MER-A

From Wikinfo

MER-A ("Spirit") is the first of the two Mars Exploration Rover Missions. It successfully landed on Mars on January 3, 2004. Its twin, MER-B ("Opportunity"), is expected to land on Mars January 24, 2004.

Note: Days on Mars are called Sols, the landing date (January 3) of MER-A is considered Sol 1, Sol 2 is January 4 and notable as the rover first responded to NASA commands on Sol 2.

Landing site: Columbia Memorial Station

MER-A landed in Gusev crater about 10 km from the center of the target ellipse at latitude 14.5718� S � 30 meters, longitude 175.4785� E � 0.5 meters [1]. A panorama [2] shows a slightly rolling surface, littered with small rocks, with hills on the horizon up to 27 km away. The MER team named the landing site "Columbia Memorial Station", in honor of the seven astronauts killed in the Space Shuttle Columbia disaster.

Events and discoveries

Sleepy Hollow

"Sleepy Hollow," a shallow depression in the Mars ground near NASA's Spirit rover, was targetted as an early destination when the rover drove off its lander platform. NASA scientists were very interested in this crater. It is 9 meters (30 feet) across and about 12 meters (40 feet) north of the lander.

First 3-D panorama of landing site: the crater under the sun is "Sleepy Hollow" received on January 5. (Enlarge image)

"Just as the ancient mariners used sextants for 'shooting the Sun,' as they called it, we were successfully able to shoot the Sun with our panorama camera, then use that information to point the antenna," said JPL's Matt Wallace, mission manger.

First color photograph

Below is the first color image of Mars taken by the panoramic camera on the Mars Exploration Rover Spirit. It is the highest resolution image ever taken on the surface of another planet. "We're seeing a panoramic mosaic of four pancam images high by three wide," said camera designer Jim Bell of Cornell. There are actually 12 million pixels in this image, it's 4,000 high by 3,000 wide. This, however, is only the tip of the iceberg, as this image, received on January 6, 2004, is about one eighth of a single pancam panorama and isn't stereo.

Part of the first color photograph sent from Spirit. The depression known as "Sleepy Hollow" is visible at the right of this photograph. (Enlarge image)

Adirondack

Adirondack is the nickname for rover's first target rock. Scientists chose Adirondack to be Spirit's first target rock rather than another rock, called Sashimi, that would have been a shorter, straight-ahead drive. Spirit traversed the sandy martian terrain at Gusev Crater to arrive in front of this football-sized rock on Sunday, Jan. 18, 2004, just three days after it successfully rolled off the lander.

The rock was selected as Spirit's first target because its dust-free, flat surface is ideally suited for grinding. Clean surfaces also are better for examining a rock's top coating. Scientists named the angular rock after the Adirondack mountain range in New York. The word Adirondack is Native American and is interpreted by some to mean "They of the great rocks." Spirit's Moessbauer spectrometer detected a mineral called olivine, which does not survive weathering well. The lack of weathering suggested by the presence of olivine might be evidence that the soil particles are finely ground volcanic material. Another possible explanation is that the soil layer where the measurements were taken is extremely thin, and the olivine is actually in a rock under the soil.

(enlarged image)

Timeline

2003

June 6 - June 8 - Two launch attempts cancelled due to weather conditions at Kennedy Space Center.
June 10 - MER-A ("Spirit") was successfully launched aboard a Delta II rocket.

