Astronomers may not have far to proceed to research a Part of the remote, icy region
COME FROM AWAY Several interplanetary dust particles that end up in Earth’s atmosphere may have started life at the inexplicable Kuiper Belt (exemplified ), a region of icy objects farther from the sun than Neptune.
THE WOODLANDS, Texas — Grains of dust in the border of the solar system may be finding their way to Earth. And NASA may already have a handful of their debris, scientists report.
Having an estimated 40,000 heaps of space dust settling in Earth’s stratosphere every calendar year, the U.S. space agency was flying balloon and aircraft missions because the 1970s to collect samples. ) The particles, that can be only a couple tens of micrometers wide, have long been believed to come mostly from comets and asteroids closer to the sun than Jupiter (SN Online: 3/19/19).
But it turns out that a number of the particles may have come from the Kuiper Belt, a distant region of icy objects orbiting beyond Neptune, NASA planetary scientist Lindsay Keller stated March 21 in the Lunar and Planetary Science Conference. Assessing these particles could reveal what distant, mysterious objects in the Kuiper Belt are made of, and perhaps the way they formed (SN Online: 3/18/19).
“We are not going to find a mission out to some Kuiper Belt object to really gather [dust] samples anytime soon,” Keller explained. “But we’ve got samples of these things from the stratospheric dust collections here at NASA.”
One way to locate a dust grain’s home is to probe the particle for microscopic tracks where heavy charged particles from solar flares punched through. The more monitors a grain gets, the more it has wandered in distance and the more probable it originated way from Earth, ” says Keller, who works in the Johnson Space Center at Houston.
However, to determine exactly how long a dust grain has invested travel distance, Keller first needed to understand how many monitors a grain typically picks up annually. Measuring that rate necessitated a sample with a known age and understood track density — standards fulfilled only by moon rocks brought down to the Apollo missions. But the final track-rate quote was done in 1975 and less exact instruments than can be found today.
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