When Will Mars Be Close to Earth?

Approximately every two years, Earth and Mars are at the closest point to each other in their orbits (i.e. opposition). Credit: NASA

As neighboring planets, Earth and Mars have a few things in common. Both are terrestrial in nature (i.e. rocky), both have tilted axes, and both orbit the Sun within its circumstellar habitable zone. And during the course of their orbital periods (i.e. a year), both planets experience variations in temperature and changes in their seasonal weather patterns.

However, owing to their different orbital periods, a year on Mars is significantly longer than a year on Earth – almost twice as long, in fact. And because their orbits are different, the distance between our two planets varies considerably. Basically, every two years Earth and Mars will go from being “at conjunction” (where they are farther from each other) to being “at opposition” (where they are closer to each other).

Orbital Period:

Earth orbits the Sun at an average distance (semi-major axis) of 149,598,023 km (92,955,902 mi; or 1 AU), ranging from 147,095,000 km (91,401,000 mi) at perihelion to 152,100,000 km (94,500,000 mi) at aphelion. At this distance, and with an orbital velocity of 29.78 km/s (18.5 mi/s) the time it take for the planet to complete a single orbit of the Sun (i.e. orbital period) is equal to about 365.25 days.

A top-down image of the orbits of Earth and Mars. Credit: NASA

Mars, meanwhile, orbits the Sun at an average distance of 227,939,200 km (141,634,850 mi; or 1.523679 AU), ranging from 206,700,000 km (128,437,425 mi) at perihelion to 249,200,000 km (154,845,700 mi) at aphelion. Given this difference in distance, Mars orbits the Sun at a slower speed (24.077 km/s; 14.96 mi/s) and takes about 687 Earth days (or 668.59 Mars sols) to complete a single orbit.

In other words, a Martian year is almost 700 days long, which works out to being 1.88 times as long as a year on Earth. This means that every time Mars completes a single orbit around the Sun, the Earth has gone around almost twice. During the moments when they are on opposite sides of the Sun, this is known as a “conjunction”. When they are on the same side of the Sun, they are at “opposition”.

Mars Opposition:

By definition, a “Mars opposition” occurs when planet Earth passes in between the Sun and planet Mars. The term refers to the fact that Mars and the Sun appear on opposite sides of the sky. Because of their orbits, Mars oppositions happens about every 2 years and 2 months – 779.94 Earth days to be precise. From our perspective here on Earth, Mars appears to be rising in the east just as the Sun sets in the west.

About every two years, the Earth passes Mars as they orbit around the Sun. Credit: NASA

After staying up in the sky for the entire night, Mars then sets in the west just as the Sun begins to rise in the east.  During an opposition, Mars becomes one of the brightest objects in the night sky, and is easy to see with the naked eye. Through small telescopes, it will appear as a large and bright object. Through larger telescopes, Mars’ surface features will even become apparent, which would include its polar ice caps.

An opposition can also occur anywhere along Mars’ orbit. However, opposition does not necessary mean that the two planets are at their closest overall. In truth, it just means that they are are at their closest point to each other within their current orbital period. If Earth and Mars’ orbits were perfectly circular, they would be closest to each other whenever they were at opposition.

Instead, their orbits are elliptical, and Mars’ orbit is more elliptical than Earth’s – which means the difference between their respective perihelion and aphelion is greater. Gravitational tugging from other planets constantly changes the shape of our orbits too – with Jupiter pulling on Mars and Venus and Mercury affecting Earth.

Color composite of Mars from seven of its previous oppositions, taken with the Hubble Space Telescope. Credit: NASA/ESA/HST

Lastly, Earth and Mars do not orbit the Sun on the exact same plane – i.e. their orbits are slightly tilted relative to each other. Because of this, Mars and Earth become closest to each other only over the long-term. For instance, every 15 or 17 years, an opposition will occur within a few weeks of Mars’ perihelion. When it happens while the Mars is closest to the sun (called “perihelic opposition”), Mars and Earth get particularly close.

And yet, the closest approaches between the two planets only take place over the course of centuries, and some are always closer than others. To make matters even more confusing, over the past few centuries, Mars’ orbit has been getting more and more elongated, carrying the planet even nearer to the Sun at perihelion and even farther away at aphelion. So future perihelic oppositions will bring Earth and Mars even closer.

On August 28th, 2003, astronomers estimated that Earth and Mars were just 55,758,118 km (34,646,488 mi; 0.37272 AU) apart. This was the closest the two planets had come to each other in almost 60,000 years. This record will stand until August 28th, 2287, at which point the planets will be an estimated 55,688,405 km (34,603,170.6 mi; 0.372254 AU) from each other.

Future Oppositions:

Want to organize your schedule for the next time Mars will be close to Earth? Here are some upcoming dates, covering the next few decades. Plan accordingly!

  • July 27th, 2018
  • October 13th, 2020
  • December 8th, 2022
  • January 16th, 2025
  • February 19th, 2027
  • Mar 25th, 2029
  • May 4th, 2031
  • June 27th, 2033
  • September 15th, 2035
  • November 19th, 2037
  • January 2nd, 2040
  • February 6th, 2042
  • March 11th, 2044
  • April 17th, 2046
  • June 3rd, 2048
  • August 14th, 2050

And in case your interested, Mars will be making close approaches on two occasions this century. The first will take place on August 14th, 2050, when Mars and Earth will be 55.957 million km (34.77 million mi; or 0.374051 AU) apart; and on September 1st, 2082, when they will be 55,883,780 km (34,724,571 mi; 0.373564 AU) apart.

There’s a reason missions to Mars depart from Earth every two years. Seeking to take advantage of shorter travel times, rovers, orbiters and landers are launched to coincide with Mars being at opposition. And when it comes time to send crewed mission to Mars (or even settlers) the same timing will apply!

We have written many interesting articles about Mars here at Universe Today. Here’s How Far is Mars from Earth?, How Long Does it Take to Get to Mars?, How Long is a Year on Mars?, How Far is Mars from the Sun?, and How Long Does it Take Mars to Orbit the Sun?

For more information, here’s a comprehensive schedule of upcoming Mars oppositions.

Astronomy Cast also has some wonderful episodes on the Red Planet. Here’s Episode 52: Mars, and Episode 91: The Search for Water on Mars.

