The mission, which began earlier this year, is the U.S. space agency’s most ambitious attempt yet to study the inner-workings of the moon. Speaking Thursday, NASA officials said Gravity Recovery and Interior Laboratory (GRAIL) mission controllers tasked with operating the pair of the probes have already began taking steps to engineer a controlled crash into the lunar surface.
“Twin lunar-orbiting NASA spacecraft that have allowed scientists to learn more about the internal structure and composition of the moon are being prepared for their controlled descent and impact on a mountain near the moon’s north pole at about 2:28 p.m. PST (5:28 p.m. EST) Monday, December 17,” NASA officials said in a statement.
The crash landing, which will conclude the year-long mission, could yield valuable data for scientists here on Earth. The mission has already provided astronomers with key data concerning the surface of the moon and its evolution. GRAIL’s primary mission took place from March to May, during which the spacecraft zipped around the moon at an average altitude of 34 miles. Ebb and Flow, the names assigned to the pair of probes, have extensively studied the moon’s gravitational field, creating one of the most detailed maps of the moons gravitational field.
“GRAIL has produced the highest-resolution, highest-quality gravity field for any planet in the solar system, including Earth,” GRAIL principal investigator Maria Zuber, of Massachusetts Institute of Technology (MIT), told reporters during a press conference.
“It is going to be difficult to say goodbye,” added Zuber. “Our little robotic twins have been exemplary members of the GRAIL family, and planetary science has advanced in a major way because of their contributions.”
The mountain where the two spacecraft will make contact is located near a crater named Goldschmidt, according to NASA. Both spacecraft will hit the surface at 3,760 mph (1.7 kilometers per second); no imagery of the impact is expected because the region will be in shadow at the time, the space agency said.
While the crash landing is drawing a lot of attention to the mission itself, a number of people have questioned whether the probes will endanger the historic moon landing sites. In a statement released through the Jet Propulsion Laboratory (JPL) in Pasadena, California, NASA officials explained that the location would not endanger any of the lunar sites.
“NASA wanted to rule out any possibility of our twins hitting the surface anywhere near any of the historic lunar exploration sites like the Apollo landing sites or where the Russian Luna probes touched down,” said David Lehman, GRAIL project manager at NASA’s JPL. “Our navigators calculated the odds before this maneuver as about seven in a million. Now, after these two successful rocket firings, there is zero chance.”
At an estimated cost of $496 million, the notion of intentionally crashing a pair of probes into the moon has raised some eyebrows. However, Recent research suggests Earth may have had a second smaller moon that collided with our present moon, producing a mountainous region. The GRAIL mission may help flush out that theory, Zuber said, as crashing the probes will likely eject a large amount of material that will yield endless data.
One thing is for certain, though: regardless of price, our fascination with the moon will continue.
“Nearly every human who’s every lived has looked up at the moon and admired it,” said Zuber. “The moon has played a really central role in the human imagination and the human psyche.”