Posted on by Nancy Atkinson

Possibility of Past Water on Mars Takes a Hit

Details from the Ascraeus channel (red), meandering across the surface of Mars. The insets in the black boxes show close-ups of some of the structures that lava can form: (left) branched channels, (middle) a snaking channel and (right) rootless vents; the rootless vents are also marked by yellow spots on the main image. Credit: Jacob Bleacher

[/caption]

Images of Mars taken from orbit show a massive system of riverbeds and canyons etched by water. Or maybe not. A new study of one channel shows that it was formed by lava flow and not water, and the results make “a strong case that fluid lava can produce channels that look very much like water-generated features,” said Jim Zimbelman from the Smithsonian Institution in Washington, one of the researchers. “So, we should not jump to a water-related conclusion when we see such channels on other planets.”

Whether channels on Mars were formed by water or by lava has been debated for years and the outcome is thought to influence the likelihood of finding life there. Images from various Mars orbiters reveal details resembling the erosion of soil by water: terracing of channel walls, formation of small islands in a channel, hanging channels that dead-end and braided channels that branch off and then reconnect to the main branch. “These are thought to be clear evidence of fluvial [water-based] erosion on Mars,” said Jacob Bleacher from Goddard Spaceflight Center, who presented the results at the Lunar and Planetary Science Conference last week.

Lava flow usually creates big, open channels, such as the ones commonly seen in Hawaii. But detailed looks at both channels on Mars and in Hawaii shed a whole new light on the formation of channels and other features on Mars.

The research team carried out a careful study of a single channel on the southwest flank of Mars’ Ascraeus Mons volcano, one of the three clustered volcanoes collectively called the Tharsis Montes. To piece together images covering more than 270 kilometers (~168 miles) of this channel, the team relied on high-resolution pictures from three cameras—the Thermal Emission Imaging System (THEMIS), the Context Imager (CTX) and the High/Super Resolution Stereo Color (HRSC) imager—as well as earlier data from the Mars Orbiter Laser Altimeter (MOLA). These data gave a much more detailed view of the surface than previously available.

Because the fluid that formed this and other Ascraeus Mons channels is long-gone, its identity has been hard to deduce, but the visual clues at the source of the channel seem to point to water. These clues include small islands, secondary channels that branch off and rejoin the main one and eroded bars on the insides of the curves of the channels.

The Tharsis region of Mars, including the three volcanoes of Tharsis Montes (Arsia, Pavonis and Ascraeus Mons), as well as Olympic Mons in the upper left corner. Credit: NASA/Jet Propulsion Lab

But at the channel’s other end, an area not clearly seen before, the team found a ridge that appears to have lava flows coming out of it. In some areas, “the channel is actually roofed over, as if it were a lava tube, and lined up along this, we see several rootless vents,” or openings where lava is forced out of the tube and creates small structures, he explains. These types of features don’t form in water-carved channels, he notes. Bleacher argues that having one end of the channel formed by water and the other end by lava is an “exotic” combination. More likely, he thinks, the entire channel was formed by lava.

To find out what kinds of features lava can produce, Bleacher, Zimbelman and W. Brent Garry examined the 51-kilometer (~32 mile) lava flow from the 1859 eruption of Mauna Loa on the Big Island of Hawaii. Their main focus was an island nearly a kilometer long in the middle of the channel; Bleacher says this is much larger than islands typically identified within lava flows. To survey the island, the team used differential GPS, which provides location information to within about 3 to 5 centimeters (1.1 to 1.9 inches), rather than the roughly 3 to 5 meters (9.8 to 16.4 feet) that a car’s GPS can offer.

“We found terraced walls on the insides of these channels, channels that go out and just disappear, channels that cut back into the main one, and vertical walls 9 meters (~29 feet) high,” Bleacher says. “So, right here, in something that we know was formed only by flowing lava, we found most of the features that were considered to be diagnostic of water-carved channels on Mars.”

Further evidence that such features could be created by lava flows came from the examination of a detailed image of channels from the Mare Imbrium, a dark patch on the moon that is actually a large crater filled with ancient lava rock. In this image, too, the researchers found channels with terraced walls and branching secondary channels.

