Cosmic Dust from Distant Comet Comes to Earth
ANDREA SEABBROOK, host:
And speaking of outer space, earlier this year, NASA's Stardust mission returned from a seven year, three billion mile trip to the far reaches of the solar system. The capsule brought back a canister of dust particles and pieces of a comet. Some of this material is being studied at the National High Magnetic Field Laboratory at Florida State University.
Diane Roberts visited the lab recently to hear the news from space.
(Soundbite of machine noise)
Dr. MUNIR HUMAYUN (National High Magnetic Field Laboratory): I don't know if that looks like carbon in the (unintelligible).
DIANE ROBERTS: This is the sound of a mass spectrometer. A mass spectrometer can tell you what you're made of. It can tell what's anything's made of, down to the last proton and electron. Soon it will be used to study the samples brought back from Comet Wild 2 on NASA's stardust mission.
Dr. HUMAYUN: See that bright thing? Right? That's the bolts of light reflected as the laser - as the sample explodes makes a...
ROBERTS: Dr. Munir Humayun is with the National High Magnetic Field Lab here in Tallahassee, Florida. He's part of the team who'll be studying the comet dust.
Dr. HUMAYUN: So this is the first time dust has been collected and brought back from a comet. Comets are dirty snowballs. There are lots of ice and debris in there. And then dust and debris are thought to be pre-solar grains that were made in stars a long time before the solar system formed. And this dust was in the interstellar medium when the sun formed.
ROBERTS: When comets are way out there beyond the giant planets, their temperature can be around minus 370 degrees Fahrenheit. Most of them are too small for us to detect. From earth, we see a comet when a new orbit brings it into the inner solar system, where the sun heats it up. The ice evaporates, the comet body is illuminated, and the solar wind blows out the tail. But pretty as it is in the night sky, a cooked comet is no good for science. Lucky for us, Comet Wild 2 is still very cold - languishing as it is in the far suburbs of the solar system.
Dr. HUMAYUN: It was observed to come and make a near pass at Jupiter in 1974. It then got stuck in an orbit around Jupiter. And so we know exactly its history when it started coming in to the inner solar system. We know it's not made many passes into the inner solar system. We know that the stuff is the most pristine material we can recover without going out beyond the orbit of Pluto and trying to drill into a comet and then fly that stuff back.
ROBERTS: Sir Harry Kroto, Nobel Prize winner and professor of chemistry at Florida State, has been studying the chemistry of space. He says there's a connection between stars, comets and life on earth.
Professor HAROLD KROTO (Chemistry, Florida State University; Nobel Prize Winner): The stuff of life comes out a star - every single atom, every single carbon atom, oxygen atom and nitrogen atom in your body was in a star probably more than four-and-a-half thousand million years ago was actually synthesized from hydrogen, helium in a star - that length of time ago. If anybody tells you anything different, they're mad.
ROBERTS: Kroto says much of the carbon that's in our atmosphere arrived as the earth was forming four-and-half billion years ago. Comets and commentary material delivered carbon and all the other elements necessarily for life into the air's atmosphere. Some of these ancient substances from four-and-a-half billion years ago can be found on the grains from Comet Wild 2. Dr. Humayun explains.
Dr. HUMAYUN: We know there are large numbers of organic molecules in interstellar space. And it's on the grain surfaces that the chemical reactions that make the gas molecule in the interstellar medium occur. And those gas molecules from - of what we know of them indicate that the precursors to life were already present before the solar system formed - the precursors being organic molecules, not living organisms necessarily.
ROBERTS: So maybe we'll prove that the stuff of life got here to the blue ball of earth via comets, those glittering tourists of the solar system. Maybe the matter that became all of us was a souvenir from the long ago past and the distant stars. Again, Sir Harry Kroto.
Prof. KROTO: I think it's a wonderful thought that we - we're all really aliens and we all came from outer space. So if you want to see an alien, just look at yourself in the mirror.
ROBERTS: And as you do look in the mirror, consider this: The next time somebody asks you where you're from, instead of saying Seattle or Sylacauga, Ann Arbor or Sarasota, say Antares or Aldebaran. Or just gesture in the general direction of the large Magellanic Cloud.
For NPR News, this is Diane Roberts in Tallahassee.