[meteorite-list] Mars Science Laboratory: Engineers, Scientists Tackle Challenges

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed Jun 7 22:46:03 2006
Message-ID: <200606071602.JAA08919_at_zagami.jpl.nasa.gov>

http://space.com/businesstechnology/060607_msl_scientists.html

Mars Science Laboratory: Engineers, Scientists Tackle Challenges
By Leonard David
space.com
07 June 2006

PASADENA, California - Picking where to land the next wheeled robot on
Mars is a formidable task - but plunking down a $1.5 billion rover on the
planet safe, sound and ready for prime-time science is also a daunting job.

To be launched in 2009, NASA's six wheeled Mars Science Laboratory (MSL)
is to gather specimens of martian soil and rock. It will then analyze
those samples for organic compounds and gauge environmental conditions
that could have supported microbial life on that planet, now or in the past.

At the first MSL landing site workshop, held here May 31-June 2, Mars
researchers and rover mission designers began a multi-year task of
working together. The goal: to mesh stringent engineering constraints
with the best locations on Mars to further scientific scrutiny of the
red planet.

The meeting became part Mars beauty pageant, part high-tech trust in
space hardware.

No gambling allowed

"If you don't land safely, you've got nothing," said Matt Golombek,
co-chair of the landing site steering committee and a leading Mars
scientist at the Jet Propulsion Laboratory (JPL) in Pasadena,
California. "Basically, it's a mission critical event."

Dozens of possible MSL landing zones were reviewed during the three-day
gathering.

"You want to learn everything you can about the site," Golombek said.
"It's one thing to write a science paper that presents a viable working
hypothesis...it's another thing to risk a billion dollar mission on that
interpretation. I take this very seriously. I don't go to Las Vegas. I
don't gamble."

Culling through a lengthy inventory of prospective MSL touchdown zones,
a first-cut priority list emerged.

The Nili Fossae trough received high marks and was considered an
excellent opportunity to investigate habitability on early Mars.
Likewise, Holden crater received a large show of hands as it preserves a
diverse assemblage of sedimentary deposits and was judged an accessible
and scientifically compelling target.

Then there's Terby Crater that hosts a diverse suite of geomorphic units
and landforms including massive layered ridges and mantled ramps - also
deemed ideal for MSL's sophisticated suite of instruments.

Marwth Vallis percolated to a high ranking given recent detection by
Europe's Mars Express of hydrated phyllosilicates in that area.
Potentially, rocks containing phyllosilicates, it was pointed out, could
themselves still host biorelics if ever life emerged at Mars.

"Nothing is falling off the table at this point," said John Grant,
co-chair of the MSL landing site steering committee and a geologist at
the Center for Earth and Planetary Studies at the National Air and Space
Museum in Washington, D.C. "Nobody should be sobbing wildly in tears if
their site doesn't end up as one of the top five," he advised, noting
that extra sites are likely to crop up in the near-term.

Extra-special attention

Steve Ruff, faculty research associate in the Department of Geological
Sciences at Arizona State University in Tempe said the site picking
process is working as advertised.

"We're seeing in these landing sites the hopes and desires of this
community of where to go in its most basic, raw form," Ruff told
SPACE.com. "It's encouraging to see how the new data sets have really
refined our ability to select where we should go to satisfy MSL mission
goals."

What's ahead is making a list and checking it twice - maybe even more
given the fleet of red planet orbiters, particularly the recent arrival
of the super-powerful Mars Reconnaissance Orbiter (MRO).

Promising MSL landing sites will receive extra-special attention, not
only by using data accumulated by NASA's MRO, Mars Odyssey, and Mars
Global Surveyor, but also the European Space Agency's Mars Express.
Given all that sensor power, the touchdown point of MSL in 2010 will be
the most studied locale on Mars in space exploration history.

Nevertheless, getting MSL onto the planet in the first place requires a
bit of engineering magic.

Guided entry

Mars Science Laboratory will be the first planetary mission to use
precision landing techniques, outfitted with onboard smarts to steer
itself toward pre-selected landscape - akin to the way the space shuttle
controls its entry through the Earth's upper atmosphere.

MSL's guided entry makes the landing ellipse small - compared to the
dimensions of real estate targeted by earlier landers - down to some 6
miles (10 kilometers) radius. That allows scientists to pick a lot of
places to go...places that have not been available, said Richard Cook, MSL
Project Manager at JPL, in a pre-landing site meeting interview.

