Special Guest:
This week’s special guest is Brad Peterson. Brad is a returning guest, and since his last appearance, he has been asked by NASA to serve as a community co-chair, with Debra Fischer of Yale, for the Science and Technology Definition Team for the Large Ultraviolet, Optical, and Infrared Surveyor (LUVOIR).
Brad has carried out research on active galactic nuclei for his entire career. He has been developing the technique of reverberation mapping for over 25 years. He is currently on appointment at STScI as Distinguished Visiting Astronomer, after retiring from the faculty of The Ohio State University in 2015 with 35 years of service, the last nine as chair of the Department of Astronomy. He is also a member of the NASA Advisory Council, for which he chairs the Science Committee. He was recently named chair-elect for the Astronomy Section of the AAAS.
We use a tool called Trello to submit and vote on stories we would like to see covered each week, and then Fraser will be selecting the stories from there. Here is the link to the Trello WSH page (http://bit.ly/WSHVote), which you can see without logging in. If you’d like to vote, just create a login and help us decide what to cover!
Announcements:
On Friday, May 12, the WSH will welcome authors Michael Summers and James Trefil to the show to discuss their new book, Exoplanets: Diamond Worlds, Super Earths, Pulsar Planets and the New Search for Life Beyond Our Solar System. In anticipation of their appearance, the WSH Crew is pleased to offer our viewers a chance to win one of two hard cover copies of Exoplanets. Two winners will be drawn live by @fraser during our show on May 12th. To enter for a chance to win a copy of Exoplanets, send an email to: [email protected] with the Subject: Exoplanets. Be sure to include your name and email address in the body of your message so that we can contact the winners afterward. All entries must be electronically postmarked by 23:59 EST on May 10, 2017, in order to be eligible. No purchase necessary. Two winners will be selected at random from all eligible entries. Good luck!
If you’d like to join Fraser and Paul Matt Sutter on their tour to Iceland in February 2018, you can find the information at astrotouring.com.
If you would like to sign up for the AstronomyCast Solar Eclipse Escape, where you can meet Fraser and Pamela, plus WSH Crew and other fans, visit our site linked above and sign up!
If you would like to join the Weekly Space Hangout Crew, visit their site here and sign up. They’re a great team who can help you join our online discussions!
We record the Weekly Space Hangout every Friday at 12:00 pm Pacific / 3:00 pm Eastern. You can watch us live on Universe Today, or the Universe Today YouTube page<
This image of Ceres approximates how the dwarf planet's colors would appear to the eye. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
Sometimes they see it, sometimes they don’t. That’s why scientists have never been completely sure if Ceres has an atmosphere or not. But now data from the Dawn spacecraft — in orbit of Ceres — confirms the dwarf planet really does have a very weak atmosphere, but it comes and goes.
The on-again-off-again nature of Ceres’ atmosphere appears to be linked to solar activity. When energetic particles from the Sun hit exposed ice within the craters on Ceres, the ice can sublimate and create an “exosphere” that lasts for a week or so.
Michaela Villarreal from UCLA, lead author of the new study, and her team wrote in their paper that the “atmosphere appeared shortly after the passage of a large enhancement in the local flux of high-energy solar protons,” and explained that when energetic particles from the Sun hit exposed ice and ice near the surface of the dwarf planet, it transfers energy to the water molecules as they collide. This frees the water molecules from the ground, allowing them to escape and create a tenuous atmosphere.
NASA’s Dawn spacecraft determined the hydrogen content of the upper yard, or meter, of Ceres’ surface. Blue indicates where hydrogen content is higher, near the poles, while red indicates lower content at lower latitudes. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI
A process like this could also be taking place on the Moon, and is likely similar to the process similar to what takes place on comets.
“Our results also have implications for other airless, water-rich bodies of the solar system, including the polar regions of the moon and some asteroids,” said Chris Russell, principal investigator of the Dawn mission, also at UCLA. “Atmospheric releases might be expected from their surfaces, too, when solar activity erupts.”
There have been hints of an atmosphere at Ceres since the early 1990’s. In 1991, the International Ultraviolet Explorer satellite detected hydroxyl emission from Ceres, but not in 1990. Then, in 2007, the European Southern Observatory’s Very Large Telescope searched for a hydroxide emission, but came up empty. The European Space Agency’s Herschel Space Observatory detected water vapor as a possible weak atmosphere, on three occasions, but did not on a fourth attempt.
Dwarf planet Ceres is located in the asteroid belt, between the orbits of Mars and Jupiter. Observations by ESA’s Herschel space observatory between 2011 and 2013 find that the dwarf planet has a thin water-vapour atmosphere. It is the first unambiguous detection of water vapour around an object in the asteroid belt. The inset shows the water absorption signal detected by Herschel on 11 October 2012. Copyright ESA/ATG medialab/Küppers et al.