2004

January 3 (Sol 1) JPL Images from 1/3/2004
- 20:35 PST - MER-A landed in Gusev crater, however not exactly at its appointed landing spot within the crater (believed by scientists to once have been a crater lake). It later became apparent that the rover had landed six miles downrange from its planned landing site, but has landed in an area possibly even more favorable for the tests scientists want the rover to perform. Three decent images showed its progress as it came down. [3]
- It returns black and white photographs via a relay through Mars-orbiting satellites.
January 4 (Sol 2) JPL Images from 1/4/2004
- MER-A starts its first day of "work", receiving and responding to commands from NASA.
January 5 (Sol 3) JPL Images from 1/5/2004
- The lander locks on its high-gain antenna and begins transmitting color photographs directly to Earth.
- The first 3D Stereogram images are sent back from Spirit.
- Four of five planned tests on scientific instruments on MER-A have been successful, the fifth instrument test is expected to occur later tonight. See Scientific instuments on the rovers.
January 6 (Sol 4) JPL Images from 1/6/2004
- 08:00 PST - U.S. President George W. Bush calls JPL to congratulate the MER team for a successful landing.
- The first high resolution, full color image is received from Spirit. [4]
- Throughout the day, a series of high quality color images were sent from Spirit to NASA. During a news conference about the day's events Steve Squyres, science chief of the MER mission said "This is just a tiny taste of what's to come", refering to the first color images coming back.
- 12:15 PST - The MER team decides to name the specific spot that Spirit landed on within the Gusev Crater "Columbia Memorial Station", in honor of the seven astronauts killed in the disaster. [5]
January 7 (Sol 5) JPL Images from 1/7/2004
- 09:00 PST - Daily news briefing broadcast from JPL over NASA TV. A few new images are released, mainly polished versions of earlier images. Events from Sol 4 are reviewed, including a diagnostic test of a high gain antenna motor voltage spike(which occured on Sol 2), which did not show any problems and was attributed to debris in the antenna machine housing. Airbag retraction was continued on Sol 4. Sol 5 activities are discussed, scientists and engineers on the MER team are anxious to get Spirit separated from its lander and moving around the martian surface.
- A plot is released by JPL showing the "Dust Optical Depth" of the Gusev Crater and Meridiani Planum areas of Mars. The plot shows a measure of the amount of dust in the martian atmosphere as taken by instruments on the orbiting Mars Global Surveyor satellite. Recent dust storms in December and January on Mars have greatly increased the amount of dust in the atmosphere around Meridiani Planum, the expected landing site of MER-A's sister rover Opportunity, landing 1/24/2004. It is unknown at this point if this increased dust activity will hinder Opportunity's mission. [6]
January 8 (Sol 6) JPL Images from 1/8/2004
- 09:00 PST - Daily news briefing from JPL, apparently the activities to further retract the airbag under Spirit's lander were unsuccessful. On Sol 6 JPL engineers will try 6 rotations to try and force the partially deflated airbags fully under the lander. If this attempt fails, Spirit may have to turn itself around on the lander and attempt egress via another route.
- Engineers will also begin Spirit's two step lifting process to "stand up" on the lander. Step 1 is to raise Spirit up on its back 4 wheels, and Step 2 is to deploy the currently retracted front wheels.
- It is predicted that the airbag problem will delay Spirit's egress from the lander to January 14 or later. Currently the plan is to lift landing petal on the lander that Spirit is preparing travel down and attempt to tuck the excess airbag material under the petal. [7]
January 9 (Sol 7) JPL Images from 1/9/2004
- During the night of Sol 6 Spirit successfully completed parts one and two of the "stand up" operation and now has its front wheels deployed and is almost ready to egress. Parts three and four of the stand up operation will be executed tonight. [8]
- Images of data from Spirit's Mini-TES were released [9]
- Another attempt to pack the inflated airbags under the ramp petals of the lander failed. Now JPL engineers will attempt to turn the rover around while still on the lander and egress down one of the other ramps on the lander. This activity has been practiced before MER mission launch and is expected to work.

January 10 (Sol 8) JPL Images from 1/10/2004
- The Spirit Rover completed its stand up operation and is now standing with all six wheels deployed and locked, with one final connection between the lander and Spirit remaining.
January 11 (Sol 9) JPL Images from 1/11/2004
- At the conclusion of Sol 8 the Spirit Rover's science arm, which features tools for digging into and taking close up images of rocks, was moved from its stowed launch position to its forward "drive" position.
January 12 (Sol 10) JPL Images from 1/12/2004
- During Sol 9 the Spirit Rover performed science activities and returned data from the Pancam, completing the 360 panoramic image it took of its surroundings last week. Mini-TES data suggests more evidence that the Gusev site may have been a water filled lake.
- Engineers plan the egress operation Spirit will begin on Sol 10 using a replica of the Spirit rover and lander. The tests go well, and no problems are expected.
January 13 (Sol 11) JPL Images from 1/13/2004
- Sol 10 activities included successfully cutting the last link between the Spirit rover and lander. The first 45 degree turn was successful and the rover is preparing for egress. On Earth, mission details for the rover's exploration of the martian surface are being planned now that it is known exactly where Spirit is within Gusev.
January 14 (Sol 12)

