Mars Exploration Rovers Update - February 24, 2004

"Ralph Nesbitt" wrote
Here's a shot of what looks to be dust on Opportunity's solar cells, sol
26:
http://tinyurl.com/2f6et

The "track area" in the above image has the image of soggy material
squeezed
together similar to that created by tracked equipment in frozen wet soils.

A lot of people have said that, but there seems to be a little hydrophobia
on the subject. Present water has hardly been addressed officially. The only
question about the tracks seemed to flummox the panel. As for brine, there
has only been some handwaving about briny water possibly "hundreds of
meters" below the surface. Safely out of reach. That's the great thing about
Mars. Anything is possible if you only go deep enough, out of the range of
current sensors. Short of pools of water or snowbanks, the current equipment
has no means to detect water directly.

However, taking a step back from the cult of the latest press
release/mission, last year the Mars Odyssey orbiter's neutron spectrometer
inferred large quantities of water (20%) in the top *1 meter* of the
surface at both the Gusev and Meridiani sites. How can this be? Wouldn't
pure ice sublimate, so it would have to be continuously replenished? So is
there a flux of water from below? Or does it accumulate via frost or by some
other transfer from the atmosphere? And with all that salt, why can't it be
liquid at least in transition? Why was the brine placed only hundreds of
meters down in last week's press conference?

Whatever the round objects in the undisturbed area are, some appear to
have
a hole in them.

Is this a common phenomena in the area traversed to date?

I don't think very many of them have those holes.

Do the rovers have any provision for detecting/determining the temperature
of the actual surface material?

Not sure. Maybe they can infer the surface temperature with the mini-TES?

Joe

Joe Knapp wrote:

"Ralph Nesbitt" wrote
Here's a shot of what looks to be dust on Opportunity's solar cells, sol
26:
http://tinyurl.com/2f6et

The "track area" in the above image has the image of soggy material
squeezed
together similar to that created by tracked equipment in frozen wet soils.

A lot of people have said that, but there seems to be a little hydrophobia
on the subject. Present water has hardly been addressed officially. The only
question about the tracks seemed to flummox the panel. As for brine, there
has only been some handwaving about briny water possibly "hundreds of
meters" below the surface. Safely out of reach. That's the great thing about
Mars. Anything is possible if you only go deep enough, out of the range of
current sensors. Short of pools of water or snowbanks, the current equipment
has no means to detect water directly.

However, taking a step back from the cult of the latest press
release/mission, last year the Mars Odyssey orbiter's neutron spectrometer
inferred large quantities of water (20%) in the top *1 meter* of the
surface at both the Gusev and Meridiani sites. How can this be? Wouldn't
pure ice sublimate, so it would have to be continuously replenished?

The water could be bound as crystal water in some salts, e.g. the sulfates
in the white rock.

So is
there a flux of water from below? Or does it accumulate via frost or by some
other transfer from the atmosphere? And with all that salt, why can't it be
liquid at least in transition? Why was the brine placed only hundreds of
meters down in last week's press conference?

Whatever the round objects in the undisturbed area are, some appear to
have
a hole in them.

Is this a common phenomena in the area traversed to date?

I don't think very many of them have those holes.

Do the rovers have any provision for detecting/determining the temperature
of the actual surface material?

Not sure. Maybe they can infer the surface temperature with the mini-TES?
They already did this, and there wa a press release about it some time
ago.



Joe

--
http://www.geocities.com/carla_sch/index.html

"Carla Schneider" wrote
However, taking a step back from the cult of the latest press
release/mission, last year the Mars Odyssey orbiter's neutron
spectrometer
inferred large quantities of water (20%) in the top *1 meter* of the
surface at both the Gusev and Meridiani sites. How can this be? Wouldn't
pure ice sublimate, so it would have to be continuously replenished?

The water could be bound as crystal water in some salts, e.g. the sulfates
in the white rock.

I suppose this could be tested by seeing if the levels of jarosite (~10% of
El Capitan) and kieserite (dehydrated epsom salt; ~40%) is consistent with
the hydrogen levels found by Odyssey.

Here is an article for reference:
http://mars.astrobio.net/news/article210.html

"In the map of hydrogen abundance from orbit, Gusev shows a high hydrogen
abundance. The hydrogen abundance at Gusev and Meridiani are similar to that
closer to the poles (~50% latitude) and could represent between 20-50% of
subsurface H2O within one meter of the surface. This is particularly
intriguing because Gusev and Terra Meridiani (the destination for the
companion Opportunity rover) are positioned as one of only several
equatorial areas with high hydrogen compositions."

Joe

In article m,
says...

"Ralph Nesbitt" wrote

snip

Do the rovers have any provision for detecting/determining the temperature
of the actual surface material?

Not sure. Maybe they can infer the surface temperature with the mini-TES?

Um... yes. That's exactly what the mini-TES is -- a "visual"
thermometer. The name means "thermal emissions spectrometer." It shows
the intensities of various wavelengths of heat energy. Not only does
this let you directly observe the temperatures of various materials, it
lets you characterize the mineralogical make-up and other
characteristics of the materials viewed by the instrument, because
certain materials have very characteristic heat emissions, reflectance
and "thermal inertia" at given wavelengths.

So, the mini-TES lets you *directly* observe temperatures. What it lets
you *infer* is mineralogical content and thermal inertia.

Doug

"Carla Schneider" wrote in message
...

Tech people are telling press release writers: It is getting winter on
Mars( meaning the whole mars, as it is moving away from the sun).

Are the maxium/minimun/mean temps during maxium/minimum orbit distances well
constrained at the current time? If so a link would be apreciated.
Ralph Nesbitt

"Doug..." wrote in message
...
In article m,
says...

"Ralph Nesbitt" wrote

snip

Do the rovers have any provision for detecting/determining the
temperature
of the actual surface material?

Not sure. Maybe they can infer the surface temperature with the
mini-TES?

Um... yes. That's exactly what the mini-TES is -- a "visual"
thermometer. The name means "thermal emissions spectrometer." It shows
the intensities of various wavelengths of heat energy. Not only does
this let you directly observe the temperatures of various materials, it
lets you characterize the mineralogical make-up and other
characteristics of the materials viewed by the instrument, because
certain materials have very characteristic heat emissions, reflectance
and "thermal inertia" at given wavelengths.

So, the mini-TES lets you *directly* observe temperatures. What it lets
you *infer* is mineralogical content and thermal inertia.

Doug
Thanks.
Ralph Nesbitt