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If you already have
played the claw machine at an arcade, you know how difficult it can be to maneuver
the metal "hand" to win a prize. Imagine playing this game
when the claw is on Mars, the objects you are trying to grab are a lot more
fragile than a teddy bear and all you have is a sewn panorama set of
the environment in which you work. Oh, and there could be a dust storm.
InSight of NASA
The lander, due to arrive on November 26, 2018, will be the first mission of
use a robotic arm to grab the instruments from the probe and release them into
place on another planet. These instruments will help scientists to study the depths
inside of Mars for the first time.
"We have an
a lot about the robotic arm of InSight, so we practiced our version of
the game of claw dozens of times, "said Tom Hoffman, project of InSight
Head of NASA's Jet Propulsion Laboratory in Pasadena, California. "The
The difference, of course, is that, unlike designers of claw machines, our robotics
Team arm works hard to enable us to win every time. "
InSight & # 39; s
robotic arm (called the instrument deployment arm) will detect two
scientific packages from the spacecraft bridge and gently lower them to the ground:
the heat flux package and physical properties, which will evaluate the interior of Mars
energy, and seismic experience for the inner structure, which will study
ground vibrations triggered by earthquakes and meteorite impacts. Insight
also need to place a heat shield and wind on the seismometer, as a
bell – or rounded flat cover – during a refined table service.
"The
robotic arm must place everything perfectly, "said Ashitey Trebi-Ollennu,
team leader for In – JPL instrument deployment system operations. "But
we love challenges. "
Fortunately,
the engineers did not have to start from scratch. The JPL technical team had
storage of a robotic arm rest – manufactured for the March Mars 2001 Surveyor
mission that has never stolen. The arm was not as sturdy as those built for missions like the Curiosity of Mars
Rover, who carries more weight at the end of his arm. But the arm of 2001 was
designed for lifting, making it suitable for the mission of InSight. And it was
long (5.9 feet, or 1.8 meters, to be exact). InSight must put the
seismometer and thermal probe at a significant distance from itself for sensitive people
instruments to function optimally.
As with everything
vintage machine, the engineers had to refurbish the arm and customize it for
Insight. They separated it, replaced parts, relubricated and repainted
he. The engineers also added a color camera and a grapple (the claw).
L & # 39; original
the design of the grapple had two stiff "toes" emanating from a central base,
Trebi-Ollennu looks like a goose paw. Each instrument has been equipped with
a button, or "grapple", that looks like a lollipop with a long stem for the stiff
foot to grab. When tested on sloping surfaces, the pacifier was often stuck in the toes.
Given the possibility of slight slopes at the landing site InSight, the engineers
did not want to take this chance.
The second
the proposed design was a familiar one for those who saw Junkyard operators
maneuver crushed cars. The engineers hung a magnet on an umbilical cord
Robotic arm and put steel plates on the instruments. The tests, however, showed
accumulated dust on both the surface of the magnet and on the steel plate of the instruments, which decreases the ability of
both parties to stick together. Since the landing date of InSight is less than
the typical season of dust storms on Mars, the engineers decided not to use this magnet
design.
The third idea
was the charm: a clawed grapple with five metal fingers along the length of
human fingers (about 2.5 inches, or 63 millimeters, long) hooked to the end
of an umbilical cord to compensate for slopes. The grappling on each
instrument looked like the original spherical lollipop, but with the top half of
the cut sphere and a shorter stem.
One especially
The particularity of this robotic hand, explained Trebi-Ollennu, is that fusion
paraffin wax – a common constituent of candles and pencils – controls the
InSight finger opening.
To begin
process, an actuator heats a very pure paraffin wax to 84 ° F (29 ° C), which takes
about 15 minutes at an average room temperature of about minus 60 ° F on Mars
(minus 50 ° C). The wax expands by melting and repels a stem that grows on a
spring that opens the fingers. When the fingers open, a microswitch extinguishes
heating, and cooling, contracting wax allows the rod – and therefore
fingers – retract. At rest, the fingers are closed so that if the hand
happens to lose power, he will not drop an instrument.
A few days later
Upon landing, InSight engineers will put the robotic arm into action. The arm goes
move so that the camera attached to it can take pictures of the area around the lander
site. Back on Earth, engineers will use these images to determine where the
the instruments can be safely deposited. They will also practice the deployment of
instruments in a Mars-type test stand at JPL. Once the team is confident,
have a robust plan – that could take weeks – the arm with his grappling hook will slowly
start deploying these instruments for real on Mars.
"Were looking
looking forward to the demanding work of moving the InSight claw machine ",
said Bruce Banerdt, senior investigator of InSight at JPL. "But the
price for the InSight team will not be a fuzzy bear. This will be the flow of
scientific data flock to accurately placed instruments – tell us what
Mars is really like inside. "
JPL
a division of Caltech in Pasadena, California, manages InSight for NASA
Directorate of Scientific Missions in Washington. InSight is part of NASA's Discovery
Program, run by the agency's Marshall Space Flight Center in Huntsville,
Alabama. The InSight satellite, including its cruising and landing stages, was
built and tested by Lockheed Martin Space in Denver.
Find
more information about InSight at the address:
https://mars.nasa.gov/insight/
Media contact
Andrew Good / D.C. Agle
Jet Propulsion Laboratory, Pasadena, California
818-393-2433 / 393-9011
[email protected] / [email protected]
Written by Jia-Rui Cook
2018-242
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