Per ulteriori approfondimenti sul problema delle collisioni orbitali e dei detriti spaziali potete consultare le newsletter del NASA Orbital Debris Program Office. Non ho capito bene perché, forse per i contatti con la Russia, più probabilmente per la forte attenzione nei confronti del programma spaziale di Pechino, ma l'agenzia cinese Xinhua offre un coverage dettagliatissimo sulla vicenda, raccogliendo dichiarazioni di molte fonti interessanti. Tutti i lanci sono raccolti in questa pagina, che vi suggerisco di consultare subito. Fonti americane, russe e delle Nazioni Unite (attraverso il United Nations Office for Outer Space Affairs) hanno invocato misure e regolamentazioni destinate a evitare in futuro questi incidenti, che oltre a recare danno a infrastrutture spaziali operative possono liberare in orbita pericolosi detriti radioattivi provenienti dai satelliti ad alimentazione nucleare. Lo statement ufficiale di Iridium lo trovate qui. Il 22 febbraio dovrebbe partire una nuova missione Shuttle ma non si prevedono rischi legati a questo inatteso incidente.
Feb 11, 2009 06:15 PM
Space crash: Commercial and Russian satellites collide in orbit
By John Matson in 60-Second Science Blog
A commercial satellite collided with a Russian satellite over Siberia yesterday, yielding a cloud of fragments, according to a NASA scientist tracking space debris. The collision between the commercial satellite, belonging to the American communications firm Iridium, and the Russian satellite, believed to be defunct based on its advanced age, was the first of its kind, says Nicholas Johnson, chief scientist at the NASA Orbital Debris Program at Johnson Space Center in Houston. (A spokesperson for Iridium said a statement on the incident would be released shortly.)
"In the past almost 20 years, there have been three other accidental collisions between objects in orbit, but they've all been very minor," Johnson says. "The most debris ever produced in an event was like four debris, and this is two intact spacecraft colliding, and we have hundreds of debris out there. We don't know exactly how many yet."
According to Johnson, the military sky-watchers who track satellites in orbit picked up the collision 490 miles (790 kilometers) above Earth Tuesday. "One of the things that they discovered yesterday afternoon ... was all of a sudden, where two satellites used to be, there were two clouds of debris," he says. The actual crash appears to have occurred just minutes before noon, Eastern Standard Time.
Johnson says NASA has already determined that the debris cloud poses "no significant new risk to the International Space Station." The next space shuttle mission, which may launch as early as February 22, should be in the clear as well, according to the space agency.
Such a collision between two intact spacecraft may be unprecedented, but it is not completely unexpected. "There are no rules of the road in space," Johnson says. "Anybody can fly anywhere they want." Even concerted efforts to track and guide spacecraft in orbit are subject to some uncertainty in trajectory estimates. At seven miles (11 kilometers) per second, Johnson says, "a little error means a lot."