The Dawn spacecraft itself saw evidence of a transient atmosphere when it arrived at Ceres in March 2015, with data from its Gamma Ray and Neutron Detector instrument. It also has found ample evidence for water in the form of ice, found just underground at higher latitudes, where temperatures are lower. Ice has been detected directly at the small bright crater called Oxo and in at least one of the craters that are persistently in shadow in the northern hemisphere. Other research has suggested that persistently shadowed craters are likely to harbor ice. Additionally, the shapes of craters and other features are consistent with significant water-ice content in the crust.
The team’s research shows the atmosphere doesn’t necessarily show up when Ceres is close to the Sun or when sunlight hits the ice directly, but from energetic particles released by the Sun when its activity level is high. For example, the best detections of Ceres’ atmosphere did not occur at its closest approach to the Sun.
Also, the times where no atmosphere was detected coincided with lower solar activity, so the researchers say this suggests that solar activity, rather than Ceres’ proximity to the Sun, is a more important factor in generating an exosphere.
Ceres actually is now getting closer to the Sun. However, since the Sun appears to be in a very quiet period, Villarreal, Russell and team predict an atmosphere won’t show up, that the dwarf planet will have little to no atmosphere for some time. However, they said both Dawn and other observatories should keep an eye on what’s happening at Ceres.
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.
Images from the Hubble Space Telescope of activated asteroid P/2013P5 where the dust tail can be seen. Source: NASA/ESA.
In the 18th and 19th centuries, astronomers made some profound discoveries about asteroids and comets within our Solar System. From discerning the true nature of their orbits to detecting countless small objects in the Main Asteroid Belt, these discoveries would inform much of our modern understanding of these bodies.
A general rule about comets and asteroids is that whereas the former develop comas or tails as they undergo temperature changes, the latter do not. However, a recent discovery by an international group of researchers has presented another exception to this rule. After viewing a parent asteroid in the Main Belt that split into a pair, they noted that both fragments formed tails of their own.
The reason asteroids do not do behave like comets has a lot to do with where they are situated. Located predominantly in the Main Belt, these bodies have relatively circular orbits around the Sun and do not experience much in the way of temperature changes. As a result, they do not form tails (or halos), which are created when volatile compounds (i.e. nitrogen, hydrogen, carbon dioxide, methane, etc.) sublimate and form clouds of gas.
Images of the P/2016 J1 asteroid pair taken on May 15th, 2016. They show a central region, the asteroid, and a diffuse blot corresponding to the dust tail. Credit: IAA
As astronomical phenomena go, asteroid pairs are quite common. They are created when an asteroid breaks in two, which can be the result of excess rotational speed, impact with another body, or because of the destabilization of binary systems (i.e. asteroid that orbit each other). Once this happens, these two bodies will orbit the Sun rather than being gravitational bound to each other, and progressively drift farther apart.
However, when monitoring the asteroid P/2016 J1, an international team from the Institute of Astrophysics in Andalusia (IAA-CSIC) noticed something interesting. Apparently, both fragments in the pair had become “activated” – that is to say, they had formed tails. As Fernando Moreno, a researcher at IAA-CSIC who led the project, said in an Institute press release:
“Both fragments are activated, i.e., they display dust structures similar to comets. This is the first time we observe an asteroid pair with simultaneous activity… In all likelihood, the dust emission is due to the sublimation of ice that was left exposed after the fragmentation.”
While this is not the first instance where asteroids proved to be an exception to the rule and began forming clouds of sublimated gas around them, this is the first time it was observed happening with an asteroid pair. And it seems that the formation of this tail was in response to the breakup, which is believed to have happened six years ago, during the previous orbit of the asteroid.
An artist’s conception of two tidally locked objects orbiting the Sun from afar (2010 WG9). Credit: zmescience
In 2016, the research team used the Great Telescope of the Canary Islands (GTC) on the island of La Palma and the Canada-France-Hawaii Telescope (CFHT) at Mauna Kea to confirm that the asteroid had formed a pair. Further analysis revealed that the asteroids were activated between the end of 2015 and the beginning of 2016, when they reached the closest point in their orbit with the Sun (perihelion).
This analysis also revealed that the fragmentation of the asteroid and the bout of activity were unrelated. In other words, the sublimation has happened since the breakup and was not the cause of it. Because of this, these objects are quite unique as far as Solar System bodies go.