Sources:

What Are You Doing For Yuri’s Night?

What are you doing for Yuri's Night? Credit: yurisnight.net

On April 12th, 1961, history was made when the first human being – Russian cosmonaut Yuri Gagarin – went into space. Similarly, on April 12th, 1981, the inaugural launch of the Space Shuttle took place. In recognition of these accomplishments, people from all around the world have been celebrating “Yuri’s Night” – a global festival honoring humanity’s past, present, and future in space – for over a decade and a half.

This year will mark the 56th anniversary of Yuri Gagarin’s historic flight and of human spaceflight in general. As with every Yuri’s Night that has happened since 2001, this year’s festivities will feature educational events, presentations and games (along with general revelry) at venues located all across the world. Do you have any plans for Yuri’s Night 2017? And if not, perhaps you would like to know what’s happening?

Plenty of events have been planned for this year that are sure to appeal to science enthusiasts and those with a passion for space exploration. One of the highlights for 2017 is a chance to enjoy a virtual reality space vacation, which comes courtesy of the fun folks at Guerilla Science – a London and New York-based group that specializing in creating educational events and installations for festivals, museums, galleries, etc.

Screen shot from Guerilla Science’s “space vacation” VR app. Click to see the animation. Credit: guerillascience.org

For the sake of this year’s Yuri’s night, they are offering people a chance to experience a VR application that allows people to experience a trip to Mars’ Mariner Valley, or to take a self-guided tour on the Moon using the clicker to navigate. To learn more about this application (which is also available for beta testing), be sure to check out Guerilla Science’s “Intergalactic Travel Bureau“. As they describe the bureau’s purpose on their website:

“The Intergalactic Travel Bureau is a live, interactive experience that explores the incredible possibilities of space tourism through personalized space vacation planning experiences. It’s a little bit like Virgin Galactic and SpaceX meet the Jetsons and Mad Men. Bringing together space scientists, astronomers, science educators, actors and the general public, the Bureau has popped up all over the UK and the US since 2011.”

In addition, a virtual event is being hosted by Spacelog, a volunteer organization dedicated to sharing mission transcripts and photographs that celebrate the history of space exploration. In commemoration of Gagarin’s historic flight, they will be publishing the transcripts of the Vostok 1 mission on their Facebook page. Like the mission itself, the event will start at 4:10 am UTC and conclude at 07:55 UTC on Wednesday, April 12th.

For those interested, the Yuri’s Night Global Team (led by Veronica Ann Zabala-Aliberto) is still seeking Regional Team Leaders to help provide support, coordination, and resources for the hundreds of Yuri’s Night parties that have been planned. In addition to organizers and outreach personnel, the Global Team is also seeking translators who are fluent in Arabic and Turkish. To check out what positions are available, go to their website.

Statue of Yuri Gagarin, the first man in space, at the Baikonur Cosmodrome. Credit: AFP

So far, a total of 127 events have been registered in 38 countries, and on 7 continents. That’s right, an event has even been planned for Antarctica, specifically in Loung B3 at the South Pole Station (located at the geographic South Pole). So if you’re in the area – for whatever reason, possibly doing field studies on Emperor Penguins or something! – be sure to swing by!

To find an event in your neck of the woods, consult the full list here. And if you are interested in hosting one, you can register at the Yuri’s Night website. The website is also looking for donations to keep their volunteer and community efforts going.

Wherever you happen to land on April 12th, be sure to raise a glass to all those who have risked life and limb over the past fifty-plus years to establish humanity as a space-faring species!

Further Reading: Yuri’s Night

A Star Going Supernova In Slow Motion Discovered

Artistic impression of a star going supernova, casting its chemically enriched contents into the universe. Credit: NASA/Swift/Skyworks Digital/Dana Berry

A supernova is a rare and wondrous event. Since these intense explosions only take place when a massive star reaches the final stage of its evolutionary lifespan – when it has exhausted all of its fuel and undergoes core collapse – or when a white dwarf in a binary star system consumes its companion, being able to witness one is quite the privilege.

But recently, an international team of astronomers witnessed something that may be even rarer – a supernova event that appeared to be happening in slow-motion. Whereas supernova of its kind (SN Type Ibn) are typically characterized by a rapid rise to peak brightness and a fast decline, this particular supernova took an unprecedentedly long time to reach maximum brightness, and then slowly faded away.

For the sake of their study, the research team – which included members from the UK, Poland, Sweden, Northern Ireland, the Netherlands and Germany – studied a Type Ibn event known as OGLE-2014-SN-13. These types of  explosions are thought to be the result of massive stars (which have lost their outer envelop of hydrogen) undergoing core-collapse, and whose ejecta interacts with a cloud of helium-rich circumstellar material (CSM).

OGLE-2014-SN-131 (blue circle) in a VLT acquisition (left), and an NTT image showing no visible host at the SN location (right). Credit: Karamehmetoglu et al.

The study was led by Emir Karamehmetoglu of The Oskar Klein Center at Stockholm University. As he told Universe Today via email:

“Type Ibn supernovae are thought to be the explosions of very massive stars, surrounded by a dense region of extremely helium-rich material. We infer the existence of this Helium via the presence of narrow helium emission lines in their optical spectra. We also believe that there is very little, if any Hydrogen in the immediate surrounding of the star, because if it was there, it would show up much stronger than the Helium in the spectra. As you can imagine, this sort of configuration is very rare, since hydrogen is the most abundant element in the universe by far.”

As already noted, Type Ibn supernova are characterized by a sudden and dramatic increase in their brightness, then a rapid decline. However, when observing OGLE-2014-SN-131 – which they detected on November 11th, 2014 using the Optical Gravitational Lensing Experiment (OGLE) at the Warsaw University Astronomical Observatory – they witnessed something completely different.

“OGLE-2014-SN-131 was different because it took almost 50 days, as compared to the more typical ~1 week, for it to become bright,” said Karamehmetoglu. “Then it declined relatively slowly as well. The fact that it took several times longer than the typical rise to maximum brightness, which is unlike any other Ibn that has been studied before, makes it a very unique object.”

