Observations of Comet Siding Spring Oct. 19 by the Mars Orbiter Mission. Credit: Indian Space Research Organisation
Feeling lucky? Events such as the Comet Siding Spring approach by Mars in October only happen about once every eight million years, according to NASA.
And after we were treated to spectacular views from the agency’s spacecraft (see Curiosity and Opportunity and MAVEN, for example), we now have fresh pictures this month from an Indian mission. Also, NASA has released science results suggesting that the chemistry of Mars’ atmosphere could be changed forever from the close encounter.
“The image in the center shows a streak … radiating out of the comet’s nucleus (out of frame), possibly indicating the jet from [the] comet’s nucleus,” the Indian Science Research Organisation wrote of the above image sequence on its Facebook mission page.
“Usually jets represent outgassing activity from [the] vents of the comet-nucleus, releasing dust and ice crystals. The outgassing activity gradually increases as the comet moves closer to the Sun.”
Artist view of the comet passing closest to Mars this Sunday. At the time, the Mars orbiters from the U.S., Europe and India will be huddled on the opposite side of the planet to avoid possible impacts from comet dust. Credit: NASA
The comet’s dust likely produced a meteor shower or meteor storm when particles from it crashed into the upper atmosphere, which “literally changed the chemistry,” added Jim Green, director of NASA’s planetary science division, in a recent discussion highlighted on an agency blog.
The agency says the dust created vaporized metals, which will eventually transform to dust or “meteoric smoke.” MAVEN (which stands for Mars Atmosphere and Volatile EvolutioN) will be monitoring the long-term effects. Possible results include high-altitude clouds or at the most extreme, maybe permanently altering what the chemistry of the atmosphere is. Not a bad thing for a mission to study shortly after it arrived at Mars.
You can view more science results from NASA’s studies of Siding Spring in this recent Universe Today story from Bob King, which talks in more detail about the meteor shower, new layers in the Mars atmosphere and the omnipresent dust.
The Opportunity rover's view on Sol 3,839 on Nov. 11, 2014, shortly after it pushed past 41 kilometers (nearly 28.5 miles) of driving on the Red Planet. Credit: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ. (panorama: Elizabeth Howell)
And even as the rover works through aging problems, the science team is still able to push it further — it just crested 41 kilometers (25.48 miles) on Sol Sol 3,836 (around Nov. 9)! Check out some recent pictures from the rover below.
The NASA machine is roaming the west edge of Endeavour Crater on its way to an area nicknamed “Marathon Valley”, which could contain clay minerals. Clays are considered a sign of water being in a region in the ancient past, which feeds into NASA’s ongoing search for habitable environments on Mars.
By the way, Opportunity is now just shy of a marathon’s worth of driving on Mars (which would be 26 miles, or 41.8 kilometers). In the meantime, we’ve collected some raw images from Opportunity to share. What new horizons will the plucky rover find next, as it draws close to its 11th anniversary on Mars in January?
The Opportunity rover continues to make tracks after passing 41 kilometers (28.5 miles) on Mars. View from Sol 3,846 in November 2014. Credit: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ.Solar panels from the Opportunity Mars rover shine against the mottled ground on Sol 3,846 in November 2014. Credit: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ.The wind-swept plains of Mars as seen by the Opportunity rover on Sol 3,846 in November 2014. Credit: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ.A close-up of the cracked Martian ground taken by the Opportunity rover on Sol 3,846 in November 2014. Credit: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ.The shadow of the Opportunity rover (bottom) lies dark against Mars ground on Sol 3,841 in November 2014. Credit: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ.
The Mars Society prototype habitat in Utah conducts studies on what it would be like to live on Mars.
Credit: Mars Society MRDS
If you wanna get humans to Mars, there are so many technical hurdles in the way that it will take a lot of hard work. How to help people survive for months on a hostile surface, especially one that is bathed on radiation? And how will we keep those people safe on the long journey there and back?
NASA is greatly concerned about the radiation risk, and is asking the public for help in a new challenge as the agency measures radiation with the forthcoming uncrewed Orion test flight in December. There’s $12,000 up for grabs across at least a few awards, providing you get your ideas into the agency by Dec. 12.
