NASA: Mysterious space whisper could be Mars Polar Lander
January 28, 2000
Web posted at: 9:09 a.m. EST (1409 GMT)
From CNN Space Correspondent Miles O'Brien
PASADENA, California (CNN) -- Managers of the Mars Polar
Lander Team say a series faint radio signals captured by a
dish antenna at Stanford University are offering some
"tantalizing" circumstantial evidence that the spacecraft may
be phoning home.
A series of additional tests will likely give engineers more definitive word after the weekend.
"We are trying to keep an even keel," said Project Scientist
Richard Zurek. "On Monday morning we may have some answers."
Since December 3rd, the date the $165 million spacecraft was
supposed land, the Stanford antenna has sent commands to the
spacecraft to activate its low power UHF antenna four times.
In two of those instances, December 18th and January 14th,
the antenna received transmissions on the correct frequency,
from the right direction and at the anticipated times.
| MESSAGE BOARD|
"It is plausible that it is real," said Polar Lander Flight
Director Sam Thurman. "But we're not there yet. We do not
have a smoking gun."
The absence of signals on during the two other attempts (on
December 10th and 14th) can be attributed to problems on the
ground either sending or recording the transmissions - and
thus are not being interpreted as evidence that would
undermine a theory that MPL is transmitting. In fact, because
the problems were on Earth, the dearth of signals on those
occasions actually makes it less likely that the UHF signals
are from another source.
In order to draw some conclusions, scientists Stanford are
conducting a series of tests. In one, they will fine tune the
antenna to better isolate the signal. In another, they will
command the lander to turn itself on and off at precise times
- then check for comparisons in the received signals. They
will also deliberately point the antenna away from Mars - to
further exclude the possibility they may be capturing stray
signals from an earthbound source. UHF radio signals are used
in wireless communications and TV broadcast transmissions.
"If we can duplicate the results," said Thurman. "then we may
get to the point where these things look like a lander."
The UHF transmitter on Mars Polar Lander was not designed to
transmit directly to Earth. It was supposed to use the Mars
Climate Orbiter - and then after its loss - the Mars Global
Surveyor (in Mars orbit) - as a relay. Isolating such a faint
signal is a difficult challenge.
"There is a tremendous amount of (radio) clutter," says
Zurek. "It takes a lot of processing to pull these signals
The Polar Lander team has asked their colleagues at Stanford
to take their time processing the data. Both teams will be
working through the weekend. While the Stanford team looks
for this cosmic needle in the haystack, the team at the Jet
Propulsion Lab will be planning what to do if the lander is
If the lander is alive, it reamins doubtful it will be able
to return any scientific results. If its UHF transceiver is
working, ground controllers will only be able to issue very
rudimentary commands - "Questions with a 'yes' or 'no'
answer," said Zurek.
But answers to those queries might give engineers valuable
insight into what went wrong during the lander's descent.
NASA abandons attempts to contact Polar Lander
January 17, 2000
NASA to give up search for silent Mars Polar Lander
January 16, 2000
Silence on Mars as NASA's 'last silver bullet' misses mark
December 7, 1999
One more good chance to find Mars lander
December 6, 1999
NASA 'less confident' but won't give up on Mars Lander
December 5, 1999
Mars lander misses first chance to communicate
December 3, 1999
Mars Polar Lander Official Website
Mars Exploration Program
Mars Global Surveyor
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