Not only are they two more exceptions to the rule governing comets and asteroids (there are only about twenty known cases of asteroids forming tales), the timing of their breakup also means that they are the youngest asteroid pair in the Solar System to date. Not bad for a bunch of rocks!
Artist's concept of Trojan asteroids, small bodies that dominate our solar system. Credit: NASA
If we are indeed stardust, then what will our future hold? And what happened to all that other dust that isn’t in people or planets? These are pretty heady questions perhaps best left for late at night. Since the age of Galileo and perhaps even beforehand these inquisitive night goers have sought an understanding of “What’s out there?” Paul Murdin in his book “Rock Legends – the Asteroids and Their Discoverers” doesn’t answer the big questions directly but he does shed some capricious light upon what the night time reveals and what the future may hold.
We’re pretty confident that our solar system evolved from a concentration of dust. Let’s leave aside the question about where the dust came from and assume that, at a certain time and place, there was enough free dust that our Sun was made and so too all the planets. In a nice, orderly universe all the dust would have settled out. However, as we’ve discovered since at least the time of Galileo this didn’t happen. There are a plethora of space rocks — asteroids — out wandering through our solar system.
And this is where Murdin’s book steps up. Once people realized that there more than just a few asteroids out there, they took to identifying and classifying them. The book takes a loosely chronological look at this classification and at our increasing knowledge of the orbits, sizes, densities and composition of these space wanderers.
Fortunately this book doesn’t just simply list discovery dates and characteristics. Rather, it includes significant amounts of its contents on the juicy human story that tags along, especially with the naming. It shows that originally these objects were considered special and refined and thus deserved naming with as much aplomb as the planets; i.e. using Greek and Roman deities. Then the number of discovered asteroids outpaced the knowledge of ancient lore, so astronomers began using the names of royalty, friends and eventually pets. Today with well over a million asteroids identified setting a name to an asteroid doesn’t quite have the same lustre, as the author is quick to point out with his own asteroid (128562) Murdin. Yet perhaps there’s not much else to do while waiting for a computer program to identify a few hundred more accumulations of dust, so naming some of the million nameless asteroids could happily fill in some time.
With the identifying of the early asteroid discoverers and the fun names they chose, this part of the book is quite light and simple. It expands the fun by wandering a bit just like the asteroids. From it you learn of the discovery of palladium, the real spelling of Spock’s name and the meaning of YORP. Sometimes the wandering is quite far, as with the origins of the Palladium Theatre, the squabbling surrounding the naming of Ceres and the status of the Cubewanos. Yet it is this capriciousness that gives the book its flavour and makes it great for a budding astronomer or a reference for a generalist. The occasional bouts of reflection on the future of various asteroids and even of the Earth add a little seriousness to an otherwise pleasant prose.
So if you’re wondering about the next occultation of Eris or the real background of the name (3512) Eriepa then you’re into asteroids. And perhaps you’re learning how to survive on a few hours of sleep so you can search for one more faint orbiting mote. Whether that’s the case or you’re just interested in how such odd names came to represent these orbiting rocks then Paul Murdin’s book “Rock Legends – the Asteroids and Their Discoverers” will be a treat. Read it and maybe you can use it to place your own curve upon an asteroid’s name.
An asteroid strike that could wreak some serious havoc against Earth may be statistically unlikely. But it's not like there's no precedent for one. Artist's Image: . Credit: NASA
Everyone knows it was a large asteroid striking Earth that led to the demise of the dinosaurs. But how many near misses were there? Modern humans have been around for about 225,000 years, so we must have come close to death by asteroid more than once in our time. We would have had no clue.
Of course, it’s the actual strikes that are cause for concern, not near misses. Efforts to predict asteroid strikes, and to catalogue asteroids that come close to Earth, have reached new levels. NASA’s newest tool in the fight against asteroids is called Scout. Scout is designed to detect asteroids approaching Earth, and it just passed an important test. Scout was able to give us 5 days notice of an approaching asteroid.
Here’s how Scout works. A telescope in Hawaii, the Panoramic Survey Telescope & Rapid Response System (Pan-STARRS) detected the asteroid, called 2016 UR36, and then alerted other ‘scopes. Three other telescopes confirmed 2016 UR36 and were able to narrow down its trajectory. They also learned its size, about 5 to 25 meters across.
The Pan STARRS telescope in Hawaii. Image: Institute for Astronomy, University of Hawaii.
After several hours, we knew that UR 36 would come close to us, but was not a threat to impact Earth. UR 36 would pass Earth at a distance of about 498,000 km. That’s about 1.3 times further away than the Moon.
The key part of this is that we had 5 days notice. And five days notice is a lot more than the few hours that we usually have. The approach of 2016 UR36 was the first test for the Scout system, and it passed the test.
