Course of Mars Lander corrected for December landing
Before its launch, the Mars Polar Lander is lowered toward a spin table for testing
October 30, 1999
Web posted at: 5:00 p.m. EDT (2100 GMT)
PASADENA, California (CNN) -- NASA engineers say they
successfully performed a critical course correction Saturday
that should send the Mars Polar Lander spacecraft to a
desired landing zone near the planet's south pole in
A 12-second thruster burst successfully shifted the course of
the 1,200-pound Lander during the 1:28 p.m. EDT maneuver.
"Preliminary indications are it went well," said Mary Beth
Murrill, spokesperson for the Jet Propulsion Laboratory in
| MESSAGE BOARD|
"The spacecraft performed as it was supposed to." Engineers
will watch navigational data over the next few hours to
confirm their initial conclusion, she said.
Saturday's trajectory correction maneuver was the fourth
since the Lander blasted off on January 3 from Cape
Canaveral, Florida. Another such maneuver is scheduled for
November 30, days before a planned December 3 landing.
Sister ship was Climate Orbiter
The lander's sister ship, the $125-million Mars Climate
Orbiter, was lost as it entered the orbit of Mars in
September. Mission managers say the cause of the mishap was
confusion over the type of units used to measure the strength
of thruster firings.
While JPL engineers assumed they were using metric
measurements (Newtons), engineers at Lockheed Martin
Astronautics in Denver, the prime contractor for the mission,
were feeding them data in English units (pounds).
The problem has been corrected for the Mars Polar Lander,
space engineers said.
The lander's projected landing site is located near the
northern edge of the south pole's layered terrain.
Mission scientists and engineers opted on Tuesday not to
redirect the craft to a backup landing site, which had been
considered after high-resolution images showed the primary
site was rougher than originally anticipated.
"At the scale of the lander, even something like a table
could represent an obstacle," said Richard Zurek, project
manager for the Mars Polar Lander.
"Something that is a meter up here and down here can give you
problems when you are landing on three legs."
While the polar lander has a radar altimeter and rocket
thrusters to guide and slow the craft before landing, they
can't guide it away from potential hazards.
Landing on a steep slope could be catastrophic. It could
leave the orbiter intact but listing, placing it in a bad
position for six solar panels to capture the sun's energy and
convert it into power.
Yet the same features that pose the greatest landing hazards
have also enticed scientists. Alternating light and dark
bands beneath the surface of the south pole appear to be
deposits of ice and dust. Scientists think the layers could
offer clues about the climate history of Mars, like growth
rings on a tree.
Craft can analyze chemical composition of soil
Should the craft land near a steep hill or cliff, it could
document some exposed layering. Equipped with a shovel and
small furnace, the lander will dig into the Martian surface
and heat the soil to analyze the chemical composition.
The lander is also equipped with three cameras. One will
capture its descent to the surface. Another will offer
stereoscopic panoramas. The third, located on the wrist of
the shovel arm, will show scientists close-ups of Martian
The lander is scheduled to conduct a 60-day mission, but it
could transmit data for up to 90 days if the conditions are
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Three panels to investigate Mars orbiter loss
September 28, 1999
NASA gives up search for missing Mars orbiter
September 24, 1999
Mars craft possibly dead
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Australia fossil to help in search for life on Mars
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Mars Climate Orbiter
Mars Global Surveyor
Mars Meteorite Home Page (JPL)
Fossil Record of the Cyanobacteria
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