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Location: UFOUpDatesList.Com > 1999 > Apr > Apr 1

Deployed Antenna Sending Streams Of New Mars Images

From: NASANews@hq.nasa.gov
Date: Mon, 29 Mar 1999 11:50:18 -0500 (EST)
Fwd Date: Thu, 01 Apr 1999 18:49:03 -0500
Subject: Deployed Antenna Sending Streams Of New Mars Images

Douglas Isbell
Headquarters, Washington, DC                  March 29, 1999
(Phone:  202/358-1547)

Mary Hardin
Jet Propulsion Laboratory, Pasadena, CA
(Phone:  818/354-0344)

RELEASE:  99-48


       A steady stream of new data from Mars, including high-
resolution images, will begin arriving next week at Earth
receiving stations following yesterday's deployment of the Mars
Global Surveyor's high-power communications antenna.

       "Having a deployed, steerable high-gain antenna is like
switching from a garden hose to a fire hose in terms of data
return from the spacecraft," said Joseph Beerer, flight
operations manager for Mars Global Surveyor at NASA's Jet
Propulsion Laboratory.

       "Up until now, we have been using the high-gain antenna
in its stowed position, so periodically during the first three
weeks of our mapping mission, we had to stop collecting science
data and turn the entire spacecraft to transmit data to Earth,"
Beerer explained.  "Now that the high-gain antenna is deployed
and steerable, we have the ability to simultaneously study Mars
and communicate with Earth."

       The antenna was deployed at about midnight EST, Sunday,
March 28. It had been stowed since launch in November 1996 to
reduce its chances of being contaminated by exhaust from the
spacecraft's main engine, which was fired periodically
throughout the mission.  The spacecraft entered orbit around
Mars in September 1997 and used a technique called aerobraking
to gradually lower the spacecraft's altitude to the desired
orbit for mapping.  The mapping mission began March 9;
full-scale mapping begins April 4.

       Because engineers were uncertain that a device intended
to dampen the force of the deployment would work correctly,
engineers used the antenna in its stowed configuration for the
first three weeks of mapping. This allowed the team to meet the
mission's minimum science objectives before risking the antenna

       Last night, the dish-shaped high-gain antenna, 5 feet in
diameter, was deployed on a 6.6-foot-long boom and was pushed
outward from the spacecraft by a powerful spring. The suspect
dampening device worked as it should have, cushioning the force
of the spring and limiting the speed of the deployment, similar
to the automatic closer on a screen door. With the antenna
successfully deployed, Mars Global Surveyor will return a nearly
constant stream of observations of Mars for the next two years.

       Information from the science instruments is recorded 24
hours a day on solid state recorders on board the spacecraft.
Once a day, during a 10-hour tracking pass over a Deep Space
Network antenna, the data are transmitted to Earth.  In
addition, every third day a second tracking pass is used to
transmit data "live" at a very high rate directly to Earth
without being put on the recorder.  These data, which will
contain high-resolution images of Mars, will be transmitted at
rates between 40,000 and 80,000 bits per second.

        Mars Global Surveyor is managed by the Jet Propulsion
Laboratory for NASA's Office of Space Science, Washington, DC.
Lockheed Martin Astronautics of Denver developed and operates
the spacecraft.  The Jet Propulsion Laboratory is a division of
the California Institute of Technology.

     Further information about the mission is available on the
Internet at:


                          - end -

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