Asteroids that come close to Earth are called Near Earth Objects (NEOs) and finding them and tracking them has become a growing concern for NASA. In fact NASA has about 15,000 NEOs catalogued, and they’re still finding about 5 more every night.
NASA is getting much better at discovering and detecting NEOs. Image: NASA/NEO Program.
Not only does NASA have the Scout system, whose primary role is to speed up the confirmation process for approaching asteroids, but they also have the Sentry program. Sentry’s role is a little different.
Sentry’s job is to focus on asteroids that are large enough to wipe out a city and cause widespread destruction. That means NEOs that are larger than about 140 metres. Sentry has over 600 large NEOs catalogued, and astronomers think there are a lot more of them out there.
NASA also has the Planetary Defense Coordination Office (PDCO), which has got to be the greatest name for an office ever. (Can you imagine having that on your business card?) Anyway, the PDCO has the over-arching role of preparing for asteroid impacts. The Office is there to make emergency plans to deal with the impact aftermath.
5 days notice for a small asteroid striking Earth is a huge step for preparedness. Resources can be mobilized, critical infrastructure can be protected, maybe things like atomic power plants can be shut down if necessary. And, of course, people can be evacuated.
We haven’t always had any notice for approaching asteroids. Look at the Chelyabinsk meteor from 2013. It was a 10,000 ton meteor that exploded over the Chelyabinsk Oblast, injuring 1500 people and damaging an estimated 3,000 building in 6 cities. If it had been a little bigger, and reached the surface of the Earth, the damage would have been widespread. 5 days notice would likely have saved a lot of lives.
Smaller asteroids may be too small to detect when they’re very far away. But larger ones can be detected when they’re still 10, 20, even 30 years away. That’s enough time to figure out how to stop them. And if you can reach them when they’re that far away, you only need to nudge them a little to deflect them away from Earth, and maybe to the Sun to be destroyed.
Large asteroids with the potential to cause widespread destruction are the attention-getters. Hollywood loves them. But it may be more likely that we face numerous impacts from smaller asteroids, and that they could cause more damage overall. Scout’s ability to detect these smaller asteroids, and give us several days notice of their approach, could be a life-saver.
An artist’s concept of the Psyche spacecraft, a proposed mission for NASA’s Discovery program that would explore the huge metal Psyche asteroid from orbit. Credit: NASA/JPL-Caltech.
Water has been showing up in all sorts of unexpected places in our Solar System, such as the Moon, Mercury and Jupiter’s moon Ganymede. Add one more place to the list: Asteroid 16 Psyche. This metal-rich asteroid may have traces of water molecules on its surface that shouldn’t be there, researchers say.
Psyche is thought to be the largest metallic asteroid in the Solar System, at 300 km (186 miles) across and likely consists of almost pure nickel-iron metal. Scientists had thought Psyche was made up of the leftover core of a protoplanet that was mostly destroyed by impacts billions of years ago, but they may now be rethinking that.
“The detection of a 3 micron hydration absorption band on Psyche suggests that this asteroid may not be metallic core, or it could be a metallic core that has been impacted by carbonaceous material over the past 4.5 Gyr,” the team said in their paper.
While previous observations of Psyche had shown no evidence for water on its surface, new observations with the NASA Infrared Telescope Facility found evidence for volatiles such as water or hydroxyl on the asteroid’s surface. Hydroxyl is a free radical consisting of one hydrogen atom bound to one oxygen atom.
“We did not expect a metallic asteroid like Psyche to be covered by water and/or hydroxyl,” said Vishnu Reddy, from the University of Arizona’s Lunar and Planetary Laboratory, a co-author of the new paper about Psyche. “Metal-rich asteroids like Psyche are thought to have formed under dry conditions without the presence of water or hydroxyl, so we were puzzled by our observations at first.”
Asteroids usually fall into two categories: those rich in silicates, and those rich in carbon and volatiles. Metallic asteroids like Psyche are extremely rare, making it a laboratory to study how planets formed.
he asteroid Psyche is one of the larger asteroids. Credit: Lindy T. Elkins-Tanton
For now, the source of the water on Psyche remains a mystery. But Redddy and his colleagues propose a few different explanations. One is, again, Psyche may not be as metallic as previously thought. Another option is that the water or hydroxyl could be the product of solar wind interacting with silicate minerals on Psyche’s surface, such as what is occurring on the Moon.
The most likely explanation, however is that the water seen on Psyche might have been delivered by carbonaceous asteroids that impacted Psyche in the distant past, as is thought to have occurred on early Earth.
