“Different objects in our solar system have characteristic H-isotopic signatures. We can use the H-isotopic signature of the water in the lunar samples as a fingerprint that we then match to known values of other solar system objects,” said Barnes. Researchers can thenuse these signatures to determine where the water in the lunar samples actually came from, she said.

Having analyzed the signatures, the researchers noticed that the hydrogen isotopic signature measured for these lunar samples was comparable to that of some chondrite meteorites found on Earth. This means that such meteorites could have delivered water to the moon, said Barnes. And, she added, “the signature is also strikingly similar to that estimated for the Earth’s mantle, indicating that the water in the interiors of the Earth and the moon may share a common heritage.”