Archive for the ‘Home Plate’ category

Spirit is no longer a Rover

January 27, 2010

An animation of Spirit's final attempts to adjust its position in the soft soil of "Troy". Image credit: NASA/JPL-Caltech (click to view if the image is not animating)

In a news conference yesterday, NASA announced that Spirit’s driving days are likely over, but by virtue of remaining stationary, new science possibilities are opened up. Here’s the text from the press release:

After six years of unprecedented exploration of the Red Planet, NASA’s Mars Exploration Rover Spirit no longer will be a fully mobile robot. NASA has designated the once-roving scientific explorer a stationary science platform after efforts during the past several months to free it from a sand trap have been unsuccessful.

The venerable robot’s primary task in the next few weeks will be to position itself to combat the severe Martian winter. If Spirit survives, it will continue conducting significant new science from its final location. The rover’s mission could continue for several months to years.

“Spirit is not dead; it has just entered another phase of its long life,” said Doug McCuistion, director of the Mars Exploration Program at NASA Headquarters in Washington. “We told the world last year that attempts to set the beloved robot free may not be successful. It looks like Spirit’s current location on Mars will be its final resting place.”

Ten months ago, as Spirit was driving south beside the western edge of a low plateau called Home Plate, its wheels broke through a crusty surface and churned into soft sand hidden underneath.

After Spirit became embedded, the rover team crafted plans for trying to get the six-wheeled vehicle free using its five functioning wheels – the sixth wheel quit working in 2006, limiting Spirit’s mobility. The planning included experiments with a test rover in a sandbox at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., plus analysis, modeling and reviews. In November, another wheel quit working, making a difficult situation even worse.

Recent drives have yielded the best results since Spirit became embedded. However, the coming winter mandates a change in strategy. It is mid-autumn at the solar-powered robot’s home on Mars. Winter will begin in May. Solar energy is declining and expected to become insufficient to power further driving by mid-February. The rover team plans to use those remaining potential drives for improving the rover’s tilt. Spirit currently tilts slightly toward the south. The winter sun stays in the northern sky, so decreasing the southward tilt would boost the amount of sunshine on the rover’s solar panels.

“We need to lift the rear of the rover, or the left side of the rover, or both,” said Ashley Stroupe, a rover driver at JPL. “Lifting the rear wheels out of their ruts by driving backward and slightly uphill will help. If necessary, we can try to lower the front right of the rover by attempting to drop the right-front wheel into a rut or dig it into a hole.”

At its current angle, Spirit probably would not have enough power to keep communicating with Earth through the Martian winter. Even a few degrees of improvement in tilt might make enough difference to enable communication every few days.

“Getting through the winter will all come down to temperature and how cold the rover electronics will get,” said John Callas, project manager at JPL for Spirit and its twin rover, Opportunity. “Every bit of energy produced by Spirit’s solar arrays will go into keeping the rover’s critical electronics warm, either by having the electronics on or by turning on essential heaters.”

Even in a stationary state, Spirit continues scientific research.

“There’s a class of science we can do only with a stationary vehicle that we had put off during the years of driving,” said Steve Squyres, a researcher at Cornell University and principal investigator for Spirit and Opportunity. “Degraded mobility does not mean the mission ends abruptly. Instead, it lets us transition to stationary science.”

One stationary experiment Spirit has begun studies tiny wobbles in the rotation of Mars to gain insight about the planet’s core. This requires months of radio-tracking the motion of a point on the surface of Mars to calculate long-term motion with an accuracy of a few inches.

“If the final scientific feather in Spirit’s cap is determining whether the core of Mars is liquid or solid, that would be wonderful — it’s so different from the other knowledge we’ve gained from Spirit,” said Squyres.

Tools on Spirit’s robotic arm can study variations in the composition of nearby soil, which has been affected by water. Stationary science also includes watching how wind moves soil particles and monitoring the Martian atmosphere.

Spirit and Opportunity landed on Mars in January 2004. They have been exploring for six years, far surpassing their original 90-day mission. Opportunity currently is driving toward a large crater called Endeavor and continues to make scientific discoveries. It has driven approximately 12 miles and returned more than 133,000 images.

Time is Running out for Spirit Rover

January 14, 2010

JPL just released this update on Spirit’s status and it doesn’t look good:

The list of remaining maneuvers being considered for extricating Spirit is becoming shorter. Results are being analyzed Wednesday, Jan. 13, from a drive on Sol 2143 (Jan. 12, 2010) using intentionally very slow rotation of the wheels. Earlier drives in the past two weeks using wheel wiggles and slow wheel rotation produced only negligible progress toward extricating Spirit.

The right-front wheel has not rotated usefully since Sol 2117 (Dec. 16, 2009). With the right-rear wheel also inoperable since Sol 2099 (Nov. 28, 2009), Spirit now drives with only four wheels.