The Optical Gravitational Lensing Experiment (OGLE), a project being undertaken by the Astronomical Observatory at the University of Warsaw. Credit: astrouw.edu.pl

Thanks to data obtained by the OGLE-IV Transient Detection System, they were able to place OGLE-2014-SN-131 at a distance of about 372 ± 9 megaparsecs (1183.95  to 1242.66 million light years) from Earth. This was then followed-up with photometric observations using the OGLE telescope at the Las Campanas Observatory in Chile and the Gamma-Ray Burst Optical/Near-Infrared Detector (GROND) at the La Silla Observatory.

The team also obtained spectroscopic data using the ESO’s New Technology Telescope (NTT) at La Silla and the Very Large Telescope (VLT) at the Paranal Observatory (both located in Chile). In addition to having an unusually long rise-time, the combined data also indicated that the supernova had an unusually broad light curve. To explain all this, the team considered a number of possibilities.

For starters, they considered standard radio-active decay models, which are known to power the lightcurves of most other Type I and Type II supernovae. However, these could not account for what they had observed with OGLE-2014-SN-131. As such, they began considering more exotic scenarios, which included energy being input from a young, rapidly spinning neutron star (aka. a magnetar) nearby.

While this model would explain the behavior of OGLE-2014-SN-131, it was limited in that it is not yet known what circumstances would be needed to invoke a magnetar. As such, Karamehmetoglu and his team also considered the possibility that the explosions might be powered by shocks created by the interaction of ejected material from the supernova with the helium-rich CSM.

Supernova 2008D in galaxy NGC 2770 (Type Ib), shown in X-ray (left) and visible light (right). Credit: NASA/Swift Science Team/Stefan Immler

Thanks to the spectral data obtained by the NTT and VLT, they knew that such material existed around the star, and the model was therefore able to reproduce the observed behavior. As Karamehmetoglu explained, it is for this reason that they favor this model over the others:

“In this scenario, the reason OGLE-2014-SN-131 is different from other Type Ibn SNe is due to the unusually massive nature of its progenitor star. A very massive star, between 40-60 times the mass of our Sun, located in a low-metallicity galaxy, probably gave rise to this SN by expelling a great amount of helium-rich matter, then eventually exploding as a SN.”

In addition to being a unique event, this study also some drastic implications for astronomy and the study of supernovae. Thanks to the detection of OGLE-2014-SN-131, any future models that attempt to explain how Type Ibn supernovae form now have a stringent constraint. At the same time, astronomers now have an existing model to consider if and when they witness other supernovae which exhibit particularly long rise times.

Looking ahead, this is precisely what Karamehmetoglu and his colleagues hope to do. “In our next effort, we will study other, less-rare, types of SN that have long rise times, and therefore are probably created by very massive stars,” he said. “We will get to take advantage of the comparison frame-work we developed when studying OGLE-2014-SN-131.”

Once more, the Universe has taught us that two of the more important aspects of scientific research are adaptability and a commitment to continuous discovery. When things don’t conform to existing models, develop new ones and test them out!

Further Reading: arXiv

World’s Largest Rocket Will Be Recoverable & Reusable

The Falcon Heavy, once operational, will be the most powerful rocket in the world. Credit: SpaceX

When Elon Musk launched SpaceX in 2002, he did so with the intention of making reusability a central feature of his company. Designed to lower the costs associated with launches, being able to reuse boosters was also a means of making space more accessible. “If one can figure out how to effectively reuse rockets just like airplanes,” he said, “the cost of access to space will be reduced by as much as a factor of a hundred.”

And with last week’s successful launch of the first reusable Falcon 9 (the SES-10 Mission) Musk chose to unveil more details about his company’s next major milestone. According to Musk, the demonstration flight of the Falcon Heavy – which is scheduled to take place this summer – will involve two recovered Falcon 9 cores and the attempted recovery of the rocket’s upper-stage.

In other words, on its maiden flight, two of the three boosters sending the Falcon Heavy into orbit will be reused, and SpaceX may even try to attempt to make the first-ever recovery of a second stage. Such a feat, if successful, will signal that Musk’s dream of total reusability – where the first stage, payload fairings, and second stage of their launch vehicles are all recoverable – has come to fruition.

An artist's illustration of the Falcon Heavy rocket. Image: SpaceX
An artist’s illustration of the Falcon Heavy rocket. Image: SpaceX

According to details shared at the news conference that accompanied the launch of SES-10, Musk indicated that the test flight would make use of boosters that were recovered from two successful Falcon 9 launches, and that all three would be recovered after launch. As he was quoted as saying by Stephen Clark at SpaceFlightNow:

“That will be exciting mission, one way or another. Hopefully in a good direction. The two side boosters will come back and do sort of a synchronized aerial ballet and land. Two of the side boosters will land back at the Cape. That’ll be pretty exciting to see two come in simultaneously, and the center core will land downrange on the drone ship.”

On the following day – Friday, March. 31st, 11:44 am – Musk followed this up with a tweet that indicated that the test flight could also involve something that has never before been attempted. “”Considering trying to bring upper stage back on Falcon Heavy demo flight for full reusability,” he wrote. “Odds of success low, but maybe worth a shot.”

Such a plan is in keeping with what Musk had initially hoped for his company, which was to make all of its rockets entirely reusable. While reusable boosters were not a part of the initial designs for the Falcon Heavy, the numerous successful recoveries (on land and at sea) of the first stage of the Falcon 9 indicated that the Heavy‘s outer cores could be recovered and reused in the same way.

Chart comparing the lift capacity of major launch systems to Low Earth Orbit (LEO). Credit: SpaceX

Musk also reiterated that the demo flight would be taking place this summer, and that it would be carrying something comically-inspired. “Silliest thing we can imagine!” he tweeted, in response to a question of what the cargo would be. “Secret payload of 1st Dragon flight was a giant wheel of cheese. Inspired by a friend & Monty Python.”

For those unfamiliar with what Musk was referring to “The Cheese Shop”, a classic Monty Python sketch. From this, we can safely assume that Musk has something similar in mind for the inaugural Falcon Heavy launch. Perhaps some wine and bread to go with that cheese?

The demonstration flight – which will take place on launch pad 39A at the Kennedy Space Center in Florida – is already expected to be a momentous event. With the ability to lift payloads of over 64 metric tons (64,000 kg or 141,096 lbs) to Low Earth Orbit (LEO), the Falcon Heavy will be the most powerful rocket currently in operation.

