NASA Headquarters, Washington, DC
Jet Propulsion Laboratory, Pasadena, CA

November 4, 1997


After operating on the surface of Mars three times longer than expected and returning a tremendous amount of new information about the red planet, NASA's Mars Pathfinder mission is winding down.

Flight operators at NASA's Jet Propulsion Laboratory, Pasadena, CA, made the announcement today after attempting to reestablish communications with the spacecraft over the last month. With depletion of the spacecraft's main battery and no success in contacting Mars Pathfinder via its main or secondary transmitters, the flight team cannot command the spacecraft or the small rover named Sojourner that had been roving about the landing site and studying rocks.

"We concede that the likelihood of hearing from the spacecraft again diminishes with each day," said Pathfinder Project Manager Brian Muirhead. "We will scale back our efforts to reestablish contact but not give up entirely.

"Given that, and the fact that Pathfinder is the first of several missions to Mars, we'll say 'see you later' instead of saying goodbye," he said.

At the time the last telemetry from the spacecraft was received, Pathfinder's lander had operated nearly three times its design lifetime of 30 days, and the Sojourner rover operated 12 times its design lifetime of seven days.

"I want to thank the many talented men and women at NASA for making the mission such a phenomenal success. It embodies the spirit of NASA, and serves as a model for future missions that are faster, better, and cheaper. Today, NASA's Pathfinder team should take a bow, because America is giving them a standing ovation for a stellar performance," said NASA Administrator Daniel S. Goldin.

Since its landing on July 4, 1997, Mars Pathfinder has returned 2.6 billion bits of information, including more than 16,000 images from the lander and 550 images from the rover, as well as more than 15 chemical analyses of rocks and extensive data on winds and other weather factors. The only remaining objective was to complete the high-resolution 360-degree image of the landing site called the "Super Pan," of which 83 percent has already been received and is being processed. The last successful data transmission cycle from Pathfinder was completed at 3:23 a.m. Pacific Daylight Time on Sept. 27, which was Sol 83 of the mission.

"This mission has advanced our knowledge of Mars tremendously and will surely be a beacon of success for upcoming missions to the red planet," added Dr. David Baltimore, president of the California Institute of Technology, which manages JPL for NASA. "Done quickly and within a very limited budget, Pathfinder sets a standard for 21st century space exploration."

The Mars Pathfinder team first began having communications problems with the spacecraft on Saturday, Sept. 27. After three days of attempting to reestablish contact, they were able to lock on to a carrier signal from the spacecraft's auxiliary transmitter on Oct. 1, which meant that the spacecraft was still operational. They locked on to the same carrier signal again on Oct. 6, but were not able to acquire data on the condition of the lander. At that time, the team surmised that the intermittent communications were most likely related to depletion of the spacecraft's battery and a drop in the spacecraft's operating temperatures due to the loss of the battery, which kept the lander functioning at warmer temperatures.

Over the last month the operations team has been working through all credible problem scenarios and taking a variety of actions in attempting to recover the link with Pathfinder. With all of the most plausible possibilities exhausted, the team plans to continue sending commands and listening for a spacecraft signal on a less frequent basis.

"Basically we are shifting to a contingency strategy of sending commands to the lander only periodically, perhaps once a week or once per month," said Mission Manager Richard Cook. "Normal mission operations are over, but there is still a small chance of reestablishing a link, so we'll keep trying at a very low level."

Although the true cause of the loss of lander communications may never be known, recent events are consistent with predictions made at the beginning of the extended mission in early August, Muirhead said. When asked about the life expectancy of the lander, project team members predicted that the first thing that would fail on the lander would be the battery; this apparently happened after the last successful transmission September 27.

After that, the lander was expected to begin getting colder at night and go through much deeper day-night thermal cycles. Eventually, the cold or the cycling would probably render the lander inoperable. According to Muirhead, it appears that this sequence of events has probably taken place. The health and status of the rover is also unknown, but since initiating its onboard backup operations plan a month ago, the rover is probably circling the vicinity of the lander, attempting to communicate with it.

The rover, which went into a contingency mode on Oct. 6, or Sol 92 of the mission, had completed an alpha proton X-ray spectrometer study of a rock nicknamed Chimp, to the left of the Rock Garden, when it was last heard from. The rover team had planned to send the rover on its longest journey yet -- a 165-foot (50-meter) clockwise stroll around the lander -- to perform a series of technology experiments and hazard avoidance exercises when the communications outage occurred. That excursion was never initiated once the rover's contingency software began operating.

