Speaker
Description
An important application is seen in the collection and avoidance of space debris, up to active de-orbiting of LEO satellites which have failed or reached the end of their lifetime.
For active de-orbiting of unusable satellites, safe and reliable capture technologies have to be designed and developed. Clamping technologies are one of the building blocks of ADR missions, and an interesting development for in-orbiting servicing in general. The e.Deorbit particular demanding case (large object, etc.) can indeed serve as a good demonstrator of the capabilities developed and the lessons learned can be transferred to other ADR activities.
A Clamping Mechanism (CLM) technology is currently being developed under an ESA contract in the framework of the e.Deorbit mission within ESA CleanSpace activities.
The objectives of the activity are:
• To design a clamping mechanism (CLM) for clamping a chaser spacecraft to an interface on a Launch Adapter Ring (LAR) of Envisat spacecraft during a debris removal mission
• Manufacture & test a breadboard of the CLM to reach TRL 4 of the CLM technology by the end of the activity
The CLM presents several features which make the project a very interesting example of what can be accomplished for future ADR missions:
• Large size of the target debris object, with its about 10 m and 7800 kg, which translates to corresponding large efforts and demanding stiffness to cope with the about 1.7 kN de-orbiting thrusts (and corresponding bending torques)
• The robotic arm grasps the LAR and approximates the CLM to its nominal position within certain accuracy, which results on potential misalignments of ±25 mm and ±2.5º, which results in a relatively wide region to be covered by the CLM closing motion and requires specific means to adapt to the potential variations
• The CLM has to compensate these misalignments against the backdriving reaction efforts of the robotic arm, up to 20 N and 80 N.m
• Actual LAR status is unknown, so the CLM has to be able to deal with manufacturing tolerances, presence of (potentially degraded) thermal tape, micrometeoroid-caused damage and large thermal gradients (which, for the hot scenario of +140ºC limit significantly the aluminum LAR structural strength)
• Once clamped, the CLM has to provide stack alignment capability up to ±20º to compensate for the uncertainties on the position of the target center of mass. This realignment capability has to be also available between de-orbiting thrusts
The presentation will address the status and main challenges overcome during the activity.