Spirit's empty nest

January 15 Images from 1/2/2004
- Spirit leaves the launch vehicle.
January 16
- A 3-D perspective image [10] is taken by the panoramic camera onboard the Mars Exploration Rover Spirit showing "Adirondack," the rover's first target rock.
January 20 Images from 1/20/2004
- NASA Mars Rover�s First Soil Analysis Yields Surprises Among these suprises, is the detection of olivine, which does not survive weathering well.
January 21 (Sol 18) Spirit stops transmitting data and no longer responds to commands.
January 22 (Sol 19)
- The rover radioed a 7.8 bps beep Thursday morning confirming that it had received a transmission from Earth. The 7.8 bps indicates that the spacecraft believes it's in a fault mode. Still, it has not returned any data since early Wednesday. Flight-team engineers for NASA's Mars Exploration Rover Project are working to diagnose the cause of communications difficulties.
- Pete Theisinger at the Jet Propulsion Laboratory in Pasadena, Calif., described the situation as "a very serious anomaly." He did say however that "If this problem on Spirit is somehow a software corruption issue, or memory corruption issue that's reflecting itself in software, and there's not a serious power fault, Spirit can go for quite a long time and we can pick up the pieces again."
- Steve Squyres, the Cornell astronomy professor who heads the Mars mission's science team, said "It's cause for concern, certainly, but it's not cause for alarm. I've been in this business for almost 25 years now, and I've been involved in over a dozen different planetary missions. I don't know of a single one that hasn't had a problem like this somewhere along the line, and I include in that list missions like Voyager and Magellan that were spectacular successes. This kind of thing is part of the business of operating complicated spacecraft far from Earth." He continued stating that "This vehicle knows how to protect itself when something goes wrong, and can do so for long periods of time." He concluded saying "I'm very optimistic that we'll get this straightened out, and get back to the business of exploring Gusev crater."
- The NASA team plans to instruct the craft to send back engineering data from Spirit's onboard memory (for diagnostic purposes) and possibly send commands to restore normal communication at around 6 a.m. EST tommorow.
- On NASA Television, JPL Director Charles Elachi said "We are cautiously encouraged," and added "It is a pretty smart machine that we have up there and the key thing that we are going to do next is to communicate with it tomorrow morning and ask it to send us some data down so we can do a diagnostic of what's the problem"
January 23
- NASA's Spirit rover communicated with Earth in a signal detected by NASA's Deep Space Network antenna complex near Madrid, Spain, at 12:34 Universal Time (4:34 a.m. PST) this morning. The transmissions came during a communication window about 90 minutes after Spirit woke up for the morning on Mars. The signal lasted for 10 minutes at a data rate of 10 bits per second. Mission controllers at NASA's Jet Propulsion Laboratory, Pasadena, Calif., plan to send commands to Spirit seeking additional data from the spacecraft during the subsequent few hours. [11]
- The flight team for NASA's Spirit received actual data from the rover in another communication session that began at 13:26 Universal Time (5:26 a.m. PST) and lasted 20 minutes at a data rate of 120 bits per second. [12]
- Shortly before noon, controllers were surprised to receive a relay of data from Spirit via the Mars Odyssey orbiter. Spirit sent 73 megabits at a rate of 128 kilobits per second.
- At a news briefing, Pete Theisinger said, "The software is in X-band fault mode. We surmise it got there because of some problem with the high-gain antenna pointing, and that is why the second high-gain antenna pass on Wednesday did not work. It gives us a little bit of a tale-tell for what is going on with the processor now. But as I pointed out to you, the flight software is not functioning normally. The two times we have gone and communicated with the system, we have gotten different flight software behaviors. Therefore we do not have assurance the next time we go and ask for it we will get either one of those two behaviors or perhaps a third behavior. " Later Theisinger said that the Spirit is in "critical condition" and stated that "We do not know to what extent we can restore functionality to the system because we don't know what's broke. We don't know what started this chain of events. I think, personally, that is a sequence of things. And we don't know, therefore, the consequences of that. I think it is difficult, at this very preliminary stage, to assume that we did not have some type of hardware event that caused this to start. Therefore, we don't know to what extent we can work around that hardware event and to what extent we can get the software to ignore that hardware event, if that is what we eventually have to do. "
- An anomaly team has been formed, completely separate from the Opportunity team. They will be working a schedule that will look like 0500 Mars Time to about 1500 Mars Time.
- At the press conference, Theisinger said that Spirit "has been in a processor reset loop of some type, mostly since Wednesday, we believe, where the processor wakes up, loads the flight software, uncovers a condition that would cause it to reset. But the processor doesn't do that immediately. It waits for a period of time - at the beginning of the day it waits for 15 minutes twice and then for the rest of the day it waits for an hour - and then it resets and comes back up." He added that Spirit's central computer has rebooted itself more than 60 times over the past two days. Theisinger also noted that "The indications we have on two occasions is that the thing that causes the reset is not always perceived to be the same."
- At the press conference, two computer animations of Spirit's landing were released.[13], [14] Also released was an image of Spirit's landing site taken by the Mars Orbiter Camera on the Mars Global Surveyor. [15] [16]