The conclusion that lava probably made the channel on Mars “not only has implications for the geological evolution of the Ascraeus Mons but also the whole Tharsis Bulge [volcanic region],” says Andy de Wet, a co-author at Franklin & Marshall College, Lancaster, Penn. “It may also have some implications for the supposed widespread involvement of water in the geological evolution of Mars.”

Source: NASA

Posted on by Nancy Atkinson

MRO Radar Maps Extensive Subsurface Martian Ice

A radar on NASA's Mars Reconnaissance Orbiter has detected widespread deposits of glacial ice in the mid-latitudes of Mars.NASA/JPL-Caltech/ASI/University of Rome/Southwest Research Institute

[/caption]

Sure, it’s big news the Moon has water ice on the north pole, but Mars is loaded! A new extensive radar mapping of the middle-latitude region of northern Mars shows that thick masses of buried ice are quite common beneath the surface. The Mars Reconnaissance Orbiter’s Shallow Radar instrument has detected subsurface ice deposits that extend for hundreds of kilometers in the rugged region called Deuteronilus Mensae, about halfway from the equator to the Martian north pole. “We have mapped the whole area with a high density of coverage,” said Jeffrey Plaut from JPL. “These are not isolated features. In this area, the radar is detecting thick subsurface ice in many locations.”

The Shallow Radar instrument has been charting the locations of these hidden glaciers and ice-filled valleys, finding that the most common locations are around the bases of mesas and scarps, and confined within valleys or craters. After obtaining more than 250 observations of the study area, which is about the size of California, the science team is beginning to understand how these deposits may have been left as remnants when regional ice sheets retreated.

“The hypothesis is the whole area was covered with an ice sheet during a different climate period, and when the climate dried out,” Plaut said, “these deposits remained only where they had been covered by a layer of debris protecting the ice from the atmosphere.”

These buried masses of ice are a significant fraction of the known non-polar ice on Mars. The ice could contain a record of environmental conditions at the time of its deposition and flow, making the ice masses an intriguing possible target for a future mission with digging capability.

MRO will continue mapping the area to provide more insight into the buried ice.

Source: JPL

Posted on by Nancy Atkinson

Follow Closest Flyby of Phobos in Real Time

Phobos from Mars Express. Credit: ESA/DLR/FU Berlin (G. Neukum).

[/caption]
Mars Express will skim over the surface of Mars’ largest moon on Wednesday, making the closest flyby of Phobos by any spacecraft. Passing at just 67 km above the surface, precise radio tracking will allow researchers to virtually peer inside the mysterious moon. You can follow the flyby in “real time,” — allowing for the current 6 minute and 30 second light time delay from Mars (13 minutes round trip) – on the Mars Express blog. The flyby will take place on March 3, at 20:55 GMT.

The straight-line distance between Mars Express and Earth is now about 116 million km.

Flying by at such close range, Mars Express will be pulled ‘off-course’ by the gravitational field of Phobos. This will amount to no more than a few millimeters every second and will not affect the mission in any way. However, to the tracking teams on Earth, it will allow a unique look inside the moon to see how its mass is distributed throughout. Phobos’ shape is 27 km × 22 km × 19 km, and has a mass of 1.072 x 1016 kg, or about one-billionth the mass of Earth.

To make the very sensitive measurements of Phobos’ interior, all the data signals from the spacecraft will be turned off. The only thing that the ground stations will listen out for is the ‘carrier signal’ – the pure radio signal that is normally modulated to carry data.

With no data on the carrier signal, the only thing that can modulate the signal is any change in its frequency caused by Phobos tugging the spacecraft. The changes will amount to variations of just one part in a trillion, and are a manifestation of the Doppler effect – the same effect that causes an ambulance siren to change pitch as it zooms past.

Two dress rehearsals for this exacting operation have already taken place, allowing ground station personnel and spacecraft controllers to practice.

Originally, the closest flyby was going to only 50 km above the surface, but a slight ‘over performance’ during a maneuver last week had put the spacecraft on a trajectory that included an occultation by Phobos. This meant that Mars Express would pass behind Phobos as seen from Earth. As this would jeopardize the tracking measurements, it was decided to perform another maneuver to position the flyby at a slightly higher altitude than originally planned.