“One of the major human health issues facing future space travelers venturing beyond low-Earth orbit is the hazardous effects of galactic cosmic rays (GCRs),” NASA wrote in a press release.
“Exposure to GCRs, immensely high-energy radiation that mainly originates outside the solar system, now limits mission duration to about 150 days while a mission to Mars would take approximately 500 days. These charged particles permeate the universe, and exposure to them is inevitable during space exploration.”
Orion in orbit in this artists concept. Credit: NASA
Here’s an interesting twist, too — more data will come through the Orion test flight as the next-generation spacecraft aims for a flight 3,600 miles (5,800 kilometers) above Earth’s surface. That’s so high that the vehicle will go inside a high-radiation environment called the Van Allen Belts, which only the Apollo astronauts passed through in the 1960s and 1970s en route to the Moon.
While a flight to Mars will also just graze this area briefly, scientists say the high-radiation environment will give them a sense of how Orion (and future spacecraft) perform in this kind of a zone. So the spacecraft will carry sensors on board to measure overall radiation levels as well as “hot spots” within the vehicle.
You can find out more information about the challenge, and participation details, at this link.
Credit: NASA/MRO/Rendering: James Dickson, Brown University
Though the surface of Mars is a dry, dessicated and bitterly cold place today, it is strongly believed that the planet once had rivers, streams, lakes, and flowing water on its surface. Thanks to a combination of spacecraft imagery, remote sensing techniques and surface investigations from landers and rovers, ample evidence has been assembled to support this theory.
However, it is hard to reconcile this view with the latest climate models of Mars which suggest that it should have been a perennially cold and icy place. But according to a new study, the presence of warm, flowing water may have been an episodic occurrence, something that happened for decades or centuries when the planet was warmed sufficiently by volcanic eruptions and greenhouse gases.
The study, which was conducted by scientists from Brown University and Israel’s Weizmann Institute of Science, suggests that warmth and water flow on ancient Mars were probably episodic, related to brief periods of volcanic activity that spewed tons of greenhouse-inducing sulfur dioxide gas into the atmosphere.
The work combines the effect of volcanism with the latest climate models of early Mars and suggests that periods of temperatures warm enough for water to flow likely lasted for only tens or hundreds of years at a time.
The notion that Mars had surface water predates the space age by centuries. Long before Percival Lowell observed what he thought were “canals” on the Martian surface in 1877, the polar ice caps and dark spots on the surface were being observed by astronomers who thought that they were indications of liquid water.
Curiosity found evidence of an ancient, flowing stream on Mars at a few sites, including the “Hottah” rock outcrop pictured here. Credit: NASA/JPL
But with all that’s been learned about Mars in recent years, the mystery of the planet’s ancient water has only deepened. The latest generation of climate models for early Mars suggests that the atmosphere was too thin to heat the planet enough for water to flow. Billions of years ago, the sun was also much dimmer than it is today, which further complicates this picture of a warmer early Mars.
“These new climate models that predict a cold and ice-covered world have been difficult to reconcile with the abundant evidence that water flowed across the surface to form streams and lakes,” said James W. Head, professor of earth, environmental and planetary sciences at Brown University and co-author of the new paper with Weizmann’s Itay Halevy. “This new analysis provides a mechanism for episodic periods of heating and melting of snow and ice that could have each lasted decades to centuries.”
Halevy and Head explored the idea that heating may have been linked to periodic volcanism. Many of the geological features that suggest water was flowing on the Martian surface have been dated to 3.7 billion years ago, a time when massive volcanoes are thought to have been active.
And whereas on Earth, widespread volcanism has often led to global dimming rather than warming – on account of sulfuric acid particles reflecting the sun’s rays – Head and Halevy think the effects may have been different in Mars’ dusty atmosphere.
To test this theory, they created a model of how sulfuric acid might react with the widespread dust in the Martian atmosphere. The work suggests that those sulfuric acid particles would have glommed onto dust particles and reduced their ability to reflect the sun’s rays. Meanwhile, sulfur dioxide gas would have produced enough greenhouse effect to warm the Martian equatorial region so that water could flow.
