[meteorite-list] Robot Arm Simulates Close Approach to ESA's Asteroid Mission

[Ron Baalke]

http://www.esa.int/Our_Activities/Space_Engineering_Technology/Asteroid_Impact_Mission/Robot_arm_simulates_close_approach_of_ESA_s_asteroid_mission

Robot Arm Simulates Close Approach to ESA's Asteroid Mission
European Space Agency
December 8, 2015

The final approach to an asteroid has been practised for ESA's proposed 
Asteroid Impact Mission using a real spacecraft camera mounted on a robot 
arm.

The 2020 AIM mission would find its way across deep space as usual with 
startrackers and radio ranging but the real challenge would come after 
arrival at its target Didymos double asteroids: picking its way around 
these unprecedented surroundings to close in on the smaller asteroid for 
detailed observations and setting down a lander.

The rehearsal took place at the Madrid headquarters of Spain's GMV company, 
with ESA's arm-mounted camera using dedicated navigation software to 
close in on a model asteroid.

"By including an actual navigation camera in the loop, we made the test 
as realistic as possible," explains ESA guidance specialist Massimo 
Casasco.

AIM and lander

As the Rosetta comet adventure showed last year, landing on a small body 
is no easy task.

"One of AIM's objectives is to put down a lander on the smaller of 
the Didymos asteroids using onboard autonomy and very limited resources," 
says Ian Carnelli, ESA's AIM project manager.

The low-budget AIM will avoid costly dedicated proximity sensors, instead 
calling on smart visual navigation software to track its motion over the 
surface. 

 
In addition, it might reuse its laser communication package for measuring 
height above the surface.

ESA's camera took images for the processing software to first select 
landmark "feature points' within the field of view and then to follow 
them from frame to frame.

The camera itself has a detector that acquires the images, a "frame 
store" for their intermediate storage and an image-processing chip to 
perform the feature tracking, before providing the information to AIM's 
guidance and navigation computer.

"The changing tracks of the various feature points over time (shown 
in purple in the video) are checked against the onward and rotational 
motion of the spacecraft to determine its position and orientation," 
says ESA guidance expert Olivier Dubois-Matra.

"The ultimate goal for AIM is to demonstrate new ways to explore small 
Solar System bodies in the future," adds Ian, "so we are testing this 
approach as fully as possible. In effect, the test bench is a fully fledged 
optical and robotic laboratory, testing AIM's approach and the lander 
descent right down to deployment altitude."

Camera on robot arm

With a launch window opening in October 2020, AIM would be humanity's 
first mission to a double asteroid. Its first major design review next 
month will allow detailed design to begin in February.

The Mascot-2 lander is being designed and tested by Germany's DLR space 
agency and is based on the lander scheduled to reach asteroid Ryugu as 
part of Japan's Hayabusa-2 in July 2018.

NASA's own Double Asteroid Redirection Test, or DART, probe will impact 
the same asteroid, with AIM providing detailed before-and-after mapping 
to help assess the effects and test planetary defence techniques.