CU-Boulder/NASA Mars Mission Obiter To Take Rare Look at Comet
Oct. 17, 2014
David Brain
This Sunday just past noon, Mountain time, a fast moving comet will
whiz by Mars for a one-in-a-million encounter with the red planet, and the
NASA spacecraft MAVEN will be there to study this rare encounter.
MAVEN, which stands for Mars Atmosphere and Volatile EvolutioN,
began orbiting Mars last month and is on a one-year CU-Boulder-led mission
to study the planet’s upper atmosphere.
The instruments on board the spacecraft are perfect for analyzing such
an encounter, says an excited David Brain, CU-Boulder planetary scientist and
MAVEN mission co-investigator.
CUT 1 “Two atmospheres in the solar system may be colliding with one
another and as a scientist you immediately say, ‘Cool. That’s really great.’ And
then you start to wonder what effect the comet’s tail would have on the
Martian atmosphere. (:16) And this kind is science is exactly the kind of
science that MAVEN is equipped to understand. We have all of the right
instruments.” (:24)
But there are dangers associated with observing this chance encounter
with comet ‘Siding Spring,’ as it’s called.
Tiny particles from the comet’s dust tail, some no bigger than a half
millimeter across, will be traveling at 35 miles per second. At that speed,
though tiny, they could severely damage MAVEN’s instruments if they struck
the spacecraft.
But Brain says there are two things they can do to protect the orbiter.
CUT 2 “We can orient the spacecraft. We can basically turn it so that the least
sensitive side is exposed to the direction from which dust is coming. And so
we will twist the spacecraft so that one side would bear the brunt of any dust
impacts. (:15) The second thing that we’ll do is that we will phase the orbit.
That means we will position MAVEN relative to Mars such that MAVEN is
actually hiding behind the planet. And the planet would bear the brunt of any
dust impacts and MAVEN will be shielded.” (:31)
Brain says the best way to analyze the effect of the comet’s dust tail on
the Martian atmosphere is to take readings of the atmosphere before and
after the comet zips by.
CUT 3 “For a couple of days before and a couple of days after we’re going to
make observations of the Martian atmosphere. A couple of days before will
give us a sense of what the Martian atmosphere is like before the comet
passes by and a couple of days after will let us know how the atmosphere has
responded.” (:17)
A decade ago in the early planning stages of MAVEN Brain says there
was no indication that this kind of opportunity was even possible.
But now with only days to go before the comet grazes Mar’s
atmosphere, Brain says everyone involved with the mission is eager to find
out what will happen.
CUT 4 “I think no matter what happens this will be tremendously interesting.
And as a great example of how spacecraft missions work, often the most
exciting discoveries that a spacecraft mission makes are the ones that weren’t
anticipated at all. (:15) And here we have this event that we couldn’t have
planned for a decade ago that’s going to give us our first science results.”
(:22)
At it’s closest approach comet ‘Siding Spring’ will rip past Mars at a
distance of about 83,000 miles, about a third of the distance between the
Earth and moon. By comparison, the closest comets to zoom by Earth have
been at least ten times more distant.
Scientists calculate the greatest danger to the orbiter will be 90
minutes after the comet’s closest approach and last roughly 20 minutes.
For more information about the mission visit
http://www.nasa.gov/maven or http://lasp.colorado.edu/home/maven/.