Image of the McMurdo Dry Valleys, Antarctica, acquired by Landsat 7’s Enhanced Thematic Mapper plus (ETM+) instrument. Credit: NASA/EO
Head has been doing fieldwork for years in Antarctica and thinks the climate on early Mars may have been very similar to what he has observed in the cold, desert-like.
“The average yearly temperature in the Antarctic Dry Valleys is way below freezing, but peak summer daytime temperatures can exceed the melting point of water, forming transient streams, which then refreeze,” Head said. “In a similar manner, we find that volcanism can bring the temperature on early Mars above the melting point for decades to centuries, causing episodic periods of stream and lake formation.”
As that early active volcanism on Mars ceased, so did the possibility of warmer temperatures and flowing water.
According to Head, this theory might also help in the ongoing search for signs that Mars once hosted life. If it ever did exist, this new research may offer clues as to where the fossilized remnants ended up.
“Life in Antarctica, in the form of algal mats, is very resistant to extremely cold and dry conditions and simply waits for the episodic infusion of water to ‘bloom’ and develop,” he said. “Thus, the ancient and currently dry and barren river and lake floors on Mars may harbor the remnants of similar primitive life, if it ever occurred on Mars.”
MAVEN's Ultraviolet Imaging Spectrograph (IUVS) uses limb scans to map the chemical makeup and vertical structure across Mars' upper atmosphere. It detected strong enhancements of magnesium and iron from ablating incandescing dust from Comet Siding Spring. Credit: NASA
NASA’s newest Mars spacecraft is “go” for at least a year — and potentially longer. After taking a time-out from commissioning to observe Comet Siding Spring whizz by the Red Planet in October, the Mars Atmosphere and Volatile Evolution (MAVEN) officially began its science mission Monday (Nov. 17). And so far things are going well.
“From the observations made both during the cruise to Mars and during the transition phase, we know that our instruments are working well,” stated principal investigator Bruce Jakosky, who is with NASA’s Goddard Space Flight Center in Maryland. “The spacecraft also is operating smoothly, with very few ‘hiccups’ so far. The science team is ready to go.”
MAVEN arrived in orbit Sept. 16 after facing down and overcoming a potential long delay for its mission. NASA and other federal government departments were in shutdown while MAVEN was in final launch preparations, but the mission received a special waiver because it is capable of communicating with the rovers on Mars. Given the current relay spacecraft are aging, MAVEN could serve as the next-generation spacecraft if those ones fail.
Three views of an escaping atmosphere, obtained by MAVEN’s Imaging Ultraviolet Spectrograph. By observing all of the products of water and carbon dioxide breakdown, MAVEN’s remote sensing team can characterize the processes that drive atmospheric loss on Mars. Image Credit: University of Colorado/NASA
But that’s providing that MAVEN can last past the next year in terms of hardware and funding. Meanwhile, its primary science mission is better understanding how the atmosphere of Mars behaves today and how it has changed since the Red Planet was formed.
“The nine science instruments will observe the energy from the Sun that hits Mars, the response of the upper atmosphere and ionosphere, and the way that the interactions lead to loss of gas from the top of the atmosphere to space,” Jakosky added.
“Our goal is to understand the processes by which escape to space occurs, and to learn enough to be able to extrapolate backwards in time and determine the total amount of gas lost to space over time. This will help us understand why the Martian climate changed over time, from an early warmer and wetter environment to the cold, dry planet we see today.”
It's not much, but it's the clearest view taken by NASA's Curiosity Rover of C/2013 A1 Siding Spring as it passed near Mars on October 19th. The comet is the fuzzy streak moving from right to left. Click for a full-sized view. Credit: NASA/JPL-Caltech/MSSS/TAMU
NASA’s Curiosity Rover spends most of its time staring at the ground, but like humans, it looks up once in a while too. As reported earlier, NASA ground controllers pointed the rover’s Mast Camera (mastcam) skyward to shoot a series of photos of Comet Siding Spring when it passed closest to the Red Planet on October 19th. Until recently, noise-speckled pictures available on the raw image site confounded interpretation. Was the comet there or wasn’t it? In these recently released versions, the fuzzy intruder is plain to see, tracking from right to left across the field of view.