January 24
- At a press conference which started at 3:00 EST, Theisinger says that the there is a problem with spirits flash memory and the software that writes to it. The Spirit is in crippled mode and can operate using RAM instead of flash. In this mode, the rover has obeyed commands about communicating and going into sleep mode. Spirit communicated successfully at 120 bits per second for nearly an hour.
- "The rover has been upgraded from critical to serious," said Mars Exploration Rover Project Manager Peter Theisinger
January 25
- At a press conference, Theisinger says that the NASA team been able to successfully run the first master sequence since the anomoly prevented the completition of a task on Wednesday. He adds that the team is moving towards regarding the situation as a "guarded condition" as opposed to the current "serious condition." He says that the flash hardware is in fact believed to be working correctly but the file management module in the software is "not robust enough" for the operations the Spirit was engaged in when the problem occurred, indicating a software bug, as opposed to faulty hardware.
January 27
- At today's 12:00 EST press conference, Jennifer Trosper explains the current situtation regarding Spirit: "First comm window of the day is happening as we speak. Not a lot of new data yet. Subsystems all nominal. Batteries are in good shape. No degradation from discharge a couple nights ago. Thermal working. Today our intent was to try to get a trace of the task causing the problem. We don't have that data yet. Maybe at a later comm today. We've done some analysis of data we already had on ground plus some testing in testbed. One data is the position of the HGA based on potentiometers. Rover doesn't rely on that, just for measurements. HGA was active when we started to get problems. We got info that in the mooring of sol 18 our comm dropped out 10 minutes early. As a result we attempted to command a HGA session. We saw nothing. It had a calibration where we move to hardstop and then track earth. Position now indicates that it only moved through calibration half way. Important because activity that started the reset was not in the HGA because it moved fully to the correct position after the reset problem. That's good news. The other information we got was a result of running tests in our avionics test environment. Loading up a bunch of files. Couldn't reproduce it fully. Got some key aspects of the problem. Looking forward to getting more data down. Continuing to dump out the flash memory, get that data down. Yesterday only about 18.5 megabits. Expect to get 80 megabits today."
January 29

Spirit's extended arm
- NASA's Mars Exploration Rover Spirit took and returned this image on January 28, 2004 (= Sol 25), the first picture from Spirit since problems with communications began a week earlier. The image from the rover's front hazard identification camera shows the robotic arm extended to the rock called Adirondack. As it had been instructed a week earlier, the Moessbauer spectrometer, an instrument for identifying the minerals in rocks and soils, is still placed against the rock. Engineers are working to restore Spirit to working order so that the rover can resume the scientific exploration of its landing area.