[meteorite-list] Phoenix Mars Lander Status Report: Tasks En Route to Mars Include Course Tweak, Gear Checks

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri, 2 Nov 2007 09:22:53 -0700 (PDT)
Message-ID: <200711021622.JAA00683_at_zagami.jpl.nasa.gov>

http://www.nasa.gov/mission_pages/phoenix/news/phoenix-20071030.html

Phoenix Mars Lander Status Report:
Tasks En Route to Mars Include Course Tweak, Gear Checks

10.30.07

NASA's Phoenix Mars Lander, launched on Aug. 4 and headed to Mars, fired
its four trajectory correction thrusters Wednesday for only the second
time. The 45.9-second burn nudged the spacecraft just the right amount
to put it on a course to arrive at the red planet seven months from today.

At Mars, Phoenix will face a challenging 7-minute descent through the
atmosphere to land in the far north on May 25, 2008. After landing, it
will use a robotic digging arm and other instruments during a
three-month period to investigate whether icy soil of the Martian arctic
could have ever been a favorable environment for microbial life. The
solar-powered lander will also look for clues about the history of the
water in the ice and will monitor weather as northern Mars' summer
progresses toward fall.

The second course adjustment had been postponed a week to allow time for
carefully returning the spacecraft to full operations after a cosmic-ray
strike disrupted a computer memory chip Oct. 6. Experiences with
previous spacecraft have shown hits by cosmic rays are a known hazard in
deep space. The Phoenix spacecraft properly followed its onboard safety
programming by putting itself into a precautionary standby state when
the event occurred. Mission controllers then followed step-by-step
procedures to understand the cause and resume regular operations.

"Our engineers responded in a very careful and deliberate manner. Since
this was a very well-understood anomaly, it was a good experience for
the team," said Phoenix Project Manager Barry Goldstein of NASA's Jet
Propulsion Laboratory, Pasadena, Calif.

This week's trajectory correction maneuver, plus the flight's first one
on Aug. 10, were planned in advance to adjust for a launch-day course
that was intentionally designed to be slightly offset from Mars. The
offset had prevented the possibility of the third stage of the launch
vehicle hitting Mars.

Before the Oct. 24 maneuver, the spacecraft's planned trajectory would
have missed Mars by about 95,000 kilometers (59,000 miles). Now, Phoenix
is on track to intercept Mars in its orbit next year.

"The first and second trajectory correct maneuvers were designed
together," said JPL's Brian Portock, chief of the navigation team for
Phoenix. "We gain a more efficient use of fuel by splitting the
necessary adjustment into two maneuvers." The second maneuver changed
the velocity of the spacecraft by about 3.6 meters per second (8.05
miles per hour), about one-fifth as much as the first maneuver.

Four additional opportunities for trajectory corrections are scheduled
in April and May 2008. "The remaining ones are really for fine tuning,"
Portock said. The landing site is a broad valley at about 68 degrees
north latitude, 233 degrees east longitude.

Initial in-flight checks of all the science instruments were completed
with Oct. 26 testing of the Canadian-provided weather station, which
includes a laser-reflection device called a lidar. "With the activation
of Canada's weather station, the testing of the precision lidar
instrument and the temperature and pressure sensors, we will be
receiving our first space weather report from Phoenix as it continues
its voyage to Mars," said Alain Berinstain, Director of Planetary
Exploration and Space Astronomy at the Canadian Space Agency.

In recent weeks, flight controllers have conducted two sessions of
heating the spacecraft's Thermal and Evolved-Gas Analyzer to drive off
water vapor that was carried from Earth in the instrument. Results
indicate that the process is successfully removing water vapor.
Additional "bake-out" sessions for this instrument are planned prior to
landing.

The Phoenix mission is led by Peter Smith of the University of Arizona,
Tucson, with project management at JPL and development partnership at
Lockheed Martin, Denver. International contributions are provided by the
Canadian Space Agency; the University of Neuchatel, Switzerland; the
universities of Copenhagen and Aarhus, Denmark; the Max Planck
Institute, Germany; and the Finnish Meteorological Institute. JPL is a
division of the California Institute of Technology in Pasadena.

Additional information on Phoenix is available online at:
http://www.nasa.gov/phoenix and at http://phoenix.lpl.arizona.edu .
Additional information on NASA's Mars program is available online at:
http://www.nasa.gov/mars .


Media contacts: Guy Webster 818-354-6278
guy.webster at jpl.nasa.gov
Jet Propulsion Laboratory, Pasadena, Calif.

Dwayne Brown 202-358-1726
dwayne.c.brown at nasa.gov
NASA Headquarters

Sara Hammond 520-626-1974
shammond at lpl.arizona.edu
University of Arizona, Tucson

Gary Napier 303-971-4012
gary.p.napier at lmco.com
Lockheed Martin Space Systems, Denver

2007-124
Received on Fri 02 Nov 2007 12:22:53 PM PDT