Remember the monster sunspot group on bold display during last month’s partial solar eclipse? It was the largest group of the current solar cycle and largest recorded in 24 years. Here it is again (lower left) – returning for a second time – as seen by Curiosity on November 10th. Click for raw version. Credit: NASA/JPL-Caltech
Ten exposures of 25 seconds each were taken between 4:33 p.m. and 5:54 p.m. CDT on October 19th to create the animation. The few specks you see are electronic noise, but the sharp, bright streaks are stars that trailed during the time exposure. Curiosity’s Mastcam camera system has dual lenses – a 100mm f/10 lens with a 5.1° square field of view and a 34mm, f/8 lens with a 15° square field of view. NASA didn’t include the information about which camera was used to make the photos, but if I had to guess, the faster, wide-angle view would be my choice. Siding Spring was moving relatively quickly across the Martian sky at closest approach.
Sunspot region 2192 (lower left) has returned for an encore in this photo taken by NASA’s Solar Dynamics Observatory. The same group is visible in images taken 4 days earlier from Mars. Credit: NASA/SDO
Prowling through the Curiosity raw image files, I came across this photo of the Sun on November 10th. Three dark spots at the left are immediately obvious and a dead-ringer for Active Region 2192, now re-named 2209 as it rounds the Sun for Act II. You’ll recall this was the sunspot group that nearly stole the show during the October 23rd partial solar eclipse. From Mars’ perspective, which currently allows Curiosity to see further around the solar “backside”, AR 2209 showed up a few days before it was visible from Earth.
Because of Mars’ position relative to the Sun, Curiosity saw the return of sunspot group 2192 before it was visible from Earth. The Sun had to rotate about another 4 days to carry the group into Earth’s line of sight. Source: Solarsystemscope with additions by the author
Although it’s slimmed down in size, the region is still large enough to view with the naked eye through a safe solar filter. More importantly, it possesses a complex beta-gamma-delta magnetic field where magnetic north and south poles are in close proximity and ripe for reconnection and production of M-class and X-class flares. Already, the region’s crackled with three moderate M-class flares over the past two days. In no mood to take a back seat, AR 2209 continues to dominate solar activity even during round two.
Phobos is very small but orbits close enough for someone on the surface to see its shape with the naked eye, especially when it’s high in the sky and closest to the observer. Phobos is about 1/3 the size of our Moon. This photo was taken by Curiosity on October 20th and shows the moon’s largest crater, Stickney, at top. Credit: NASA/JPL-Caltech with toning by the author to bring out details
Mars possesses two small moons, Deimos and Phobos. Curiosity has photographed them both before including an occultation Deimos (9 miles/15 km) by the larger Phobos (13.5 miles/22 km). Phobos orbits closer to Mars than any other moon does to its primary in the Solar System, just 3,700 miles (6,000 km). As a result, it moves too fast for Mars’ rotation to overtake it the way Earth’s rotation overtakes the slower-moving Moon, causing it to set in the west overnight. Contrarian Phobos rises in the western sky and sets in the east just 4 hours 15 minutes later. When nearest the horizon and farthest from an observer, it’s apparent size is just 0.14º. At the zenith it grows to 0.20º of 1/3 the diameter of the Moon.
Phobos occults Deimos in real time photographed by the Curiosity Rover on August 1, 2013. Credit: NASA/JPL-Caltech
One longish observing session on the planet would cover a complete rise-set cycle during which Phobos would first appear as a crescent and finish up a full moon a few hours later. All this talk about Phobos is only meant to direct you to the picture above taken by Curiosity on October 20, 2014 when the moon was a thick crescent. As on Earth, where Earthshine fills out the remainder of the crescent Moon, so too does Mars-shine provide enough illumination to see the full outline of Phobos.
Four-wheel drive only! Curiosity took this photo showing a sea of dark dunes from the Pahrump Hills outcrop on November 13th. Credit: NASA/JPL-Caltech
Curiosity has also photographed Earth, sunsets and transits of Phobos across the Sun while rambling across the dusty red landscape since August 2012. Before we depart, it seems only fair to aim our gaze Mars-ward again to see what’s up. Or down. The rover’s been doing a geological “Walkabout” in the Pahrump Hills outcrop at the base of Mt. Sharp in Gale Crater since September. Earlier this fall it drilled and sampled rock there containing more hematite than at any of its previous stops. Hematite is an iron oxide that’s often associated with water.