Now known as the Sagan Memorial Station, the Mars Pathfinder lander was designed primarily to demonstrate a low-cost way of delivering a set of science instruments and a free-ranging rover to the surface of the red planet. Landers and rovers of the future will share the heritage of spacecraft designs and technologies first tested in this "pathfinding" mission.

Part of NASA's Discovery program of low-cost planetary missions, the spacecraft used an innovative method of directly entering the Martian atmosphere. Assisted by a 36-foot-diameter (11-meter) parachute, the spacecraft descended to the surface of Mars on July 4 and landed, using airbags to cushion the impact. The spacecraft's novel entry was successful.

Scientific highlights of the Mars Pathfinder mission are:

Engineering milestones of the mission included demonstrating a new way of delivering a spacecraft to the surface of Mars by way of direct entry into the Martian atmosphere. In addition, Mars Pathfinder demonstrated for the first time the ability of engineers to deliver a semi-autonomous roving vehicle capable of conducting science experiments to the surface of another planet.

The Mars Pathfinder mission is managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, Washington, DC. The mission is the second in the Discovery program of fast track, low-cost spacecraft with highly focused science goals. JPL is managed by the California Institute of Technology, Pasadena, CA.


Mars Pathfinder Mission Status

October 22, 1997

The Mars Pathfinder operations team is continuing its efforts to reestablish communications with the Pathfinder lander. Although they are experiencing communications difficulties, the team is confident that the spacecraft is still operating on the surface of Mars, according to Mission Manager Richard Cook. The last time they were able to send a command to the Pathfinder lander instructing it to transmit a signal back to Earth was on Sol 93, which was Tuesday, October 7, at 7:21 a.m. Pacific Daylight Time.

Team members suspect that the spacecraft may not be receiving commands from Earth properly because the lander's hardware has become much colder than normal. In regular operations, when the lander's transmitter is turned on, spacecraft hardware warms up sufficiently to operate normally. Since the transmitter has not been on for several days, engineers suspect that temperatures within the lander are considerably colder than normal. Predicted internal temperatures drop to as low as -50 C (-58 F) in the early morning and only rise to about -30 C (-22 F) in the late afternoon. These temperatures are about 20 C (38 F) colder than the coldest previous operational temperatures.

The lower temperatures cause the spacecraft radio hardware to operate outside the range of radio frequencies that ground controllers have used in the past. During the past three weeks the operations team has been transmitting to the spacecraft at a lower frequency and sweeping through a wider frequency range, a technique that has been used on other missions to attempt to cause the spacecraft receiver to lock on to the transmitted signal. Once ground controllers finish this, they send commands instructing the lander to turn on its transmitter and send a signal back to Earth.

To be certain that they investigate all possibilities, team members are also consulting with experts knowledgeable about the radio and other key elements of the spacecraft. They have identified some new scenarios that are being pursued to regain communications. These recommendations include doing more testing of the engineering model hardware in the laboratory to better understand how the spacecraft might be behaving. Another recommendation has suggested shifting and increasing the range of frequencies being swept through much more than previously attempted.

According to Project Manager Brian Muirhead, the possibility exists that an unrecoverable problem may have occurred. Team members expected that, once the lander's onboard battery died, cold and thermal cycling could result in a failure of some other element of Pathfinder and thereby end the mission. "However, the team will continue to do everything possible to reestablish communications until all options have been exhausted," Muirhead said. The mission has already exceeded all of its goals in terms of spacecraft lifetime and data return.

The science team, meanwhile, continues to process and analyze the large volume of data sent back by Pathfinder's lander and rover. Further science products are planned and new results will continue to be presented as they develop.

From the "JPL Universe"

October 3, 1997

Pathfinder continues extended mission Sojourner has survived 10 times longer than its primary mission design


After 83 days of atmospheric, soil and rock studies, NASA's Mars Pathfinder lander and rover are continuing extended mission activities that will take the rover on its longest trek yet and the lander into new photographic endeavors.

"The lander and rover performance continue to be nothing short of extraordinary," said Project Manager Brian Muirhead. "We have proven that we know how to design robust robots to operate in the hostile environment of Mars."

The rover has just completed its last alpha proton X-ray spectrometer study for a while, taking measurements of a rock nicknamed Chimp, located just behind and to the left of the Rock Garden. Once data from the spectrometer have been retrieved, Sojourner will begin a 164-foot (50-meter), clockwise stroll around the lander to perform a series of technology experiments and hazard avoidance exercises.

