Saturday, November 14, 2009

The View From Space: Two New Experiments Take Fresh Looks at Earth's Coast, Atmosphere

They've only been on orbit a couple of months, but two new sensors examining our upper atmosphere and oceans already are demonstrating the International Space Station's value as an Earth science observing platform.

The experiments - the Hyperspectral Imager for the Coastal Ocean, or HICO, and the Remote Atmospheric and Ionospheric Detection System, or RAIDS -- work in tandem as the HICO and RAIDS Experiment Payload, or HREP. The joint payload is operated by the U.S. Naval Research Laboratory in Washington and its partners.

HICO is the first hyperspectral sensor specifically designed to investigate the coastal ocean and nearby land regions from space. Its imaging shows unique characteristics across the electromagnetic spectrum, including those ranges not visible to the human eye, such as ultraviolet and infrared light.

HICO image taken over Midway Island on Tuesday, Oct. 20, 2009. Image Credit: NASA

RAIDS, built jointly by the Naval Research Laboratory and The Aerospace Corporation in El Segundo, Calif., is a hyperspectral sensor suite used to study the Earth's thermosphere and ionosphere -- layers of the atmosphere where the space shuttle and space station orbit. Its eight optical instruments measure the chemistry, composition and temperature of the thermosphere and ionosphere. It also is testing new techniques for remotely sensing these atmospheric regions, which are very difficult to measure, yet very important for understanding the behavior of low-altitude satellites, space junk and sub-orbital rocket systems.

"The instruments take advantage of the space station as a host platform for Earth observation," said Julie Robinson, International Space Station program scientist at the Johnson Space Center in Houston. "The space station was designed to host numerous instruments for looking at Earth and space, providing attachments sites, power and data."

HICO image taken over a coastal region of the South China Sea near Hong Kong, China, on Friday, Oct. 2, 2009. Image Credit: NASA

The paired HREP experiments launched to the space station in September aboard the Japan Aerospace Exploration Agency's H-II Transfer Vehicle -- an unmanned cargo ship for station resupply. HICO and RAIDS are also the first U.S. remote sensing instruments to be mounted on the space station and the first to be installed on the Japanese Experiment Module's Exposed Facility -- a multipurpose platform where science experiments can be deployed and operated in open space.

A portrait of the refurbished RAIDS scan head and IR detector box (left) before experiment integration. Image Credit: NASA

"The HICO experiment completed checkout in October, and already has acquired many high-quality hyperspectral images of land and coastal scenes," said Mike Corson, principal investigator for HICO at the Naval Research Laboratory. HICO is serving as a pathfinder for technologies and environmental product algorithms to be used for future free-flying instruments, but will in addition provide an immediate return of hyperspectral image data that can be analyzed.

This graphic shows the RAIDS viewing geometry. RAIDS views aft (anti-RAM) as the ISS orbits viewing the atmospheric limb by scanning near the horizon. Image Credit: NASA

The RAIDS experiment checkout, also completed in October, gathered atmospheric observations using all eight of its sensors. "RAIDS has collected sufficient data to satisfy its secondary science objective -- measuring the low-altitude source of daytime radiation in the ionosphere," said Scott Budzien, principal investigator for RAIDS at the Naval Research Laboratory. "RAIDS began science operations on Oct. 23, and is now focused on collecting data to address the primary science objective, which is to measure temperature and its variability in the thermosphere."

The experiments are operated and managed from the Payload Operations Center at the Marshall Space Flight Center in Huntsville, Ala. in cooperation with the Naval Research Laboratory. The HREP payload was sponsored by the Office of Naval Research. Payload integration and launch to the space station were provided by the U.S. Department of Defense Space Test Program.

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by Lori Meggs, AI Signal Research, Inc.
NASA's Marshall Space Flight Center

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