“Our discovery of carbon and water on an asteroid that isn’t supposed to have those compounds supports the notion that these building blocks of life could have been delivered to our Earth early in the history of our solar system,” said Reddy.
If we’re lucky, we won’t have to wait too long to find out more about Psyche. A mission to Psyche is on the short list of mission proposals being considered by NASA, with a potential launch as early as 2020. Reddy and team said an orbiting spacecraft could explore this unique asteroid and determine if whether there is water or hydroxyl on the surface.
Image of the Martian Moon of Deimos, as imaged by the Mars Reconnaissance Orbiter. Credit: HiRISE/MRO/LPL (U. Arizona)/NASA
Mars and Earth have several things in common. Like Earth, Mars is a terrestrial planet (i.e. composed of silicate rock and minerals). It also has polar ice caps, a tilted axis, and evidence of liquid water on its surface. On top of that, Mars and Earth are the only terrestrial planets in the Solar System to have natural satellites.
In fact, Mars has two satellites, which are appropriately named Phobos and Deimos (named after the Greek gods of horror and terror, respectively). Of the two, Deimos is the smaller moon and orbits at a greater distance from the planet. And like Deimos, it has the characteristics of an asteroid, which is a strong indication of where it may have come from.
Discovery and Naming:
Deimos was discovered in 1877 by American astronomer Asaph Hall, who was deliberately searching for Martian moons at the United States Naval Observatory (USNO). Its name was suggested shortly thereafter by Henry Madan, the Science Master of Eton College, and was derived from Homer’s The Iliad.
Phobos and Deimos, photographed by the Mars Reconnaissance Orbiter. Credit: NASA/JPL
Size, Mass and Orbit:
Deimos has a mean radius of between 6 and 6.38 km (3.73 – 3.96 mi). However, the moon is not a round body, and measures roughly 15 × 12.2 × 11 km (9.32 x 7.58 x 6.835 mi), making it 0.56 times the size of Phobos. At 1.4762 × 1015 kg, or 1.4762 trillion metric tons, Deimos is 1/49,735,808 times as massive as the Moon. As a result, Deimos’ surface gravity is very weak, just 0.003 m/s – or 0.000306 g.
Deimos’ orbit is nearly circular, ranging from 23455.5 km at periapsis (closest) to 23470.9 km at apoapsis (farthest) – which works out to an average distance (semi-major axis) of 23,463.2 km. With an average orbital speed of 1.3513 km/s, it takes 30 hours, 18 minutes and 43.2 seconds to complete a single orbit (or 1.263 days).
Composition and Surface Features:
Deimos, like Phobos, is similar in composition to carbonaceous chondrite and silicate/carbon-rich (C- and D-type) asteroids. Though the surface is cratered, it is considerably smoother than Phobos’ surface, which is due to its craters being filled with regolith.
Only two geological features on Deimos have been given names – the craters of Voltaire and Swift. These features take their names from the famous 17th/18th century French and English writers who speculated about the existence of two Martian moons before they were even discovered.
Image of Deimos captured by HiRISE, showing the craters of Voltaire and Swift in the upper left corner. Credit: NASA/JPL/University of Arizona
Origin:
The origin of Mars’ moons remains unknown, but some hypotheses exist. The most widely-accepted theory states that, based on their similarity to C- or D-type asteroids, they are objects that were kicked out of the Asteroid Belt by Jupiter’s gravity. They were then captured by Mars’ and fell into their current orbits due to atmospheric drag or tidal forces.
However, this theory remains controversial since Mars’ current atmosphere is too thin. As such, it is highly unlikely that it would have been able to cause enough drag to slow either moon down enough for them to have achieved their current orbits. A modified version of this hypothesis is that Phobos and Deimos were once a binary asteroid, which was then captured and separated by tidal forces.
Other popular hypotheses include that they were formed by accretion in their current orbits, or that Mars was once surrounded by many large asteroids which were ejected into orbit it after a collision with a planetesimal – like the one that formed Earth’s Moon. Over time, these would have fallen back to the surface until only Phobos and Deimos remained.
Exploration:
Overall, Deimos history of exploration is tied to that of Mars and Phobos. While no landings have been made on its surface, several have been proposed in the past. The first of these were made as part of the Soviet Phobos (Fobos) program, which involved two probes – Fobos 1 and 2 – that were launched in July of 1988.
If the first proved successful in landing on Phobos, the second would been diverted to make a landing on Deimos. However, the first probe was lost en route to Mars while the second managed to returned some data and images of Phobos surface before contact was lost.
In 1997-1998, NASA selected the proposed Aladdin mission as a finalist for its Discovery Program. The plan was to visit both Phobos and Deimos with sample return missions involving an orbiter and lander. After reaching the surface, the landers would collect samples and then launch them back to the orbiters (which would return them to Earth). However, the mission was passed over in favor of the MESSENGER probe, which was sent to study Mercury.
