You might say that the Philae landing vehicle had earned its frequent flyer miles the hard way, hitching a ride on the space probe Rosetta on a journey of over 6.4 billion miles that lasted 10 years. And, that was the easy part, the most difficult challenge was making a safe, solo landing at the end of its journey. (don’t we all hope for a safe landing at the end of our flying journeys?) The challenge for Philae was to land on a comet. Land, not on the moon, not on Mars, but on a comet!