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ZL2VAL > ROVERS 12.02.04 11:45l 196 Lines 7933 Bytes #999 (0) @ WW
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Subj: The next generation, 2009
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Sent: 040212/1010Z @:ZL2AB.#46.NZL.OC #:35659 [New Plymouth] FBB7.00g
From: ZL2VAL@ZL2AB.#46.NZL.OC
To : ROVERS@WW
Next Generation Rover: The Mars Science Laboratory
By Leonard David
Senior Space Writer
posted: 07:00 am ET
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.
=========================
73 de Alan, (Sysop ZL2AB).
AX25:ZL2VAL@ZL2AB.#46.NZL.OC
APRS:!3903.34S/17406.45E]
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Message timed: 23:07 on 2004-Feb-12 (NZ local)
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Points to ponder
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Some mistakes are too much fun to only make once.
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