Articles by Donald
F.
Robertson
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The Mars Reconnaissance Orbiter's camera is by far the largest ever
sent to Mars, or to any planet other than Earth. With a
resolution of
twenty-five to thirty-two centimeters
per pixel, scientists will be able to
identify objects on Mars about one
meter across. The Martian Spy
Satellite (an Acrobat file) was my editor's title, not mine, but it
is
appropriate.
This article first appeared in Astronomy
Now.
Most moons in the Solar System are very small compared to their
planets.
Ganymede is bigger than the planet Mercury but it must be a grave
disappointment to its parent, Jupiter. Even Titan, in spite of
its
name and for all its methane streams and rain, is positively tiny
compared to Saturn. There are two exceptions. Earth's moon
weighs in at
about 1.2 percent of
Earth. Pluto's Charon is ten to fifteen percent of Pluto's
mass. Why?
Jupiter's water world Europa is, without doubt, one of the most interesting places in the Solar System. If ever there were a chance of finding familiar carbon-based life, it is in Europa's deep oceans -- under the relatively thin but impenetrable shell of ice. What are the chances of finding evidence for life on the surface where we can see it? (Acrobat file.)