SCIENCE DATA

Lunar Prospector circles the Moon in a polar orbit 100 km above the lunar surface. A Satellite in a polar orbit circles the planet perpendicular to the planet's rotational plane, traveling from pole to pole. This is opposed to an equatorial orbit where the satellite travels parallel to the rotational plane never passing either pole. The Lunar Prospector team wanted to put the craft into a polar orbit because it is important to map the Moon's polar regions. It is there that they hope to find large deposits of water ice deep in the shadowed craters. Traveling at the speed of neasly 5,517 km/hour, the craft comleates one full trip around the Moon every 118 minutes.

As Prospector speeds around the Moon in a constant path, the landscape is steadily shifting beneath it due to the Moon's normal rotation. The surface will have shifted most dramatically at points on teh equator, about 26km, while at polar regions barely at all. This makes it so Prospector "sees" both poles on nearly every pass, while seeing specific equatorial regions for only about 15 minutes each month.

Prospectors instruments are constantly collecting data from the lunar surface, they send back data to Earth in packets. A packet is a set of data about a given section of the moon. Prospector transmits the data it has collected (a packet) to mission control. It then continues on and, thirty-two seconds later, transmits another packet containing its most recent findings .These "packets" contain information collected from the 150 km longitudinal strip of surface that the craft has traveled over since its last transmission.

After about three transmissions the scientists on Earth will have received information on a "footprint". A foot print is a 150km x 150km section of the lunar surface. It might be seen as analogous to a pixel your computer screen. If you were to look at the screen closely enough, you would see only blocks of solid color called pixels. However, when viewed normally the pixels form a contiguous image. Similarly, when all the footprints are put together they will give us an entire "picture" of the moon. The footprints overlap one another. The overlap makes it so that, each month, Prospector spends about fifteen minutes over some portion of any given footprint along the equator.

After orbiting at 100 km for a year, mission control will drop Prospector to an altitude of only 10 km, where it will be able to examine the surface in more detail. It will remain there until it runs out of fuel and impacts the lunar surface.