An illustration showing the ESA's Mars Express mission. Credit: ESA/Medialab)

Mars Express will zoom past Phobos seven more times after Wednesday’s closest approach. The first planned High Resolution Stereo Camera (HRSC) observations will be on March 7, when the spacecraft will be at 107 km altitude above Phobos.

In addition to the tracking experiment, known as MaRS for Mars Radio Science, the MARSIS radar has already been probing the subsurface of Phobos with radar beams. “We have performed a preliminary processing of the data and the Phobos signature is evident in almost all the data set,” says Andrea Cicchetti, Italian Institute of Physics of Interplanetary Space, Rome, and one of the MARSIS team.

Source: ESA

Posted on by Nancy Atkinson

Stunning New Looks at the Mars Avalanche

A single-image photoclinometric 3D reconstruction of the Mars avalanche from HiRISE. Image data: NASA/JPL/UA; 3D model: Bernhard Braun

[/caption]

Remember the amazing image of an avalanche on Mars back in 2008, captured by the HiRISE camera on the Mars Reconnaissance Orbiter? Bernhard Braun from UnmannedSpaceflight.com has now created several different 3-D views of the event, providing never-seen-before, ground-level observations by using special software he developed that can create three dimensional images from one 2-dimensional picture. Normally, to create a 3-D image you need at least two images, or you have to combine images with data from an instrument such as a laser altimeter. But Braun’s single-image photoclinometric 3D reconstruction algorithm, also known as “shape from shading” allows the shape of three dimensional objects to be recovered from shading in a two-dimensional image. Braun told Universe Today that since developing the software, one of the areas he has wanted to “visit from the ground” is the famous dust avalanche caught live in action by HiRISE. His images provide an entirely new — and stunning — view of Mars.

A single-image photoclinometric 3D reconstruction of the Mars avalanche from HiRISE. Image data: NASA/JPL/UA; 3D model: Bernhard Braun

Braun said that the software is useful to look at various areas of interest, in particular where we have no other (i.e stereo-imaging based) detailed 3D reconstructions yet. Previously, we’ve shown 3-D movies on Universe Today that Doug Ellision and others from UnmannedSpaceflight.com have created from HiRISE DEMs (Digitial Elevation Models) which are a grid, or raster file describing elevation values at regularly spaced points, or posts. HiRISE DEMs are made from two high-resolution images of the same area, taken from different look angles by the spacecraft. The HiRISE folks say that creating a DEM is complicated and involves sophisticated software and a lot of time, both computing time and man-hours.

But Braun’s software (although it took him quite some time to develop) allows for a moderate processing time, about 15 minutes per medium-resolution image, using about 2 gigabytes of memory. Also, no texturing or additional coloring/shading was applied when rendering the surface, and every detail visible is real 3D down to the pixel-level.

But, Braun doesn’t think his method is in any way “superior” to the HiRISE team’s efforts.

“Quite to the contrary,” he told me via email. “Traditionally, single-image shape-from-shading methods like the one that I developed, are considered to nicely complement the multi-image (stereo) methods because the weaknesses of one method (large scale distortions in single-image-methods vs. less detail resolution in multi-image methods ) is the strength of the other. Also, the official HiRISE DEMs are generally more accurate at exactly reproducing absolute terrain heights (also using altimeter-based calibration), which is important for scientific usage, whereas my DEMs are less well calibrated because they are mainly intended for visualization purposes.”

The main advantage of the single-image method is that it can be used on almost arbitrary images of areas where there isn’t 3D coverage yet, such as capturing an event like an avalanche.

“In a way, it opens the door to an entirely new view of large existing 2D-only data sets, Braun said. “For example, currently I am working on an extension of the method to radar images for hi-resolution 3D reconstructions of the highest-resolution Venus Magellan data sets.”

Braun’s software method could be considered more of an art form.

“I view my software and algorithms not so much as a scientific measuring instrument,” Braun told me in an email, “but more as a tool for visualization that leaves a bit of artistic license, a degree in freedom of interpretation i.e. the means for creating atmospheric images and it is those images that are the real “publishable end product” of the whole process. The algorithms and software are just the ‘painters brush and easel’ or the photographer’s virtual camera so to speak.”

