Half Of Aeroshell Structure That Will Protect Space Probe
Lockheed Martin recently delivered the backshell for the Mars
Science Laboratory (MSL) to NASA's Jet Propulsion Laboratory in
Pasadena, CA. The backshell is half of the large and sophisticated
two-part aeroshell that will encapsulate and protect the MSL rover
during its deep space cruise to Mars, and from the intense heat and
friction that will be generated as the system descends through the
Martian atmosphere.
Lockheed Martin has designed and built nearly every capsule
flown by NASA for space exploration since Apollo, but none as large
as the MSL aeroshell at about 15 feet in diameter. For comparison,
the heatshields of the Spirit and Opportunity Mars Exploration
Rovers measured 8.5 feet and Apollo capsule heatshields measured
just under 13 feet.
In addition to protecting the rover, the backshell provides the
structural support for the parachute and unique sky crane, a system
that will lower the rover to a soft landing on the surface of Mars.
The MSL biconic-shaped backshell is made of an aluminum honeycomb
structure sandwiched between graphite-epoxy face sheets. It is
covered with a thermal protection system composed of the
cork/silicone super light ablator (SLA) 561v that originated with
the Viking landers.
SLA
561v has been used on the heatshields of all Mars landers mission
of past, but this is the first time it will be used on the
backshell of a Mars mission. Lockheed Martin used the proprietary
ablator on the backshell of the successful Genesis mission.
"The biggest challenge for the MSL aeroshell is its gigantic
size," said Steve Jolly, Lockheed Martin Space Systems Company
program manager for the MSL aeroshell. "It's almost double the size
of our Mars Exploration Rovers' [Spirit and Opportunity]
aeroshells. When you are building a structure that big, there are
many considerations we had to take into account, including the fact
that this is a lifting capsule that is steerable."
Designed to provide a more-precise landing than previous
missions, the steering capability is produced by ejecting ballast
that off-sets the center-of-mass prior to entry into the
atmosphere. This off-set creates lift as it interacts with the thin
Martian atmosphere and allows roll control and autonomous steering
through the use of thrusters.
Scheduled for launch in the fall of 2009, the Mars Science
Laboratory -- built by the Jet Propulsion Laboratory -- will
support the Mars Exploration Program's strategy of "follow the
water" and will have the science goals of determining whether the
planet was ever habitable, characterizing the climate and geology
of Mars, and preparing for human exploration.
The second half of the MSL aeroshell, the heat shield, is still
in production at Lockheed Martin's Denver, CO facilities and is
currently undergoing installation of the Phenolic Impregnated
Carbon Ablator (PICA) tiles. It is scheduled to ship to Kennedy
Space Center in April 2009.
The shipping of the MSL backshell comes just four months after
the spectacular entry, descent, and landing of the Phoenix Mars
Lander which also used an aeroshell system. Both the aeroshell and
lander were designed and built by Lockheed Martin.