The mission may spend weeks or months at the outcrop looking for and drilling new target rocks before moving further up the geological layer cake better known as Mt. Sharp.
As of November 2014, these are all of the planetary, lunar and small body surfaces where humanity has either lived, visited, or sent probes to. Composition by Mike Malaska, updated by Michiel Straathof. Image credits: Comet 67P/C-G [Rosetta/Philae]: ESA / Rosetta / Philae / CIVA / Michiel Straathof. Asteroid Itokawa [Hayabusa]: ISAS / JAXA / Gordan Ugarkovic. Moon [Apollo 17]: NASA. Venus [Venera 14]: IKI / Don Mitchell / Ted Stryk / Mike Malaska. Mars [Mars Exploration Rover Spirit]: NASA / JPL / Cornell / Mike Malaska. Titan [Cassini-Huygens]: ESA / NASA / JPL / University of Arizona. Earth: Mike Malaska
Correction, 11:33 a.m. EST: The University of Central Florida’s Phil Metzger points out that the image composition leaves out Eros, which NEAR Shoemaker landed on in 2001. This article has been corrected to reflect that and to clarify that the surfaces pictured were from “soft” landings.
And now there are eight. With Philae’s incredible landing on a comet earlier this week, humans have now done soft landings on eight solar system bodies. And that’s just in the first 57 years of space exploration. How far do you think we’ll reach in the next six decades? Let us know in the comments … if you dare.
More seriously, this amazing composition comes courtesy of two people who generously compiled images from the following missions: Rosetta/Philae (European Space Agency), Hayabusa (Japan Aerospace Exploration Agency), Apollo 17 (NASA), Venera 14 (Soviet Union), the Spirit rover (NASA) and Cassini-Huygens (NASA/ESA). Omitted is NEAR Shoemaker, which landed on Eros in 2001.
Before Philae touched down on Comet 67P/Churyumov–Gerasimenko Wednesday, the NASA Jet Propulsion Laboratory’s Mike Malaska created a cool infographic of nearly every place we’ve lived or visited before then. This week, Michiel Straathof updated the infographic to include 67P (and generously gave us permission to use it.)
And remember that these are just the SURFACES of solar system bodies that we have visited. If you include all of the places that we have flown by or taken pictures from of a distance in space, the count numbers in the dozens — especially when considering prolific imagers such as Voyager 1 and Voyager 2, which flew by multiple planets and moons.
To check out a small sampling of pictures, visit this NASA website that shows some of the best shots we’ve taken in space.
A mock-up of a future Chinese Martian rover was displayed at the International Industry Fair in Shanghai (Credit: South China Morning Post)
For many space-faring nations, ambitions for Mars run broad and deep. Now, add China to the list of countries with Mars in their sights. News reports from China disclosed that country is considering a future Mars rover mission, with a potential 2020 launch date. Additionally came other hints that China may be looking to develop a next-generation heavy-lift launch system.
This new project, while early in development, reveals how Chinese aspirations are growing rapidly. Human space flight successes have been followed by recent lunar mission successes of the Yutu lunar rover and the Chang’e-5 T1 test of a sample return mission. The Chinese Mars missions could influence future plans of ESA, India and NASA or more simply raise the urgency to execute missions in concept or early development without hesitation.
China View reporter Lai Yuchen is seen describing and pointing out the future Sino-Mars rover with plans for a 2020 launch coinciding with the NASA/JPL Mars 2020 rover mission . (Click still image for video Link) (Photo/Video Credit: China View)
The Mars rover mock-up display was presented at the aerospace show by China Aerospace Science and Technology Corporation (CASC). The design appears similar to the Yutu rover which landed successfully on the Moon late in 2013. While Yutu’s mobility system failed prematurely, many mission milestones were achieved.
The Mars rover design is significantly larger than Yutu but includes changes that can be attributed to the challenges of roving Mars at tens of millions of kilometers distance and under more gravitational force. The wheels are beefed up, since it must withstand more force and rugged martian terrain (gravity on Mars is 37% of the Earth’s in strength but 2.25 times the strength of gravity on the Moon’s surface.) The the solar panels are larger due to 1.) less sunlight at Mars – 35% to 50% of Earth’s, and 2.) more electrically demanding instruments.