Another single-image photoclinometric 3D reconstruction of the Mars avalanche from HiRISE. Image data: NASA/JPL/UA; 3D model: Bernhard Braun

Emily Lakdawalla did a wonderful job of explaining the whys and hows of the entire process in the Planetary Society Blog: (go there if you’d like a more detailed description) “Imagine a crumpled piece of paper lit by a spotlight. Facets of the crumpled paper that are perpendicular to the spotlight will appear brightest; facets tilted away from the spotlight will appear dark. If you assume that everything in the picture reflects light in the same way, then you can tell by its albedo, or brightness, whether it is tilted toward or away from the light source. ”
A Mars Avalanche, taken by NASAs HiRISE instrument on the Mars Reconnaisance Orbiter (Credit: NASA/HiRISE)

Above is the original image from HiRISE. When looking at these images, remember that this particular scarp on Mars is a high cliff over 700 m (2300 ft) tall and slopes at over 60 degrees. A mixture of ice, rock and dust can be seen, frozen in time, as it is plummeting down the slope, ejecting a plume of dust as the debris begins to settle on the gentle slope at the bottom of the cliff. The ejected cloud is approximately 180 meters across and extends about 190 meters beyond the base of the cliff.

Braun told us he is working on some new images which we hope to be able to share with you soon, and we extend our thanks to him for allowing us to post the avalanche images on Universe Today.

Follow this link to look at Braun’s entire gallery of wonderful color 3D renderings of the avalanche, derived from the originally published HiRISE image, rendered under various viewing positions and light source directions.

Posted on by Jean Tate

Ozone on Mars: Two Windows Better Than One

An illustration showing the ESA's Mars Express mission. Credit: ESA/Medialab)


Understanding the present-day Martian climate gives us insights into its past climate, which in turn provides a science-based context for answering questions about the possibility of life on ancient Mars.

Our understanding of Mars’ climate today is neatly packaged as climate models, which in turn provide powerful consistency checks – and sources of inspiration – for the climate models which describe anthropogenic global warming here on Earth.

But how can we work out what the climate on Mars is, today? A new, coordinated observation campaign to measure ozone in the Martian atmosphere gives us, the interested public, our own window into just how painstaking – yet exciting – the scientific grunt work can be.

[/caption]
The Martian atmosphere has played a key role in shaping the planet’s history and surface. Observations of the key atmospheric components are essential for the development of accurate models of the Martian climate. These in turn are needed to better understand if climate conditions in the past may have supported liquid water, and for optimizing the design of future surface-based assets at Mars.

Ozone is an important tracer of photochemical processes in the atmosphere of Mars. Its abundance, which can be derived from the molecule’s characteristic absorption spectroscopy features in spectra of the atmosphere, is intricately linked to that of other constituents and it is an important indicator of atmospheric chemistry. To test predictions by current models of photochemical processes and general atmospheric circulation patterns, observations of spatial and temporal ozone variations are required.

The Spectroscopy for Investigation of Characteristics of the Atmosphere of Mars (SPICAM) instrument on Mars Express has been measuring ozone abundances in the Martian atmosphere since 2003, gradually building up a global picture as the spacecraft orbits the planet.

These measurements can be complemented by ground-based observations taken at different times and probing different sites on Mars, thereby extending the spatial and temporal coverage of the SPICAM measurements. To quantitatively link the ground-based observations with those by Mars Express, coordinated campaigns are set up to obtain simultaneous measurements.

Infrared heterodyne spectroscopy, such as that provided by the Heterodyne Instrument for Planetary Wind and Composition (HIPWAC), provides the only direct access to ozone on Mars with ground-based telescopes; the very high spectral resolving power (greater than 1 million) allows Martian ozone spectral features to be resolved when they are Doppler shifted away from ozone lines of terrestrial origin.

A coordinated campaign to measure ozone in the atmosphere of Mars, using SPICAM and HIPWAC, has been ongoing since 2006. The most recent element of this campaign was a series of ground-based observations using HIPWAC on the NASA Infrared Telescope Facility (IRTF) on Mauna Kea in Hawai’i. These were obtained between 8 and 11 December 2009 by a team of astronomers led by Kelly Fast from the Planetary Systems Laboratory, at NASA’s Goddard Space Flight Center (GSFC), in the USA.

