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Mars Rover Opportunity Gets Green Light To Enter Crater



 
 
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  #1  
Old June 5th 04, 12:49 AM
Ron
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Default Mars Rover Opportunity Gets Green Light To Enter Crater

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA 91109. TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov

Guy Webster (818) 354-6278
Jet Propulsion Laboratory, Pasadena, Calif.

Donald Savage (202) 358-1547
NASA Headquarters, Washington, D.C.

NEWS RELEASE: 2004-142 June 4, 2004

Mars Rover Opportunity Gets Green Light To Enter Crater

NASA has decided the potential science value gained by sending
Opportunity into a martian impact crater likely outweighs the risk of
the intrepid explorer not being able to get back out.

Opportunity has been examining the rim of the stadium-sized "Endurance
Crater" since late May. The rover team used observations of the
depression to evaluate potential science benefits of entering the
crater and the traversability of its inner slopes.

The soonest Opportunity could enter Endurance is early next week. It
will drive to the top of a prospective entry-and-exit route on the
southern edge of the crater and make a final check of the slope. If
the route is no steeper than what recent testing runs at NASA's Jet
Propulsion Laboratory, Pasadena, Calif., suggest a rover can climb,
controllers plan to radio Opportunity the command to go into the
crater.

"This is a crucial and careful decision for the Mars Exploration
Rovers' extended mission," said Dr. Edward Weiler, NASA's associate
administrator for space science. "Layered rock exposures inside
Endurance Crater may add significantly to the story of a watery past
environment that Opportunity has already begun telling us. The
analysis just completed by the rover team shows likelihood that
Opportunity will be able to drive to a diagnostic rock exposure,
examine it, and then drive out of the crater. However, there's no
guarantee of getting out again, so we also considered what science
opportunities outside the crater would be forfeited if the rover
spends its remaining operational life inside the crater."

Opportunity and its twin, Spirit, successfully completed their primary
three-month missions on Mars in April.

At a rock outcrop in a small impact feature nicknamed, "Eagle Crater,"
where Opportunity first landed, the rover found small-scale rock
textures and evaporite mineral compositions testifying that a body of
salty water covered the site long ago.

The wet environment may have been a suitable habitat for life, if it
ever existed on Mars. However, only the uppermost layer of the
region's layered crust was exposed at Eagle Crater, not deeper layers
that could reveal what the environment was like earlier.

The rock layer seen at Eagle Crater appears at Endurance Crater, too.
At Endurance, though, it lies above exposures of thicker, older
layers, which are the main scientific temptation for sending
Opportunity inside the crater.

"Answering the question of what came before the evaporites is the most
significant scientific issue we can address with Opportunity at this
time," said Dr. Steve Squyres of Cornell University, Ithaca, N.Y.,
principal investigator for the science instruments on both rovers.
"We've read the last chapter, the record of the final gasps of an
evaporating body of water. What came before? It could have been a
deep-water environment. It could have been sand dunes. It could have
been a volcano. Whatever we learn about that earlier period will help
us interpret the upper layer's evidence for a wet environment and
understand how the environment changed."

Richard Cook, project manager at JPL for the rovers, said that
reaching one exposure of the older rock layers inside Endurance
requires driving only about 5 to 7 meters (16 to 23 feet) into the
130-meter-diameter (140-yard-diameter) crater. The rover is on the rim
at that site, which had been dubbed "Karatepe."

"We'll take an incremental approach, edging our way down to the
target," Cook said. The plan is to use the tools on Opportunity's
robotic arm to analyze the exposed layers for several days, then drive
in reverse back up the slope and exit the crater. The slope between
the rim and the layered outcrop at Karatepe is about 25 degrees.

"We have done testing that says we can do 25 degrees, provided the
wheels are on a rock surface and not loose sand," Cook said. Engineers
and scientists on the rover team built a test surface mimicking the
rocks and sand seen in Opportunity's images of Endurance Crater. The
surface was tilted to 25 degrees, and a test rover climbed it. If
portions of the route to the outcrop turn out to be between 25 and 30
degrees, the team plans to proceed slowly and use Opportunity to
assess the amount of traction the rover is getting.

JPL, a division of the California Institute of Technology in Pasadena,
manages the Mars Exploration Rover project for NASA's Office of Space
Science, Washington, D.C. Images and additional information about the
project are available from JPL at

http://marsrovers.jpl.nasa.gov

and from Cornell University, Ithaca, N.Y., at

http://athena.cornell.edu .

