Packed along with three and a half tons of cargo to be delivered to the International Space Station next Tuesday on the Cygnus resupply mission is a new camera that will give scientists their first space-based look at the chemical composition of meteors. From a window in the floor of the U.S. Destiny lab module, the Meteor experiment will use a visible-light spectrometer to capture high-resolution video of meteoroids as they enter Earth’s atmosphere.
During the nighttime portion of every orbit, the instrument’s software will scan for bright flashes in the darkness below; if it spots any, video of the event will be sent to scientists on Earth for analysis. Meteor will also record the chemical spectra of meteors to learn what they’re made of. You might think this had already been done from space, considering that astronauts routinely see meteors below them when looking out the station’s windows. But no.
“There have been some studies about meteors entering the atmosphere, but nothing long-term, and nothing I know of that involves the spectral observations. So that’s the one thing that’s a little bit different about the Meteor instrument,” says Meteor principal investigator Michael Fortenberry.
About 15,000 tons of space debris falls into Earth’s atmosphere every year. Most of that material is cosmic dust and tiny grains of grit, but sometimes larger chunks of rock come speeding in. For scientists studying comets and asteroids, meteorites offer free samples of extraterrestrial material delivered right to Earth.
Most objects that hit Earth’s atmosphere die swift, fiery deaths. Particles moving at 72,000 miles per hour—a typical speed for a meteoroid—ionize the air around them, causing it to give off light. That’s why we see meteors as flashes across the night sky. At the same time the outer part of the meteoroid burns away, which is why so few make it to the ground.
Although scientists monitor meteors from the ground, the atmosphere tends to get in the way. The ozone layer absorbs the exact wavelengths of light emitted by organic carbon, and weather and other atmospheric disturbances can distort a meteor’s light. Looking down from the space station above, Meteor will have a better view.
It’s also difficult to trace meteorites that fall to Earth back to their parent asteroid or comet. But astronomers know the source of most regularly occurring meteor showers. The Perseid shower, for example, is known to be a trail of debris from Comet Swift-Tuttle; Earth’s orbit carries us through that trail every August. By observing the chemical spectra of the Perseid meteors from space, scientists will learn more about what makes up Comet Swift-Tuttle and how it formed.
Meteor’s prime viewing is timed for the peak of major showers like the Perseids. Off-peak times will be secondary priorities, along with smaller showers. The rest of the time, Meteor will keep an eye out in hopes of identifying new meteor showers that haven’t previously been seen from the ground. Meteor may also help NASA observe de-orbiting spacecraft as they burn up during re-entry.
The project is a collaboration between the Southwest Research Institute and the Planetary Exploration Research Center at Japan’s Chiba Institute of Technology, which developed the instrument. It originally was planned to reach orbit in October 2014, but was destroyed along with the ORB-3 Cygnus cargo vessel during its launch.
A second attempt fared no better. “We got the ground spare and got it ready for flight, and it was launched on SpaceX-7 CRS-7 last June, which was destroyed,” says Fortenberry. “Since we didn't have any more ground spares after the second flight, we have a new instrument that is ready for this launch.”
If the third time’s the charm, and Meteor launches as planned late Tuesday night from Cape Canaveral, it will share its ride to the station with several other science payloads, including Saffire-I, which will perform the first large-scale fire experiment in space and the Additive Manufacturing Facility, a 3D printer for parts, tools, and experimental equipment.
In late April, the station astronauts are scheduled to install Meteor in the Window Observational Research Facility, or WORF, an Earth-facing window made of special glass that minimizes optical distortion. Meteor’s team plans to calibrate the instrument during a couple of small meteor showers before its first big test: the Perseid shower’s peak around August 12.