[meteorite-list] Opportunity Rover to Prowl its Entry Debris for Mars Secrets

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue Dec 21 17:37:49 2004
Message-ID: <200412212237.OAA19617_at_zagami.jpl.nasa.gov>

http://space.com/missionlaunches/opportunity_heatshield_041221.html

Opportunity Rover to Prowl its Entry Debris for Mars Secrets
By Leonard David
space.com
21 December 2004

The Opportunity Mars rover has turned into a junkyard dog, prowling ever
closer to a hunk of space litter at Meridiani Planum -- a discarded heat
shield.

During its January 25 plunge toward the red planet, the Opportunity
rover was encapsulated in a protective aeroshell comprised of two key
parts: a heat shield and a backshell that contained essential landing gear.

After taking the brunt of atmospheric friction, the heat shield was
jettisoned high above Mars. The hardware fell several miles before
hitting the Meridiani Planum landscape at a smashing speed.

Double bonus

Fresh from exploring the remarkable Endurance Crater, the Opportunity
rover is now rolling toward the beat up heat shield that's been sitting
on Mars for nearly 11 months.

Steve Squyres, scientific Principal Investigator for the Mars
Exploration Rover effort from Cornell University, said the Opportunity
assessment of the heat shield offers a double-bonus.

"For the scientists, it may be a chance to look at the deepest fresh
hole in the ground that we'll ever see on Mars. For the engineers, it's
an unprecedented chance to see how a heat shield performed during entry
through the martian atmosphere. There's something for everybody,"
Squyres told SPACE.com.

As the robot wheels across the martian ponderosa that is Meridiani
Planum, its Panoramic Camera (Pancam) has begun snapping clearer and
clearer images of the distant heat shield. The Pancam is a
high-resolution color stereo pair of CCD cameras located on a camera bar
that sits on top of the mast of the rover.

Furthermore, there is discussion about making more than a drive-by
camera shooting of the refuse -- perhaps using the robot's microscopic
imager (MI) to examine the spent heat shield up-close and personal.

"We'll definitely do a lot of careful imaging with Pancam. We will use
the MI only if we find that it's safe and productive to do so. Stay
tuned," Squyres added.

What happened during entry and impact?

Both en route to and wheel stop at the spacecraft part, there's good
science ahead, said Ray Arvidson, an Earth and planetary sciences expert
at Washington University in St. Louis, Missouri, and deputy principal
investigator for the Mars Exploration Rover instruments.

"The heat shield campaign is focused on an inventory of the heat shield
and its components, including analyses of what happened during entry and
impact," Arvidson told SPACE.com.

Arvidson said that along the way to and by the shield, Opportunity
scientists will be conducting observations aimed at understanding the
mechanical properties of the surface, based on excavations during the
impact.

"We are also interested in looking at the soils and rocks exposed during
impact and making imaging and other measurements of these materials.
This latter set of experiments will allow us to probe subsurface
characteristics," Arvidson explained.

First-ever inspection

Spacecraft engineers are keen on making the first-ever inspection of a
heat shield that penetrated Mars' atmosphere.

Lockheed Martin Space Systems in Denver, Colorado designed and built the
Mars Exploration Rover aeroshell structure and thermal protection system.

The blunt-nosed cone of a heat shield was covered with a layer of
phenolic honeycomb. A phenolic compound is made from benzene and is
typically used in various plastics, disinfectants, and pharmaceuticals.
This phenolic honeycomb is filled with an ablative material -- also
called an ablator -- which dissipates heat generated by atmospheric
friction.

The ablator itself is a unique blend of cork wood, binder and many tiny
silica glass spheres. The heat shield has a thick, one-half inch (12.7
millimeter) layer of the ablator.

Images taken by Opportunity might reveal how well the protective shield
withstood the atmospheric fireworks it encountered in slicing through
Mars' atmosphere, as well as yield data leading to better heat shield
designs.
Received on Tue 21 Dec 2004 05:37:39 PM PST