PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE (818) 354-5011
Contact: John G. Watson
FOR IMMEDIATE RELEASENovember 13, 1997
MARS PENETRATORS SUCCESSFULLY COMPLETE CRUCIAL SUBSYSTEM TEST
Two miniature science probes designed to penetrate the Martian surface and
analyze the water vapor content of the planet's subterranean soil in 1999 have
successfully completed a crucial subsystem test deep in the New Mexico desert.
This successful check of the batteries and soil collection drill of the mission
known as Deep Space 2 (DS2) provides a green light for subsequent integrated system
tests next spring, said
Sarah Gavit, DS2 project manager at NASA's Jet Propulsion Laboratory (JPL), Pasadena,
CA. The DS2 mission hardware will be launched in January, 1999, mounted on the Mars
Surveyor '98 Lander. Both missions will arrive on Mars in December, 1999.
DS2 is the second scheduled launch in NASA's New Millennium Program, which is
designed to test new advanced technologies prior to their use on science missions in
the 21st century. DS2 will validate the ability of small probes loaded with
sensitive, miniaturized instruments to analyze the terrain of planets and moons
throughout the Solar System.
In the late October test, a two-kilogram (4.4-pound) prototype probe containing
a soil collection drill and a circular group of eight lithium thyonal chloride cells-
batteries--was shot into the ground at more than 644 kilometers per hour (400 mph).
The drill survived a 20,000-G impact, and the batteries, nestled inside a custom-
designed casing, survived a
45,000-G impact intact. Both continued to function as designed. One G is the normal
force of gravity on Earth.
"The Mars Pathfinder lander experienced about 19 G's when it hit the Martian
terrain in July, so you can see that we are working at enormous rates of
deceleration," explained Gavit. "One
of our biggest challenges has been to find a way for our components to survive such a
high deceleration force. The items at highest risk are the batteries, their packaging
and the motor
"Although the recent test was one in a long series, it was the first test using
flight-like hardware and packaging, so it served as a complete qualification of the
battery and drill
subsystems," she added.
The probe design features two modules: a circular aftbody, five inches (13
centimeters) in diameter, containing the batteries, that remains atop the surface;
and a four-inch-long
(10-centimeter) forebody, containing the drill and a soil analysis instrument,
designed to burrow up to six feet (1.8 meters) into the Martian soil. The two modules
are connected via a flex cable
that unravels as the forebody dives into the soil after a freefall impact.
Once in the ground, the soil collection drill slowly twists out from the side of
the forebody and retracts a tiny soil sample into a chamber within the forebody,
where it is analyzed by a
water detection instrument. This instrument's key feature is a miniature tunable
diode laser, similar in principle to the lasers used in consumer CD players. The soil
sample is then heated, creating a vapor that passes through the path of the laser
beam if water is indeed present. This resulting change in the intensity of the laser
light indicates the amount of water, if any, to be found in the Martian soil sample.
The aftbody features batteries developed just for DS2. These batteries can
operate down to minus 112 degrees F (minus 80 degrees Celsius), making them the only
batteries of this type with
the dual capability of being able to survive the strong impact and work in low
temperatures. The aftbody also includes a micro-telecommunications system that,
together with miniaturized
electronics in the forebody, will relay the probe's findings to an orbiting mother
ship spacecraft for transmission to Earth via NASA's Deep Space Network.
The Oct. 29 test took place at the New Mexico Institute of Mining Technology's
Energetic Materials Research and Test Center in Socorro, NM. It was the 53rd test of
DS2 hardware since the spring of 1996, beginning with early tests of preliminary
battery and drill designs, among many other components.
JPL manages the New Millennium Program for NASA's Office of Space Science and
Office of Mission to Planet Earth, Washington, DC. JPL is a division of the
California Institute of Technology, Pasadena, CA.