Credit: Kelly Fast

About the image: HIPWAC spectrum of Mars’ atmosphere over a location on Martian latitude 40°N; acquired on 11 December 2009 during an observation campaign with the IRTF 3 m telescope in Hawai’i. This unprocessed spectrum displays features of ozone and carbon dioxide from Mars, as well as ozone in the Earth’s atmosphere through which the observation was made. Processing techniques will model and remove the terrestrial contribution from the spectrum and determine the amount of ozone at this northern position on Mars.

The observations had been coordinated in advance with the Mars Express science operations team, to ensure overlap with ozone measurements made in this same period with SPICAM.

The main goal of the December 2009 campaign was to confirm that observations made with SPICAM (which measures the broad ozone absorption spectra feature centered at around 250 nm) and HIPWAC (which detects and measures ozone absorption features at 9.7 μm) retrieve the same total ozone abundances, despite being performed at two different parts of the electromagnetic spectrum and having different sensitivities to the ozone profile. A similar campaign in 2008, had largely validated the consistency of the ozone measurement results obtained with SPICAM and the HIPWAC instrument.

The weather conditions and the seeing were very good at the IRTF site during the December 2009 campaign, which allowed for good quality spectra to be obtained with the HIPWAC instrument.

Kelly and her colleagues gathered ozone measurements for a number of locations on Mars, both in the planet’s northern and southern hemisphere. During this four-day campaign the SPICAM observations were limited to the northern hemisphere. Several HIPWAC measurements were simultaneous with observations by SPICAM allowing a direct comparison. Other HIPWAC measurements were made close in time to SPICAM orbital passes that occurred outside of the ground-based telescope observations and will also be used for comparison.

The team also performed measurements of the ozone abundance over the Syrtis Major region, which will help to constrain photochemical models in this region.
Analysis of the data from this recent campaign is ongoing, with another follow-up campaign of coordinated HIPWAC and SPICAM observations already scheduled for March this year.

Putting the compatibility of the data from these two instruments on a firm base will support combining the ground-based infrared measurements with the SPICAM ultraviolet measurements in testing the photochemical models of the Martian atmosphere. The extended coverage obtained by combining these datasets helps to more accurately test predictions by atmospheric models.

It will also quantitatively link the SPICAM observations to longer-term measurements made with the HIPWAC instrument and its predecessor IRHS (the Infrared Heterodyne Spectrometer) that go back to 1988. This will support the study of the long-term behavior of ozone and associated chemistry in the atmosphere of Mars on a timescale longer than the current missions to Mars.

Sources: ESA, a paper published in the 15 September 2009 issue of Icarus

Posted on by Nancy Atkinson

Phoenix Phone Home! Teams Still Attempting Contact with Mars Lander

Phoenix Twilight
Phoenix at Twilight. Credit: NASA

No word yet from the Phoenix Mars Lander and, really, mission managers don’t expect to hear from the lander. But that doesn’t mean they aren’t trying. Teams are currently attempting to make contact, with another — and final — series of attempts that may occur next month.

“We haven’t heard a peep since late 2008, when a dust storm combined with the onset of winter to end the mission,” said Mark Lemmon from Texas A&M University, who worked with Phoenix’s camera. “But if Phoenix did survive, a revived mission could uncover some of the climate processes in the area around Mars’ North Pole, where most of the water seems to be.”

[/caption]
Last contact with Phoenix was back in October 2008, and the teams that worked with the lander are holding out hope that some of the electronics on board survived the severe Martian winter, which dwarfs anything seen on Earth (even the Snowmageddons and Snowpocalypses). Temperatures fall to minus-180 degrees for months at a time and carbon dioxide ice likely engulfed the Phoenix lander. Still, Lemmon said he is ready to help take more pictures and analyze more data if the Lander can be restored to life.

“Phoenix accomplished its mission,” he said, “and it was never designed to survive a Martian winter. In winter, heavy amounts of carbon dioxide frost may have accumulated on its solar panels and it is possible they broke off. Without those panels, which give Phoenix its energy source, it’s pretty much powerless. In addition, other parts may have failed in the extreme cold.”

