Mars Penetrator passes tests

Nov 15 01:15 UTC 1997

From: baalke@brucie.jpl.nasa.gov (Ron Baalke)
Newsgroups: sci.space.science,sci.space.tech
Subject: Mars Penetrators Successfully Complete Crucial Subsystem Test
Date: 13 Nov 1997 21:59 UT
Organization: Jet Propulsion Laboratory
Lines: 102
Message-ID: <13NOV199721592322@brucie.jpl.nasa.gov>

Douglas Isbell
Headquarters, Washington, DC                     November 13, 1997
(Phone:  202/358-1753)

John Watson
Jet Propulsion Laboratory, Pasadena, CA
(Phone:  818/354-5011)

RELEASE:  97-265

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 4.4-pound (two-kilogram) 
prototype probe containing a soil collection drill and a circular 
group of eight lithium thyonal chloride cells -- forming two 
batteries -- was shot into the ground at more than 400 mph (644 
kilometers per hour).  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 
drill assembly.

     "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, that should 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 
the orbiting Mars Global Surveyor 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.

     Additional information about DS2 can be obtained by 
visiting the project's World Wide Web site at URL:        

               http://nmp.jpl.nasa.gov/ds2/

     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.

                           -end-