Q&A with Rolf de Groot, head of ESA’s robotic exploration office

The European Philae comet lander, out of power and presumably lost after bouncing into heavily shadowed terrain last November, phoned home Saturday after finally getting enough sunlight on its solar panels to transmit data to the Rosetta orbiter for relay to Earth.

After four years of brainstorming, custom tool development and training, two astronauts plan to venture outside the International Space Station Friday for the first of four spacewalks to repair a $2 billion cosmic ray detector. The excursions are considered the most challenging since work to service the Hubble Space Telescope.

Back on Earth after a whirlwind journey 20,000 miles around the world, an experimental re-entry demonstrator is on the way to Europe for post-flight inspections aimed at gathering design inputs for future reusable space vehicles.