The goals of the Chinese Mars rover will be to search for life and water. The NASA missions searching for indicators of habitable environments and for water has cost billions of dollars but the Chinese space program is operating on a fraction of what NASA’s annual budget is. Whereas the Chinese Mars program will be competing with the lunar program for government funds, it remains to be seen how quickly they can make progress and actually meet milestones for a 2020 launch date.
Besides video of the China View reporter presenting and discussing the Mars rover (link to photo above), the video also includes a simulation of the Chinese lunar sample return spacecraft, which is underdevelopment and was tested early this month during a the Chang’e-5 T1 circum-lunar mission that proved a small re-entry vehicle.
The future Chinese rover would be nearly as large as the MER rovers. Full scale models of all three NASA/JPL Mars rovers are shown here – Mars Pathfinder, MER and MSL in a JPL Mars yard with engineers. (Photo Credit: NASA/JPL)
The actual dimensions of this rover were not reported but an estimate of the size can be determined by the size of the high-gain directional antenna. Assuming it is an X-Band dish, like the one on the MER Rovers and Curiosity, then this Sino-rover would be near the same size as the MER rovers – Spirit and Opportunity. The Sino-rover shares a six wheel design like MER and MSL rovers.
Other reports from the China Daily indicated that industry leaders in China are urging China’s space agency to develop a more powerful heavy-lift launch system. It could be used for the nation’s human spaceflight goals to send a space station in to orbit, as well as send missions to Mars and beyond.
“It is a must for us to develop a more powerful heavy-lift rocket if we want to reach and explore deep space,” Zhang Zhi, a senior rocket researcher at the China Academy of Launch Vehicle Technology the aerospace exhibition.
Plans also call for an orbiter to likely function as a communication relay as MGS, Mars Odyssey and MRO have done for the American rovers. Whether this would involve a single spacecraft such as the NASA Vikings or dual crafts such as the present American rovers with supporting orbiters is unknown. Given the successful landing of the Yutu rover encapsuled in a soft-lander, one might expect the same for the Chinese Mars rover rather than an airbag landing used by MER. Either way, they will be challenged by the seven minutes of terror just like the American rovers. They will have to solve for themselves the entry, descent and landing of a rover. Only American-made rovers have successfully landed on Mars; all Russian attempts have ended in failure.
The Chinese Lunar Sample Return mission is show in simulation in the China View video. This mission would pave the way for a Chinese Mars sample return by 2030. (Photo Credit: China View)
The presentation also stated future plans for a sample-return mission by 2030. If the first Chineses Mars rover lands successfully in 2020, it will join up to four active rovers on the surface. Curiosity, ExoMars (ESA/NASA), Mars Rover 2020 and MER Opportunity. Six years seems like a long time but MER’s Oppy is a proven trooper having lasted over ten years. Curiosity, barring the unexpected, might last beyond 2020. ExoMars and NASA’s 2020 rover are still in development phases. Using ExoMars or 2020, NASA has plans to recover collected samples from rovers and return them to Earth in the 2020s and possibly as soon as 2022.
Clouds above the rim of "Endurance Crater" in this image from NASA's Mars Exploration Rover Opportunity. These clouds occur in a region of strong vertical shear. The cloud particles (ice in this martian case) fall out, and get dragged along away from the location where they originally condensed, forming characteristic streamers. Opportunity took this picture with its navigation camera during the rover's 269th martian day (Oct. 26, 2004). Image Credit: NASA/JPL
Predicting the weather here on Earth is never an easy thing, but predicting it on Mars may be ever trickier. Such is the argument presented by a recent study concerning “macroweather” patterns on the Red Planet, a new regime for understanding how planetary environments work.
When it comes to describing the climate of a planet, two important concepts come into play. First, there’s weather, which covers day-to-day changes due to fluctuations in the atmosphere. Second, there’s climate, which is more stable and subject to change over the course of decades. Macroweather, the latest addition to the game, describes the relatively stable periods that exist between short-term weather and long-term climate.