Phoenix landing site, August, 2009. Credit: NASA/JPL/U of Arizona. Annotations by Phil Stooke

The Phoenix Lander, which landed on Mars May 25, 2008, was designed to dig for soil samples and buried ice near Mars’ North Pole. It also studied Mars’ polar weather.

Phoenix returned more than 30,000 images and made several chemical analyses of the soil above the Martian permafrost. Those analyses found carbonate minerals in the soil, showed that the composition of the soil is near that of Earth’s oceans rather than being acidic, and found perchlorates, which are present in soils in Chile’s Atacama desert on Earth, where they are used as food by some species of bacteria.

Recent images from the Mars Reconnaissance Orbiter show frost in the area around Phoenix’s landing site is now dissipating. Last month, the Mars Odyssey spacecraft, which orbits the planet, made 30 attempts to contact Lander. All failed.

Lemmon says the Lander mission was a success by any measurement.

“The soil samples it dug up show several possible energy sources, such as perchlorates,” he adds, “and that discovery will have a big impact on future plans to explore Mars. The weather information Phoenix returned will be very useful in understanding Mars’ climate, and the discovery of water-ice snowfall near the end of the mission is still amazing.”

Source: Texas A&M University

Posted on by Nancy Atkinson

Multi-Layer Mars Parfait Provides Environmental Record

This oblique view shows geological layers of rock exposed on a mound inside Gale Crater on Mars. Image credit: NASA/JPL-Caltech/University of Arizona/USGS

[/caption]

Is Mars more like a Peanut Buster Parfait, a granola-yogurt parfait, –or perhaps — maybe a seven-layer salad? Near the center of a Martian crater about the size of Connecticut, hundreds of exposed rock layers form a mound as tall as the Rockies and reveal a record of major environmental changes on Mars billions of years ago. According to a new report by geologists using instruments on the Mars Reconnaissance Orbiter to look at the “parfait” of layers inside Gale Crater, the layers show that Mars was likely wet at one point, but gradually dried over time.

“Looking at the layers from the bottom to the top, from the oldest to the youngest, you see a sequence of changing rocks that resulted from changes in environmental conditions through time,” said Ralph Milliken from JPL. “This thick sequence of rocks appears to be showing different steps in the drying-out of Mars.”

Layers of rock exposed in the lower portion of a tall mound near the center of Gale Crater on Mars exhibit variations in layer thickness and range between dark and light tones. Image credit: NASA/JPL-Caltech/University of Arizona

Milliken and two co-authors of a paper in Geophysical Research Letters say that clay minerals, which form under very wet conditions, are concentrated in layers near the bottom of the Gale stack. Above that, sulfate minerals are intermixed with the clays. Sulfates form in wet conditions and can be deposited when the water in which they are dissolved evaporates. Higher still are sulfate-containing layers without detectable clays. And at the top is a thick formation of regularly spaced layers bearing no detectable water-related minerals.
Layers of rock in the upper portion of a tall mound near the center of Gale Crater on Mars exhibit a regular thickness of several meters, unlike the less regular pattern of layers in the lower formation on the same mound. Image credit: NASA/JPL-Caltech/University of Arizona

Rock exposures with compositions like various layers of the Gale stack have been mapped elsewhere on Mars, and researchers, including Jean-Pierre Bibring of the University of Paris, have proposed a Martian planetary chronology of clay-producing conditions followed by sulfate-producing conditions followed by dry conditions. However, Gale is the first location where a single series of layers has been found to contain these clues in a clearly defined sequence from older rocks to younger rocks.

“If you could stand there, you would see this beautiful formation of Martian sediments laid down in the past, a stratigraphic section that’s more than twice the height of the Grand Canyon, though not as steep,” said Bradley Thomson of the Johns Hopkins University Applied Physics Laboratory, Laurel, Md. He and John Grotzinger of the California Institute of Technology in Pasadena are Milliken’s co-authors.

NASA selected Gale Crater in 2008 as one of four finalist sites for the Mars Science Laboratory rover, Curiosity, which has a planned launch in 2011. The finalist sites all have exposures of water-related minerals, and each has attributes that distinguish it from the others. This new report is an example of how observations made for evaluating the landing-site candidates are providing valuable science results even before the rover mission launches.

