulfs between galaxies, there are just a handful of atoms per meter. Like it or not, much of the Universe is pretty close to being empty space, with just trace amounts of dust or gas particles to be found between all the stars, galaxies, clusters and super clusters.
So how much stuff is there in a light year? It all depends on where you look, but if you spread all the matter around by shaking the Universe up like a snow globe, the answer is very close to nothing.
Mercury and Earth, size comparison. Credit: NASA / APL (from MESSENGER)
Mercury was appropriately named after the Roman messenger of the Gods. This is owed to the fact that its apparent motion in the night sky was faster than that of any of the other planets. As astronomers learned more about this “messenger planet”, they came to understand that its motion was due to its close orbit to the Sun, which causes it to complete a single orbit every 88 days.
Mercury’s proximity to the Sun is merely one of its defining characteristics. Compared to the other planets of the Solar System, it experiences severe temperature variations, going from very hot to very cold. It’s also very rocky, and has no atmosphere to speak of. But to truly get a sense of how Mercury stacks up compared to the other planets of the Solar System, we need to a look at how Mercury compares to Earth.
Size, Mass and Orbit:
The diameter of Mercury is 4,879 km, which is approximately 38% the diameter of Earth. In other words, if you put three Mercurys side by side, they would be a little larger than the Earth from end to end. While this makes Mercury smaller than the largest natural satellites in our system – such as Ganymede and Titan – it is more massive and far more dense than they are.
Mercury, as imaged by the MESSENGER spacecraft, revealing parts of the never seen by human eyes. Image Credit: NASA/JHUAPL/Carnegie Institution of Washington
In fact, Mercury’s mass is approximately 3.3 x 1023 kg (5.5% the mass of Earth) which means that its density – at 5.427 g/cm3 – is the second highest of any planet in the Solar System, only slightly less than Earth’s (5.515 g/cm3). This also means that Mercury’s surface gravity is 3.7 m/s2, which is the equivalent of 38% of Earth’s gravity (0.38 g). This means that if you weighed 100 kg (220 lbs) on Earth, you would weigh 38 kg (84 lbs) on Mercury.
Meanwhile, the surface area of Mercury is 75 million square kilometers, which is approximately 10% the surface area of Earth. If you could unwrap Mercury, it would be almost twice the area of Asia (44 million square km). And the volume of Mercury is 6.1 x 1010 km3, which works out to 5.4% the volume of Earth. In other words, you could fit Mercury inside Earth 18 times over and still have a bit of room to spare.
In terms of orbit, Mercury and Earth probably could not be more different. For one, Mercury has the most eccentric orbit of any planet in the Solar System (0.205), compared to Earth’s 0.0167. Because of this, its distance from the Sun varies between 46 million km (29 million mi) at its closest (perihelion) to 70 million km (43 million mi) at its farthest (aphelion).
This puts Mercury much closer to the Sun than Earth, which orbits at an average distance of 149,598,023 km (92,955,902 mi), or 1 AU. This distance ranges from 147,095,000 km (91,401,000 mi) to 152,100,000 km (94,500,000 mi) – 0.98 to 1.017 AU. And with an average orbital velocity of 47.362 km/s (29.429 mi/s), it takes Mercury a total 87.969 Earth days to complete a single orbit – compared to Earth’s 365.25 days.
The Orbit of Mercury during the year 2006. Credit: Wikipedia Commons/Eurocommuter
However, since Mercury also takes 58.646 days to complete a single rotation, it takes 176 Earth days for the Sun to return to the same place in the sky (aka. a solar day). So on Mercury, a single day is twice as long as a single year. Meanwhile on Earth, a single solar day is 24 hours long, owing to its rapid rotation of 1674.4 km/h. Mercury also has the lowest axial tilt of any planet in the Solar System – approximately 0.027°, compared to Earth’s 23.439°.
Structure and Composition:
Much like Earth, Mercury is a terrestrial planet, which means it is composed of silicate minerals and metals that are differentiated between a solid metal core and a silicate crust and mantle. For Mercury, the breakdown of these elements is higher than Earth. Whereas Earth is primarily composed of silicate minerals, Mercury is composed of 70% metallic and 30% of silicate materials.
Also like Earth, Mercury’s interior is believed to be composed of a molten iron that is surrounded by a mantle of silicate material. Mercury’s core, mantle and crust measure 1,800 km, 600 km, and 100-300 km thick, respectively; while Earth’s core, mantle and crust measure 3478 km, 2800 km, and up to 100 km thick, respectively.
What’s more, geologists estimate that Mercury’s core occupies about 42% of its volume (compared to Earth’s 17%) and the core has a higher iron content than that of any other major planet in the Solar System. Several theories have been proposed to explain this, the most widely accepted being that Mercury was once a larger planet that was struck by a planetesimal that stripped away much of the original crust and mantle.
Internal structure of Mercury: 1. Crust: 100–300 km thick 2. Mantle: 600 km thick 3. Core: 1,800 km radius. Credit: MASA/JPL
Surface Features:
In terms of its surface, Mercury is much more like the Moon than Earth. It has a dry landscape pockmarked by asteroid impact craters and ancient lava flows. Combined with extensive plains, these indicate that the planet has been geologically inactive for billions of years.