Other missions have been proposed with are still under study. These include the “Hall” concept proposed in 2008, which calls for a probe that relies on solar-electric propulsion (SEP) to reach Mars and return with samples to Earth. Another was the Gulliver mission, a concept proposed in 2010 which would attempt to retrieve 1 kg (2.2 lbs) of material from Deimos’ surface.
The planners behind the OSIRIS-REx mission have also proposed mounting a second mission that would return samples from Phobos and Deimos. And at the 2014 Lunar and Planetary Science Conference, a proposal was made for a low-cost mission based on the Lunar Atmosphere Dust and Environment Explorer. It is named the Phobos and Deimos & Mars Environment(PADME) mission, and would involve an orbiter being sent to Mars by 2021.
Deimos has been photographed from the surface of Mars by both the Opportunity and Curiosity rovers. And someday, actual astronauts may be able to look up at it from the Martian surface. From their point of view, Deimos would appear like a star to the unaided eye. At its brightest, it might look like Venus does from here on Earth.
For those watching over an extended period of time, Deimos would pass directly in front of the Sun quite regularly. It’s too small to cause a total eclipse, it would look like a black dot moving across the face of the Sun.
If you’ve seen at least one other episode of the Guide to Space, you know I’m obsessed about the Fermi Paradox. This idea that the Universe is big and old, and should be teeming with life. And yet, we have no evidence that it exists out there. We wonder, where are all the aliens?
Ah well, maybe we’re in a cosmic zoo, or maybe the Universe is just too big, or the laws of physics prevent any kind of meaningful travel or communications. Fine. I doubt it, but fine.
United Launch Alliance Atlas V rocket lifts off from Space Launch Complex 41 at Cape Canaveral Air Force Station carrying NASA’s Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer, or OSIRIS-REx spacecraft on the first U.S. mission to sample an asteroid, retrieve at least two ounces of surface material and return it to Earth for study. Liftoff was at 7:05 p.m. EDT on September 8, 2016 in this remote camera view taken from inside the launch pad perimeter. Note the newly install crew access arm and white room for astronaut flights atop Atlas starting in early 2018. Credit: Ken Kremer/kenkremer.com
United Launch Alliance Atlas V rocket lifts off from Space Launch Complex 41 at Cape Canaveral Air Force Station carrying NASA’s Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer, or OSIRIS-REx spacecraft on the first U.S. mission to sample an asteroid, retrieve at least two ounces of surface material and return it to Earth for study. Liftoff was at 7:05 p.m. EDT on September 8, 2016 in this remote camera view taken from inside the launch pad perimeter. Note the newly installed crew access arm and white room for astronaut flights atop Atlas starting in early 2018. Credit: Ken Kremer/kenkremer.com
KENNEDY SPACE CENTER, FL – Bound for Bennu, NASA’s OSIRIS-REx robotic explorer began a trailblazing 7 year round trip sampling sortie on Sept. 8 in search of the origin of life with a spectacular sky show – thrilling spectators ringing the Florida Space Coast.
Hordes of space enthusiasts from all across the globe descended on the Kennedy Space Center and Cape Canaveral region for the chance of a lifetime to witness a once in a lifetime liftoff to the carbon rich asteroid – which could potentially bring back samples infused with the organic chemicals like amino acids that are the building blocks of life as we know it.
NASA’s Origins, Spectral Interpretation, Resource Identification, Security – Regolith Explorer (OSIRIS-REx) spacecraft departed Earth with an on time engine ignition of a United Launch Alliance Atlas V rocket under crystal clear skies on Thursday, September 8 at 7:05 p.m. EDT from Space Launch Complex 41 at Cape Canaveral Air Force Station.
Blastoff of NASA’s OSIRIS-Rex asteroid sampling spacecraft on September 8, 2016 from Cape Canaveral Air Force Station, FL as seen from Playalinda Beach. Credit: Jillian Laudick
Everything went exactly according to plan for the daring mission bolding seeking to gather rocks and soil from Bennu – using an ingenious robotic arm named TAGSAM – and bring at least a 60-gram (2.1-ounce) sample back to Earth in 2023 for study by scientists using the world’s most advanced research instruments.
“We got everything just exactly perfect,” said Dante Lauretta, the principal investigator for OSIRIS-REx at the University of Arizona, at the post launch briefing at the Kennedy Space Center. “We hit all our milestone within seconds of predicts.
The space rock measures about the size of a small mountain at about a third of a mile in diameter.