Posted on by Nancy Atkinson

Movies of Spirit’s Last Moves Before Winter

Even though the Spirit rover is stuck in a Martian sandtrap, the rover drivers were actually able to move her quite a bit, and therefore improving her chances of surviving the winter. This video shows recent drives by the Spirit rover from Jan. 14 to Feb. 4, 2010 (Sols 2145 to 2165), where the center of the rover approximately 13.4 inches (34 centimeters) backwards. Since Jan 26 (sol 2157), drive commands have concentrated on placing Spirit into a favorable tilt toward the sun as the Martian winter approaches.

Posted on by Nancy Atkinson

Can an Immobile Spirit Rover Survive the Martian Winter?

Mission managers for the Mars Exploration Rover program announced this week that the Spirit rover will likely never rove again on Mars. But that doesn’t mean her life is over. However, with the rover virtually immobile and stuck in a sand trap, she currently is in a very vulnerable and potentially “deadly” situation as winter approaches on Mars’ southern hemisphere. Pointing the rover’s solar panels towards the sun is critical if the rover is to survive, and the rover team has just a handful of drives to make it so. And the winters are long and harsh on Mars. “The temperatures will be colder than anything Spirit has experienced before,” said John Callas, project manager for the MER mission. “This is a much more difficult and dangerous situation for Spirit, and we’re heading into a regime where vehicle is going to get colder than it ever has.”

What is Spirit facing, and what are her odds?

“Spirit will be experiencing decreasing power levels, and we will likely see energy levels that will drop below 160 watt hours,” said Callas, which is the level of power the rover needs to maintain so it can communicate daily with Earth. “If we can’t maintain that level, that will trip a low power fault where the rover shuts down or hibernates, taking the necessary steps to preserve as much power as possible. Everything is turned off except the master clock, and all the photons that hit solar arrays go into charging the batteries.”

In this low-power fault, a timer wakes the rover up occasionally to check battery levels, and if there is enough power, Spirit will wake up enough to see how charged the batteries are and attempt to communicate with Earth. “Spirit will be like a polar bear hibernating, possibly for several months, maybe on the order of 6 months that the rover will be in this state,” said Callas. “It won’t be like the Phoenix lander where it shuts down virtually completely. The rover will still be electrically active, but not with enough power to be awake each day.”

Callas predicted it will be in the March-April time frame here on Earth when they run out of ability to communicate with rover because there won’t be enough power.

Normally the rover stays warm enough simply by being “on” and running, like running your car in the winter to warm it up. But since rover will be deeply sleeping, temperatures on the rover will drop.

Callas and his team are concerned that temperatures on the rover will get very cold. Based on past winters, they expect about -40 to -50 C temperatures on Mars during the depths of winter. The electronics on the rover can withstand -40 degrees C when operating and -50 c when the rover is idle. But these standards are for a brand-new out-of-the-box rover, Callas said, not a 6 year-old rover with electronics have gone through many different temperature cycles.

Ironically, the fumaroles or steam vents that likely created the very scientifically rich “Troy” area where Spirit sits would have made it a “hot spot” on Mars. But, of course, the fumaroles are no longer active.

The rovers do have three 1-watt Radioisotope Heater Units (RHUs) which are tiny thermal heating units used to keep motors and batteries warm on the rover, so Spirit’s important insides will not get as cold as the outside.

But power from the solar panels is very important for keeping the computer and other electronics active, and right now, the position of the solar panels is not at all optimal.

“Our primary mission is to get solar panels pointed toward sun improve her chances,” said rover driver Ashley Stroupe. “Ideally the solar panels should be pointed toward the sun, to maximize the energy the rover receives. If we can get enough power to keep the rover warm, that will shorten the amount of time Spirit may have to be in a low power state.”

In upcoming drives, the team will try to get left rear wheel of the rover lifted up, by driving backward and improving its northerly tilt. Spirit is sitting in a small crater with the rim behind her, so as it moves backwards, it is slowly climbing up on the rim, tilting the rover. “On the last drive we saw 1-2 degree improvement in tilt,” Stroupe said on Tuesday. “So we’re going to do as much improvement as we can by continuing to drive backward. We can an also attempt to rotate the rover in place, so that the roll isn’t pointed as much towards the south as it is now.”

