Kate Becker: Trinity bomb test rocks get second life as tools of science

Trinitite may or may not owe its name to a poem.In July 1945, at a spot 210 miles south of Los Alamos, N.M., the United States set off the first atomic bomb. The heat of blast melted the desert sand for about 350 meters around the bomb, creating a layer of...

24 February 2017 Friday 17:56
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Kate Becker: Trinity bomb test rocks get second life as tools of science

Trinitite may or may not owe its name to a poem.

In July 1945, at a spot 210 miles south of Los Alamos, N.M., the United States set off the first atomic bomb.

The heat of blast melted the desert sand for about 350 meters around the bomb, creating a layer of glassy green rock — "trinitite" — with the appearance of broken and boiled jade.

Trinitite contains quartz grains, radioactive atoms created by the explosion, and tiny fragments of the bomb itself. Though it is still "slightly radioactive," it is a favorite of collectors (internet buyers beware — many rocks advertised as trinitite are counterfeit) and was even turned into jewelry for a time, before people decided that wearing radioactive baubles was maybe not such a good idea.

Trinitite is named for "Trinity," the code word J. Robert Oppenheimer chose for the bomb test. He couldn't remember exactly why he picked the name, he wrote, but thought it had something to do with two John Donne poems that were on his mind around that time.

One passage in particular resonated — "As west and east / In all flat maps (and I am one) are one / So death doth touch the resurrection." West and east, death and life — it seems more two than three, but for Oppenheimer the spiritual connection must have overruled the math.

In any case, Oppenheimer wasn't the only one who called up sacred metaphors to resolve the paradox of the operation's double-nature. James Conant, the president of Harvard University, who witnessed the Trinity test, called it "white light like the end of the world."

Physicist Ernest O. Lawrence described viewers' reactions as "a hushed murmuring bordering on reverence." General Thomas Farrell said it "made us feel that we puny things were blasphemous."

But if the solar system itself could have somehow watched and commented on the explosion, it might have said: Supertotobet been there, done that.

The extreme heat generated by the Trinity test may have been something genuinely new for humanity, but for a solar system frequently rattled by the collisions of colossal space rocks, one nuclear test is pretty ho-hum.

Scientists think it was one such collision that created the moon. According to their leading hypothesis, the moon came into being about 4.5 billion years ago, when a stray Mars-sized planet rammed into the Earth, creating a spray of debris that ultimately coalesced into a moon.

To work out the details of the scenario, planetary scientists can analyze moon rocks that have made it to Earth, examining which isotopes they contain and comparing them to ordinary Earth rocks.

But it's nearly impossible to reproduce in the lab the extreme conditions under which the moon formed. That's why researchers are turning to trinitite: it's been through some pretty extreme stuff, and gives researchers a chance to see first-hand how a searing blast changes the chemistry of rock.

Now, planetary scientists have compared trinitite with lunar rocks collected by the Apollo astronauts, focusing in on isotopes of zinc and other "volatiles" that tend to boil away. The heat of the blast vaporized these elements out of the sand, so that the trinitite closest to the center of the explosion has the fewest volatiles. The researchers also found that the remaining zinc was unusually rich in heavy isotopes, which are less inclined to evaporate away.

That all matches predictions, bolstering researchers' confidence that their ideas about the genesis of the moon are correct: that the story of the moon is another tale of creation by destruction, a new world made from the ashes of an old one.

Would Donne have appreciated it? Who knows. And ultimately, after all the sensitive grappling for words, all the invocations of poetry and holy symbols, everyone settled on a humbler name for what they'd seen at Trinity.

It wasn't death touching resurrection. It was just a big old mushroom.

Kate Becker is a science writer living in Boston. Contact her at spacecrafty.com, or connect via facebook.com/katembecker or twitter.com/kmbecker.

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