An Israeli spacecraft approaches the Moon and lands on 11 April at Mare Serenitatis in the northern hemisphere on the near side of the Moon. Onboard is an experiment that is smaller than a computer mouse, and it could enable the arrival of future landers with robots and humans.
The Beresheet Spacecraft whose name in Hebrew means "Genesis" or "At the Beginning", launched on February 21st. The Explorer is a joint project of the nonprofit group SpaceIL and the company Israel Aerospace Industries. Since the launch, Beresheet has performed a series of orbital maneuvers to orbit and launch a landing.
For the Leap to the Moon, a NASA laser retroreflector array of eight quartz cube corner mirrors set into a dome-shaped aluminum frame is placed. This arrangement is lightweight, radiation cured and durable.
Related: Israel's 1
When Beresheet Successfully Plants on the Moon on April 11 NASA Lunar Reconnaissance Orbiter (LRO ) will eventually shoot laser pulses onto the retroreflector with its laser altimeter. With this technique, the lunar location of Beresheet can be localized to 10 centimeters, according to the project staff.
NASA is interested in dotting the moon with many such reflectors in the future. These would serve as permanent "landmarks" on the moon meaning that future aircraft could use them as a reference for precision landings.
The NASA instrument, called Beresheet (NASA Goddard Space Flight) Center / MIT Laser Retroreflector Array (LRA) for Lunar Landers, is located on the top of the Israeli Landing Vehicle and is visible from above.
LRA is a passive instrument. It is used in conjunction with the Lunar Orbiter Laser Altimeter by LRO or LOLA. The laser beams of this altimeter hit the lunar surface and are scattered back from there. For each laser beam LOLA measures its flight time or range.
An attempt is made to remove the reflector from LRO until Beresheet is no longer active on the moon. This will ensure that the LRO laser does not damage sensitive detectors in the Israeli lander, said David Smith of the Massachusetts Institute of Technology, lead investigator for LOLA and an emeritus researcher at NASA Goddard in Greenbelt, Maryland.
Subsequently, LOLA attempts to perform LRO distance measurements to the lander.
"This is an experiment to determine feasibility, and it will be possible to make measurements on the array indefinitely, or as long as the LOLA instrument continues to work on LRO, which will last nearly ten years in June 2019," Smith said opposite Space.com.
Related: Latest Moon Photos from NASA's Moon Exploration Orbit
The laser array was designed and designed by Smith and Xiaoli Sun at NASA Goddard about 15 years ago for NASA's Mars Marslander .
"It was intended to work with the laser altimeter that we had on NASA's Mars Global Surveyor probe. However, when the lander landed on Mars, the instrument was no longer active, "Smith said.The purpose of the Mars and Moon arrays is to try to determine the position of lunar orbiting stars in a orbiting spacecraft that is a laser system
In principle, NASA will be able to determine the location of the lander by switching to the reflector array several times, but the accuracy of this method is limited by the size of the spot illuminated by the laser on the surface.
A laser that creates a spot of 5 meters (16.5 feet) on the surface requires a very accurate laser alignment, Smith said, making it easier for a wide-beam laser to detect the reflector array, but the knowledge The position of the array on the surface is more uncertain, he said.
A Lonely Lunar Laser
"A properly designed rangefinder could solve this problem," Smith said. "LOLA was designed for altitude measurement, not a small reflector array, but it's the only laser on the moon for the immediate future."
Images taken by the soaring LRO can clearly tell where Beresheet is in Israel's moon. So, the laser retro-reflector array is an experiment to see how difficult it will be for LRO to make the range measurements to the lander, Smith said.
"A small grouping of these small arrays around a landing pad, for example, could help a lander return to a location at a later date," Smith said. "The arrays could be needed for decades or more."
Smith said that there are also possible applications for these small reflectors on other celestial bodies. like asteroids . If you place a series of small arrays on the surface of a body – perhaps drop it – nearby probes could monitor the rotation and position of the object and determine its shape.
"Because the reflectors could last for decades, the object could be monitored on later visits from other spacecraft, and would of course help with landing on the object, if desired," Smith added.
Of course, the small size of the reflectors limits the range from which they can be detected. Smith suggested that buildable laser concepts at NASA Goddard could enable measurements from a distance of more than 10,000 kilometers.
"These small reflectors weigh only about 20 grams [0.7 ounces] but could be much larger and even be recognized remotely for greater range," said Smith. "Bigger, however, would be harder, and one of the attractions of these little reflectors is that they have a very small mass, so almost every lander can carry them."
Leonard David wrote the forthcoming book "Moon Rush: The New Space Race" will be released by National Geographic in May 2019. As a longtime author of Space.com, David has been covering the space industry for more than five decades Join us on Twitter @SpaceTOTCOM or Facebook .