posted on Jun, 18 2009 @ 11:51 AM
Nasa LCROSS Press Release
LCROSS also uses the spent second stage of the Atlas rocket, the Centaur, as an SUV-sized kinetic impactor–
something that has never been done before-to excavate a small crater in the bottom of a permanently shadowed lunar crater.
To maximize the creation of a debris plume, the impacts of the Centaur rocket and the LCROSS shepherding spacecraft need sufficient speed and a high
angle of impact. Engineers have estimated that the Centaur and LCROSS spacecraft will impact the lunar surface at approximately 1.55 miles per second
(2.5 km/s), five times faster than a bullet fired from a .44 Magnum. The projected angle of impact is approximately 80 degrees with respect to the
To achieve this high angle of impact, the LCROSS spacecraft and the Centaur will execute a flyby of the moon approximately five days after launch
entering into an extended LGALRO. This portion of the mission is expected to be four months.
The exact length of the LGALRO is dependent on exact time of launch and is calculated to satisfy a number of mission constraints including achieving
the targeted crater and the correct phase and tilt of the moon for proper illumination of the debris plume at the time of impact.
At launch, the LCROSS team will announce the lunar pole and the primary target crater. Factoring any additional information,
a final determination of the target crater will be made 30 days before impact.
On final approach to the moon, the LCROSS spacecraft and the Centaur will separate. The shepherding spacecraft will perform
a braking maneuver and will reorient to point the instrument payload to capture the Centaur impact.
After the Centaur impacts, the LCROSS spacecraft will have up to four minutes of data collection and transmit that data back to LCROSS
LCROSS is required to achieve a targeting accuracy of approximately 6.2 miles (10 km) radius, but is expected to be significantly
more accurate (0.75 or 1.2 km radius).
The Centaur impact crater is expected to be approximately 90 feet (27 m) in diameter by 16 feet (5 m) deep, while the
LCROSS spacecraft impact crater is expected to be approximately 60 feet (18 m) in diameter by 10 feet (3 m) deep. The
impact is expected to create a very brief visible flash that will last less than 100 milliseconds. Most of the excavated material
or ejecta will be thrown upward at a velocity of more than 820 feet per second (250 m/sec.)
Studies using the Ames Vertical Gun Range indicate the LCROSS impacts will create a significantly larger crater than Lunar
Prospector (LP) that impacted the moon at 1 mile/sec (1.7 km/sec) with a mass of 348 pounds (158 kg) at a glancing angle
of 6 degrees.
A couple things according to that release.. We've got a long time till the actual impact occurs (4+months). Its much larger & faster than anything
that's been done before.