Physics 9 Fall 1999
Homework 5 (last one) Due Dec 9
1. Please draw sketches to illustrate the interior compositions of
the 9 planets. Then explain how we know these compositions.
2. Please write a one paragraph summary of the following.
MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov
FOR IMMEDIATE RELEASE November 30, 1999
MARS POLAR LANDER, DEEP SPACE 2 SET FOR ARRIVAL
NASA returns to the surface of Mars on December 3 with a
spacecraft that will land on the frigid, windswept steppe near
the edge of Mars' south polar cap. Piggybacking on the lander are
two small probes that will smash into the Martian surface to test
new technologies.
The lander mission is the second installment in NASA's long-
term program of robotic exploration of Mars, which was initiated
with the 1996 launches of the currently orbiting Mars Global
Surveyor and the Mars Pathfinder lander and rover, and included
the recently lost Mars Climate Orbiter.
Mars Polar Lander will advance our understanding of Mars'
current water resources by digging into the enigmatic layered
terrain near one of its poles for the first time. Instruments on
the lander will analyze surface materials, frost, weather
patterns and interactions between the surface and atmosphere to
better understand how the climate of Mars has changed over time.
Polar Lander carries a pair of basketball-sized microprobes
that will be released as the lander approaches Mars and dive
toward the planet's surface, penetrating up to about 1 meter (3
feet) underground to test 10 new technologies, including a
science instrument to search for traces of water ice. The
microprobe project, called Deep Space 2, is part of NASA's New
Millennium Program.
A key scientific objective of the two missions is to
determine how the climate of Mars has changed over time and where
water, in particular, resides on Mars today. Water once flowed on
Mars, but where did it go? Clues may be found in the geologic
record provided by the polar layered terrain, whose alternating
bands of color seem to contain different mixtures of dust and
ice. Like growth rings of trees, these layered geological bands
may help reveal the secret past of climate change on Mars and
help determine whether it was driven by a catastrophic change,
episodic variations or merely a gradual evolution in the planet's
environment.
Today the Martian atmosphere is so thin and cold that it
does not rain; liquid water does not last on the surface, but
quickly freezes into ice or evaporates into the atmosphere. The
temporary polar frosts which advance and retreat with the seasons
are made mostly of condensed carbon dioxide, the major
constituent of the Martian atmosphere. But the planet also hosts
both water-ice clouds and dust storms, the latter ranging in
scale from local to global. If typical amounts of atmospheric
dust and water were concentrated today in the polar regions, they
might deposit a fine layer every year, so that the top meter (or
yard) of the polar layered terrains could be a well-preserved
record showing 100,000 years of Martian geology and climatology.
The lander and microprobes will arrive December 3, 1999.
They are aimed toward a target sector within the edge of the
layered terrain near Mars' south pole. The exact landing site
coordinates were selected in August 1999, based on images and
altimeter data from the currently orbiting Mars Global Surveyor.
Like Mars Pathfinder, Polar Lander will dive directly into
the Martian atmosphere, using an aeroshell and parachute scaled
down from Pathfinder's design to slow its initial descent. The
smaller Polar Lander will not use airbags, but instead will rely
on onboard guidance and retro-rockets to land softly on the
layered terrain near the south polar cap a few weeks after the
seasonal carbon dioxide frosts have disappeared. After the heat
shield is jettisoned, a camera will take a series of pictures of
the landing site as the spacecraft descends. These are recorded
onboard and transmitted to Earth after landing.
As the lander approaches Mars about 10 minutes before
touchdown, the two Deep Space 2 microprobes are released. Once
released, the projectiles will collect atmospheric data before
they crash at about 200 meters per second (400 miles per hour)
and bury themselves beneath the Martian surface. The microprobes
will test the ability of very small spacecraft to deploy future
instruments for soil sampling, meteorology and seismic
monitoring. A key instrument will draw a tiny soil sample into a
chamber, heat it and use a miniature laser to look for signs of
vaporized water ice.
About 60 kilometers (35 miles) away from the microprobe
impact sites, Mars Polar Lander will dig into the top of the
terrain using a 2-meter-long (6 1/2-foot) robotic arm. A camera
mounted on the robotic arm will image the walls of the trench,
viewing the texture of the surface material and looking for fine-
scale layering. The robotic arm will also deliver soil samples to
a thermal and evolved gas analyzer, an instrument that will heat
the samples to detect water and carbon dioxide. An onboard
weather station will take daily readings of wind temperature and
pressure, and seek traces of water vapor. A stereo imager perched
atop a 1.5-meter (5-foot) mast will photograph the landscape
surrounding the spacecraft. All of these instruments are part of
an integrated science payload called the Mars Volatiles and
Climate Surveyor.
Also onboard the lander is a light detection and ranging
(lidar) experiment provided by Russia's Space Research Institute.
The instrument will detect and determine the altitude of
atmospheric dust hazes and ice clouds above the lander. Inside
the instrument is a small microphone, furnished by the Planetary
Society, Pasadena, CA, which will record the sounds of wind
gusts, blowing dust and mechanical operations onboard the
spacecraft itself.
The lander is expected to operate on the surface for 60 to
90 Martian days through the planet's southern summer (a Martian
day is 24 hours, 37 minutes). The mission will continue until the
spacecraft can no longer protect itself from the cold and dark of
lengthening nights and the return of the Martian seasonal polar
frosts.
Mars Polar Lander and Deep Space 2 are managed by the Jet
Propulsion Laboratory for NASA's Office of Space Science,
Washington, DC. Lockheed Martin Astronautics Inc., Denver, CO, is
the agency's industrial partner for development and operation of
the orbiter and lander spacecraft. JPL designed and built the
Deep Space 2 microprobes. JPL is a division of the California
Institute of Technology, Pasadena, CA.