Failed Russian Mars Probe May Crash in Indian Ocean Sunday

by Mike Wall, SPACE.com Senior Writer

Date: 11 January 2012 Time: 05:45 PM ET

A doomed Russian Mars probe that's been stuck in Earth orbit for two months may finally come crashing down Sunday (Jan. 15) over the Indian Ocean, Russian space officials say.

The 14.5-ton Phobos-Grunt spacecraft should fall back to Earth sometime between Saturday and Monday (Jan. 14 to Jan. 16), Russia's Federal Space Agency, known as Roscosmos, announced in a statement today (Jan. 11).

If Phobos-Grunt comes down at the "central point" in that window — 4:18 a.m. EST (0918 GMT) on Sunday — it will fall over a stretch of empty ocean west of the Indonesian island of Java, according to a re-entry projection map Roscosmos published with the update.

But these projections are far from set in stone. The predicted time and place of re-entry may change as engineers continue to track the spacecraft's decaying orbit, officials said. All that's known for sure is that Phobos-Grunt will come down somewhere between 51 degrees north latitude and 51 degrees south latitude. [Photos of the Phobos-Grunt mission]

Falling back to Earth

Phobos-Grunt launched Nov. 8 on a mission to collect soil samples from the Mars moon Phobos and return them to Earth ("grunt" means "soil" in Russian). However, the probe's main engines failed to fire as planned to send it toward Mars, and the craft got stuck orbiting Earth.

Russian officials still aren't sure what caused the failure. They recently raised the possibility that some form of sabotage may have crippled Phobos-Grunt and doomed its $165 million mission.

The spacecraft has been spiraling lower and lower for months, on an inevitable collision course with Earth's atmosphere. The minimum altitude of Phobos-Grunt's orbit as of today is about 106 miles (171 kilometers), according to Roscosmos.

The huge probe is carrying about 7.5 tons of toxic hydrazine fuel, prompting some observers to worry about potential environmental impacts of the probe's looming re-entry. Russian space officials have repeatedly dismissed those concerns, however, saying that the fuel — which is encased in an aluminum tank — should burn up high in Earth's atmosphere.

Most of Phobos-Grunt should meet that same fate. Experts predict that just 20 to 30 pieces, weighing a maximum of 440 pounds (200 kilograms) in total, will actually hit the Earth.

Phobos-Grunt's demise comes close on the heels of two other uncontrolled satellite falls recently. NASA's 6.5-ton UARS climate satellite re-entered over the Pacific Ocean in September, and Germany's 2.7-ton ROSAT satellite crashed over the Indian Ocean a month later.

Both the UARS and ROSAT re-entries were expected, however, and the two satellites had long since completed their primary science missions. No one on the ground was hurt in either instance.

http://www.space.com/14215-phobos-grunt-mars-probe-crash-indian-ocean.html