|
23 Sep 99 : MARS CLIMATE ORBITER IS BELIEVED
TO BE LOST due to a suspected navigation error. Early this
morning at about 2 a.m. Pacific Daylight Time the orbiter
fired its main engine to go into orbit around the planet.
All the information coming from the spacecraft leading up
to that point looked normal. The engine burn began as planned
five minutes before the spacecraft passed behind the planet
as seen from Earth. Flight controllers did not detect a signal
when the spacecraft was expected to come out from behind the
planet.
24 Sep 99 : Flight controllers are to ABANDON
THE SEARCH for the spacecraft at 3 p.m. PDT today. The team
has been using the 70-metre-diameter (230-foot) antennas of
the Deep Space Network in an attempt to regain contact with
the spacecraft. Engineers now estimate that the altitude of
the spacecraft's closest approach to Mars as it was firing
its engine to enter orbit around the planet was 57 kms (35
miles). The original target altitude had been about 140 kms
(about 90 miles). The spacecraft team estimates that the minimum
survivable altitude for the spacecraft was between 85 & 100
kms (about 53 to 62 miles).
30 Sep 99 : A failure to recognise and correct
AN ERROR in a transfer of information between the spacecraft
team in Colorado and the mission navigation team in California
led to the loss of the spacecraft last week, preliminary findings
by NASA's Jet Propulsion Laboratory internal peer review indicate.
"People sometimes make errors," said Dr. Edward Weiler, NASA's
Associate Administrator for Space Science. The peer review
preliminary findings indicate that one team used English units
(e.g., inches, feet and pounds) while the other used metric
units for a key spacecraft operation. This information was
critical to the manoeuvres required to place the spacecraft
in the proper Mars orbit. "Our inability to recognise and
correct this simple error has had major implications," said
Dr. Edward Stone, director of the Jet Propulsion Laboratory.
IN AN IDEAL WORLD: On
board the spacecraft was the Mars Colour Imager, known as
MARCI, designed with the help of two Cornell University astronomers.
James F. Bell, Cornell assistant professor of astronomy and
a member of the imaging team says, "We will be doing many
things with MARCI that haven't yet been done. For example,
using high resolution colour imaging, we'll be examining how
Mars' past climate has been preserved in its rocks and minerals,
much like you can learn about the Earth's geologic past by
looking at the colouring and stratigraphy of the Grand Canyon
or other similar structures. MARCI will fill a big gap between
the spectacular black-and-white images being returned now
from the Mars Global Surveyor mission and the coarser-resolution
colour data sent back by the Viking missions more than 20
years ago."
|
"People sometimes
make errors."
|
