Meteoroid and debris shielding


ESA activities related to protection of spacecraft against hypervelocity impacts (space debris or meteoroids) go back to the Giotto programme. The motivation in the early eighties was to ensure the mission success by a proper design and an adequate verification of the spacecraft shield against the comet Halley’s dust tail. Most of the work performed during the nineties was devoted to exploring possible protections for the European Module of the Space Station (Columbus and ATV). The driver here was to ensure the manned pressurized module would not leak after a space debris impact with a high probability of success. This was needed to comply with safety requirements linked to the presence of man on board. More recent work has focused on unmanned spacecraft. The logic here recognizes the very constraining limitation linked to requirements similar to the one used for manned modules: no perforation of the main body. The new approach is thus to accept perforation of the spacecraft structure and to assess the vulnerability of mission critical equipments (Pressure Vessels, batteries, electronic boxes, harness). This technological field can be broadly split into three domains:
  1. Material and configurations characterisations under hypervelocity impacts
  2. Experimental and diagnostic techniques
  3. Validation of numerical simulations

 
Each of these domains is driven by stringent requirements linked to the nature of hypervelocity impacts:

Very short transient (time scales in microseconds)

Materials under high strain rates (104 to 107 s-1)

Material phase changes (local pressures range up to mega-bars)
 
 
EMI test 3915, 4.0 mm aluminium sphere, 7.2 km/s, 45 degrees
 
EMI test 3915, 4.0 mm aluminium sphere, 7.2 km/s, 45 degrees 1.2 mm Al7075 bumper 49.5 mm spacing 3.3 Al7075 backwall After the development and validation phases for the Columbus Module and ATV Shields, the attention has been focused on survivability of unmanned spacecraft to space debris impacts. The approach is to characterize the impact conditions which can impair the performances of various subsystems or equipment. Electronic boxes, Harness, Piping, Pressure Vessels are among the studied items.
 
 
Assembly of an electronic box target
 
Assembly of an electronic box target
 
 
In order to cause temporary or permanent failure of the e-box function, projectile diameters ranged from 2.3 mm to 5 mm, depending on the stand-off to the Al H/C SP structure wall (0 mm and 300 mm, respectively). These values have to be compared to the typical 1 mm projectile diameter required to perforate the external wall of a typical spacecraft.
 
 
Debris cloud
   
Debris cloud
 
Similar improvement of the perceived vulnerability of various other equipment have been experimentally substantiated. The final purpose of this effort is to support ESA programmes providing realistic assessment of spacecraft vulnerability to space debris impacts
 
 
 High Speed Video Shadowgraph of Exp. 3931; shutter time 80 ns (pict. 1-6) Exp. 3931: Whipple shield, 1.2 mm Al 7075-T73, S=49.5, 3.3 mm Al 7075-T7351, Al-projectile d=4.999 mm,
v=7.0 km/s, α =60°, result: > BL
 
 
  
Last update: 7 January 2013