Meanwhile, the Pathfinder lander camera is continuing to image the Martian landscape in full resolution color as part of its goal to provide a "super panorama" image of the Ares Vallis landing site. Each frame of this panorama is imaged using 12 color filters plus stereo.

"The super pan will be our biggest and best imaging-data product," Muirhead said. "It is made up of 1 gigabit (1 billion bits) of data, of which we've received more than 80 percent. Given our limited downlink opportunities, we should have the full image by the end of October."

The 22-pound (10.5-kilogram) rover has survived 10 times longer than its primary mission design of seven days, while the lander has now been operating 2.5 times longer than it was originally expected to operate, according to Richard Cook, Mars Pathfinder mission manager.

Both vehicles are solar powered, but carried batteries to conduct nighttime science experiments and keep the lander warm during the sub-freezing nights on Mars. Normal usage has fully depleted the rover's non-rechargeable batteries, limiting it to daylight activities only. The lander battery, which packed more than 40 amp-hours of energy on landing day, performed perfectly during the 30-day primary mission, but is now down to less than 30 percent of its original capacity.

"We expected to begin seeing this type of degradation on both vehicles and, of course, designed both the lander and rover to operate without batteries altogether," Cook said. "If everything else continues to operate properly, we could continue conducting surface experiments for months."

About once every two weeks, the lander battery is used to perform some nighttime science experiments, he added. The primary activity is acquiring meteorological data and images of morning clouds, as well as images of Mars' two small moons, Phobos and Deimos.

Despite the lack of battery power, the rover has continued taking successful spectrometer readings during the day. In the next week, engineers will drive the vehicle back to a magnetic target on the ramp from which Sojourner first touched Martian soil.

"This analysis of the dust on the ramp magnet is a very important science measurement," noted Pathfinder Project Scientist Dr. Matthew Golombek. "The results should give us a clue about how all this magnetic dust was formed."

Recent images and movies continue to be posted on the Mars Pathfinder home page.

For latest news on the exploration of Mars by Pathfinder and Sojourner please consult the following pages.

Previous news on ASTRONET:

  • English: Pathfinder and Sojourner on Mars

  • Nederlands: Pathfinder en Sojourner op Mars

    NASA Headquarters, Washington, DC Jet Propulsion Laboratory, Pasadena, CA

    August 8, 1997


    NASA's Mars Pathfinder spacecraft -- a novel mission to send an inexpensive lander and roving prospector to the surface of Mars -- has concluded its primary mission, fulfilling all of its objectives and returning a wealth of new information about the red planet.

    The robotic lander, which continues to explore an ancient outflow channel in Mars' northern hemisphere, completed its milestone 30-day mission on Aug. 3, capturing far more data on the atmosphere, weather and geology of Mars than scientists had expected. In all, Pathfinder has returned 1.2 gigabits (1.2 billion bits) of data and 9,669 tantalizing pictures of the Martian landscape to date.

    "The data returned by the Sagan Memorial Station and Sojourner has been nothing short of spectacular, and it will help provide a scientific basis for future Mars missions, including a sample return, for years to come," said Dr. Wesley Huntress, NASA associate administrator for space science. "The Pathfinder team's "can do" attitude not only was critical to overcoming several complex technical challenges during development and cruise, but has carried through the uncharted territory of operating a solar- powered lander and mobile rover on the surface of a planet millions of miles from Earth."

    "This mission demonstrated a reliable and low-cost system for placing science payloads on the surface of Mars," said Brian Muirhead, Mars Pathfinder project manager at NASA's Jet Propulsion Laboratory (JPL), Pasadena, CA. "We've validated NASA's commitment to low-cost planetary exploration, shown the usefulness of sending microrovers to explore Mars, and obtained significant science data."

    A new portrait of the Martian environment has begun to emerge in the 30 days since Pathfinder and its small, 23-pound rover began to record weather patterns, atmospheric opacity and the chemical composition of rocks washed down into the Ares Vallis flood plain. The rover's alpha proton X-ray spectrometer team, led by principal investigator Dr. Rudolph Rieder, has been able to analyze the first-ever in-situ measurements of Mars rocks.

    "We are seeing much more differentiation of volcanic materials than we expected to see," said Dr. Matthew Golombek, Mars Pathfinder project scientist at JPL. "The high silica content of one of the rocks we've measured, nicknamed Barnacle Bill, suggests that there was more crustal activity -- heating and recycling of materials -- early in Mars' history than we thought."

