San Francisco
NASA engineers are now hopeful that they can salvage the troubled Mars Global
Surveyor mission. But its sister spacecraft, Mars Pathfinder, seems finally to
have died after a successful stint on the Red Planet鈥檚 surface.
Last month, flight engineers at NASA鈥檚 Jet Propulsion Laboratory in Pasadena,
California, were forced to suspend Global Surveyor鈥檚 鈥渁erobraking鈥� manoeuvre.
The craft was using the friction of its solar panels to slow down from its
current highly elliptical orbit into the circular orbit needed to map the
Martian surface. But when one panel appeared to start buckling under the
pressure, mission controllers pulled the craft into a higher orbit
(This Week, 25 October, p 24).
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Flight engineers now conclude that the crippled panel can withstand about
one-third the pressure it was designed for. They intend to resume aerobraking
this week, taking things much more slowly to protect the panel. This means that
Surveyor may not reach its final orbit until March 1999鈥攁 full year later
than planned.
Meanwhile, Pathfinder鈥檚 controllers have heard almost nothing from the lander
since its radio began to fail on 27 September, nearly three months after its
landing. Engineers believe the radio was damaged by extreme cold after
Pathfinder鈥檚 batteries died. The spacecraft then had to rely on solar power,
putting it at the mercy of the elements at night.
鈥淲e only planned power for a 30-day mission,鈥� says Pathfinder mission manager
Richard Cook. 鈥淲e feel lucky it went on for so long.鈥� He says that mission
control will abandon its daily struggle to restore contact with the craft this
week if it fails to respond. But NASA will hail Pathfinder monthly in the hope
that the problem will correct itself as summer approaches on the Ares Vallis
plain鈥擯athfinder鈥檚 resting place.