The water-releasing impacts occurred on January 9, April 2, April 5 and April 9 in 2014.
"Most of the geological processes we deal with in planetary science are very slow - we nearly never get to see something respond dynamically over the scale of hours like we did here", lead author Mehdi Benna, a planetary scientist at NASA Goddard Space Flight Center in Greenbelt, Maryland, told Space.com.
When a speck of space debris strikes the moon it vaporises on impact, creating a shock wave that resonates through the lunar soil. When meteorites whack the lunar surface, the impact brings out some of this water.
Using an instrument on aboard NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE), planetary scientist Doctor Mehdi Benna said that it picked up "high anomalously high and episodic amounts of water in the lunar atmosphere". To continue this measure of misfortune after some time, they recommended that this water either was available when the moon shaped, about 4.5 billion years back, or was conveyed by enormous effects from water-loaded shakes not long after the moon was conceived. And more recently, NASA's Lunar Reconnaissance Orbiter (LRO) has also detected evidence of "bouncing water molecules" on the surface.
"But when the Moon passed through one of these meteoroid streams, enough vapour was ejected for us to detect it". For a sufficiently large impactor, this shock wave can breach the soil's dry upper layer and release water molecules from a hydrated layer below. The idea that the Moon releases water when objects hit it is something humans have known since the first time an Indian spacecraft named Chandrayaan-1 sent a probe hurtling into the Moon's surface, kicking up a lot of dust and a surprising amount of water.
Below this, they calculate that water is uniformly present at concentrations up to about 0.05 per cent.
These findings could help explain the deposits of ice in cold traps in the dark reaches of craters near the poles.
The researchers estimated that meteoroid impacts cause the moon to lose as much as 220 tons (200 metric tons) of water annually.
"The water being lost is likely ancient, either dating back to the formation of the Moon or deposited early in its history", Benna added.
"We know that some of the water must be coming from the Moon because the mass of water being released is greater than the water mass within the meteoroids coming in", Dana Hurley from Johns Hopkins University Applied Physics Laboratory, said.
Earlier models had predicted that meteoroid impacts could release water from the Moon as a vapour, but scientists hadn't yet observed the phenomenon.
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