And the picture perfect near sunset launch rewarded photographers from near and far with a spectacular series of richly hued photo and video recordings.
So I’ve gathered here a variety of launch imagery from multiple vantage points shot by friends, colleagues and myself – for the enjoyment of readers of Universe Today and Beyond!
Liftoff of NASA’s OSIRIS-Rex asteroid sampling spacecraft on September 8, 2016 from Cape Canaveral Air Force Station, FL. Credit: Julian Leek
As you’ll see and hear the ULA Atlas V rocket integrated with OSIRIS-Rex on top thundered off the Cape’s pad 41 and shot skyward straight up along an equatorial path into Florida’s sun.
From every vantage point the rocket and its ever expanding vapor trail were visible for some 4 or 5 minutes or more. From my location on the roof of NASA’s Vehicle Assembly Building (VAB) the rocket finally arched over nearly straight above us and the sun produced a magnificent thin and nearly straight shadow of the vapor trail on the ground running out to the Atlantic Ocean towards Africa.
Blastoff of NASA’s OSIRIS-Rex asteroid sampling spacecraft on September 8, 2016 from Cape Canaveral Air Force Station, FL as seen from Playalinda Beach. Credit: John Kraus
It was truly an unforgettable sight to behold. And folks at Playalinda Beach, the best public viewing spot just a few miles north of pad 40 had an uninhibited view of the rocket to the base of the pad – while they waded and swam in the oceans waters with waves crashing on shore as the Atlas rocket blasted to space.
OSIRIS-REx separated as planned from the Atlas V rockets liquid oxygen and liquid hydrogen fueled second stage rocket to fly free at 8:04 p.m. on Sept. 8 – 55 minutes after launch.
The pair of solar arrays deployed as planned to provide the probes life giving power.
The spacecraft was built by prime contractor Lockheed.
“The spacecraft is healthy and functioning properly,” Richard Kuhns, Lockheed Martin OSIRIS-REx program manager, told me in an interview at the post-launch briefing.
Members of the OSIRIS-REx mission team celebrate the successful spacecraft launch on Sept. 8, 2016 atop ULA Atlas V at the post-launch briefing at the Kennedy Space Center, FL. Principal Investigator Dante Lauretta is 4th from right, NASA Planetary Science Director Jim Green is center, 5th from left. Richard Kuhns, Lockheed Martin OSIRIS-REx program manager, 2nd from right. Credit: Ken Kremer/kenkremer.com
“The primary objective of the OSIRIS-Rex mission is to bring back pristine material from the surface of the carbonaceous asteroid Bennu, OSIRIS-Rex Principal Investigator Dante Lauretta told Universe Today in a prelaunch interview in the KSC cleanroom with the spacecraft as the probe was undergoing final preparations for shipment to the launch pad.
“We are interested in that material because it is a time capsule from the earliest stages of solar system formation.”
“It records the very first material that formed from the earliest stages of solar system formation. And we are really interested in the evolution of carbon during that phase. Particularly the key prebiotic molecules like amino acids, nucleic acids, phosphates and sugars that build up. These are basically the biomolecules for all of life.”
The asteroid is 1,614-foot (500 m) in diameter and crosses Earth’s orbit around the sun every six years.
After a two year flight through space, including an Earth swing by for a gravity assisted speed boost in 2017, OSIRIS-REx will reach Bennu in Fall 2018 to begin about 2 years of study in orbit to determine the physical and chemical properties of the asteroid in extremely high resolution.
While orbiting Bennu starting in 2018 it will move in close to explore the asteroid for about two years with its suite of science instruments, scanning in visible and infrared light. After a thorough site selection, it will move carefully towards the surface and extend the 11 foot long TAGSAM robotic arm and snatch pristine soil samples containing organic materials from the surface using the TAGSAM collection dish over just 3 to 5 seconds.
Once a good sample collection is confirmed, the dish will then be placed inside the Earth return canister and be brought back to Earth for study by researchers using all of the most sophisticated science instruments available to humankind.
Using the 11 foot long TAGSAM robotic arm that functions somewhat like a pogo stick, OSIRIS-REx will gather rocks and soil and bring at least a 60-gram (2.1-ounce) sample back to Earth on Sept 24, 2023. It has the capacity to scoop up to about 2 kg or more.
ULA Atlas V rocket lifts off on September 8, 2016 from Space Launch Complex 41 at Cape Canaveral Air Force Station carrying NASA’s OSIRIS-REx asteroid sampling spacecraft, in this remote camera view taken from inside the launch pad perimeter. Credit: Ken Kremer/kenkremer.com
The two stage ULA Atlas V performed flawlessly and delivered OSIRIS-Rex into a hyperbolic trajectory away from Earth.
