A well-established model for general travel to the moon will be used to carry the rover and lander from Earth onto the lunar surface. However, the physical and logistical complexities associated with delivering a payload to the moon require each step in the trip to be carefully coordinated.
After takeoff from Earth, the craft will be placed into low earth orbit (LEO). Then additional thrust will be applied to move the craft into a lunar transfer orbit (LTO)—an elliptic orbit which will intersect the desired low lunar orbit (LLO) at a lunar orbit insertion (LOI) point. When the craft reaches the LOI point, its thrusters will boost its velocity, shifting it into a circular, retrograde LLO. From LLO, the craft will initiate its descent to the lunar surface.
The following subtleties must be considered for a successful flight:
- Because the moon orbits the Earth, and the travel time from the Earth to the moon is about 5 days, the launch must be carefully timed so that the moon and craft arrive at the same physical location at the same time.
- The Earth's moon is somewhat uncharacteristic of most moons in that its orbital plane is aligned with the ecliptic, and not the earth's equatorial plane. Since the LEO will be equatorial, but the LTO will reside in the moon's orbital plane, these two orbital planes must be aligned when the craft transfers between them.
- The orbit of the moon is somewhat eccentric. Time and fuel savings may therefore be realized by launching the craft so that it arrives when the moon is at perigee.
The launch has been scheduled for January 25, 2010 at 20:59:35 UTC. A travel time of about 4.5 days will place the craft at the LOI point on January 30, 2010 at 10:04:00 UTC, the precise time of the moon’s closest perigee in 2010. The rover will be placed in orbit with Lockheed Martin’s Athena II launch vehicle, launching from Cape Canaveral.