Spacewalks aren't easy. Ask astronaut Heide Stefanyshyn Piper.
She was several hours into a grueling seven-hour spacewalk outside the International Space Station Tuesday, when a grease gun exploded in her tool bag.
"Oh, great", she said, the frustration clearly apparent in the sudden and unexpected mess.
She was trying to clean the mess off her gloves and a camera, when the tool bag slipped away and drifted off into space.
The tool bag is one of the largest items to be lost on a spacewalk. It contained two grease guns, a putty knife, and some cleaning wipes.
The tool bag apparently slipped from its tether. It's loss complicates the remaining space walks to finish working on the solar array with the broken joint because the space shuttle Endeavour didn't carry up extra grease guns, or much spare grease.
In lieu of the grease guns flight controllers are considering using caulk guns that were designed to fix a hole on the space shuttle. NASA has to trade the risk of using one of those guns to fix the solar array, with the possibility of needing the gun to fix a space shuttle.
Spacewalk Officer John Ray commented on the loss of the bag, saying "What it boils down to, all it takes is one small mistake for a tether not to be hooked up correctly." He went on to compliment Piper. "Heidi did a great job on the rest of the EVA. She showed great character and recovered well," Ray said.
Spacewalks look deceptively easy when you are watching them on TV, floating around above the Earth with great views in zero gravity. But the truth is an EVA, extravehicular activity, is hard work.
Astronaut Piers Sellers has spent 41 hours on spacewalks. He told ABC News before his last mission what makes it such a challenge. "It's a little bit like standing in a little rowboat with an ocean swell, trying to paint the side of a ship that you're up against. You have to compensate for the waves and the sways. But you can do that, people do it every day with rowboats. And we'll see if we can do it in space."
Sellers lost a spatula on one of his spacewalks. He called it his favorite spatula. Once something slips out of your hands on orbit it is gone, destined to become just another piece of space junk, or orbital debris in NASA speak.
Veteran spacewalker Jim Reilly said it is quite tiring working in a spacesuit. It may look like a big fluffy marshmallow but it is really a small space ship.
"The thing that probably affects you more and makes you more tired is operating in a low vacuum, or low pressure. We are working inside of a suit that is pressurized at 4.3 PSI so it is fairly rigid. So you have to learn how to do things differently. You just don't reach up and grab it like this, otherwise you will wear your self out.
NASA is tracking the lost tool bag to make sure it doesn't threaten the International Space Station or Endeavour. At last report it was 4,000 meters in front of, and 200 meters below the ISS.