[meteorite-list] MSL Postpones Adjusting Course

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri, 2 Dec 2011 08:47:38 -0800 (PST)
Message-ID: <201112021647.pB2GlcFq011756_at_zagami.jpl.nasa.gov>

http://www.spaceflightnow.com/atlas/av028/111201noburn.html

Mars Science Laboratory postpones adjusting course
BY JUSTIN RAY
SPACEFLIGHT NOW
December 1, 2011

The first scheduled opportunity for the Mars Science Laboratory to tweak
its trajectory on the interplanetary cruise from Earth to the red planet
won't be needed for awhile, flight controllers announced Thursday.

The car-sized rover, packed inside the protective descent capsule, was
successfully blasted off from Cape Canaveral last Saturday atop the
powerful United Launch Alliance Atlas 5 rocket at 10:02 a.m. EST (1502
GMT).

Following a pair of firings, the cryogenic Centaur upper stage released
the spacecraft on the Mars-bound flight path 44 minutes after launch.

Officials at the Jet Propulsion Laboratory in Pasadena, Calif., had been
preparing for a possible course-correction maneuver 15 days after
launch. But navigators have determined the trajectory is spot-on and
needs no refinement right now.

"This was among the most accurate interplanetary injections ever," said
Louis D'Amario, mission design and navigation manager for Mars Science Lab.

Engineers tentatively plan to execute a maneuver in late December or
early January to begin the process of steering the spacecraft toward
Mars. A burn in early June will start eyeing the precise landing site.

As with any planetary launch, the rocket actually aims off-center from
the target. In this case, the Atlas put Mars Science Lab on a track to
miss Mars by 38,000 miles to ensure the Centaur upper stage that is
following the spacecraft won't hit the planet. The rocket motor wasn't
subjected to the thorough cleaning to prevent Earth's microbes from
contaminating Mars, thus the deliberate effort to prevent an impact.

The pre-planned trajectory for this mission included 6 correction
maneuvers that would use 8 thrusters located on the donut-shaped cruise
ring atop the spacecraft. The last could occur as late as 9 hours before
landing to fix any errors prior to entry into the Martian atmosphere.

The $2.5 billion mission is headed for a late-night landing (California
time) August 5 between 10 and 10:30 p.m. PDT (1 and 1:30 a.m. EDT Aug.
6) in Gale Crater.

Meanwhile, controllers reported that the spacecraft experienced a
computer reset Tuesday because of star-identifying software in the
attitude control system. The glitch resulted in the craft briefly
entering a precautionary safe mode.

"Engineers restored it to normal operational status for functions other
than attitude control while planning resumption of star-guided attitude
control," NASA said in a statement.

Also on Tuesday, the onboard thrusters were fired to reduce the craft's
rotation rate from 2.5 rotations per minute to 2.05 rotations per minute
for the cruise.

By mid-day Friday, the spacecraft will have traveled 10.8 million miles
of its 352-million-mile trek to Mars, moving at 7,500 mph relative to
Earth and at 73,800 mph relative to the sun.

Mars Science Lab is communicating with Earth at a downlink rate of 25
kilobits per second. Electrical output from the cruise ring's solar
arrays is 800 watts.
Received on Fri 02 Dec 2011 11:47:38 AM PST