New remote-sensing instrument to blaze a trail on the International Space Station

September 8, 2014, NASA's Goddard Space Flight Center
This artist's rendition of the Cloud-Aerosol-Transport System (CATS) shows its location on the International Space Station, where it will measure the character and worldwide distribution of the tiny particles that make up haze, dust, air pollutants and smoke in the atmosphere. Credit: NASA

The Cloud-Aerosol Transport System (CATS), a new instrument that will measure the character and worldwide distribution of the tiny particles that make up haze, dust, air pollutants and smoke, will do more than gather data once it's deployed on the International Space Station this year.

"CATS is a groundbreaking science and technology pathfinder," said Colleen Hartman, deputy center director for science at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "Not only will it make critical measurements that will tell us more about the global impact of pollution, smoke and dust on Earth's climate, it will demonstrate promising new technology and prove that inexpensive missions can make critical measurements needed by the modelers to predict future climate changes."

A Technological First

Technologically, NASA has never before flown an instrument like CATS.

Developed by a Goddard team led by scientist Matt McGill, the refrigerator-size CATS will demonstrate for the first time three-wavelength laser technology for measuring volcanic particles and other aerosols from space. It is intended to operate for at least six months and up to three years aboard the Japanese Experiment Module-Exposed Facility, augmenting measurements gathered by NASA's CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) mission.

However, the big difference between the two is that CALIPSO uses two wavelengths—the 1,064- and 532-nanometer wavelengths—to study the same phenomena.

That's not the only difference, McGill said. CATS, which was developed with NASA and Goddard research and development funding, also carries extremely sensitive detectors that can count individual photons, delivering better resolution and finer-scale details. It also will fire 5,000 laser pulses per second, using only one millijoule of energy per second. In sharp contrast, CALIPSO delivers 20 per second, using a whopping 110 millijoules of energy in each of those pulses.

"As a pathfinder mission, what we're trying to determine is whether the addition of the third wavelength—355 nanometers, which is in the ultraviolet—will produce the results we expect it to generate," McGill said. "We believe it will deliver more detailed information revealing whether the particles scientists see in the atmosphere are dust, smoke or pollution." Though it adds an advanced capability, particularly when coupled with the new detectors, engineers believe the ultraviolet wavelength may be particularly susceptible to damage caused by contamination, McGill said.

"If you get contamination on any of your outgoing optics, they can self-destruct, and then your system's dead," he said. "You end up with very limited lifetime. The way to find out is to fly a relatively inexpensive payload aboard an existing platform, like the International Space Station."

As it turns out, the space station is a very useful berth for gathering aerosol measurements, McGill said. The station travels in a precessing orbit—it shifts around and around, traveling from 51 degrees north latitude to 51 degrees south latitude. As a result, CATS will provide good coverage of what's happening over most population centers.

"In addition, the station passes over and along many of the primary aerosol-transport paths within Earth's atmosphere," McGill added. One of Earth's primary transport routes for airborne pollutants is from Southeast Asia. Circulation cells in Earth's atmosphere transport particles over Japan, northward south of Alaska, and then south toward the West Coast of the United States, making a big, inverted "U" shape. Another atmospheric circulation cell moves aerosols from western Canada eastward and then southward, over the Great Lakes and the East Coast.

"Because smoke-darkened skies over cities and communities can pose health risks to populations, especially to the medically vulnerable, the ability to track those aerosols and deliver warnings is critical," McGill said. Long-term data also can reveal the shifts that are occurring in global climate—whether changes are occurring in cloud cover or whether the level of pollutants is increasing or decreasing—over geographic distances and time.

The Future of Technology Demos

"What excites us so much about CATS is the fact that it will add to the observations of the aging CALIPSO," Hartman added. "It also will show that inexpensive missions, like CATS, can be installed on the space station, pointing nadir, to make critical measurements over months at a time. Think of all the Earth-observing science that might be done in a cost-effective manner from the International Space Station."

McGill agreed. "In our current budget-constrained environment, we need to use what we already have, such as the , to do more with less," McGill said, adding that if the instrument works, it can be scaled up to be a free-flier mission. "One of the most exciting things for me has been the opportunity to develop a small, low-cost, quick-turnaround payload for the International Space Station, a pathfinder project representing what's possible for future technology investigations," he added. "We did this using a small team, a streamlined process, and a build-to-cost mentality—and we proved it can be done."

Explore further: CATS Earth remote sensing instrument to debut on space station

Related Stories

Catching aerosols in a CATS eye

July 29, 2013

Quick looks by a special CATS-eye attached to the International Space Station will help scientists catalog and track particles in Earth's atmosphere and act as a pathfinder for a new satellite planned for 2021.

OCO-2 takes the A-Train to study Earth's atmosphere

July 4, 2014

( —Every day, above our planet, five Earth-observing satellites rush along like trains on the same "track," flying minutes, and sometimes seconds, behind one another. They carry more than 15 scientific instruments ...

NASA's IceCube no longer on ice

July 31, 2014

NASA's Science Mission Directorate (SMD) has chosen a team at NASA's Goddard Space Flight Center in Greenbelt, Maryland, to build its first Earth science-related CubeSat mission.

Recommended for you

Magnetized inflow accreting to center of Milky Way galaxy

August 17, 2018

Are magnetic fields an important guiding force for gas accreting to a supermassive black hole (SMBH) like the one that our Milky Way galaxy hosts? The role of magnetic fields in gas accretion is little understood, and trying ...

First science with ALMA's highest-frequency capabilities

August 17, 2018

The ALMA telescope in Chile has transformed how we see the universe, showing us otherwise invisible parts of the cosmos. This array of incredibly precise antennas studies a comparatively high-frequency sliver of radio light: ...

Six things about Opportunity's recovery efforts

August 17, 2018

NASA's Opportunity rover has been silent since June 10, when a planet-encircling dust storm cut off solar power for the nearly-15-year-old rover. Now that scientists think the global dust storm is "decaying"—meaning more ...

Another way for stellar-mass black holes to grow larger

August 17, 2018

A trio of researchers with The University of Hong Kong, Academia Sinica Institute of Astronomy and Astrophysics in Taiwan and Northwestern University in the U.S., has come up with an alternative theory to explain how some ...

Sprawling galaxy cluster found hiding in plain sight

August 16, 2018

MIT scientists have uncovered a sprawling new galaxy cluster hiding in plain sight. The cluster, which sits a mere 2.4 billion light years from Earth, is made up of hundreds of individual galaxies and surrounds an extremely ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

2 / 5 (1) Sep 08, 2014
It would be good if the article mentioned when it's going up and aboard which launch vehicle.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.