NASA celebrated the successful launch of its Wide-field Infrared Survey Explorer (WISE) spacecraft from Vandenberg Air Force Base, California, yesterday morning. But why launch from a base in California rather than the old standby, Cape Canaveral Air Force Station, Florida?
The main reason is that the WISE telescope requires a polar orbit so it can benefit from constant sunlight and the power it provides.
Vandenberg works well for such missions because a launch track to polar orbit from that site takes the rocket mostly over Pacific waters rather than over land. A Florida launch would take such a flight over America’s East Coast, and New Englanders don’t like missiles shot over their heads.
One of the disadvantages of launching into a polar orbit is that it takes a lot more power. The reason: Earth spins eastward at some 1,000 mph (at the equator). Thus, a rocket taking off eastward from an equatorial region enjoys a 1,000 mph advantage at liftoff!
Such a rocket taking off from Vandenberg Air Force Base enjoys no such 1,000 mph advantage and has to make it up with pure power. That means it takes a larger rocket to launch a payload into polar orbit.
At one time, there were plans to launch space shuttles out of Vandenberg into polar orbits. Unfortunately, the shuttle didn’t have the lift capability to place the Air Force’s satellites into polar orbit, and the service had to switch to unmanned rockets to do the job. And that may be the reason that NASA used an unmanned rocket for yesterday’s launch. No human has ever flown in polar orbit.