-end-
  #2  
Old June 5th 04, 11:23 AM
Bart Declercq
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Default Mars Rover Opportunity Gets Green Light To Enter Crater


"We have done testing that says we can do 25 degrees, provided the
wheels are on a rock surface and not loose sand," Cook said. Engineers
and scientists on the rover team built a test surface mimicking the
rocks and sand seen in Opportunity's images of Endurance Crater. The
surface was tilted to 25 degrees, and a test rover climbed it. If
portions of the route to the outcrop turn out to be between 25 and 30
degrees, the team plans to proceed slowly and use Opportunity to
assess the amount of traction the rover is getting.


They did tests on Earth. Wouldn't the lesser gravity on Mars (1/3 Earth
normal) make it possible to climb steeper slopes, as the rover be only 1/3
of the weight, or did they lighten the simulation rover by removing stuff?

Bart
  #3  
Old June 5th 04, 12:18 PM
George
external usenet poster
 
Posts: n/a
Default Mars Rover Opportunity Gets Green Light To Enter Crater


"Bart Declercq" wrote in message
t.net...

"We have done testing that says we can do 25 degrees, provided the
wheels are on a rock surface and not loose sand," Cook said. Engineers
and scientists on the rover team built a test surface mimicking the
rocks and sand seen in Opportunity's images of Endurance Crater. The
surface was tilted to 25 degrees, and a test rover climbed it. If
portions of the route to the outcrop turn out to be between 25 and 30
degrees, the team plans to proceed slowly and use Opportunity to
assess the amount of traction the rover is getting.


They did tests on Earth. Wouldn't the lesser gravity on Mars (1/3 Earth
normal) make it possible to climb steeper slopes, as the rover be only 1/3
of the weight, or did they lighten the simulation rover by removing stuff?

Bart


The lower gravity may actually make slipping on a steep slope more likely.


  #4  
Old June 5th 04, 01:56 PM
Hud Nordin
external usenet poster
 
Posts: n/a
Default Mars Rover Opportunity Gets Green Light To Enter Crater

In article t,
Bart Declercq wrote:
They did tests on Earth. Wouldn't the lesser gravity on Mars (1/3 Earth
normal) make it possible to climb steeper slopes, as the rover be only 1/3
of the weight, or did they lighten the simulation rover by removing stuff?


http://marsrovers.jpl.nasa.gov/spotlight/opportunity/b20_20040309.html

During their on-Earth of testing of the slippage experienced while
climbing out of Eagle crater, they used the Surface System Test Bed
(SSTB), which has a full-size, full-weight copy of the MER rovers.
I suspect the lighter weight of the rovers on Mars is offset by the
lesser traction, but I don't know the physics of it.

In any case, they have good experience at using the SSTB to predict
what might happen on Mars. What they predicted for Eagle crater was
tried and measured and compared to the predictions. The biggest unknown
seems to be the precise characteristics of the soil, but builders sand
surprisingly echoed the actual performance of the Meridiani soil. They
have a lot of confidence in what they can predict.
--
Hud Nordin Silicon Valley
  #5  
Old June 5th 04, 04:29 PM
CL Vancil
external usenet poster
 
Posts: n/a
Default Mars Rover Opportunity Gets Green Light To Enter Crater

Bart Declercq wrote in message et.net...
"We have done testing that says we can do 25 degrees, provided the
wheels are on a rock surface and not loose sand," Cook said. Engineers
and scientists on the rover team built a test surface mimicking the
rocks and sand seen in Opportunity's images of Endurance Crater. The
surface was tilted to 25 degrees, and a test rover climbed it. If
portions of the route to the outcrop turn out to be between 25 and 30
degrees, the team plans to proceed slowly and use Opportunity to
assess the amount of traction the rover is getting.


They did tests on Earth. Wouldn't the lesser gravity on Mars (1/3 Earth
normal) make it possible to climb steeper slopes, as the rover be only 1/3
of the weight, or did they lighten the simulation rover by removing stuff?

Bart


It's more complicted than that. Soil doesn't hold together in exactly
the same way it does on Earth. That is to say the angle of repose is
slightly different.

--Chris Vancil
  #6  
Old June 5th 04, 09:31 PM
Henry Spencer
external usenet poster
 
Posts: n/a
Default Mars Rover Opportunity Gets Green Light To Enter Crater

In article t,
Bart Declercq wrote:
They did tests on Earth. Wouldn't the lesser gravity on Mars (1/3 Earth
normal) make it possible to climb steeper slopes, as the rover be only 1/3
of the weight...


No, because as a result, it also has only 1/3 of the traction. (It would
need only 1/3 as much *power* for the climb, but at the speed the rovers
move, that's a lesser issue.)

If I recall correctly, to a first approximation, questions of *stability*
(whether of the rover or the soil underneath it) are independent of
gravity, because the major factors that influence stability scale up and
down together as gravity changes.