In fact, its capacity will be about twice that of the Arianespace Ariane 5 and United Launch Alliance’s Delta IV Heavy rockets – which are capable of lifting 21,000 kg (46,000 lb) and 28,790 kg (63,470 lb) to LEO, respectively. However, SpaceX has indicated that the payload performance to geosynchronous transfer orbit (GTO) would be reduced with the addition of reusable technology.

Artist’s concept of the SpaceX Red Dragon spacecraft launching to Mars on SpaceX Falcon Heavy as soon as 2018. Credit: SpaceX

Whereas its original capacity to GTO was said to be 22,200kg (48,940 lb), full reusability on all three booster cores will reduce this to 7,000 kg (15,000 lb), while having two reusable outside cores will reduce it to approximately 14,000 kg (31,000 lb). But of course, these reductions in payloads have to be considered against significantly reduced launch costs.

For the time being, the plan is to recover all three boosters of the Falcon Heavy. This may change, depending on the success of the maiden flight, to the point where just the outer boosters are deemed reusable and the central core expendable. And depending on the success of the second stage recovery, SpaceX may begin pursuing reusability with the second stages of their Falcon 9 as well.

Musk has also indicated that at present, SpaceX will be primarily focused on the many commercial missions it has planned using the Falcon 9 launch vehicle. But if all goes according to plan, this summer will be the second time in the space of a single year that Musk’s and the aerospace company he started knocked it out of the park and silenced all those who said he was attempting the impossible.

Further Reading: SpaceFlightNow, SpaceX

Venus 2.0 Discovered In Our Own Back Yard

Artist's impression of Kepler-1649b, the "Venus-like" world orbiting an M-class star 219 light-years from Earth. Credit: Danielle Futselaar

It has been an exciting time for exoplanet research of late! Back in February, the world was astounded when astronomers from the European Southern Observatory (ESO) announced the  discovery of seven planets in the TRAPPIST-1 system, all of which were comparable in size to Earth, and three of which were found to orbit within the star’s habitable zone.

And now, a team of international astronomers has announced the discovery of an extra-solar body that is similar to another terrestrial planet in our own Solar System. It’s known as Kepler-1649b, a planet that appears to be similar in size and density to Earth and is located in a star system just 219 light-years away. But in terms of its atmosphere, this planet appears to be decidedly more “Venus-like” (i.e. insanely hot!)

The team’s study, titled “Kepler-1649b: An Exo-Venus in the Solar Neighborhood“, was recently published in The Astronomical Journal. Led by Isabel Angelo – of the SETI Institute, NASA Ames Research Center, and UC Berkley – the team included researchers also from SETI and Ames, as well as the NASA Exoplanet Science Institute (NExScl), the Exoplanet Research Institute (iREx), the Center for Astrophysics Research, and other research institutions.

Diagram comparing the Solar System to Kepler 69 and its system of exoplanets. Credit: NASA Ames/JPL-Caltech

Needless to say, this discovery is a significant one, and the implications of it go beyond exoplanet research. For some time, astronomers have wondered how – given their similar sizes, densities, and the fact that they both orbit within the Sun’s habitable zone – that Earth could develop conditions favorable to life while Venus would become so hostile. As such, having a “Venus-like” planet that is close enough to study presents some exciting opportunities.

In the past, the Kepler mission has located several extra-solar planets that were similar in some ways to Venus. For instance, a few years ago, astronomers detected a Super-Earth – Kepler-69b, which appeared to measure 2.24 times the diameter of Earth – that was in a Venus-like orbit around its host the star. And then there was GJ 1132b, a Venus-like exoplanet candidate that is about 1.5 times the mass of Earth, and located just 39 light-years away.

In addition, dozens of smaller planet candidates have been discovered that astronomers think could have atmospheres similar to that of Venus. But in the case of Kepler-1649b, the team behind the discovery were able to determine that the planet had a sub-Earth radius (similar in size to Venus) and receives a similar amount of light (aka. incident flux) from its star as Venus does from Earth.

However, they also noted that the planet also differs from Venus in a few key ways – not the least of which are its orbital period and the type of star it orbits. As Dr. Angelo told Universe Today via email:

“The planet is similar to Venus in terms of it’s size and the amount of light it receives from it’s host star. This means it could potentially have surface temperatures similar to Venus as well. It differs from Venus because it orbits a star that is much smaller, cooler, and redder than our sun. It completes its orbit in just 9 days, which places it close to its host star and subjects it to potential factors that Venus does not experience, including exposure to magnetic radiation and tidal locking. Also, since it orbits a cooler star, it receives more lower-energy radiation from its host star than Earth receives from the Sun.”

Artist’s impression of a Venus-like exoplanet orbiting close to its host star. Credit: CfA/Dana Berry

In other words, while the planet appears to receive a comparable amount of light/heat from its host star, it is also subject to far more low-energy radiation. And as a potentially tidally-locked planet, the surface’s exposure to this radiation would be entirely disproportionate. And last, its proximity to its star means it would be subject to greater tidal forces than Venus – all of which has drastic implications for the planet’s geological activity and seasonal variations.

Despite these differences, Kepler-1649b remains the most Venus-like planet discovered to date. Looking to the future, it is hoped that next-generations instruments – like the Transiting Exoplanet Survey Satellite (TESS), the James Webb Telescope and the Gaia spacecraft – will allow for more detailed studies. From these, astronomers hope to more accurately determine the size and distance of the planet, as well as the temperature of its host star.

This information will, in turn, help us learn a great deal more about what goes into making a planet “habitable”. As Angelo explained:

“Understanding how hotter planets develop thick, Venus-like atmospheres that make them inhabitable will be important in constraining our definition of a ‘habitable zone’. This may become possible in the future when we develop instruments sensitive enough to determine chemical compositions of planet atmospheres (around dim stars) using a method called ‘transit spectroscopy’, which looks at the light from the host star that has passed through the planet’s atmosphere during transit.”

The development of such instruments will be especially useful given joust how many exoplanets are being detected around neighboring red dwarf stars. Given that they account for roughly 85% of stars in the Milky Way, knowing whether or not they can have habitable planets will certainly be of interest!

