MELISSA BLOCK, HOST:
A thumbs-up tweet today from the account associated with a space probe on a comet millions of miles away - life on 67-P is good, the tweet crows, about three hours sunlight a day and feeling energized. The Philae Lander has woken up after seven months of hibernation. It made history back in November, becoming the first lander ever to set down on a comet, which are essentially speeding chunks of ice and rock. But that landing was rough. It couldn't charge its solar array, and it entered a deep sleep. Well, now the Philae Lander is back in contact, and that's great news for Valentina Lommatsch. She's a Philae operations engineer at the Lander Control Center in Cologne, Germany. Welcome to the program.
VALENTINA LOMMATSCH: Hi.
BLOCK: And what were your thoughts when you first heard that Philae was back communicating?
LOMMATSCH: I was just completely blown away. I couldn't believe it. I had started to lose hope, actually, and it was just really, really great to hear from Philae.
BLOCK: Started to lose hope - you thought maybe Philae was gone for good.
LOMMATSCH: Yeah. I do the predictions for the solar array, and I had predicted that we had enough energy to switch on Philae already in February. Unfortunately, the temperature said something different. And when we did a thermal analysis, we found out that he's not going to wake up until probably between June and August or, perhaps, not at all, which was a bit unfortunate if that had been the case - luckily, it wasn't.
BLOCK: And now the comet is getting closer to the sun, so the solar array is - is what? It's firing up again.
LOMMATSCH: The solar array has been active the entire time, but unfortunately the temperature was just too low. Philae isn't able to switch itself on until the internal compartment reaches a temperature of minus 45 degrees. And the comet has an outside temperature, at least in November, of minus 170 degrees. So you can imagine...
BLOCK: Yeah.
LOMMATSCH: ...It's a bit hard to stay warm when it's so cold outside.
BLOCK: Well, apart from the thrill and the burst of excitement about actually landing the Philae Lander on a comet - first time ever that's been done - what do you hope to learn? What kind of data would it be able to send back that would be really exciting for you?
LOMMATSCH: The instrument that a lot of scientists are very excited about is the SD2 drill, which will take a sample of the comet and then give that to three different instruments - a camera, which is basically a microscope, can look at how the material looks, and two mass spectrometers, which can tell us what the comet is made of. And it's very interesting to find out what comets are made of because, hypothetically, they are left over from when the universe was created. And so it's nice to see what the building blocks were for the earth and the solar system and the universe.
BLOCK: That's pretty big stuff.
LOMMATSCH: Yeah, exactly.
BLOCK: Well, Valentina Lommatsch, thanks so much for talking to us about it.
LOMMATSCH: No problem, thank you.
BLOCK: Valentina Lommatsch is an operations engineer for the Philae Lander. It's just woken up after seven months of hibernation. She works at the Lander Control Center in Cologne, Germany. Transcript provided by NPR, Copyright NPR.