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ESA’s Asteroid Impact Mission
TRIPLE GOALS OF DOUBLE ASTEROID EXPLORATION
ESA’s Asteroid Impact Mission is a proposed venture to the Didymos double asteroid, which will come a comparatively close
16 million km to Earth in October 2022. The 800 m-diameter main body is orbited by a 170 m-diameter moon, informally called
Didymoon. This smaller body is AIM’s focus: the spacecraft will explore its properties, in particular probing its interior using radar.
It will also set down a microlander on Didymoon and deploy two CubeSats in the asteroid’s vicinity.
If the mission is approved, it would be launched in the window that opens in October 2020, with three main goals:
AIM will thoroughly investigate Didymoon
and observe as a NASA probe collides with
it at high speed. The results will help to
build high-fidelity computer models
of impacts to help plan for deflecting
future approaching bodies.
AIM will be humanity’s first mission to
a double asteroid, which account for
around one in six of known asteroids.
Each close encounter has revolutionised
our understanding, and there is still
much more to know. Asteroid interiors
remain blank spots in our knowledge.
Are they loose rubble or large monoliths,
or are there gaping voids within them?
AIM will probe Didymoon’s deep
interior while investigating its
surface. How does asteroid material
behave in low gravity?
AIM will demonstrate new technologies
for future deep-space missions, including
laser communications back to Earth,
flexible networking between CubeSats
and a lander, and close-proximity
operations in low gravity, including the
semi-autonomous deployment of
Four months after arriving at Didymos, AIM will be briefly joined
by a terrestrial companion: NASA’s Double Asteroid Redirection
Test (DART) probe will home in on Didymoon, crashing into it at
about 6 km/s in an attempt to divert its path. AIM will be on hand
to record the results of this historic first attempt to shift the orbit
of a Solar System body – a ground-breaking test of planetary
defence methods. These two missions are collectively known as
the Asteroid Impact and Deflection Assessment (AIDA) mission.
While built and run separately, the two spacecraft are being
planned in coordination to maximise their overall results. AIDA’s
main measurement will be the change in Didymoon’s orbit after
impact (the pair’s orbit around the Sun will remain unchanged).
The event will also be monitored by terrestrial telescopes and
radars thanks to the rare close approach to Earth.
After flying for about 18 months, AIM will reach Didymos in mid-2022 to begin the mission’s real work:
intensive study of its target by visual, thermal and radar instruments, delivery of its lander and CubeSats,
and laser-based communications back to Earth. Then comes DART’s collision with Didymoon, with AIM
providing a detailed before-and-after comparison of the asteroid and its changed orbit.
1 EARLY CHARACTERISATION PHASE:
LASER COMMUNICATION WITH EARTH
4 DEPLOYMENT OF SMALL LANDER
5 DETAILED CHARACTERISATION PHASE:
ANATOMY OF AIM
1.4 x 1.4 x 1.8 m (solar wings stowed); 1.4 x 1.4 x 7.7 m
(solar wings deployed). 12 bipropellant 1 N thrusters
for attitude control and close proximity operations;
four 22 N thrusters for orbit corrections.
MASCOT-2 ASTEROID MICROLANDER
Deployed after arrival at Didymos.
OPTICAL COMMUNICATION SYSTEM
Laser communication system to test downlink capabilities
to ESA’s Optical Ground Station in Tenerife. Close to Earth,
it will be several times faster than the equivalent radio
system. As an altimeter, it will also help to navigate AIM
and to map the asteroid.
Fixed X-band antenna to receive telecommands from Earth.
All images: ESA/ScienceOffice.org
AIM will carry a pair of 3-unit CubeSats – nanosatellites based
on standardised 10 cm units, much cheaper and simpler to
build than standard satellites. Concepts being studied include
taking a close-up look at the composition of the asteroid surface,
measuring the gravity field, assessing the dust environment,
imaging the impact’s ejecta plume from close by, and landing
a CubeSat for seismic monitoring.
AIM will carry a 15 kg microlander for Didymoon, ESA’s first
touchdown on a small body since Rosetta’s Philae landed on a
comet in November 2014. Like Philae, Mobile Asteroid Surface
Scout-2 (Mascot-2) will be provided by the DLR German Aerospace
Center. Mascot-1 is already flying on Japan’s Hayabusa-2, launched
in December 2014 to land on an asteroid in 2018. Mascot-2 will
include low-frequency radar antennas to sound Didymoon’s
interior structure and a solar panel to let it survive for several
weeks on the surface. In addition it will carry a microcamera,
a radiometer and an accelerometer.
FACTS AND FIGURES
Spacecraft launch mass
740 kg (including 306 kg propellant)
October–November 2020 from Kourou, French Guiana on Soyuz rocket
1.5-year cruise and 6 months of operations at Didymos
Small mission of opportunity demonstrating asteroid deflection, investigating the properties of a binary asteroid
and demonstrating new technologies
AIM’s target binary asteroid, 65803 Didymos, was discovered in 1996. The smaller asteroid is in a 1.1 km-altitude,
11.9-hour orbit around the primary; both have been observed with radars from Earth
AIM would be a precursor for future small deep-space missions such as monitoring space weather and returning
samples from small Solar System bodies.
For more information: firstname.lastname@example.org www.esa.int
An ESA Communications Production Copyright © 2016 European Space Agency