May 17, 2002

Space StationMeteor Shower




The crew of the International Space Station enjoyed a unique view of the 2001 Leonid meteor storm.




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May 17, 2002: "It looked like we were seeing UFOs approaching the earth flying in formation, three or four at a time," recalls astronaut Frank Culbertson. "There were hundreds per minute going beneath us, really spectacular!"


That was last November, and Culbertson, then the commander of the International Space Station (ISS), was watching the 2001 Leonid meteor storm. No UFOs, just lots and lots of "shooting stars."

Right: The ISS high above Earth. [



News reports had warned sky watchers in advance: On Nov. 18, 2001, Earth was due to plow through a minefield of debris shed by Comet Tempel-Tuttle. Innumerable bits of comet dust would become meteors when they hit Earth's atmosphere at 144,000 mph. Experts predicted an unforgettable display ... and it came.




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Millions of people saw the show, but only three of them -- the ones on board the space station -- saw it from above. "We had to look down to see the meteors," says Culbertson. "That's because the atmosphere (where comet dust burns up) is below the station."

"A typical Leonid disintegrates about 100 km above Earth's surface," explains NASA scientist Rob Suggs. "The ISS is much higher than that. The station (like the space shuttle) orbits our planet at an altitude of about 350 km." Suggs is the leader of the Space Environments group at the Marshall Space Flight Center; he helped organize the crew's observations of the Leonids.

"I had seen [meteors] on shuttle flights before," continued Culbertson, "but when the Leonids happened it was supposed to be one of the best showers in a long time, so we stayed up late to see them. Mikhail Tyurin and I were inside the Pirs docking compartment, which had the darkest windows." (Pirs is one of the Russian-built parts of the ISS; it serves as a docking port for visiting Progress supply ships and Soyuz crew capsules.)

Gazing at the nightside of the earth below, they spotted so many meteors that they soon lost count of all the flashes. Culbertson used a handheld video camera to film parts of the storm, but it wasn't designed for low-light photography. The best images were the ones Culbertson saw using nothing but his eyes: "The storm was pretty spectacular," he said again.


Left: This still frame from a video captured by Frank Culbertson during the 2001 Leonid meteor shower shows a distant sunrise (the wedged-shaped glow) and a Leonid fireball exploding in the foreground. Click on the image for a .

Leonid meteors come from the direction of the constellation Leo -- hence the name Leonids. At one point during the storm, the space station passed almost directly between Leo (above) and the Earth (below). Peering out the window, Culbertson could see meteoroids disintegrating directly underneath the station. "Then's when you start thinking," he recalled, "they're coming right by us! It's like being in the middle of a hailstorm."

"We didn't have any damage, but Vladamir (Dezhurov) said he heard some little pings on the outside of the module," Culbertson said with a smile. "I'm not sure if he really did ... he jokes a lot."

In fact, the station was in little danger. "There are several hundred different shields protecting the crew and critical hardware," says Eric Christiansen, the station's Shielding Subsystem Manager at the Johnson Space Center. "The heavier shielding typically includes meteoroid/debris blankets. These are made of a ceramic fabric (NextelTM) backed by KevlarTM -- the same material found in bullet-proof vests."

The station's windows are sturdy, too. Each one consists of at least two panes -- "always with primary and redundant pressure panes," says Christiansen. "In some cases, the windows include transparent 'debris panes' specifically designed to protect them from meteoroid impacts." Others are shielded (when not in use) by metal shutters and debris blankets.


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Although Leonid meteoroids travel much faster than bullets, the vast majority of them are microscopic and fragile. They make pretty lights when they hit Earth's atmosphere -- but that's all. They are not tough enough to penetrate the station's defenses.


Right: Tiny comet flakes like this are at the heart of fiery-looking Leonid meteors. This one is only 10 microns across. [more]

Culbertson was grateful for the protection. "We literally did see thousands of Leonids all at once. It makes you think how crowded it is in space sometimes, why it's so important to have those shields on the outside."

Another Leonid meteor storm is due on Nov. 19, 2002, and forecasters say it could be even more intense than the one last year. Unfortunately, a glaring full Moon will diminish the show -- as much for the crew of the ISS as for sky watchers on the ground below.

Air molecules and aerosols -- that is, water droplets, dust and smoke -- scatter bright moonlight. Earth's atmosphere literally glows when the Moon is full. Sky watchers looking up at the Leonids will see them through a 100-km thick layer of glowing air. Astronauts looking down at the Leonids will see them streaking on top of that same glowing layer.


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Left: Leonid meteors over Japan in 2001. Credit: Yukio Sanuki. [more]


Moonlight will reduce the number of visible Leonids by some factor between 2 and 5. Even so, that's not necessarily enough to wipe out a full-fledged Leonid meteor storm. If predictions are correct, sky watchers -- on Earth and in space -- could see hundreds or thousands of shooting stars in spite of the glare.

Rob Suggs notes that astronauts have two advantages: "They see a lot more of the sky than we do from the ground, and they can't be clouded out!" The crew can probably look forward to another good show.

Culbertson won't be one of them, though. He's back on the ground. "I was fortunate to have that perspective," he says of the 2001 Leonids from space. After all, it's not every day you can look down ... and see meteors beneath your feet.



Editor's Note: Frank Culbertson's recollections of the 2001 Leonid meteor shower were recorded during a speech he delivered at the Marshall Space Flight Center on March 27, 2002.

more information


NASA Human Spaceflight -- Learn more about the space station and its crew.

The Truth about the 2002 Leonid Meteor Storm -- (Science@NASA) Another Leonid meteor storm is due in 2002. Rumor has it that a full Moon will ruin the show ... but maybe not.


Earth-orbiting MSX satellite recorded these Leonid meteors in 1997.
Leonids 2001 Gallery -- ( Sky watchers who saw it will never forget it: the 2001 Leonid meteor storm.


Right: The Earth-orbiting MSX satellite recorded these Leonid meteors in 1997. [more]

Jaw-dropping Leonids -- (Science@NASA) Recollections from the 1998 Leonid fireball shower.

Listening to Leonids -- (Science@NASA) On Nov. 18, 2001, millions of sky watchers saw a dazzling storm of Leonid meteors. Some observers heard them too!

Explosions on the Moon -- (Science@NASA) During the 2001 Leonid meteor storm, astronomers observed a curious flash on the Moon -- a telltale sign of meteoroids hitting the lunar surface and exploding.

Meteoroid and Debris Hazards: Hypervelocity Impact Test Facility (Johnson Space Center); Orbital Debris Program (Johnson Space Center); Space Environment and Effects Program (Marshall Space Flight Center)


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