Looked at more closely, that isn't quite true, because secondary issues
which don't scale the same way have some influence.

A more important factor for Opportunity is that the properties of the soil
under its wheels are not known very precisely. That introduces large
uncertainties into any attempt to predict such things.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |
  #7  
Old June 6th 04, 01:13 AM
Bill
external usenet poster
 
Posts: n/a
Default Mars Rover Opportunity Gets Green Light To Enter Crater

I believe that news release states that they expect to go in and out
of the creator on a rock surface. Didn't we have a discussion in this
newsgroup (at nauseam) about traction in reduced gravity :-)
I wonder why the plans have changed,they had said they were going
to get other things done on the plains before going in,now it's seems
like they want to get in there right away. Maybe the rovers power is
more critical then what we previously thought.....

(CL Vancil) wrote in message . com...
Bart Declercq wrote in message et.net...
"We have done testing that says we can do 25 degrees, provided the
wheels are on a rock surface and not loose sand," Cook said. Engineers
and scientists on the rover team built a test surface mimicking the
rocks and sand seen in Opportunity's images of Endurance Crater. The
surface was tilted to 25 degrees, and a test rover climbed it. If
portions of the route to the outcrop turn out to be between 25 and 30
degrees, the team plans to proceed slowly and use Opportunity to
assess the amount of traction the rover is getting.


They did tests on Earth. Wouldn't the lesser gravity on Mars (1/3 Earth
normal) make it possible to climb steeper slopes, as the rover be only 1/3
of the weight, or did they lighten the simulation rover by removing stuff?

Bart


It's more complicted than that. Soil doesn't hold together in exactly
the same way it does on Earth. That is to say the angle of repose is
slightly different.

--Chris Vancil

  #8  
Old June 6th 04, 10:34 AM
Carsten Troelsgaard
external usenet poster
 
Posts: n/a
Default Mars Rover Opportunity Gets Green Light To Enter Crater


"Henry Spencer" skrev i en meddelelse
...
In article t,
Bart Declercq wrote:
They did tests on Earth. Wouldn't the lesser gravity on Mars (1/3 Earth
normal) make it possible to climb steeper slopes, as the rover be only

1/3
of the weight...


No, because as a result, it also has only 1/3 of the traction. (It would
need only 1/3 as much *power* for the climb, but at the speed the rovers
move, that's a lesser issue.)

If I recall correctly, to a first approximation, questions of *stability*
(whether of the rover or the soil underneath it) are independent of
gravity, because the major factors that influence stability scale up and
down together as gravity changes.


That's my impression too

Looked at more closely, that isn't quite true, because secondary issues
which don't scale the same way have some influence.

A more important factor for Opportunity is that the properties of the soil
under its wheels are not known very precisely. That introduces large
uncertainties into any attempt to predict such things.


I'll guess that the spherules are the danger. Riding on solid rock should be
safe, but a sudden slide on the spherules can bring the rover into
unforeseeable situations.

I were a bit 'piqué' when some JPL staff member was prized for his ability
to bring the missions into public attention - it made me, as a scientific
observer, feel possibly manipulated by the choice of published material. I
wonder weather the decision of going in is in part to catch a bit more
public attention. It's non the less a courageous one that I look forward to
follow.
How much trouble do they get for loosing the rower in the attempt? I suspect
that part of the problem in taking the decision is, that even in the crater,
the rower will not be able to 'climb up' to the exposed profiles.

Does anyone by the way have an idea of how come the rock-surfaces are so
plane. Is it a function of the very blast, or is it a later erosional
feature. The topology and stratified nature of the crater-rim as seen in the
profile seems to me to suggest a horizontal compression that 'thickened' the
strata into an elevated rim more than the ejected material have made a build
up on top of the familiar 'evaporitic' strata. Maybe the lack of ejected
blocks next to the crater, more than anything else, gives a clue about the
kind of blast that has taken place. Aren't these craters the first unique
opportunity for the astro/planetary people to study a 'pristine' crater?

Carsten


  #9  
Old June 6th 04, 05:32 PM
Bill
external usenet poster
 
Posts: n/a
Default Mars Rover Opportunity Gets Green Light To Enter Crater

that's what I thought the concern would be also the spherules.Like
riding over hundreds of ball bearings on a slope,could be tricky !?
I believe that Steve Squyres in the May 6th briefing said that all
the layers were laid out there where the crater is the most easily
accessible so there shouldn't be any trouble getting to all the
layers.


"Carsten Troelsgaard" wrote in message ...
"Henry Spencer" skrev i en meddelelse
...
In article t,
Bart Declercq wrote:
They did tests on Earth. Wouldn't the lesser gravity on Mars (1/3 Earth
normal) make it possible to climb steeper slopes, as the rover be only

1/3
of the weight...