The 189 foot tall ULA Atlas V rocket launched in the rare 411 configuration for only the 3rd time on this mission – which is the 65th for the Atlas V.
The Atlas 411 vehicle includes a 4-meter diameter large Payload Fairing (PLF) and one solid rocket booster that augments the first stage. The Atlas booster for this mission is powered by the RD AMROSS RD-180 engine and the Centaur upper stage was powered by the Aerojet Rocketdyne RL10A.
The RD-180 burns RP-1 (Rocket Propellant-1 or highly purified kerosene) and liquid oxygen and delivers 860,200 lb of thrust at sea level.
The strap on solid delivers approximately 348,500 pounds of thrust.
The Centaur delivers 22, 230 lbf of thrust and burns liquid oxygen and liquid hydrogen.
The solid was jettisoned at 139 seconds after liftoff.
Launch of NASA’s OSIRIS-REx on September 8, 2016 from Cape Canaveral Air Force Station, FL as seen from LC-39 Gantry. Credit: Jen Saxby
This is ULA’s eighth launch in 2016 and the 111th successful launch since the company was formed in December 2006.
NASA’s OSIRIS-REx blasts off to asteroid Bennu on ULA Atlas V rocket prior on Sept. 8, 2016 from Space Launch Complex 41 on Cape Canaveral Air Force Station, FL, as seen from the VAB roof. Credit: Lane Hermann/SpaceHeadNews
OSIRIS-REx will return the largest sample from space since the American and Soviet Union’s moon landing missions of the 1970s.
Watch these pair of up close videos (from myself and Jeff Seibert) captured directly at the pad with the sights and sounds of the fury of launch:
Video Caption: ULA Atlas V rocket lifts off on September 8, 2016 from Space Launch Complex 41 at Cape Canaveral Air Force Station carrying NASA’s OSIRIS-REx asteroid sampling spacecraft, in this remote camera view taken from inside the launch pad perimeter. Credit: Ken Kremer/kenkremer.com
Video Caption: Compilation of my launch videos from the ULA Atlas 5 launch in support of the NASA OSIRIS_REx asteroid sample return mission to the asteroid Bennu (#101955). It was launched on September 8th, 2016 from Pad 41 of CCAFS. It is scheduled to land in UTAH with asteroid samples on September 24, 2023. Credit: Jeff Seibert
OSIRIS-REx is the third mission in NASA’s New Frontiers Program, following New Horizons to Pluto and Juno to Jupiter, which also launched on Atlas V rockets.
NASA’s Goddard Space Flight Center in Greenbelt, Maryland, is responsible for overall mission management.
OSIRIS-REx complements NASA’s Asteroid Initiative – including the Asteroid Redirect Mission (ARM) which is a robotic spacecraft mission aimed at capturing a surface boulder from a different near-Earth asteroid and moving it into a stable lunar orbit for eventual up close sample collection by astronauts launched in NASA’s new Orion spacecraft. Orion will launch atop NASA’s new SLS heavy lift booster concurrently under development.
Launch of NASA’s OSIRIS-REx on September 8, 2016 from Cape Canaveral Air Force Station, FL as seen from VAB roof. Credit: J.Sekora/SEKORAPHOTO
Watch for Ken’s continuing OSIRIS-REx mission and launch reporting from on site at the Kennedy Space Center and Cape Canaveral Air Force Station, FL.
Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.
NASA’s OSIRIS-Rex asteroid sampling spacecraft streaks to orbit on September 8, 2016 from Cape Canaveral Air Force Station, FL as seen from Playalinda Beach. Credit: Jillian Laudick
Liftoff of NASA’s Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer, or OSIRIS-Rex asteroid sampling spacecraft on September 8, 2016 from Cape Canaveral Air Force Station, FL. Credit: Ken Kremer/kenkremer.com
A United Launch Alliance Atlas V rocket lifts off from Space Launch Complex 41 at Cape Canaveral Air Force Station carrying NASA’s Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer, or OSIRIS-REx spacecraft on the first U.S. mission to sample an asteroid, retrieve at least two ounces of surface material and return it to Earth for study. Liftoff was at 7:05 p.m. EDT on September 8, 2016. Credit: Ken Kremer/kenkremer.com
View of science instrument suite and TAGSAM robotic sample return arm on NASA’s OSIRIS-REx asteroid sampling spacecraft inside the Payloads Hazardous Servicing Facility at NASA’s Kennedy Space Center. Probe is slated for Sep. 8, 2016 launch to asteroid Bennu from Cape Canaveral Air Force Station, FL. Credit: Ken Kremer/kenkremer.com