Pending results of the latest drive, the rover team is developing plans for their final few attempts, such as driving backwards and using Spirit’s robotic arm to sculpt the ground directly in front of the left-front wheel, the only working wheel the arm can reach. Such activities may take several sols to implement, but time is getting short as winter approaches and the team needs to focus on Spirit’s winter survival.

The amount of energy that Spirit has each day is declining as autumn days shorten on southern Mars. If NASA does determine that the rover will not be able to get away from its current location, some maneuvers to improve the tilt toward the winter sun might be attempted.

I’m on downlink duty for Pancam this week, and I can say that watching each day tick by with, often, just fractions of a millimeter of progress is painful. The team is generally upbeat in the meetings, but there’s a sense of urgency and all eyes are on the calendar as we inch closer to dark days on Mars. Spirit has survived previous Martian winters, but that was with the rover tilted toward the sun to maximize the power available. Right now, Spirit’s tilt is not so good, and I don’t know if we’ll be able to fix it in time.

For more thoughts on the current predicament, head over to the Planetary Society blog.

AGU 2009 – Day 1

December 16, 2009

For those not familiar with the conference, the fall meeting of the American Geophysical Union is a terrifyingly, overwhelmingly large conference. Each year, something like 16,000 geoscientists descend on San Francisco to share their work. It is also one of the major planetary science conferences, so a lot of new results are first presented here.

Moscone Center in San Francisco. This building is filled with science at every fall AGU meeting.

This year, the first talks that I checked out on Monday were about radar observations of Mars. By sending radar waves from spacecraft to the surface and then recieving the reflected waves, we can learn a lot about Mars. In particular, since radar penetrates tens to hundreds of meters below the visible surface, it can reveal otherwise hidden structures. This has been especially successful at mapping the structure of the polar caps, because radar penetrates through ice quite well.

Roger Phillips gave a talk summarizing some of the results from the SHARAD radar instrument on MRO. Among other thers, SHARAD has found evidence that the spiral troughs in the north polar ice cap have migrated over time, as predicted many years ago by theoretical models. SHARAD has also found ancient buried canyons in the polar ice, which menas the ice caps have been around for quite a while. There are also some exiting new results implying that the material filling valleys in the Deuteronilus Mensae area is quite transparent to radar waves, and might in fact be something like glacier ice.

Image credits: NASA/ESA/JPL-Caltech/ASI/University of Rome/University of Washington St. Louis

After the radar talks, there were a whole bunch of presentations about aqueous alteration on Mars. One of the main lessons that I took away from those talks was that Mars is still a very confusing place. For example, Hap McSween used data from the Mars rovers and characterized typical soils at both landing sites. He found that the compositions of soils are roughly 70% unaltered material and 30% alteration products. He also showed that the soil compositions are quite similar between the two landing sites, which are on opposite sides of the planet, and that the unaltered portion of the soil is similar to the rocks at both sites.

However, the next talk by Josh Bandfield used orbital data and found that in general rocks on Mars have more of the mineral olivine than the soils. This is a somewhat different result than the rover data, and it might imply that rocks on Mars actually have more magnesium and iron than previously thought.

Other talks related to Mars alteration focused on “clay” and sulfate minerals detected on Mars. One that I found particularly interesting was by Paul Niles, who pointed out that Mars is an “obliquity-driven” planet. In other words, its tilt varies widely, and the Mars we see now is not typical. Niles suggested that during more typical periods, ice might have formed large layers at Mawrth Vallis, a location known for its strong hydrated mineral features. Melting at the base of that ice could have leached the rocks, explaining the presence of specific Al-bearing clay minerals.

Map of water-bearing minerals at Mawrth Vallis. Image credit: ESA/OMEGA team

Another interesting talk was by Itav Halevy, who took a look at how the presence of SO2 gas influences the formation of carbonate minerals. It turns out, even a tiny amount of SO2 gas (which is often released by volcanoes) can prefent the formation of CaCO3. If there is iron around, FeCO3 (the mineral siderite) forms instead. The implication is that sulfur minerals should form in different locations than clay minerals and siderite.

Continuing with the sulfur theme, Albert Yen talked about some results from the Spirit rover. He said that basically, if the rover had to get stuck, it picked a really fascinating place to do it! Based on the compositions measured, it turns out that there is too much sulfur in the soil to balance it out by assuming it is combined with other elements like Fe and Mg. That means there might be pure elemental sulfur mixed in with the soil, which would be consistent with hydrothermal activity!