Further Reading: The Astronomical Journal

Mars’ Trojans Show Remains Of Ancient Planetoid

A new study led by researchers from OU indicates that the outer planets could be why Mars is significantly smaller than Earth. Credit: NASA

Trojan asteroids are a fascinating thing. Whereas the most widely known are those that orbit Jupiter (around its L4 and L5 Lagrange Points), Venus, Earth, Mars, Uranus and Neptune have populations of these asteroids as well. Naturally, these rocky objects are a focal point for a lot of scientific research, since they can tell us much about the formation and early history of the Solar System.

And now, thanks to an international team of astronomers, it has been determined that the Trojan asteroids that orbit Mars are likely the remains of a mini-planet that was destroyed by a collision billions of years ago. Their findings are detailed in a paper that will be published in The Monthly Notices of the Royal Astronomical Society later this month.

For the sake of their study, the team – which was led by Galin Borisov and Apostolos Christou of the Armagh Observatory and Planetarium in Northern Ireland, examined the composition of Marian Trojans. This consisted of using spectral data obtained by the XSHOOTER spectrograph on the Very Large Telescope (VLT) and photometric data from the National Astronomical Observatory‘s two-meter telescope, and the William Herschel Telescope.

Diagram of Jupiter and the inner Solar System, showing the Jupiter and Martian Trojans (light green) and the Main Belt (teal). Credit: Wikipedia Commons/AndrewBuck

Specifically, they examined two members of the Eureka family – a group of Martian Trojans located at the planet’s L5 point. It is here that eight of Mars’ nine known Trojans exist in stable orbits (the other being at L4), and which are named after the first Martian Trojan ever discovered – 5261 Eureka. Like all Trojans, the Eurekas are thought to have orbited Mars ever since the formation of the Solar System.

In fact, astronomers have suspected for some time that the Martian Trojans could be the survivors of an early generation of planetesimals from which the inner Solar System formed. As Dr. Christou told Universe Today via email:

“[The Trojan family] is unique in the Solar System, in more ways than one. Unlike every other family that exists in the Main Asteroid Belt between Mars and Jupiter, it is made up of olivine-rich asteroids. Also, the asteroids are < 2km across, much smaller than we can see at other families, basically because they are much closer to the Earth than other asteroids. Finally, it is the closest family we know to the Sun, and this has implications on how it formed in that the tiny but continuous action of sunlight may have played a role.”

After combining spectrographic and photometric data on these asteroids, the team found that they were rich in the mineral olivine – a magnesium iron silicate that is a primary component of the Earth’s mantle and (it is believed) other terrestrial planets. This was unusual find as far as asteroids go, but it was even more interesting when compared to 5261 Eureka itself – which also has an olivine-rich composition.

The first X-ray view of Martian soil by Curiosity rover at the “Rocknest” (October 17, 2012),  showing traces of feldspar, pyroxenes, and olivine. Credit: NASA/JPL-Caltech/Ames

Given that the Eureka asteroids also have similar orbits, the team concluded that every member of this family is likely to have a common composition – and hence, a common origin. These findings could have drastic implications for both the origin of Martian Trojans, and the origin of the inner Solar System. As Dr. Christou explained:

“The presence of asteroids with exposed olivine on their surfaces constrains the sequence of events that led to Mars’ formation. Olivine forms within objects that grew large enough to differentiate into a crust, mantle and core. Therefore, these objects must have formed before Mars did and were available to participate in Mars’ formation. To expose the olivine, it is necessary to break these objects up through collisions. Our ongoing work indicates that this is unlikely to have happened after the Solar System settled down in its current configuration, therefore there must have been period of intense collisional evolution during the planet formation process.”

In other words, if Mars formed from several types of material that was mixed together, these asteroids would be samples of the original source – i.e. planetesimals. By examining these asteroids further, scientists will be able to learn more about the process through which Mars came to be and (as Christou says) help us “unscramble the Martian omelette.”

This research is also likely to reveal much about the formation of Earth and the other terrestrial planets of the Solar System. Similar efforts will be made with NASA’s upcoming Lucy mission, which is scheduled to launch in October of 2021. Between 2027 and 2033, this probe will study Jupiter’s Trojan population, obtaining information on six of the asteroid’s geology, surface features, compositions, masses and densities to learn more about their origins.

Further Reading: MNRAS, Armagh Observatory

Deepest X-ray Image Ever Made Contains Mysterious Explosion

A mysterious flash of X-rays has been discovered by NASA’s Chandra X-ray Observatory in the deepest X-ray image ever obtained. Credit: NASA/Chandra/Harvard

For over sixty years, astronomers have been exploring the Universe for x-ray sources. Known to be associated with stars, clouds of super heated gas, interstellar mediums, and destructive events, the detection of cosmic x-rays is challenging work. In recent decades, astronomers have been benefited immensely from by the deployment of orbital telescopes like the Chandra X-ray Observatory.

Since it was launched on July 23rd, 1999, Chandra has been NASA’s flagship mission for X-ray astronomy. And this past week (on Thurs. March 30th, 2017), the Observatory accomplished something very impressive. Using its suite of advanced instruments, the observatory captured a mysterious flash coming from deep space. Not only was this the deepest X-ray source ever observed, it also revealed what could be an entirely new phenomenon.

Located in the region of the sky known as the Chandra Deep Field-South (CDF-S), this X-ray emission source appeared to have come from a small galaxy located approximately 10.7 billion light-years from Earth. It also had some remarkable properties, producing more energy in the space of a few minutes that all the stars in the galaxy combined.

Artist illustration of the Chandra X-ray Observatory, the most sensitive X-ray telescope ever built. Credit: NASA/CXC/NGST

Originally detected in 2014 by a team of researchers from Penn State University and the Pontifical Catholic University of Chile in Santiago, Chile, this source was not even detected in the X-ray band at first. However, it quickly caught the team’s attention as it erupted and became 1000 brighter in the space of a few hours. At this point, the researchers began gathering data using Chandra’s Advanced CCD Imaging Spectronomer.

A day after the flare-up, the X-ray source had faded to the point that Chandra was no longer able to detect it. As Niel Brandt – the Verne M. Willaman Professor of Astronomy and Astrophysics at Penn State and part of the team that first observed it – described the discovery in a Penn State press release:

“This flaring source was a wonderful surprise bonus that we accidentally discovered in our efforts to explore the poorly understood realm of the ultra-faint X-ray universe. We definitely ‘lucked out’ with this find and now have an exciting new transient phenomenon to explore in future years.”

