NASA’s LRO Spacecraft Captures Images of LADEE’s Impact Crater

This image shows the area of the LADEE impact after spacecraft's planned impact into the eastern rim of Sundman V crater. 

Image Credit: NASA/Goddard/Arizona State University

NASA’S Lunar Reconnaissance Orbiter (LRO) spacecraft has spied a new crater on the lunar surface; one made from the impact of NASA’s Lunar Atmosphere and Dust Environment Explorer (LADEE) mission.

“The Lunar Reconnaissance Orbiter Camera (LROC) team recently developed a new computer tool to search Narrow Angle Camera (NAC) before and after image pairs for new craters, the LADEE impact event provided a fun test, said Mark Robinson, LROC principal investigator from Arizona State University in Tempe.

“As it turns there were several small surface changes found in the predicted area of the impact, the biggest and most distinctive was within 968 feet (295 meters) of the spot estimated by the LADEE operations team. What fun!”

The LADEE mission ended on April 18, 2014, with the spacecraft’s planned impact into the eastern rim of Sundman V crater on the far side of the moon.

LRO has taken an image of the LADEE impact site on the eastern rim of Sundman V crater.

The image was created by ratioing two images, one taken before the impact and another afterwards. 

The bright area highlights what has changed between the time of the two images, specifically the impact point and the ejecta.

Image Credit: NASA /Goddard /Arizona State University

LADEE's engines fired April 11, 2014, to perform a final orbital maintenance maneuver and adjust to guarantee it would impact on the farside of the moon and away from the Apollo landing sites.

Over a seven-day period, LADEE's orbit decreased and the spacecraft orbited very low to the surface and close to the walls of lunar craters and mountain ridges to give the team a chance to collect valuable science data.

Finally, LADEE impacted the eastern rim of Sundman V crater on April 18. The impact site is about half a mile (780 meters) from the crater rim with an altitude of about 8,497 feet (2,590 meters) and was only about two tenths of a mile (300 meters) north of the location mission controllers predicted based on tracking data.

The impact crater is small, less than ten feet (three meters) in diameter, barely resolvable by the LROC NAC.

The crater is small because the spacecraft, compared to most celestial impacts, was not traveling very fast, approximately 3,800 miles per hour (1,699 meters per second) and had a low mass and a low density.

The size of the impact crater made it hard to identify among the myriad of small fresh craters on the lunar surface. Images acquired of the impact region before the impact, were compared with images obtained after the impact to identify the crater.

Artist concept of the Lunar Reconnaissance Orbiter with Apollo mission imagery of the moon in the background.

Image Credit: NASA's Goddard Space Flight Center

Since the NAC images are so large (250 mega-pixels) and the new crater is so small, the LROC team co-registered the before and after images (called a temporal pair) and then divided the before image by the after image. By doing this, changes to the surface become evident.

The ejecta from the impact forms a triangular pattern primarily downrange to the west, extending about 656-984 feet (200-300 meters) from the impact site.

There is also a small triangular area of ejecta up range but it extends only about 66-98 feet (20-30 meters).

The ejecta pattern is oriented northwest, consistent with the direction the spacecraft was traveling when it impacted the surface.

"I'm happy that the LROC team was able to confirm the LADEE impact point," said Butler Hine, LADEE project manager at Ames Research Center in Moffett Field, California.

"It really helps the LADEE team to get closure and know exactly where the product of their hard work wound up."

NASA LRO Searches Lunar Landscape for Lost Moon Probes

The moon is the final resting ground for scads of landed and crashed spacecraft, many of which have been pinpointed recently by sleuthing scientists.

Using observations by NASA's Lunar Reconnaissance Orbiter, for example, researchers have located and imaged Apollo moon landing leftovers, old Soviet-era spacecraft and, more recently, the impact locales of NASA’s twin Grail spacecraft that were deliberately driven into a mountain near the moon’s north pole.

But the search is ongoing to find the exact location of several pioneering moon landers.

"We are still looking for [the Soviet Union’s] Luna 9 and 13," said Jeff Plescia, a space scientist at the The Johns Hopkins University’s Applied Physics Laboratory in Laurel, Md.

"Those were the small 'beach ball' shaped spacecraft," Plescia told reporters "The beach ball might be hard to find, but it made a descent on a larger vehicle which then popped the beach ball off."

Plescia said he had assumed that it would be possible to find the landing sites of Luna 9 and 13 by spotting albedo marks — a change in the lunar surface brightness made by their descent engines.

Plescia is joined in the hunt by Mark Robinson of Arizona State University, principal investigator for the Lunar Reconnaissance Orbiter Camera, or LROC.

"We’ve both looked, but no luck so far." Plescia said.

Yet another search involves the impact sites of Apollo lunar module ascent stages, hardware discarded once moonwalking crews were snug within their respective command modules.

Ascent stages were intentionally impacted into the surface as part of the Apollo Passive Seismic Experiment that studied the propagation of seismic waves through the moon to yield a detailed look at the body's internal structure.

"Given that we have found the impact sites from Grail, you would think we could find those craters, but, again, no luck so far," Plescia said.

These, like the craters made by the third stage of NASA's Saturn V moon rocket, "are important to locate to understand how large a crater was made and to have precise coordinates so that the old Apollo era crustal velocity measurements can be reanalyzed," he said.