[meteorite-list] ESA's Planetary Defence Test Set for 2020 (AIM)

[Ron Baalke]

http://www.esa.int/Our_Activities/Space_Engineering_Technology/ESA_s_planetary_defence_test_set_for_2020

ESA's Planetary Defence Test Set for 2020
European Space Agency
31 March 2015

If an asteroid were spotted headed towards Earth, what could humanity 
do about it? ESA's latest mission is part of a larger international effort 
to find out.

This month marked the start of preliminary design work on ESA's Asteroid 
Impact Mission, or AIM. Intended to demonstrate technologies for future 
deep-space missions, AIM will also be the Agency's very first investigation 
of planetary defence techniques.

Launched in October 2020, AIM will travel to a binary asteroid system 
- the paired Didymos asteroids, which will come a comparatively close 
11 million km to Earth in 2022. The 800 m-diameter main body is orbited 
by a 170 m moon, informally called "Didymoon".

This smaller body is AIM's focus: the spacecraft will perform high-resolution 
visual, thermal and radar mapping of the moon to build detailed maps of 
its surface and interior structure. 

AIM will also put down a lander - ESA's first touchdown on a small body 
since Rosetta's Philae landed on a comet last November.

Two or more CubeSats will also be dispatched from the mothership to gather 
other scientific data in the vicinity of the moon. AIM's findings will 
be returned by high-capacity laser link to ESA's Optical Ground Station 
on Tenerife in the Canary Islands.

AIM should gather a rich scientific bounty - gaining valuable insights 
into the formation of our Solar System - but these activities will also 
set the stage for a historic event to come.

For AIM is also Europe's contribution to the larger Asteroid Impact & 
Deflection Assessment mission: AIDA. In late 2022, the NASA-led part of 
AIDA will arrive: the Double Asteroid Redirection Test, or DART, probe 
will approach the binary system - then crash straight into the asteroid 
moon at about 6 km/s.

"AIM will be watching closely as DART hits Didymoon," explains Ian Carnelli, 
managing the mission for ESA. "In the aftermath, it will perform detailed 
before-and-after comparisons on the structure of the body itself, as well 
as its orbit, to characterise DART's kinetic impact and its consequences.

"The results will allow laboratory impact models to be calibrated on a 
large-scale basis, to fully understand how an asteroid would react to 
this kind of energy. This will shed light on the role the ejecta plume 
will play - a fundamental part in the energy transfer and under scientific 
debate for over two decades.
                                                                      
"In addition, DART's shifting of Didymoon's orbit will mark the first 
time humanity has altered the dynamics of the Solar System in a measurable 
way.

"It will also give us a baseline for planning any future planetary defence 
strategies. We will gain insight into the kind of force needed to shift 
the orbit of any incoming asteroid, and better understand how the technique 
could be applied if a real threat were to occur."

A similar collision was achieved back in 2005, when NASA's Deep Impact 
spacecraft shot a copper impactor into asteroid Tempel 1. But the Didymos 
moon is several tens of times smaller than Tempel 1, so much greater precision 
will be required to strike it - and the possibility of altering its orbit 
should be correspondingly higher.

The Didymos moon is nearly three times larger than the body thought to 
have caused the 1908 Tunguska impact in Siberia, the largest impact in 
recorded history. An equivalent asteroid striking Earth would be well 
into the "city-killer" class, leaving a crater of at least 2.5 km across 
and causing serious regional and climate damage.

The 2013 Chelyabinsk airburst, whose shockwave struck six cities across 
Russia, is thought to have been caused by an asteroid just 20 m in diameter.
                                                                      
AIM and AIDA will be discussed at this month's International Academy of 
Astronautics Planetary Defense Conference, hosted at ESA's ESRIN Earth 
observation centre in Frascati, Italy, which will be devoted to assessing 
the risk of impacts from asteroid and comets and envisaging possible responses.

This year's event features a simulated asteroid threat exercise, to which 
representatives of global space agencies and disaster response organisations 
will coordinate their reactions.