Landing on Mars

.....Late tonight, (at 10:31 PM PDT / 12:31 AM CDT / 1:31 AM EDT) the NASA Mars Science Laboratory will reach Mars, and in a period of seven minutes will attempt to go from a speed of 13,000 mph to zero.  As far as this goes, I cannot do a better job describing the challenges involved than this video.  On top of this, all of this has to be completely planned out; there will be no chance to manage any of the entry from Earth; the time that the signals take to go from the Earth to where Mars is now is fourteen minutes.  If a problem showed up in the signals coming from the spacecraft, and someone on Earth tried to respond, it would be almost half an hour until that order got to the probe.

.....Because of the time it takes a probe to go from Earth to Mars (for this trip, 253 days), we cannot track the motion of this probe by drawing a straight line from the Earth to Mars, and simply assuming the probe traveled on this path.  We must trace out a curved path from where the Earth is at launch to where Mars will be when the probe reaches Mars' orbit.  In fact, when the probe was launched, Mars was rising after midnight, just getting into position for a decent observing season.  As the Mars Science Laboratory moved through the gulf between the planets, the Earth actually passed Mars on the inside (at the beginning of March), and then on for five more months until now.  As seen in the Earth sky, Mars, Saturn, and the star Spica form a triangle low in the west just as it is getting dark.  The base of the triangle will be parallel to the horizon.  Mars will be the base "star" on the right, and Saturn will be on top.  Go out and take a look, and consider for a moment just what we as a species are attempting.

.....You may also wish to read this piece (warning! naughty words!); I will have something to say on this line tomorrow.