[meteorite-list] Next Generation Rover: The Mars Science Laboratory

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:31:21 2004
Message-ID: <200402112249.OAA03929_at_zagami.jpl.nasa.gov>

http://www.space.com/businesstechnology/technology/mars_science_lab_040211.html

Next Generation Rover: The Mars Science Laboratory
By Leonard David
space.com
11 February 2004

PASADENA, Calif. -- While the Spirit and Opportunity rovers wheel themselves
into the history books of Mars exploration, get ready for the next giant
leap in rolling across the red planet.

The Mars Science Laboratory is an all-terrain, all-purpose machine, akin to
an extraterrestrial Sport Utility Vehicle.

To be rocketed toward Mars in 2009, this long-range, long-duration robot is
a trend setter. It will scope out Mars like never before to assess that
puzzling planet as a potential habitat for life -- past or present -- and
help verify if human explorers could exist there in the future.

Imaginative engineering

Work on MSL is underway here at the Jet Propulsion Laboratory (JPL). And it
is obvious from the get-go that just getting this mega-rover onto Mars takes
a strong dose of imaginative engineering.

The Mars Science Laboratory (MSL) would make the first wheels-down landing
on the planet. No need for airbags, nor lengthy preparations to get the
mobile robot "down-and dirty" on Mars.

This Mars vehicle is lowered onto the surface via a Skycrane and ready for
action, said Brian Muirhead, JPL's chief engineer for the MSL.

Muirhead admits that the Skycrane idea evokes in some people "this is
crazy - you've got to be kidding" comments.

"I heard exactly those same words on the airbags," said Muirhead, who was a
key leader in the Mars Pathfinder/Sojourner project - NASA's first Mars
craft to use airbags. Spirit and Opportunity rovers now scuffing up martian
landscape also utilized airbags to reach their respective landing zones.

"But once you think about it a little bit - the Skycrane is absolutely better
than airbags," Muirhead advised.

Hang time

After diving through the martian atmosphere and then under blossomed
parachute, the Skycrane/MSL hardware would be set free to maneuver over
Mars.

The Skycrane frame carries propellant tanks topped-off with hydrazine
propellant, as well as two "outriggers" - each outrigger equipped with a set
of 700-pound thrust rocket motors. This suite of controllable engines first
run hot and heavy to slow the structure down. By reducing motor thrusting,
the Skycrane eases on down toward Mars.

Using guidance and navigation gear, the Mars-bound hardware enters hover
mode for a nominal five seconds. In a steady-as-she-goes manner, it hangs in
mid-air a mere 15 feet (5 meters) above a pre-determined slice of martian
real-estate.

>From there the MSL slips down a tether to reach Mars. Its depositing duty
complete, the Skycrane departs the scene for a crash landing distant from
the rover's arrival area.

No fuss. No muss. No miles of bouncing. MSL's touchdown speed would be
modest: one meter per second. "That's like falling from three inches on
Earth," Muirhead told SPACE.com . "We're six wheels on Mars instantly," he
explained.

"The concept is very solid. One of the things that we really like about
this - it's very testable on Earth," Muirhead said. A facility to help flesh
out the Skycrane idea is being built at China Lake - a large Navy test
complex about 150 miles northeast of Los Angeles.

Energizer bunny

The MSL's landing ellipse -- the zone in which a spacecraft attempts to land
within -- is some 6 miles by 3 miles (10 kilometers by 5 kilometers). That
is nearly a factor of ten better than the target zones in which the Spirit
and Opportunity exploration rovers came to rest.

Where exactly on the red planet MSL is destined to put down is still to be
determined. "We want to be able to go plus or minus 60 degrees in latitude
at any season," Muirhead said.

The mobile lab is five times larger than the current wheeled robot design
now busily at work on Mars. That class of rover is around 400 pounds (180
kilograms). The heftier MSL could tip the scale at 1,980 pounds (900
kilograms).

What drives that weight up is the science gear MSL will tote across the
martian terrain -- 10 times the payload of a Spirit/Opportunity-class rover.

MSL is designed to operate a full martian year, or two Earth years.

At present, Boeing Co. and Lockheed-Martin are working on competing nuclear
battery designs for the laboratory. Boeing's Canoga Park, Calif.-based
Rocketdyne Propulsion and Power unit is designing a so-called Multi-Mission
Radioisotope Thermoelectric Generator (RTG), a more powerful version of the
RTGs that powered NASA's Viking 1 and 2 Mars landers in the 1970s.

While the Multi-Mission RTG would not be as powerful as the RTGs aboard
NASA's Cassini Saturn probe, it is designed to be more flexible, adaptable
to both the orbiter and lander missions on the space agency's drawing
boards.

Given a nuclear power plant that it carries, the rover would be the
energizer bunny of Mars by going - and going - and going -
for a number of years.

On Mars, size matters.

"We believe that a bigger vehicle has a lot more mobility," Muirhead said.
With MSL's large wheel diameter, it can steer itself to exotic sites as well
as chalk up serious distance much easier. And thanks to a more precise
landing ellipse, the rover could touch down in a reasonably safe place and
then trek to a much more hazardous region, he said.

The now forbidden, do not trespass canyon region of Valles Marineris is a
possibility for MSL roving.

Clean as a whistle

One of the big and costly challenges facing the MSL program is planetary
protection.

MSL is being sent to Mars to story board just how habitable the planet was
in the past or whether that faraway world now serves as a haven for life.

That means the rover must be free of any hitchhiking Earth bugs, and be
organically clean too. Great care must be taken, therefore, in assuring that
any microbial life detected by MSL aren't hangers-on from our own planet.

That being said, going to a chosen region that may be an abode for life
means MSL must be sterilized. Without taking a clean as a whistle approach,
MSL could "foul the nest", so to speak at Mars.

"If you were to crash in a mud puddle on Mars -- if such a thing existed --
you would have created an environment where terrestrial bugs could grow. And
that would be terrible - contaminating the planet big time," Muirhead said.

In the event of a crash-landed rover, the robot's nuclear-energized power
supply could possibly create a liquid water region - an unwanted martian
meltdown of ice.

A major assessment is underway to agree on a spacecraft sterilization
plan-of-action.

Chemistry of whatever

Development cost of the Mars Science Laboratory is slated to be below $850
million. With the price tag of either a Delta 4 or Atlas 5 booster tossed
in, along with a rover-ready nuclear power pack, sterilization expenses and
mission operations, MSL now adds up to a billion dollar plus probe.

Later this year, the type of science gear loaded on MSL will be determined.
What's wanted is an analytic suite of instruments. Already included is a
core drill and crusher that delivers ground up samples for detailed, onboard
study.

"We can get into soil, rock, and ice. We can core anywhere," Muirhead said.
"We actually have the capability to understand the chemistry of whatever we
find on Mars," Muirhead said.

The MSL is a "discovery-driven" mission. It will be dispatched to a
scientific sweet spot on the red planet, picked because of the findings from
earlier orbiters and landers.

"What this mission is about is habitability - understanding the ability of
Mars -- past, present, or future -- to sustain life," Muirhead concluded.
Received on Wed 11 Feb 2004 05:49:48 PM PST