NASA’s Mars Pathfinder: Five Years Later

The Pathfinder lander, formally named the Carl Sagan Memorial Station following its successful touchdown, landed on July 4, 1997 with its Rover, called Sojourner. Pathfinder returned 2.6 gigabits (2.6 billion bits) of data and 16,000 tantalizing pictures of the Martian landscape, including 550 close-up images from the rover.

Assisted by an 11- meter (36-foot) diameter parachute, the spacecraft descended to the surface of Mars and landed, using airbags for the first time to cushion the impact.

Pathfinder landed right on the money, within 20 kilometers (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 hit the ground at a speed of about 18 meters per second (40 miles per hour) and bounced about 16 times across the landscape before coming to a halt.

Because the spacecraft even landed on its base petal (bottom-side), its thumb-sized antenna could communicate the successful landing to a jubilant team on Earth only three minutes after touch down. The semi-automated rover was the first such Earth-driven exploration vehicle with telemetry instructions. Sojourner performed 15 chemical analyses of rocks.

Interview with Pathfinder Project Scientist, Matt Golombek

Astrobiology Magazine had the opportunity to interview the Pathfinder project scientist, Dr. Matthew Golombek, of the Jet Propulsion Laboratory, Pasadena, Ca.

Q. What was your greatest surprise from the geological explorations of Pathfinder?
"Probably the relief and views from the landing site. The Pathfinder site has more relief than either of the Viking sites and the nearby Twin Peaks offer quite the view. From a science point of view the answer would be the putative conglomerate, which would indicate a warm and wet past."

Q. How has what was learned from Pathfinder been applied to future mission planning to Mars? "The Pathfinder science results hinted at a warmer and wetter past for Mars, which has been followed up with MGS results and are the focus of the Mars Exploration Rovers."

Q. Is there any current data analysis that continues based on the large amount of transmitted science? "Yes, data analysis continues including better understanding the wind sensor data, the APXS results, better understanding the spectral data from the camera, and further characterizing the rock fields around the lander."

Q. What in your opinion are the most critical mission elements to consider in planning: power, navigation, telescience targeting, remote control, data visualization, etc.?

"Well all are important in different ways. Power for a solar spacecraft must be managed very carefully. Managing the lag in knowledge from one day to the next is also important. Better autonomy placing instruments against rocks and targets and more autonomous roving could help look at more materials on the surface and visit more sites."

Q. In retrospect, are their moments over the last 5 years when you personally have marvelled at the success of Pathfinder? "Certainly. For deep space missions, all it takes is one mistake for the mission to fail. Even launch has a 5 times out of 100 chance of blowing up. Part of exploration is confronting the unknown and risk can never be removed completely. In cases like Pathfinder taking a little risk can result in an enormous payoff."

The impressive science highlights for the Mars Pathfinder mission included:

• Martian dust includes magnetic, composite particles, with a mean size of one micron.
• Rock chemistry at the landing site may be different from Martian meteorites found on Earth, and could be of basaltic andesite composition.
  
• The soil chemistry of Ares Vallis appears to be similar to that of the Viking 1 and 2 landing sites.
  
• The observed atmospheric clarity is higher than was expected from Earth-based microwave measurements and Hubble Space Telescope observations.
  
• Dust is confirmed as the dominant absorber of Solar radiation in Mars’ atmosphere, which has important consequences for the transport of energy in the atmosphere and its circulation. Frequent "dust devils" were found with an unmistakable temperature, wind and pressure signature, and morning turbulence; at least one may have contained dust (on Sol 62), suggesting that these gusts are a mechanism for mixing dust into the atmosphere.
  
• Evidence of wind abrasion of rocks and dune-shaped deposits was found, indicating the presence of sand.
  
• Morning atmospheric obscurations are due to clouds, not ground fog; Viking could not distinguish between these two possibilities.
  
• The weather was similar to the weather encountered by Viking 1; there were rapid pressure and temperature variations, downslope winds at night and light winds in general.
  
• Temperatures were about 10 degrees warmer than those measured by Viking 1.
• Diversity of albedos, or variations in the brightness of the Martian surface, was similar to other observations, but there was no evidence for the types of crystalline hematite or pyroxene absorption features detected in other locations on Mars.
  
• The atmospheric experiment package recorded a temperature profile different than expected from microwave measurements and Hubble observations.
  
• Rock size distribution was consistent with a flood-related deposit.
  
• The moment of inertia of Mars was refined to a corresponding core radius of between 807 miles and 1,242 miles (1,300 and 2,000 kilometers).
  
• The possible identification of rounded pebbles and cobbles on the ground, and sockets and pebbles in some rocks, suggests conglomerates that formed in running water, during a warmer past in which liquid water was stable.

Related Web Pages:

• Mars Pathfinder
• 2001 Mars Odyssey webcam
  
• Complete coverage of the 2001 Mars Odyssey launch
• 2001 Mars Odyssey home page
  
• Carbonated Mars (NASA)
• TES home page
• THEMIS home page
• GRS home page
• MARIE

Source: NASA’s Astrobiology Magazine