    Similarly, atmospheric-surface interactions, measured by a meteorology package onboard the lander, are confirming some conditions observed by the Viking landers 21 years ago, while raising questions about other aspects of the planet's global system of transporting volatiles such as water vapor, clouds and dust, said science team leader Dr. Timothy Schofield. The meteorology mast on the lander has observed a rapid drop-off in temperatures just a few feet above the surface, and one detailed 24-hour measurement set revealed temperature flucuations of 30-40 degrees Fahrenheit in a matter of minutes.

    In addition, sweeping, color panoramas of the Martian landscape, created by the Imager for Mars Pathfinder team and principal investigator Peter Smith, are revealing clear evidence that the surface of Mars has been altered by winds and flowing water.

    Sojourner, a robust rover capable of semi-autonomous "behaviors," captured the imagination of the public, which followed the mission with great interest via the World Wide Web. Twenty Pathfinder mirror sites, constructed by JPL web engineer Kirk Goodall and managed by Pathfinder webmaster David Dubov, recorded 565 million hits worldwide during the period of July 1 -- August 4. The highest volume of hits in one day occurred on July 8, when a record 47 million hits were logged, which is more than twice the volume of hits received on any one day during the 1996 Olympic Games in Atlanta.

    The rover's performance has easily surpassed its designers' minimum expectations. Engineers designed the roving vehicle's electronics, battery power and hazard avoidance features to see it through at least a week of safe roving, not knowing beforehand what conditions it might encounter on Mars. After 30 days, the rover is still healthy and has traveled 171 feet in distance, circumnavigating the lander and taking 384 spectacular views of rocks and the lander.

    "Sojourner's capabilities to detect hazards and then act on its own to overcome those hazards have been remarkable," said Dr. Jacob Matijevic, Sojourner project manager. "The technology experiments we have been able to perform with the rover's wheels have given us more information about the composition of the Martian soil, as well as rocks around the landing site. Sojourner's durability in this frigid, hostile environment also is showing us that we are on the right track to building smarter, even more durable rovers for future missions."

    Pathfinder's primary objective was to demonstrate a low-cost way of delivering an instrumented lander and free-ranging rover to the surface of the red planet. Landers and rovers of the future will share the heritage of spacecraft designs and technologies tested in this "pathfinding" mission.

    Part of NASA's Discovery program of low-cost planetary missions with highly focused science goals, the spacecraft used an innovative method of directly entering the Martian atmosphere. Assisted by a 36-foot-diameter parachute, the spacecraft descended to the surface of Mars and landed, using airbags to cushion the impact.

    This novel method of diving into the Martian atmosphere worked like a charm. "Every event during the entry, descent and landing went almost perfectly," said Richard Cook, Pathfinder mission manager. "The sequences were executed right on time and well within our margins."

    Pathfinder landed right on the money, within 13 miles of the targeted landing site. The landing site coordinates in Ares Vallis were later identified as 19.33 degrees North latitude, 33.55 degrees West longitude.

    The spacecraft's terminal velocity as it parachuted to the ground was higher than expected, said Rob Manning, Pathfinder flight system chief engineer. "Interestingly, we estimated our descent on the parachute at about 134 miles per hour. Software controlling the retro rockets recorded Pathfinder's speed at about 140 miles per hour at the time the rocket-assisted deceleration rockets fired."

    Pathfinder's performance in the Martian atmosphere will be of great value to Mars Global Surveyor, which will aerobrake through the Martian atmosphere to circularize its orbit when it reaches Mars on September 11. The Pathfinder navigation team, led by Pieter Kallemyn of JPL, estimated that horizontal wind velocities in the upper atmosphere helped accelerate the spacecraft's descent velocity by about 20 to 25 miles per hour.

    After being suspended from a 65-foot bridle and firing its retro rockets, a 19-foot diameter cluster of airbags softened Pathfinder's landing, marking the first time this airbag technique has been used on another planet. The spacecraft hit the ground at a speed of about 40 miles per hour and bounced about 16 times across the landscape for about six-tenths of a mile before coming to a halt. The airbag seems to have performed perfectly and sustained little or no damage. To top it off, the spacecraft even landed on its base petal, consequently allowing its thumb-sized antenna to communicate the successful landing to a jubilant team on Earth only three minutes after touchdown.

    Science data from the surface of Mars will continue to be collected and transmitted to Earth, then analyzed by scientists, as Pathfinder enters its extended mission. The lander was placed in a two-day hibernation period earlier this week to recharge its battery after the conclusion of the primary mission, and the flight team now will begin to power the lander battery off each Martian night to conserve energy. The rover's batteries remain in good condition, but are not rechargeable.

    The Mars Pathfinder mission is managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.

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