Thousands of hours of legacy data from the Hubble and Spitzer Space Telescopes was then consulted in order to determine the location of the CDF-S X-ray source. And though scientists were able to determine that the image of the X-ray source placed it beyond any that had been observed before, they are not entirely clear as to what could have caused it.

X-ray (left) and optical (right) images of the space around the X-ray source, made with Chandra and the Hubble Space Telescope, respectively. Credit: NASA/CXC/F. Bauer et al.

On the one hand, it could be the result of some sort of destructive event, or something scientists have never before seen. The reason for this has to do with the fact that X-ray bursts also come with a gamma-ray burst (GRB), which appears to be missing here. Essentially, GRBs are jetted explosions that are triggered by the collapse of a massive star or by the merger of two neutron stars (or a neutron star with a black hole).

Because of this, three possible explanations have been suggested. In the first, the CDF-S X-ray source is indeed the result of a collapsing star or merger, but the resulting jets are not pointed towards Earth. In the second, the same scenario is responsible for the x-ray source, but the GRB lies beyond the small galaxy. The third possible explanation is that the event was caused by a medium-sized black hole shredding a white dwarf star.

Unfortunately, none of these explanations seem to fit the data. However, these research team also noted that these possibilities are not that well understood, since none have been witnessed in the Universe. As Franz Bauer – an astronomer from the Pontifical Catholic University of Chile – said: “Ever since discovering this source, we’ve been struggling to understand its origin. It’s like we have a jigsaw puzzle but we don’t have all of the pieces.”

Not only has Chandra not observed any other X-ray sources like this one during the 17 years it has surveyed the CDF-S region, but no similar events have been observed by the space telescope anywhere in the Universe during its nearly two decades of operation. On top of that, this event was brighter, more short-lived, and occurred in a smaller, younger host galaxy than other unexplained X-ray sources.

Still image of the X-ray source observed by Chandra, showing the captured flare up at bottom Credit: NASA/CXC/Pontifical Catholic Univ./F.Bauer et al.

From all of this, the only takeaway appears to be that the event was likely the result of a cataclysmic event, like a neutron star or a white dwarf being torn apart. But the fact that none of the more plausible explanations seem to account for it’s peculiar characteristics would seem to suggest that astronomers may have witnessed an entirely new kind of cataclysmic event.

The team’s study – “A New, Faint Population of X-ray Transient“- is available online and will be published in the June 2017 issue of the Monthly Notices of the Royal Astronomical Society. In the meantime, astronomers will be sifting through the data acquired by Chandra and other X-ray observatories – like the ESA’s XMM-Newton and NASA’s Swift Gamma-Ray Burst Mission – to see if they can find any other instances of this kind of event.

And of course, future surveys conducted using Chandra and next-generation X-ray telescopes will also be on the lookout for these kind of short-lived, high-energy X-ray bursts. It’s always good when the Universe throws us a curve ball. Not only does it show us that we have more to learn, but it also teaches us that we must never grow complacent in our theories.

Be sure to check out this animation of the CDF-S X-ray source too, courtesy of the Chandra X-ray Observatory:

Further Reading:  Chandra, PennState

Space Station Drama After Vital Micrometeorite Shielding Floats Away

This week, astronauts aboard the ISS conducted an EVA which involved a close call and a bitch of a "patch up" job. Credit: NASA

This past week (on Thurs. March 30th), two crew members of Expedition 50 conducted an important spacewalk on the exterior of the International Space Station. During the seven hours in which they conducted this extravehicular activity (EVA), the astronauts reconnected cables and electrical connections on a new Pressurized Mating Adapter (PMA-3) and installed four new thermal protection shields on the Tranquility module.

These shields were required to cover the port that was left exposed when (earlier in the week) the PMA-3 was removed and installed robotically on the Harmony module. In the course of the EVA, the two astronauts – Commander Shane Kimbrough and Flight Engineer Peggy Whitson – were forced to perform an impromptu patch up job when one of the shield unexpectedly came loose.

While things flying off into space is not entirely unusual, on this occasion, there were concerns given the size and weight of the object. This shield measures about 1.5 meters by 0.6 meters (5 feet by 2 feet) and is 5 centimeters (2 inches) thick. It also weighs a little over 8 kg (18 lbs), which would make it a serious impact hazard given the relative velocity of orbital debris (28,000 km/h).

Spacewalk support personnel quickly at the Johnson Space Center, looking for a solution to the loss of thermal and micrometeoroid shield. Credit: NASA

After coming loose, the bundled-up shield quickly floated away and became visible in the distance as a white dot. In response, a team from the Mission Control Center at NASA’s Johnson Space Center began monitoring the shield as it drifted. At the same time, they began working on a contingency plan to substitute the shielding, and advised the astronauts to finish covering the port with the PMA-3 cover Whitson removed earlier that day.

The plan worked, and the cover was successfully installed, providing thermal, micrometeoroid and orbital debris protection for the port. Kimbrough and Whitson finished their EVA at 2:33 pm EDT, having successfully installed the remaining shields on the berthing mechanism port. A few hours after it came loose, Mission Control also determined that the shield posed no risk to the ISS and will eventually burn up in Earth’s atmosphere.

Before concluding their spacewalk, Kimbrough and Whitson also installed what has been nicknamed a “cummerbund” around the base of the PMA-3 adapter. This cloth shield – which also provides micrometeorite protection – is so-named because it fits around the adapter in a way that is similar to how a tuxedo’s cummerbund fits around a person’s waist.

Another highlight of this spacewalk was the fact that Peggy Whitson set two new records with this latest EVA. In addition to setting the record for the most spacewalks by a female astronaut (eight), she also set the record for most accumulated time spent spacewalking – just over 53 hours – by a female astronaut. The 57-year old astronaut now ranks fifth on the list of all-time spacewalking by any astronaut.

Astronaut Peggy Whitson signs her autograph near an Expedition 50 mission patch attached to the inside the International Space Station. Credit: NASA

On top of all that, Expedition 50 is Whitson’s third mission to the ISS, and she has spent a total of 500 days in space – also a record for any female astronaut. She arrived aboard the ISS aboard the Soyuz MS-03 – along with ESA flight engineer Thomas Pesquet and Roscosmos flight engineer Oleg Novitskiy – and is scheduled to return to Earth in June (though she may remain there until September).