Names for these features come from a variety of sources. Craters are named for artists, musicians, painters, and authors; ridges are named for scientists; depressions are named after works of architecture; mountains are named for the word “hot” in different languages; planes are named for Mercury in various languages; escarpments are named for ships of scientific expeditions, and valleys are named after radio telescope facilities.
During and following its formation 4.6 billion years ago, Mercury was heavily bombarded by comets and asteroids, and perhaps again during the Late Heavy Bombardment period. Due to its lack of an atmosphere and precipitation, these craters remain intact billions of years later. Craters on Mercury range in diameter from small bowl-shaped cavities to multi-ringed impact basins hundreds of kilometers across.
The largest known crater is Caloris Basin, which measures 1,550 km (963 mi) in diameter. The impact that created it was so powerful that it caused lava eruptions on the other side of the planet and left a concentric ring over 2 km (1.24 mi) tall surrounding the impact crater. Overall, about 15 impact basins have been identified on those parts of Mercury that have been surveyed.
Enhanced-color image of Munch, Sander and Poe craters amid volcanic plains (orange) near Caloris Basin. Credit: NASA/JHUAPL/Carnegie Institution of Washington
Earth’s surface, meanwhile, is significantly different. For starters, 70% of the surface is covered in oceans while the areas where the Earth’s crust rises above sea level forms the continents. Both above and below sea level, there are mountainous features, volcanoes, scarps (trenches), canyons, plateaus, and abyssal plains. The remaining portions of the surface are covered by mountains, deserts, plains, plateaus, and other landforms.
Mercury’s surface shows many signs of being geologically active in the past, mainly in the form of narrow ridges that extend up to hundreds of kilometers in length. It is believed that these were formed as Mercury’s core and mantle cooled and contracted at a time when the crust had already solidified. However, geological activity ceased billions of years ago and its crust has been solid ever since.
Meanwhile, Earth is still geologically active, owning to convection of the mantle. The lithosphere (the crust and upper layer of the mantle) is broken into pieces called tectonic plates. These plates move in relation to one another and interactions between them is what causes earthquakes, volcanic activity (such as the “Pacific Ring of Fire“), mountain-building, and oceanic trench formation.
Atmosphere and Temperature:
When it comes to their atmospheres, Earth and Mercury could not be more different. Earth has a dense atmosphere composed of five main layers – the Troposphere, the Stratosphere, the Mesosphere, the Thermosphere, and the Exosphere. Earth’s atmosphere is also primarily composed of nitrogen (78%) and oxygen (21%) with trace concentrations of water vapor, carbon dioxide, and other gaseous molecules.
The Fast Imaging Plasma Spectrometer on board MESSENGER has found that the solar wind is able to bear down on Mercury enough to blast particles from its surface into its wispy atmosphere. Credit: Shannon Kohlitz, Media Academica, LLC
Because of this, the average surface temperature on Earth is approximately 14°C, with plenty of variation due to geographical region, elevation, and time of year. The hottest temperature ever recorded on Earth was 70.7°C (159°F) in the Lut Desert of Iran, while the coldest temperature was -89.2°C (-129°F) at the Soviet Vostok Station on the Antarctic Plateau.
Mercury, meanwhile, has a tenuous and variable exosphere that is made up of hydrogen, helium, oxygen, sodium, calcium, potassium and water vapor, with a combined pressure level of about 10-14 bar (one-quadrillionth of Earth’s atmospheric pressure). It is believed this exosphere was formed from particles captured from the Sun, volcanic outgassing and debris kicked into orbit by micrometeorite impacts.
Because it lacks a viable atmosphere, Mercury has no way to retain the heat from the Sun. As a result of this and its high eccentricity, the planet experiences far more extreme variations in temperature than Earth does. Whereas the side that faces the Sun can reach temperatures of up to 700 K (427° C), the side that is in darkness can reach temperatures as low as 100 K (-173° C).
Despite these highs in temperature, the existence of water ice and even organic molecules has been confirmed on Mercury’s surface. The floors of deep craters at the poles are never exposed to direct sunlight, and temperatures there remain below the planetary average. In this respect, Mercury and Earth have something else in common, which is the presence of water ice in its polar regions.
Mercury’s Magnetic Field. Credit: NASA
Magnetic Fields:
Much like Earth, Mercury has a significant, and apparently global, magnetic field, one which is about 1.1% the strength of Earth’s. It is likely that this magnetic field is generated by a dynamo effect, in a manner similar to the magnetic field of Earth. This dynamo effect would result from the circulation of the planet’s iron-rich liquid core.
Mercury’s magnetic field is strong enough to deflect the solar wind around the planet, thus creating a magnetosphere. The planet’s magnetosphere, though small enough to fit within Earth, is strong enough to trap solar wind plasma, which contributes to the space weathering of the planet’s surface.
All told, Mercury and Earth are in stark contrast. While both are terrestrial in nature, Mercury is significantly smaller and less massive than Earth, though it has a similar density. Mercury’s composition is also much more metallic than that of Earth, and its 3:2 orbital resonance results in a single day being twice as long as a year.
But perhaps most stark of all are the extremes in temperature variations that Mercury goes through compared to Earth. Naturally, this is due to the fact that Mercury orbits much closer to the Sun than the Earth does and has no atmosphere to speak of. And its long days and long nights also mean that one side is constantly being baked by the Sun, or in freezing darkness.
