Swift Spring came within 100 miles of Earth ; that 's close for a comet impact . NASA protected its spacecraft orbiting the planet by letting them hide . The first of three NASA spacecraft reported to be in good condition .
Siding Spring came within 87,000 miles of Mars ; that 's close for a comet flyby . NASA protected its spacecraft orbiting the planet by having them hide . The first of three NASA orbiters reported to be in good health .