Following MSL's entry, things happen in rapid succession - such as
deployment of a huge parachute, radar sensing of the rapidly approaching
terrain, and the blazing away of retro rockets.

X-seconds of margin

Snapping his fingers quickly, landing events have to take place one
right after the other with very little time in-between, reported Michael
Watkins, Mission System Manager for the MSL project at JPL. "The less
time between those, the riskier that system is. You'd like to have
X-seconds of margin in each of those steps," he said.

The lower the altitude of the chosen landing site, Watkins added, the
more time the entire MSL landing system will have to decelerate and play
out successfully.

There is no air bag landing this trip. MSL is too massive. The rover
will be tenderly deposited onto Mars via a tether reeled out from a
Skycrane system, a rocket-powered contraption that hovers above the
landing site.

An animated view was shown of how MSL gets down on Mars in step by step,
matter-of-fact fashion, prompting one cynical scientist to say: "And
enter miracle here."

Planetary protection

A nuclear-powered MSL is built to live longer than those smaller,
solar-energized robotic twins now trekking about Mars - Spirit and
Opportunity. This week, in fact, the MSL project is undergoing a
preliminary design review, a milestone making event toward getting to Mars.

Once MSL is set down on Mars via the Skycrane, the rover will be near
ready to roll. It will take a couple of days to ready itself for
wheeling onward. Regarding rover range, JPL's Cook told SPACE.com, that
engineers are working to a requirement of being able to drive some 12
miles (20 kilometers). MSL has both "land and look" and "go to"
abilities to scout about.

The science-equipped rover is to assess whether Mars ever was, or is
still today, an environment able to support microbial life. On one hand,
MSL's mission of roaming about is geared to determine the planet's
"habitability" - but that duty is handicapped by planetary protection rules.

Warm feelings

Some Mars touchdown sites may not be as acceptable as others. A crash
landing could lead to MSL's radioisotope power source polluting water
ice in the region.

"We have to be careful about putting Earth microbes in the places where
they can grow and thrive," said John Rummel, Planetary Protection
Officer at NASA Headquarters in Washington, D.C. MSL's nuclear power
source will stay hot for a long time, he added, and coming in contact
with martian water ice, a warm little pond might make a comfy home for
microbes.

Hitchhiking microbes from Earth on MSL becoming part of the martian
water system is a no-no.

Having MSL turn-tail away from water, put off some scientists at the
workshop. In particular, not driving to a Mars gully or two - arguably,
the product of groundwater seeping to the surface - is perplexing given
that the rover's mission is to identify both Mars' past and potentially
present habitability.

"Recognizing that going to gullies may not be possible because of
planetary protection means there's something wrong with our system,"
argued Ken Edgett, a staff scientist and gully expert at Malin Space
Science Systems in San Diego, California. "How can NASA not have given
us a mission that we can't go to the kind of places where we think
liquid water may be present, or may have been present in relatively
recent times?"

Edgett said that he fully acknowledges the planetary protection
concerns. However, he wanted the science team to understand what is
going to be missed out with the MSL project.

Why not have scientists tell the engineers where exactly on Mars they
want to go...and then have designers whip up the requisite hardware? A
"here's where we want to go - now get us there" grumbling was registered
several times during the landing site workshop.

"We, the scientific community should be saying where on Mars do we want
to go...what science we want to do there...and then go back to [NASA]
Headquarters and say this is what we want to do. Can you afford this?
But we don't do that," Edgett said. "Let's turn it around for the next
decade in that direction."

Mending Fences

Indeed, the MSL mission comes fully-loaded with constraints. Altitude of
the desired landing site, as well as high winds and up and down drafts
must be accounted for. So too are big ugly rocks within the touchdown
zone. And nasty, steep slopes can foul-up wheels down day.

But getting MSL on the ground is a communal, death-defying act. It melds
engineering know-how and a quest for new insights about the red planet's
past and present.

"There's always been a merging of the two," said veteran Gentry Lee,
JPL's Chief Engineer of Solar System Exploration. "Anybody that thinks
otherwise is wrong. It is give and take, back and forth."

Lee told SPACE.com that MSL engineers have not built fences...but have
provided some guidelines.

"There are those who are on one side of the fence or the other. But you
have to put something down in the beginning" Lee said. "But the
decisions are made by blending the two. That's the process.".
Received on Wed 07 Jun 2006 12:02:51 PM PDT