NASA loses contact with Mars probe

PASADENA, Calif. (AP) -- NASA's first interplanetary weather<br>satellite failed to re-establish contact with Earth early today<br>after an engine maneuver that should have placed it in orbit around<br>Mars.<br>

Thursday, September 23rd 1999, 12:00 am

By: News On 6

PASADENA, Calif. (AP) -- NASA's first interplanetary weather
satellite failed to re-establish contact with Earth early today
after an engine maneuver that should have placed it in orbit around
Mars.

Several hours later, it was not clear whether the satellite had
completed its task, and mission organizers were trying to locate it
on different frequencies.

The Mars Climate Orbiter, one of two probes scheduled to arrive
at the red planet this year to study the weather and search for
evidence of water, should have regained contact with Earth at 2:26
a.m.

"We're ... not quite sure what's happening," said project
manager Richard Cook of NASA's Jet Propulsion Laboratory, a
half-hour after the signal was to be received on Earth.

The probe was behind the planet and out of radio contact during
most of the 17-minute engine firing that should have placed it in
orbit. Contact should have been established by 2:30 a.m. at the
latest.

Mission organizers said several features aboard the probe were
designed to reconnect it with Earth in case of a computer shutdown
or other common spacecraft problems.

"At this point, we're still confident we're going to see the
spacecraft signal in the next few hours," Cook said.

However, the orbiter's project scientist, Richard Zurek, was
less optimistic. "The longer we don't hear from it, the worse off
we are," he said, more than three hours after the satellite failed
to establish contact.

The orbiter and its companion, the Mars Polar Lander, carry
instruments designed to discover the fate of water believed to have
once formed rivers or lakes on the planet. Mission scientists say
water is the key to determining whether life ever existed on Mars.

The separately launched lander, due to arrive Dec. 3, is
supposed to use the orbiter as a communications relay. But loss of
the orbiter wouldn't be fatal to the project as the lander can
communicate directly with Earth, and the already orbiting Mars
Global Surveyor can act as a limited relay as well.

The disappearance of the Climate Orbiter comes six years after
NASA lost a billion-dollar spacecraft just as it was reaching Mars.

The 1,387-pound orbiter was to have fired its main engine early
today, slowing the spacecraft to 9,840 mph from its interplanetary
cruising speed of 12,300 mph. Within about a half-hour, the craft
was to signal that it was not zooming past Mars or plunging to the
surface.

The signal takes 11 minutes to cross the 121.9 million miles to
Earth.

The craft is supposed to establish an elliptical orbit and then,
over 45 days, dip into the planet's thin atmosphere and use the
drag to make its course more circular.

By mid-November, the probe was to be in a 262-mile-high orbit
and ready to relay data between Earth and the Mars Polar Lander
when it arrives a few weeks later.

Both probes are part of a $327.5 million mission collectively
known as Mars Surveyor '98, NASA's latest in a series of relatively
inexpensive robot probes. The orbiter rocketed into space last Dec.
11 and its sibling probe was launched Jan. 3.

In 1997, Mars Pathfinder and its rover, Sojourner, explored the
geology of the planet and found some evidence that water may once
have flowed. The Mars Global Surveyor, which arrived later that
year, mapped the surface and found more signs of once-flowing
water.

The Mars Climate Orbiter is equipped with two instruments that
will be turned on after the probe has finished relaying data from
the lander. Observations will continue for 687 days -- a full
Martian year.

The Mars Color Imager will take wide- and medium-angle snapshots
of the planet's atmosphere similar to an Earth-based weather
satellite. Another instrument called the Pressure Modulator
Infrared Radiometer will measure temperatures, dust, water vapor
and clouds from the Martian surface to above the horizon.