Houston ? Two spacewalkers sheepishly lost a spatula in orbit Wednesday. But NASA engineers didn’t mind much, because the two accomplished their main task of testing a method to apply emergency patches to a shuttle heat shield – and then some.

Discovery spacewalkers Piers Sellers and Michael Fossum improved on the method of applying a special mixture to repair the reinforced carbon leading edges of a space shuttle, using mock-ups in a suitcase in Discovery’s payload bay.

A crack allowed fiery gases to penetrate space shuttle Columbia’s reinforced carbon wing during re-entry to Earth’s atmosphere in 2003, destroying that shuttle and killing its seven astronauts.

The same peanut butter-like repair goo was used a year ago in a first test of the system, with mixed results. That test produced many bubbles that could allow killer heat to penetrate on re-entry. This time, initial results showed that some bubbles formed, but they didn’t join to become big, dangerous ones, said lead spacewalk officer Tomas Gonzalez-Torres.

Astronauts Piers Sellers, left, and Mike Fossum work in Discovery's payload bay with carbon-carbon samples, shown in the square boxes. The astronauts on Wednesday conducted tests on heat shield repair techniques.

The goo was messy, spattering the spacewalkers to the extent that Sellers told Fossum: “Mike, you look like a panda. You’ve got a few little spots.”

There was only one thing missing from the spacewalk: Sellers’ spatula.

It flew overboard, off the right side of the shuttle’s payload bay.

“No sign of the spatula. I think it’s gone, gone, gone,” Sellers said of the kitchen appliance, 14 inches long and 2 inches wide.

It is rare for spacewalkers to lose such a tool, but “it is no hazard to us,” Gonzalez-Torres said. Nonetheless, military monitors of space debris were notified of the new hazard to track.