For those of us dwelling here on planet Earth, these are familiar concepts. But researchers say this same three-part pattern applies to atmospheric conditions on Mars. The results of a new paper, published today in Geophysical Research Letters also show that the Sun plays a major role in determining macroweather.
Several dust devils cross a plain in this animation of a series of images acquired by NASA’s Mars Rover Spirit in May, 2005. (NASA/JPL-Caltech/Cornell/USGS)
The scientists chose to study Mars because of the wealth of data it has provided in recent decades, which they then used to test their theory that a transitional “macroweather” regime exists on a planet other than Earth. They used information collected from the Viking Mars lander mission from the 1970s and 1980s, and more recent data from the Mars Global Surveyor.
By taking into account how the sun heats Mars, as well as the thickness of the planet’s atmosphere, the scientists predicted that temperatures and wind would fluctuate on Mars similar to how they fluctuate on Earth. However, this transition from weather to macroweather would take place over 1.8 Martian days (about two Earth days), compared with a week to 10 days here on Earth.
“Our analysis of the data from Mars confirmed this prediction quite accurately,” said Shaun Lovejoy, a physics professor at McGill University in Montreal, Canada, and lead author of the paper. “This adds to evidence, from studies of Earth’s atmosphere and oceans, that the sun plays a central role in shaping the transition from short-term weather fluctuations to macroweather.”
Early Spring Dust Storms at the North Pole of Mars, taken by the Mars Global Surveyor spacecraft in 2002. Image Credit: NASA/JPL/Malin Space Science Systems
The findings also indicate that weather on Mars can be predicted with some skill only two days in advance, compared to 10 days on Earth.
“We’re going to have a very hard time predicting the weather on Mars beyond two days given what we have found in weather records there,” said co-author Jan-Peter Muller from the University College London Mullard Space Science Laboratory in the UK, “which could prove tricky for the European lander and rover.”
This research promises to advance scientists’ understanding of the dynamics of Earth’s own atmosphere, and could potentially provide insights into the weather of Venus, Saturn’s moon Titan, and possibly the gas giants Jupiter, Saturn, Uranus, and Neptune.
As always, in learning about other planets and their climates, scientists are finding that the planets of our Solar System may have more in common with Earth than previously thought. Because of this, studying these other worlds will inevitably help us to better understand our own.
We can only imagine what the meteor storm from Comet Siding Spring must have looked like standing on the surface of Mars on October 19, 2014. NASA scientists announced today that the planet experienced an exceptional shower during the comet's flyby, saturating the sky. Source: Stellarium
“Thousands of meteors per hour would have been visible — truly astounding to the human eye.” That’s Nick Schneider’s description of what you and I would have seen standing on Mars during Comet Siding Spring’s close flyby last month. “It would have been really mind-blowing,” he added. Schneider is instrument lead for MAVEN’s Imaging Ultraviolet Spectrograph (IUVS).
He and a group of scientists who work as lead investigators for instruments on the MAVEN and Mars Reconnaissance Orbiter (MRO) spacecraft shared the latest results from the comet flyby during a media teleconference earlier today. There were many surprises. Would we expect anything less from a comet?
Here’s a summary of the results:
A very dusty ice ball – The comet’s dust tail and the amount of dust in its coma were much larger than expected, prompting Jim Green, director of NASA’s Planetary Science Division in Washington, to remark: “It makes me very happy we hid them (the spacecraft) on the backside of Mars. That really saved them.” Siding Spring dumped several tons of fine dust into the Martian atmosphere prompting a spectacular meteor shower and possibly causing a yellow, twilight afterglow above the Curiosity landing site from vaporizing sodium atoms contained in the minerals. That, and dust in the mid-levels of the atmosphere at the time contributed to the rover’s difficulty in getting good photos of the comet itself. Scientists are still examining the images.