The Spirit rover's solar panels were covered with dust until a gust of wind blew it off. Credit: NASA.

Each degree of tilt towards the north gains 5 watt hours of improvement. One upside is that the solar panels are currently fairly free of dust accumulation.

When the rover attempts to wake up each day, it will be at about noon local time on Mars, when the electronics will have warmed up because of sunlight.

But there’s the possibility the team might not hear from the rover for months.

“We have to be prepared to go through a period like this,” said Callas. “We may not hear from rover, and it will be frustrating and challenging for the team, but we’ll have to be disciplined about this, and hopefully when power resumes we can resume communication in the spring.”

A look at the nearly buried wheels on the Spirit rover on Mars. Credit: NASA/JPL

And, worst case scenario, where is a very long period of time where they don’t hear from the rover, how long will the team attempt to communicate with Spirit?

“That’s a very complex problem,” Callas told Universe Today at the Tuesday’s press conference. “The rover will actually experience two levels of fault protection. The rover takes action based on hearing from Earth, and if we go too long without talking to the rover, it trips an up loss timer. We only keep about 6 weeks of communication tables on the rover, so that likely will have run out. All these things make for a complex recovery effort for the rover. It is hard to say how long we would try, because we would have to try many things before we exhaust the list of things we can do.”

Callas didn’t want to give odds if Spirit will make it through the winter. “Spirit’s best chance for survival is when we can stay in contact with her,” he said. “As long as we can maintain communication with rover we can look out for trouble, and advise her on how to best reapportion her limited resources.”

MER PI Steve Squyres said not having a roving rover is a “poignant moment” for the team. “We built the rovers to drive around, so we have shifted our focus to a different class of activities. It is a change and one we’ll have to adapt to. But this is a much better way that having an abrupt end to the mission, which would preclude doing the kind of science we’re looking forward to.” (Read more about the science Spirit can do in our earlier article)

“We have hope that Spirit will survive this cold dark winter that Spirit has ahead of her,” Squyres said.

Posted on by Nancy Atkinson

Big Full Moon and Mars Put on a Show Friday Night

An almost full Moon on Jan. 27, 2010. Credit and copyright: Alan Walters

[/caption]

If your skies are clear on Friday night, January 29, 2010, take advantage of one of the skywatching highlights of the year. A full Moon and Mars will be putting on a show, and the pair will be prominently close to each other in the sky. Plus, this Friday night’s full Moon is the biggest and brightest full Moon of the year. It’s a “perigee Moon,” as much as 14% wider and 30% brighter than other full Moons you’ll see later in 2010, according to Spaceweather.com. And, even though you’ve likely not gotten an email from an excited acquaintance relaying that Mars is really close to the Earth now — that is the case. Mars is at opposition on the 29th, which means it lines up opposite the Sun and is now the closest to Earth their orbits, and so will shine brighter.

The image above of the not-quite-full Moon from January 27, 2010 is shared by Universe Today reader Alan Walters, from Florida. You can see more of his wonderful photography of the night sky, launches and shuttle landings, Florida wildlife and more at Alan Walters Photography.

Positions of the Moon and Mars. Credit: McDonald Observatory

This image, courtesy of Stardate Online and the McDonald Observatory, shows the positions of the Moon and Mars in the night sky the next few evenings.

This is not a great opposition for Mars because it occurs around the time that Earth is closest to the Sun and Mars is farthest. The gap between the two planets will be a hefty 62 million miles (99 million km). The smallest possible distance at opposition is about 35 million miles (56 million km), which happened a back in August of 2003, and prompted the infamous emails that now surface every August, that Mars would be as big the full Moon, which of course, is not — and was not — true. Mars appeared more than twice as bright then as it will this year, but was still a star-like dot in the sky.

JPL is sponsoring a Facebook Event, Friday Night With the Moon and Mars, to heighten awareness of what a great sight it will be; plus its a great way to share in the experience with others online.

And for more information, see this Science@NASA article about the close encounter.

Sources: Stardate, Spaceweather.com