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Space debris - Frequently asked questions
| | | | Q2: How do we know that space debris exist?
| The concept of protected regions developed by the IADC:
- LEO: from Earth surface up to 2000 km
- GEO: from 34 786 to 36 786 km from Earth surface (equatorial latitude ± 15°)
Credits: CNES | |  |  | |
| | | | Q3: What are the main sources of information on space debris?
| A picture of the damage caused by a micrometeoroid or small piece of space debris on the solar array of the Hubble space telescope. The arrays, which were built in Europe, were returned to ESA for analysis of in-orbit degradation. The crater is about 4 millimetres in diameter and was probably made by a particle of 0.5 millimetre diameter.
Credits: ESA | | | | |
| | | | Q5: How did recent deliberate satellite intercepts affect the space debris environment?
| EISCAT Svalbard site hourly space debris detection rates before (above) and after (below) an anti-satellite test conducted by China in early 2007.
Credits: ESA | | | | |
| | | | Q6: Why does the Earth's atmosphere have a positive effect on space debris?
| Distribution of catalogued objects in space - close-up of the LEO region.
Credits: ESA | | | | |
| | | | Q10: How does the ISS protect itself against space debris?
| | By spacecraft standards, the 960-kg Giotto was quite modest in size. Its main body was a short cylinder, 1.85 m in diameter by about 1.1 m in height. It contained three interior platforms: the top platform (30 cm thick), a main platform (40 cm), and an experiment platform (30 cm). Each of these consisted of a disc within the cylinder, on which were mounted various subsystems and science experiments. On top of the cylinder was a tripod which surrounded a 1.5 m diameter high-gain dish antenna, which gave the spacecraft a total height of 2.85 m. The main rocket motor was positioned in the centre of the cylinder with the nozzle protruding from the bottom.
The most difficult problem to overcome was how to ensure that Giotto survived long enough to snap its close-up pictures of the comet nucleus when the spacecraft and the comet were heading towards each other at a combined speed of 245 000 km/hour (equivalent to crossing the Atlantic Ocean in 11 minutes!). At this speed, a 0.1-gram dust particle would be able to penetrate 8 cm of solid aluminium. Since it was out of the question to equip Giotto with a 600-kg aluminium shield, engineers turned to a more subtle, sandwich design first proposed by American astronomer Fred Whipple back in 1947 - long before the beginning of the Space Age.
The spacecraft's dust shield consisted of two protective sheets, 23cm apart. At the front was a sheet of aluminium (1-mm thick), which would vapourise all but the largest of the incoming dust particles. A 12-mm thick sheet of Kevlar at the rear would absorb any debris which pierced the front barrier. Together they could withstand impacts from particles up to 1 gram in mass and travelling 50 times faster than a bullet.
Credits: ESA | | | | |
| | | | Q11: What measures are already being take to avoid space debris - and which ones need to be taken in the future?
| ESA Space Debris Mitigation guidelines, April 2008
Credits: ESA | | | | |
| | | | Last update: 20 February 2009 | |
| | Space debris tools DISCOS DatabaseMASTER-2005More information European Cooperation for Space Standardization (ECSS)Inter-Agency Space Debris Coordination Committee (IADC)United Nations Committee on the Peaceful Uses of Outer Space (UNCOPUOUS)
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