My officemate and occasional contributor here at the Martian Chronicles, Briony Horgan, also gave a nice talk summarizing some of her recent work. For a long time there has been a question about the so-called “surface type 2” on mars. This surface type has higher than usual Si, but that could be due to a different type of lava, or alteration of the more common basalt seen elsewhere on Mars. Briony presented new evidence, based on the overall shape of the spectra of surface type 2 regions, that these areas might be due to a silica glass coating! This sort of coating could form when thin films of water from thawing ground ice altered the surface of sand grains, and would imply relatively recent alteration processes on mars.

Finally, the day ended with the Whipple prize lecture, which was unfortunately full of some misleading information about the history and status of Mars science. But that’s the topic for a future post.

Crescent Earth, Water on the Moon, and Free Spirit!

November 15, 2009

Just a quick post to update you on the latest space news and remind you to keep voting for my article about how MSL is like James Bond.

First of all, the Rosetta spacecraft, on its way to a rendezvous with a comet in 2014, swung by Earth the other day, and took some beautiful pictures:

osiris_color_2009-11-12T12.28UTC_rot_north

Crescent earth as seen by the Rosetta probe.

Second, NASA held a press conference on friday announcing that the LCROSS mission to “bomb the moon” was successful and that they found evidence for hundreds of kilograms of water in the impact plume. This means that the south pole of the moon just got a lot more appealing, both because of the potential as a resource and because the water trapped in permanently shadowed craters could be billions of years old, preserving the history of the solar system much like the ice cores of Antarctica do for the Earth’s past. Check out the Planetary Society article on the discovery for more information.

Third, the rover drivers are finally preparing to extract Spirit from the sand trap where she has spent most of the summer! Once again, the Planetary Society blog has a good summary of the recent NASA press conference.

That’s all for now. I’m off to frantically write bad sci-fi so I can keep up with NaNoWriMo!

 

Ups And Downs for Spirit Rover

May 12, 2009
This picture shows the light-toned, disturbed soil where Spirit is currently stuck. The wheels spin, but just sink deeper in the soft sand.

This picture shows the light-toned, disturbed soil where Spirit is currently stuck. The wheels spin, but just sink deeper in the soft sand.

Recently, Spirit has had some very good news and some very bad news. The good news is that we just had a huge cleaning event, with high winds blowing the solar panels clean so that we are getting power levels that we haven’t seen in years!

The bad news is that this occurred as Spirit got stuck in deep, soft sand. Last week we were commanding drives of tens of meters and getting tens of millimeters of progress. Not a good situation. The extra power boost helps, but Spirit still needs to get out of the soft soil before winter sets in. We had an all-hands meeting yesterday to discuss the plan for the next few weeks. We will be doing tons of imaging and measurements on the soil surrounding the rover to figure out what its mechanical properties are, and the mock-up rover at JPL will be put into the testbed, stuck in similar piles of soil and the engineers on the team will figure out the best way to extract ourselves.

For more info, check out this NASA press release:

May 11, 2009

Mars Exploration Rover Mission Status Report

PASADENA, Calif. — The five wheels that still rotate on NASA’s Mars Exploration Rover Spirit have been slipping severely in soft soil during recent attempts to drive, sinking the wheels about halfway into the ground.

The rover team of engineers and scientists has suspended driving Spirit temporarily while studying the ground around the rover and planning simulation tests of driving options with a test rover at NASA’s Jet Propulsion Laboratory, Pasadena, Calif.

“Spirit is in a very difficult situation,” JPL’s John Callas, project manager for Spirit and its twin rover, Opportunity, said Monday. “We are proceeding methodically and cautiously. It may be weeks before we try moving Spirit again. Meanwhile, we are using Spirit’s scientific instruments to learn more about the physical properties of the soil that is giving us trouble.”

Both Spirit and Opportunity have operated more than five years longer than their originally planned missions of three months on Mars and have driven much farther than designed. The rover team has so far developed ways to cope with various symptoms of aging on both rovers.

Spirit has been driving counterclockwise from north to south around a low plateau called “Home Plate” for two months. The rover progressed 122 meters (400 feet) on that route before reaching its current position.

In the past week, the digging-in of Spirit’s wheels has raised concerns that the rover’s belly pan could now be low enough to contact rocks underneath the chassis, which would make getting out of the situation more difficult. The right-front wheel on Spirit stopped working three years ago. Driving with just five powered wheels while dragging or pushing an immobile wheel adds to the challenge of the situation.

Favorably, three times in the past month, wind has removed some of the dust accumulated on Spirit’s solar panels. This increases the rover’s capability for generating electricity.

“The improved power situation buys us time,” Callas said. “We will use that time to plan the next steps carefully. We know that dust storms could return at any time, although the skies are currently clear.”

Behavioral problems that Spirit exhibited in early April — episodes of amnesia, computer resets and failure to wake for communications sessions — have not recurred in the past three weeks, though investigations have yet to diagnose the root causes.

JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover project for NASA’s Science Mission Directorate, Washington.

Rover Huggers

April 11, 2009

Stuart Atkinson just posted a very nice short story over at his blog Cumbrian Sky that you should all go and read. Here’s a teaser:

“Hurry up!” Catriona said loudly into her helmet mike. She didn’t bother to turn round towards her brother as she spoke. She didn’t need to; apart from herself and her mother, whose hand she was clutching tightly, he was the only other person for miles around.


Walking – ‘trudging’ was probably a more accurate term, as he begrudged every step he took – a short distance behind his mother and sister, Leo’s only reply was an angst-ridden heavy sigh. For pity’s sake, shut up Cat! he thought, glaring at the two figures, one tall and slim, one shorter and a lot stubbier, moving across the rock-strewn crown of Homeplate a hundred feet or so up ahead of him. While his mother’s stride was careful and steady, controlled… adult… Cat was bouncing along, as usual, giddy with excitement at the prospect of seeing another piece of ancient martian history. In her white EVA suit with its pink bands he thought his sister looked like a piece of candy bouncing across the ground, each footfall kicking up a small cloud of red and orange dust….


Spirit’s Bonestell Panorama

July 16, 2008

Hey folks, as you may know, the Spirit rover has been sitting at the north rim of home plate all Martian winter, struggling to stay alive through the short winter days and long nights. She’s been doing some science though: every day or so, we’ve been taking a few more pictures that will eventually go into a gigantic panorama. After more than 120 sols, we recently hit the halfway point through making the full 360 degree panorama, and the portion that is done gives a spectacular view of Home Plate. Click the images below for the full resolution versions. The top image is approximate true color, the other is false color, which is useful for bringing out the details in the rocks and soil. Enjoy!

Spirit’s science at Home Plate: SAFE!

March 27, 2008

With the MER budget scare having blown over, now is a perfect time to reflect on the science at Home Plate – and beyond – that Spirit has yet in store.  Rather than vent frustrations about the near-disaster of a 40% funding slash, I’d rather be reminded that we’re lucky – astoundingly lucky – to be operating spacecraft on the surface of another planet.  And for Spirit, I think the best is yet to come.

            Right now, Spirit is tilted towards the Sun on the north edge of Home Plate, where the rover will stay until sometime in October, when spring arrives to the south of Mars.  So – you may say – if Spirit can’t drive for 6 months anyway, why not just hibernate the ol’ girl?  I’ve heard that argument before, and here’s my response: Spirit may be a quadriplegic right now, but she’s not blind.  The MER team has a rigorous winter science campaign planned for Spirit, including the mother-of-all-panoramas: a 360-degree view of the winter scene, from the rover deck to the horizon – that’s over a hundred individual snapshots stitched together, taken in 13 unique filters.  Here’s a sneak preview of what we have so far, pieced together from “blue” filter images: 

It will take months to finish shooting this panorama, called the “Bonestell Pan”.  But when it’s done, it’ll be spectacular.  Last winter, when Spirit was parked at Low Ridge, we collected the equally monstrous McMurdo Pan, which is arguably the most scientifically-rich product that Pancam has acquired. There are plenty of Ph.D. theses in that panorama – including mine.  Over the next few months I’ll be mapping the extent of silica-rich material over the entire 360-degree McMurdo Pan, and when this winter is done, I’ll do the same over the Bonestall Pan.  In the end I’ll be able to say something about how widespread the hydrothermal activity might have been in this area.

Hydrothermal activity?  That’s right – the silica-rich stuff that Spirit has discovered is thought to have formed around hot springs and/or vents.  Think Yellowstone on Mars – without the buffalo.  (Check out this article in Astrobiology Magazine or this Scientific American podcast for more on the silica deposits.) There’s an incredible story emerging about hot springs and explosive volcanism at Gusev Crater, and Spirit is poised to continue putting the pieces together.

When spring comes and Spirit can drive again, we’ll head south to check out two features called “von Braun” and “Goddard,” both of which look similar to Home Plate, and might be the sites of ancient vents.  It’s the geologic “promised land” for Spirit – we may find more silica-rich deposits, layered volcanic sediments, lapilli, sulfur-rich soils, or something entirely new. That’s the best part: we don’t know what we’ll find.  We just know we have to go. 

As Ray Arvidson (the MER deputy principal investigator) said in the MER all-hands meeting on Monday, when Spirit’s future was up in the air, “If we lose the capability to drive spirit to Von Braun and Goddard… that’s beyond bad, that’s beyond very bad – that’s criminal.”

            So after Spirit’s near-death experience this week, I’m breathing a huge sigh of relief that we’re safe to push forward with the great science ahead of us.  Our little rover still has a lot to live for.