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Guest posted by:  GruntOfMonteCristo
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The launch of the Phobos-Grunt probe from Kazakhstan on November 8th marked the first Russian Mars mission in 15 years. Space experts now say that underfunding of the ambitious project may have doomed it from the start.  ”Way too ambitious, and way too underfunded, to reach its goal,” says space law attorney Michael Listner, who writes for The Space Review.  All went well for the spacecraft during the launch and injection into a parking orbit around the Earth, but the failure of an orbital boost stage doomed the vehicle to a slow decay through the Earth’s atmosphere until it reenters in mid-January.  

Since spacecraft reenter the Earth’s atmosphere all the time, this would not be very newsworthy except for the unusually heavy load of toxic propellants on board this vehicle. Reports vary somewhat, but indications are that there may be as much as 11 tons of hydrazine-derivative fuel and nitrogen tetroxide oxidizer on board. Both of these are extremely deadly to humans whether dispersed in the atmosphere or in direct contact to the skin.  Due to the enormous quantity involved, there is some concern about where, exactly, the vehicle may reenter over the surface of the Earth. Predictions have been complicated by autonomous thruster activity on board the vehicle that raised the orbit for a while in November before going silent.  This threw off early predictions of a mid-December reentry and delayed the spacecraft’s death plunge until at least early January.  Precise predictions of reentry locations are unlikely to be published, even though they are now becoming identifiable.  Most of the planet, everything between +/- 51.4 degrees of latitude, falls under the regular ground traces of Phobos-Grunt, and could potentially see some debris.  As for the reentry date, the Russian space agency has predicted January 10-21, 2012, and other experts agree with that estimate.  The current prediction of the spaceflight101.com site is January 15, 2012 at 14:00 UTC +/- 18 hours, as of the very end of the day on the 9th.

The Grunt has done a preliminary simulation, and the official Blog of Monte Cristo prediction at this time is for January 15, 2012 at about 1:00 UTC, which is just after Midnight, early Sunday morning in Western Europe, which is the vicinity of the reentry according to my crude analysis.  This shouldn’t be taken too seriously, because we are 5 days away from the likely burn-up, but the current simulation shows the vehicle’s final flight over France, the island of Corsica, humorously over the uninhabited island of Monte Cristo itself (I’m not kidding), and then finally being scattered over the City of Rome.  If the Spaceflight101 prediction is more correct than mine, then the reentry could occur later in the flight, perhaps over the Pacific Ocean, or potentially anywhere else on the globe.  I should note, however, that their predicted reentry time was 21:00 UTC until just a few hours ago, and they’ve been revising their time earlier, toward mine.  I’ll continue to revise my predictions over the next few days, using much better atmosphere models.  I guarantee that the predicted location will change, and at any rate, given my track record, I think I can say that the safest place on the planet is probably Rome, at this point.

The actual danger of this reentry should not be blown out of proportion, because all spacecraft are most likely to come down over water, and very little of the vehicles survive the fiery descent, anyway. However, many heavy pieces do survive and strike the ground, like the debris from Skylab that rained down across the Australian outback, or pieces of the UARS satellite that very likely fell over Washington State and Canada, despite the official claim that it happened entirely over the Pacific.  One of the particular concerns with Russian spacecraft is that they contain a lot of titanium, which is strong and light and is almost impervious to the heat of reentry.  Titanium is abundant in Russia, and is frequently used for fuel and gas spheres like the one pictured above that was recovered in Africa.

Clearly, the enormous mass of dangerous propellants on board Phobos-Grunt, combined with the possibility that they are stored in indestructible titanium tanks, makes for a real concern. Most sources are reporting that the tanks used on Phobos-Grunt are made of aluminum due to cost-cutting measures taken during construction.  This would be good news, indeed, if true.  Aluminum tanks would not survive reentry.  No one is questioning the veracity of this claim, which almost certainly was only discussed after the reentry became a certainty, but one could question it, right? Since space lawyers have indicated total Russian liability for any damage, there is plenty of reason to think that the tank material is a sensitive topic, at risk of being … manipulated.

So the danger of this particular reentry cannot be completely wished away. In fact, it’s somewhat reminiscent of a James Bond dilemma in Moonraker, in which he had to risk his life to shoot down reentering spheres containing nerve gas. In the real world, atmospheric entry of hypergolic propellants like Phobos-Grunt’s is usually avoided at all costs.  If possible, all of it is exhausted by thruster firings in orbit.  In the case of the defunct Phobos-Grunt, that can no longer be done.  So we wait.  And watch.

More reading: www.spaceflight101.com, www.heavens-above.com, www.space.com.