The Earth Story

This photo goes along with our previous post (credit comments over here).

Incoming!

Do you live anywhere near the lines on this map of the globe? If so, on May 8, give or take a few hours, you may have to, well, duck.

On April 27th, a Russian Soyuz spacecraft launched carrying a Progress supply capsule headed for the International Space Station. The spacecraft was carrying thousands of kg of food, supplies, and equipment, in addition to fuel to drive the spacecraft and the mass of the spacecraft itself.

The initial parts of the launch went fine, but as the spacecraft was approaching the final part of its launch the signals received on the ground from the spacecraft became intermittent and within a few hours they were lost completely. Russian engineers continued to try to contact the capsule and the capsule got close enough to the ISS to be visible by the astronauts, but the capsule itself has remained silent for over a week.

Unable to burn its engines or correct its course, the capsule is now in a decaying orbit around Earth. It needs to burn its engines to move higher and reach the ISS; instead, friction with the atmosphere is now causing the spacecraft to slow down and descend towards Earth.

Sometime late this week the capsule will re-enter Earth’s atmosphere and come down. The exact time is difficult to project as it is influenced by solar activity; a more active sun actually causes the upper layers of Earth’s atmosphere to rise higher and increases the friction on orbiting objects. Engineers worldwide can make educated guesses about when and where it will come down and narrow it down to within a few orbits, but that leaves error bars of several hours and most of the planet.

As the capsule enters the atmosphere it will break apart and much of the material inside will burn up due to friction, but several large parts of the capsule are likely strong enough to make it to the surface. Estimates suggest about 20% of the mass, likely over 1000 kg, will come down on the surface in an area potentially hundreds of kilometers wide.

Based on these orbits it is estimated that there is a 60% or so chance of it entirely hitting water, which is conveniently very close to the percentage of Earth’s surface covered by water anyway. The odds of it hitting a major, populated area are of course low, but this is not a game when we’d like to play the odds very often.

Hopefully Russian engineers are able to prevent problems like this on future missions, because this is actually really bad. The Space Station is well supplied enough that the loss of this spacecraft only costs money; the astronauts should be able to survive there with no issues assuming no more supply capsule failures in the near future, but uncontrolled descent of large metal objects is something we’d really like to avoid.

-JBB

Image credit: Spaceflight101 (used with permission) http://www.spaceflight101.com/progress-m-27m-re-entry.html#update

Read more: http://www.tsenki.com/en/launch_services/help_information/launch/2015/?EID=120974 http://space.stackexchange.com/questions/9042/can-we-see-the-russian-progress-59-spacecraft-burn-up-on-reentry