The top spot for most accumulated time in spacewalking is currently held by Russian cosmonaut Anatoly Solovyev, who has participated in 16 spacewalks for a grand total of 82 hours spent in EVA. And in total, spacewalkers have now spent a total of 1,243 hours and 42 minutes performing 199 spacewalks in support of the assembly and maintenance of the ISS.

When it comes to being an astronaut, one of the most important requirements is flexibility – the ability to adapt to unexpected situations and come up with solutions on the fly. Crew 50 and Mission Control certainly demonstrated that this week, maintaining a tradition that brought the Apollo 13 astronauts safely back to Earth and has kept the ISS running for almost two decades.

Further Reading: ABCnews, NASA

ARCA Unveils the World’s first Single-Stage-to-Orbit Rocket

Artist's impression of the Haas 2CA deployed to orbit. Credit: ARCA

Since the beginning of the Space Age, scientists have relied on multi-stage rockets in order to put spacecraft and payloads into orbit. The same technology has allowed for missions farther into space, sending robotic spacecraft to every planet in the Solar System, and astronauts to the Moon. But looking to the future, it is clear that new ideas will be needed in order to cut costs and expand launch services.

Hence why the ARCA Space Corporation has developed a concept for a single-stage-to-orbit (SSTO) rocket. It’s known as the Haas 2CA, the latest in  a series of rockets being developed by the New Mexico-based aerospace company. If all goes as planned, this rocket will be the first SSTO rocket in history, meaning it will be able to place payloads and crew into Earth’s orbit relying on only one stage with one engine.

The rocket was unveiled on Tuesday, March 28th, at their company headquarters in Las Cruces. The rocket is currently seeking FAA approval, and ARCA is working diligently to get it ready for its test launch in 2018 – which will take place at NASA’s Wallops Flight Facility located on Virginia’s eastern shore. If successful, the company hopes to use this rocket to deploy small satellites to orbit in the coming decade.

Artist’s impression of the Haas 2C rocket ascending into orbit. Credit: ARCA

Established in 1999 by a group of Romanian rocket enthusiasts (led by company CEO Dumitru Popescu), ARCA’s original focus was on balloon-launched rockets. In the course of the company’s history, ARCA has launched two stratospheric rockets, four large scale stratospheric balloons, and has been awarded some lucrative governmental contracts to test aerospace and space exploration technologies.

In 2003, the company joined the $10 million Ansari X Prize Competition and began work on their first demonstrator rocket. Known as the Demonstrator 2B – a single stage suborbital rocket – the rocket was successfully launched on September 9th, 2004, from Cape Midia Air Force Base. In the years that followed, they expanded their repertoire to include other concepts – like the Helen rocket, the Stabilo crewed vehicle, and the Excelsior Aerospike.

In 2013, ARCA was contracted by the European Space Agency (ESA) to create a Drop Test Vehicle (DTV) that would test the atmospheric deceleration parachutes being used by the Schiaperelli lander (as part of the ExoMars mission). Being the same weight and using the same parachute deployment systems as Schiaperelli, the DTV conducted a freefall exercise which simulated the dynamic pressure conditions of entering the Martian atmosphere

In that same year, ARCA relocated to New Mexico, where they have continued working on their rocket series and other aerospace ventures from their headquarters at the Las Cruces Airport. It was here that they introduced the Haas rocket series – named in honor of Austrian-Romanian rocketry pioneer Conrad Haas – which now consists of the Haas 2B and 2C rockets.

The Haas 2CA rocket berthed at ARCA’s headqaurters at Las Cruces Air Port in Las Cruces, New Mexico. Credit: ARCA

The 2B is a proven concept, designed for suborbital flight for the sake of space tourism. But as of this week, the 2C is now part of ARCA’s rocket family. Relying on single stage and single Executor engine, this rocket will small satellites into orbit. The rocket is fueled by hydrogen peroxide and kerosene (which combines to create a nontoxic fuel), and measures (53 feet) long and (5 feet) in diameter.

The 2C weights about 550 kg (1210 pounds) empty, and 16280 kg (35,887 pounds) when fully fueled. It will also be able to provide 22900 kg (50,500 lbs) of thrust at sea level, and about 33,565 kg (74,000 lbs) in a vacuum. In this configuration, the rocket is capable of delivering 100kg (220lbs) to Low Earth Orbit (LEO), at a cost of $1 million per launch (or $10,000/kg; $4,545/lb).

This several times less what SpaceX can do with its Falcon 9 rocket, which can deliver 22,800 km payloads to orbit for $62 million a launch – which works out to about $2719/kg or $1233/lb. However, one must take into account that the Falcon 9 is a heavier launch vehicle, and that there are additional issues that come into play where larger launch vehicles are concerned. As Dumitru Popescu told Universe Today via email:

“With the Haas 2C, the customer can launch on the desired orbit parameter, when he/she wants. Basically, the launch will be tailored on the customer needs. A more fair comparison will be between the Haas 2CA and Falcon 1 and Electron. Falcon 1 had a launch cost of $6.7 millions for a proposed payload of 670kg, or a demonstrated one of 180kg. In the best case scenario, this leads us to the same price of $10,000/kg. In the case of the Electron rocket, the cost per launch is $4.9 million for a 150kg payload. This leads us to a price of a $32.600/kg. Falcon 1, Electron, Haas 2CA have their market and a comparison with a big launcher isn’t fair in my opinion. Overall, if we will be able to keep this price, the Haas 2CA, at $1 million/launch will become the cheapest launcher in history.”

Artist’s impression of the Haas 2C rocket, shown in its launch (top) and deployment configurations (bottom). Credit: ARCA

In addition, the Haas 2C rocket benefits from the fact that it is cheaper and easier to manufacture, and that it’s SSTO configuration offers greater flexibility and reliability. 

“In the case of staged rockets, we are literally talking about more rockets combined in one vehicle to achieve orbit,” said Popsecu. “It is definitely more cost effective to operate one rocket than a vehicle made of multiple rockets, as it requires less time, less qualified manpower and less demanding transport and launch operations. The SSTO may also offer the possibility to launch from an inland spaceport, as there are no first stages that will fall on the ground after burnout.”