No, because as a result, it also has only 1/3 of the traction. (It would
need only 1/3 as much *power* for the climb, but at the speed the rovers
move, that's a lesser issue.)

If I recall correctly, to a first approximation, questions of *stability*
(whether of the rover or the soil underneath it) are independent of
gravity, because the major factors that influence stability scale up and
down together as gravity changes.


That's my impression too

Looked at more closely, that isn't quite true, because secondary issues
which don't scale the same way have some influence.

A more important factor for Opportunity is that the properties of the soil
under its wheels are not known very precisely. That introduces large
uncertainties into any attempt to predict such things.


I'll guess that the spherules are the danger. Riding on solid rock should be
safe, but a sudden slide on the spherules can bring the rover into
unforeseeable situations.

I were a bit 'piqué' when some JPL staff member was prized for his ability
to bring the missions into public attention - it made me, as a scientific
observer, feel possibly manipulated by the choice of published material. I
wonder weather the decision of going in is in part to catch a bit more
public attention. It's non the less a courageous one that I look forward to
follow.
How much trouble do they get for loosing the rower in the attempt? I suspect
that part of the problem in taking the decision is, that even in the crater,
the rower will not be able to 'climb up' to the exposed profiles.

Does anyone by the way have an idea of how come the rock-surfaces are so
plane. Is it a function of the very blast, or is it a later erosional
feature. The topology and stratified nature of the crater-rim as seen in the
profile seems to me to suggest a horizontal compression that 'thickened' the
strata into an elevated rim more than the ejected material have made a build
up on top of the familiar 'evaporitic' strata. Maybe the lack of ejected
blocks next to the crater, more than anything else, gives a clue about the
kind of blast that has taken place. Aren't these craters the first unique
opportunity for the astro/planetary people to study a 'pristine' crater?

Carsten

  #10  
Old June 6th 04, 06:14 PM
Larry O.
external usenet poster
 
Posts: n/a
Default Mars Rover Opportunity Gets Green Light To Enter Crater

This is one advantage a legged robot will have over a wheeled one



"Bill" wrote in message
om...
that's what I thought the concern would be also the spherules.Like
riding over hundreds of ball bearings on a slope,could be tricky !?
I believe that Steve Squyres in the May 6th briefing said that all
the layers were laid out there where the crater is the most easily
accessible so there shouldn't be any trouble getting to all the
layers.


"Carsten Troelsgaard" wrote in message

...
"Henry Spencer" skrev i en meddelelse
...
In article t,
Bart Declercq wrote:
They did tests on Earth. Wouldn't the lesser gravity on Mars (1/3

Earth
normal) make it possible to climb steeper slopes, as the rover be

only
1/3
of the weight...

No, because as a result, it also has only 1/3 of the traction. (It

would
need only 1/3 as much *power* for the climb, but at the speed the

rovers
move, that's a lesser issue.)

If I recall correctly, to a first approximation, questions of

*stability*
(whether of the rover or the soil underneath it) are independent of
gravity, because the major factors that influence stability scale up

and
down together as gravity changes.


That's my impression too

Looked at more closely, that isn't quite true, because secondary

issues
which don't scale the same way have some influence.

A more important factor for Opportunity is that the properties of the

soil
under its wheels are not known very precisely. That introduces large
uncertainties into any attempt to predict such things.


I'll guess that the spherules are the danger. Riding on solid rock

should be
safe, but a sudden slide on the spherules can bring the rover into
unforeseeable situations.

I were a bit 'piqué' when some JPL staff member was prized for his

ability
to bring the missions into public attention - it made me, as a

scientific
observer, feel possibly manipulated by the choice of published material.

I
wonder weather the decision of going in is in part to catch a bit more
public attention. It's non the less a courageous one that I look forward

to
follow.
How much trouble do they get for loosing the rower in the attempt? I

suspect
that part of the problem in taking the decision is, that even in the

crater,
the rower will not be able to 'climb up' to the exposed profiles.

Does anyone by the way have an idea of how come the rock-surfaces are so
plane. Is it a function of the very blast, or is it a later erosional
feature. The topology and stratified nature of the crater-rim as seen in

the
profile seems to me to suggest a horizontal compression that 'thickened'

the
strata into an elevated rim more than the ejected material have made a

build
up on top of the familiar 'evaporitic' strata. Maybe the lack of ejected
blocks next to the crater, more than anything else, gives a clue about

the
kind of blast that has taken place. Aren't these craters the first

unique
opportunity for the astro/planetary people to study a 'pristine' crater?

Carsten



 




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