Press Release

The Sky Is The Limit

By SpaceRef Editor
January 23, 2004
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The Sky Is The Limit
Mars Express

Believe it or not, some of the scientists on the Mars Exploration
Rover Science team don’t really care too much about rocks – or
for that matter anything on the surface of Mars. They have "higher"
ambitions. Their passion lies in the skies – the martian skies –
and, from the hazy glow of the atmosphere, they pull precious
pieces of information.

Two of these sky gazers are Mike Wolff and Mike Smith. They
are brimming with energy because, in the next few sols, Spirit
will be doing more atmospheric study than she’s done since
landing.

"It’s a bit of a running joke that the atmospheric team gets left
out," laughs the jovial pair. "Let’s be honest, this is
predominantly a geology mission – water and rocks."

The atmospheric team is also a little outnumbered, "There are
very few of us atmospheric scientists who want to spend
Spirit’s time looking at the sky. The vast majority of the team
wants to look at the ground."

All the joking aside, Mike and Mike know the importance of
good atmospheric data, explaining that it is crucial for
"ground-lookers" to know what they are seeing. For instance,
scientists study the light that is reflected from each surface to
determine what minerals are in the rocks on Mars. In order to
make accurate calculations, they must understand the
atmosphere through which the light traveled before reaching
the rocks and reflecting back.

"They DO need us," smiles Wolff. "Our team provides
information about the amount of dust and water vapor in the
atmosphere, allowing other teams to make sense of what
they’re seeing."

Beyond a supportive role, the atmospheric team is trying to
answer big questions about the climate on Mars that will help
all future Mars exploration. "We need a complete understanding
of the environment we’re working with – what conditions do we
need to prep for? How much dust is there, and will it interfere
with machinery? What are the temperature extremes that can
interfere with the successful operation of instruments? The
more we understand the weather on Mars, the more likely it is
that a Mars mission will have success," explains Smith in a
serious moment.

The term "weather on Mars" can mean a lot of different things,
but the atmospheric team is harvesting hypotheses from four
main elements: air temperature, water-ice clouds, water vapor,
and dust.

Air Temperature

Using the Mini-TES instrument, the atmospheric team can
determine the temperature of the Martian atmosphere at various
heights from the surface to about two kilometers (about
1.2 miles) above the surface. Orbiters and previous landed
missions could not provide this near-surface information as
precisely as Mini-TES can, and both Mikes are excited to have
it.

"All the major weather systems on Mars are affected by this
lower area, so it’s really fantastic to be seeing this detailed
data," says Smith. These temperature readings assist engineers
as they assess the rovers’ heath. Engineers need to know if
things are heating up on Mars so that they can prepare to keep
the rover cool.

Water Vapor

"Water-vapor is a fancy atmospheric term for humidity," jokes
Wolff. "If you’ve ever been in the south in the summer, you know
what water vapor is." Mars does have some water vapor, but not
much. In fact, Earth has about 10,000 times more water in its
atmosphere than Mars does. The amount of water vapor in the
atmosphere is important to scientists because it is a key part
of the current climate and potentially gives clues about the
distribution of water under the surface.

Water-Ice Clouds

Like the high, wispy, cirrus clouds we see here on earth, water
vapor in Mars’ atmosphere freezes and forms into cirrus-like
clouds on Mars. By studying the quantity, location, and
longevity of these clouds, scientists can better understand
how water is exchanged between the martian surface and
atmosphere. While orbiters have provided us with many great
images of cloud-cover on Mars, they are limited by the time of
day of their orbit and can only reveal what the clouds look like
in a particular spot at a particular time.

"With Spirit and Opportunity we can watch the clouds
throughout the day and monitor how they change," explains
Wolff.

Dust

Scientists operating a rover on the surface of Mars have one
major concern when it comes to dust: accumulation. The planet is
covered in the fine, powder-like material and daily winds blow it
across the planet forming dunes and ripples. Too much of this
dust on the solar panels could cause them to work less efficiently.
The atmospheric team monitors how much dust is in the atmosphere
and helps the engineering team evaluate the performance of
Spirit’s solar panels.

During the mission, Spirit will point its Panoramic camera and
Mini-TES instruments towards the sky, giving the atmospheric team
another chance to shine. Most of the atmospheric sequences only
take under 20 minutes, and are easy to fit into all the rover’s
other daily activities.

"We’ll hopefully have lots of these "fill-in" sequences throughout
the mission," explains a smiling Smith. "We don’t ask for much,
but we promise to deliver a lot!"

SpaceRef staff editor.