WORLD FIRST
All this testing is geared towards February
2021, when the helicopter will reach the
surface of the red planet, rmly nestled
under the belly of the Mars 2020 rover.
A few months later, it will be deployed
and test ights (up to 90 seconds long)
will begin – the rst from the surface of
another world. “Gearing up for that rst
ight on Mars, we have logged over 75
minutes of ying time with an engineering
model, which was a close approximation
of our helicopter,” says MiMi Aung, project
manager for the Mars Helicopter at
NASA’s Jet Propulsion Laboratory (JPL) in
Pasadena, California. “But this recent test
of the ight model was the real deal. This is
our helicopter bound for Mars. We needed
to see that it worked as advertised.”
While ying helicopters is commonplace
here on Earth, ying hundreds of millions of
miles away in the thin Martian atmosphere
is something else entirely. And creating the
right conditions for testing here on Earth
presents its own set of challenges. “The
Martian atmosphere is only about one per
cent the density of Earth’s,” points out
Aung. “Our test ights could have similar
atmospheric density here on Earth – if you
put your aireld 100,000 feet 30,480
metres up. So, you can’t go somewhere
and nd that. You have to make it.”
Aung and her Mars Helicopter team
did just that in JPL’s Space Simulator, a
25 foot-wide (7.62 metre-wide) vacuum
chamber. First, the team created a vacuum
that sucks out all the nitrogen, oxygen
and other gases from the air inside the
mammoth cylinder. In their place, the team
injected carbon dioxide, the chief ingredient
of Mars’ atmosphere.
“Getting our helicopter into an extremely
thin atmosphere is only part of the
challenge,” says Teddy Tzanetos, test
conductor for the Mars Helicopter at
JPL. “To truly simulate ying on Mars, we
have to take away two-thirds of Earth’s
gravity, because Mars’ gravity is that much
weaker.” The team accomplished this with a
gravity ofoad system – a motorised lanyard
attached to the top of the helicopter to
provide an uninterrupted tug equivalent to
two-thirds of Earth’s gravity. While the team
was understandably concerned with how
the helicopter would fare on its rst ight,
they were equally concerned with how the
gravity ofoad system would perform. “The
gravity ofoad system performed perfectly,
just like our helicopter,” Tzanetos conrms.
“We only required a 2-inch 5-centimetre
hover to obtain all the data sets needed
to conrm that our Mars helicopter ies
autonomously as designed in a thin Marslike
atmosphere; there was no need to go
higher. It was a heck of a rst ight.”
As Aung points out: “The next time we y,
we y on Mars. Watching our helicopter go
through its paces in the chamber, I couldn’t
help but think about the historic vehicles
that have been in there in the past. The
chamber hosted missions from the Ranger
Moon probes to the Voyagers, to Cassini,
and every Mars rover ever own. To see our
helicopter in there reminded me we are on
our way to making a little chunk of space
history as well,” she adds.
Once on Mars, the 2020 rover will
conduct geological assessments of its
landing site, determine the habitability
of the environment, search for signs
of ancient Martian life, and assess
natural resources and hazards for
future human explorers. Scientists will
use the instruments aboard the rover
to identify and collect samples of rock
and soil, encase them in sealed tubes
and leave them on the planet’s surface
for potential return to Earth on a future
Mars mission.
MARS LANDING
WINDS OF CHANGE
One key question to address is how such
a fragile craft as the Mar Helicopter will
cope with the often-cited high winds and
sandstorms to be found on Mars. This
won’t even be an issue, according to Bob
Balaram, chief engineer for the Mars
Helicopter at NASA JPL - see photo on
page 25.
“The forces of the wind on Mars are quite
low – a 100 mph wind on Mars is the same
as a 10 mph wind on Earth. In other words,
the actual physics is very different from that
shown in the movie ‘The Martian’.
“Our helicopter will not tip over on the
ground under very high winds and all the
early test ights will be when the winds
are predicted to be below 10 m/s (ie, midmorning).
We are also limited to a 30 sol
sol being the duration of a solar day on
Mars window of ights, with ve ights
lasting a few minutes each, so our overall
exposure to both winds on the ground and
winds during ight is quite low – consistent
with a Tech Demo philosophy.”
Meanwhile, a pile driver-type mechanism
on NASA’s InSight lander, called HP3, will
burrow almost 5 metres into the Martian
soil to measure the planet’s temperature.
Inside HP3, a maxon motor-built drive
consisting of a DCX 22 motor and a GP
22 HD planetary gearhead will force the
probe into the ground, while withstanding
extremely high requirements, such
as temperature uctuations and thin
atmosphere, as well as forces of anything
up to 400 g.
Members of the NASA Mars Helicopter team inspect the flight model (the actual vehicle
going to the red planet) inside the Space Simulator, a 25ft-wide (7.62m-wide) vacuum
chamber at NASA’s Jet Propulsion Laboratory in Pasadena, California.
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