A few times a year, Russia sends a small unmanned vehicle called “Progress” to the International Space Station. The cargo ship carries food, fuel and other supplies. When Progress leaves, astronauts fill it with garbage and it burns up when it re-enters the atmosphere.
The next Progress flight is set for April 27. That meant it would have arrived at the Space Station after Space Shuttle Endeavor was already docked there. Kyle Herring is with NASA:
An unpiloted Progress 17 supply vehicle departs from the International Space Station, carrying its load of trash and unneeded equipment to be deorbited and burned up in Earth’s atmosphere. Image Credit: NASA
“People think ‘Well with different docking ports, it should be okay,’ but for safety reasons we don’t like to have an unmanned vehicle arriving or departing from the international space station while the space shuttle is docked there.”
Herring says that NASA’s primary concern is exhaust plumes from the engines on “Progress.” As Progress approaches the space station and fires its jets, the exhaust could potentially damage the shuttle.
“There are small thruster jets on the supply vehicle that could — what we call ‘plume’ the windows on the shuttle and either smear them or damage them in some way. So we’re very careful about protecting the shuttle’s exterior.”
Herring says NASA was aware of the scheduling conflict and had been discussing it with the Russian space agency.
One option would have been to delay the launch of Progress, instead of the space shuttle. But Progress is going to be carrying up a time-sensitive biological experiment, so it can’t wait.
And Endeavor can.
From the KUHF Health Science and Technology Desk, I’m Carrie Feibel.