MAVEN’s Ultraviolet Imaging Spectrograph (IUVS) uses limb scans to map the chemical makeup and vertical structure across Mars’ upper atmosphere. It detected strong enhancements of magnesium and iron from ablating incandescing dust from Comet Siding Spring. Credit: NASAI’m not big into graphs either, but check out the heavy metal drama going on here. On the left is the “before” scan from MAVEN’s IUVS instrument; on the right, during the comet’s close approach. The spike in magnesium from vaporizing comet dust is impressive. Ionized magnesium is the strongest spike with neutral and ionized iron on the left in smaller amounts. Both elements are common in meteorites as well as on Earth. Credit: NASAProfiles showing spikes in the amounts of eight different metals over time detected in Mars’ atmosphere by MAVEN’s Neutral Gas and Ion Mass Spectrometer (NGIMS). The emissions faded within a short time, but chemicals from the comet will continue to interact with the Martian atmosphere over time. Credit: NASA
Chemistry of Mars’ atmosphere changed – Dust vaporized in the intense meteor shower produced a striking increase in the amount of magnesium, iron and others metals in Mars’ upper atmosphere. “We were pressed back in our chairs,” said Mike Schneider. The bombardment created a temporary new layer of comet-tainted air and may have acted as condensation nuclei for the formation of high-altitude clouds. MAVEN’s Neutral Gas and Ion Mass Spectrometer (NGIMS) recorded huge spikes in the levels of eight different metals during the comet’s passage and then trailed off a day or so later. “They came to MAVEN as a free sample from no less than an Oort Cloud comet,” said Mehdi Benna, instrument scientist for MAVEN’s Neutral Gas and Ion Mass Spectrometer.
The MARSIS instrument on the Mars Express is a ground penetrating radar sounder used to look for subsurface water and ice. It can also make soundings of the ionosphere. It was used to see the new ionospheric layer formed by vaporizing comet dust on October 19th. Credit: ESAThe Mars Express radar probed the ionosphere (upper atmosphere) at three different times. At top, before the comet arrived; middle, 7 hours later after the comet’s closest approach and bottom, hours later after the comet had departed. The middle graph shows a strong signal (blue horizontal bar) from the creation of a newly-ionized layer of the planet’s lower atmosphere from hot, fast-moving comet dust. Credit: ESA
Flaming comet dust creates new ionospheric layer – Comet dust slamming into the atmosphere at 125,000 mph (56 km/sec) knocked electrons loose from atoms in the thin Martian air 50-60 miles (80-100 km) high, ionizing them and creating a very dense ionization layer in the planet’s lower ionosphere seven hours after the comet’s closest approach. Normally, Mars ionosphere is only seen on the dayside of the planet, but even when the MARSIS instrumenton Mars Express beamed radio waves through the atmosphere on the nightside of the planet, it picked up a very strong signal.
54 red-filtered, false-color images of the comet’s nucleus-coma taken by the MRO’s HiRISE camera show changes in the flow of material leaving the comet. Based on the photos, the comet’s nucleus spins once every 8 hours. Credit: NASAThe five closest photos made with the HiRISE camera show the combined light of the nucleus and coma. Scale is 140-meter per pixel at top and 177-meters at bottom. Scientists will further process these images to separate the nucleus from the coma. Credit: NASA
Nucleus spins once during your work day – Comet Siding Spring’s icy core spins once every 8 hours and its irregular shape causes strong variations in the comet’s brightness. The comet’s size appears less certain – at least for the moment – with estimates anywhere between a few hundred meters to 2 km (1.2 miles). More analysis on images taken by MRO’s HiRISE camera should narrow that number soon.
CRISM photo and spectrum of Comet Siding Spring. The spectrum is “flat”, indicating we’re seeing ordinary sunlight reflecting off comet dust. The intriguing color variations in the image tell us the comet’s spewing dust particles of many sizes. Credit: NASA
Dust motes of many sizes – Color variations across Siding Spring’s coma seen by Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) indicate it’s releasing dust particles of different sizes – big and little.
The scientists involved in the encounter couldn’t be happier with how the instruments functioned and the amount of hard data returned. Said Jim Green: “We are so lucky to observe this once-in-a-lifetime event.” How true when you consider that it takes about 8 million years for a comet from the Oort Cloud, that vast reservoir of frozen comets extending nearly a light year from the Sun, to get here in the first place. Nick Schneider put it another way:
“Not only is this a free sample of the Oort Cloud in Mars’ atmosphere, but it gives us a chance to learn more about Mars itself.”
If you’d like to listen in to the hour-long teleconference at any time, it’ll be up for the next week or so HERE.