To prepare the rocket for its 2018 launch, ARCA is currently collaborating with NASA through its Cooperative Opportunity Program and with the help of the Ames, Kennedy, Marshall,  Stennis, and Johnson Space Centers. Popescu is also entering into discussions with the New Mexico Spaceport Authority to conduct launches from Spaceport America, and is looking to secure a partnership with a US defense agency.

If all goes well, this little aerospace company will be making spaceflight history. As Popescu said in a company press release:

“When the Haas 2CA rocket launches, it will be the first rocket in history to place itself entirely into orbit. This opens new frontiers for exploration of the Solar System as the rocket can be refueled in-orbit and re-utilize its aerospike engine thus eliminating the need for additional upper stages. After the full qualification, the vehicle could be operated from inland spaceports as there are no stages that fall on the ground at burnout. Staged rockets, even though they provide more payload performance for the same takeoff mass, are less reliable because of an increased number of parts due to flight events requested by staging and ignition of the upper stage engine. Also, staged rockets are deemed to be more expensive because they are literally made up of more than one rocket. Manufacturing and assembling more rockets in one launcher requires more, time, money, and personnel. The SSTO technology, once implemented, will increase the space flight responsiveness and lower the cost to values expected by the industry for decades. This rocket will also be the fastest vehicle to reach orbit, taking less than 5 minutes.”

In addition, the aerospace industry will have another company looking to lower the costs of launches and expanding domestic launch capability. Be sure to check out the company’s video detailing the Haas 2C and its unique characteristics:

Further Reading: ARCA

Solar Probe Plus Will ‘Touch’ The Sun

NASA's Solar Probe Plus will enter the sun's corona to understand space weather using a Faraday cup developed by the Smithsonian Astrophysical Observatory and Draper. Credit: NASA/Johns Hopkins University Applied Physics Laboratory

Coronal Mass Ejections (aka. solar flares) are a seriously hazardous thing. Whenever the Sun emits a burst of these charged particles, it can play havoc with electrical systems, aircraft and satellites here on Earth. Worse yet is the harm it can inflict on astronauts stationed aboard the ISS, who do not have the protection of Earth’s atmosphere. As such, it is obvious why scientists want to be able to predict these events better.

For this reason, the Smithsonian Astrophysical Observatory and the Charles Stark Draper Laboratory – a Cambridge, Massachusetts-based non-profit engineering organization – are working to develop specialized sensors for NASA’s proposed solar spacecraft. Launching in 2018, this spacecraft will fly into the Sun atmosphere and “touch” the face of the Sun to learn more about its behavior.

This spacecraft – known as the Solar Probe Plus (SPP) – is currently being designed and built by the Johns Hopkins University Applied Physics Laboratory. Once it is launched, the SPP will use seven Venus flybys over nearly seven years to gradually shrink its orbit around the Sun. During this time, it will conduct 24 flybys of the Sun and pass into the Sun’s upper atmosphere (corona), passing within 6.4 million km (4 million mi) of its surface.

At this distance, it will have traveled 37.6 million km (23.36 million mi) closer to the Sun than any spacecraft in history. At the same time, it will set a new record for the fastest moving object ever built by human beings – traveling at speeds of up to 200 km/sec (124.27 mi/s). And last but not least, it will be exposed to heat and radiation that no spacecraft has ever faced, which will include temperatures in excess of 1371 °C (2500 °F).

As Seamus Tuohy, the Director of the Space Systems Program Office at Draper, said in a CfA press release:

“Such a mission would require a spacecraft and instrumentation capable of withstanding extremes of radiation, high velocity travel and the harsh solar condition—and that is the kind of program deeply familiar to Draper and the Smithsonian Astrophysical Observatory.”

In addition to being an historic first, this probe will provide new data on solar activity and help scientists develop ways of forecasting major space-weather events – which impact life on Earth. This is especially important in an age when people are increasingly reliant on technology that can be negatively impacted by solar flares – ranging from aircraft and satellites to appliances and electrical devices.

According to a recent study by the National Academy of Sciences, it is estimated that a huge solar event today could cause two trillion dollars in damage in the US alone – and places like the eastern seaboard would be without power for up to a year. Without electricity to provide heating, utilities, light, and air-conditioning, the death toll from such an event would be significant.

As such, developing advanced warning systems that could reliably predict when a coronal mass ejection is coming is not just a matter of preventing damage, but saving lives. As Justin C. Kasper, the principal investigator at the Smithsonian Astrophysical Observatory and a professor in space science at the University of Michigan, said:

“[I]n addition to answering fundamental science questions, the intent is to better understand the risks space weather poses to the modern communication, aviation and energy systems we all rely on. Many of the systems we in the modern world rely on—our telecommunications, GPS, satellites and power grids—could be disrupted for an extended period of time if a large solar storm were to happen today. Solar Probe Plus will help us predict and manage the impact of space weather on society.”

To this end, the SPP has three major scientific objectives. First, it will seek to trace the flow of energy that heats and accelerates the solar corona and solar wind. Second, its investigators will attempt to determine the structure and dynamics of plasma and magnetic fields as the source of solar wind. And last, it will explore the mechanisms that accelerate and transport energetic particles – specifically electrons, protons, and helium ions.

To do this, the SPP will be equipped with an advanced suite of instruments. One of the most important of these is the one built by the Smithsonian Astrophysical Observatory with technical support from Draper. Known as the Faraday Cup – and named after famous electromagnetic scientists Michael Faraday – this device will be operated by SAO and the University of Michigan in Ann Arbor.

Designed to withstand interference from electromagnetic radiation, the Farady Cup will measure the velocity and direction of the Sun’s charged particles, and will be only two positioned outside of the SPP’s protective sun shield – another crucial component. Measuring 11.43 cm (4.5 inches) thick, this carbon composition shield will ensure that the probe can withstand the extreme conditions as it conducts its many flybys through the Sun’s corona.

Naturally, the mission presents several challenges, not the least of which will be capturing data while operating within an extreme environment, and while traveling at extreme speeds. But the payoff is sure to be worth it. For years, astronomers have studied the Sun, but never from inside the Sun’s atmosphere.

By flying through the birthplace of the highest-energy solar particles, the SPP is set to advance our understanding of the Sun and the origin and evolution of the solar wind. This knowledge could not only help us avoid a natural catastrophe here on Earth, but help advance our long-term goal of exploring (and even colonizing) the Solar System.

Further Reading: CfA