Observing with the Lunar Reconnaissance Orbiter
The accidental experiment of the upcoming crash will give planetary scientists the chance to observe a very similar crater in the light of day. It will be like seeing the LCROSS crater in full detail for the first time.
Since the impact is going to occur on the far side of the Moon, it will be out of view for Earth-based telescopes. But about two weeks after the impact, NASA’s Lunar Reconnaissance Orbiter will begin to get glimpses of the crater as its orbit takes it above the impact zone. Once conditions are right, the lunar orbiter’s camera will start taking photos of the impact site with a resolution of about a 3 feet (1 meter) per pixel. Lunar orbiters from other space agencies may also train their cameras on the crater.
The shape of the crater and ejected dust and rocks will hopefully reveal how the rocket was oriented at the moment of impact. A vertical orientation will produce a more circular feature, whereas an asymmetric debris pattern might indicate more of a belly flop. Models suggest that the crater could be anywhere from around 30 to 100 feet (10 to 30 meters) in diameter and about 6 to 10 feet (2 to 3 meters) deep.
The amount of heat generated from the impact will also be valuable information. If observations can be made quickly enough, there’s a possibility the lunar orbiter’s infrared instrument will be able to detect glowing-hot material inside the crater. This could be used to calculate the total amount of heat from the impact. If the orbiter can’t get a view fast enough, high-resolution images could be used to estimate the amount of melted material in the crater and debris field.
By comparing before and after images from the orbiter’s camera and heat sensor, scientists will look for any other subtle changes to the surface. Some of these effects can extend for hundreds of times the radius of the crater.
Why this is important
Impacts and crater formation are a pervasive phenomenon in the solar system. Craters shatter and fragment planetary crusts, gradually forming the loose, granular top layer common on most airless worlds. However, the overall physics of this process are poorly understood despite how common it is.
Observing the upcoming rocket impact and resulting crater could help planetary scientists better interpret the data from the 2009 LCROSS experiment and produce better impact simulations. With a veritable phalanx of missions planned to visit the Moon in the coming years, knowledge of lunar surface properties – especially the quantity and depth of buried ice – is in high demand.
Regardless of this wayward rocket’s identity, this rare impact event will provide new insights that may prove critical to the success of future missions to the Moon and beyond.