← INDEX — FIG. 00 — 10 FEBRUARY 2009, 16:56 GMT, 790 KM
IRIDIUM 33 × COSMOS 2251
DEBRIS
SPACE JUNK AND THE KESSLER SYNDROME
Over 25,000 tracked objects in orbit.
BEGIN — CHAPTER 01 →CH.01 / 06 — WHAT IS UP THERE
Nine thousand tonnes, mostly broken
Over 9,000 tonnes in orbit.
Explosions, then collisions.
CH.02 / 06 — TWO EVENTS IN TWO YEARS
Fengyun-1C and Iridium 33
Fengyun-1C, 11 January 2007.
Iridium 33 × Cosmos 2251, 10 February 2009.
IMPACT SPEED AND ENERGY
vrel = 2 v sin(θ/2) · E = ½ m vrel² · target shattered if E/Mtarget ≳ 40 J/g
40 J/g shattering threshold.
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CH.03 / 06 — THE ATMOSPHERE AS A BROOM
Years below 600 km, centuries above 800
NASA: several years below 600 km, centuries at 800 km.
Area-to-mass and solar activity.
ORBITAL DECAY BY DRAG (CIRCULAR ORBIT)
da/dt = −(CDA/m) ρ(h) √(μa)
Order-of-magnitude estimate.
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CH.04 / 06 — A BELT THAT FEEDS ITSELF
When collisions make debris faster than air removes it
Collision rate ∝ N².
The FCC's five-year rule.
CH.05 / 06 — FROM WARNING TO RULE
Half a century of a growing cloud
The useful orbits are not big.
CH.06 / 06 — REFERENCES