Cloud-Aerosol Transport System (CATS) - 11.04.14
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The Cloud-Aerosol Transport System (CATS) investigation uses a light detection and ranging (LiDAR) system to measure the location, composition and distribution of pollution, dust, smoke, aerosols and other particulates in the atmosphere. CATS is mounted on the Japanese Experiment Module's Exposed Facility and is used to study the atmospheric constituents that impact global climate. By gaining a better understanding of cloud and aerosol coverage, scientists can create a better model of the Earth's climate feedback processes.
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Goddard Space Flight Center, Greenbelt, MD, United States
Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)
Science Mission Directorate (SMD)
ISS Expedition Duration
September 2014 - Ongoing
Previous ISS Missions
The Cloud-Aerosol Transport System (CATS) investigation uses a remote sensing instrument designed to provide measurements of atmospheric clouds and aerosols. The impact of clouds and aerosols (e.g., pollution, dust, smoke) on a global scale with regards to energy balance and climate feedback mechanisms is not yet fully understood.
A better understanding of cloud and aerosol coverage and properties is critical for understanding of the Earth system and its associated climate feedback processes. The CATS LiDAR obtains range-resolved information which can be used to assess the climate impacts of clouds and aerosols on a global scale.
The orbit of the International Space Station (ISS) is particularly suited to measurements of this kind, because the ISS passes over and along many of the primary aerosol transport paths within the atmosphere. The ISS orbit also permits study of diurnal (day to night) changes due to the effects of aerosols and clouds in the atmosphere – something other Earth Science satellite cannot readily obtain given their orbits.
The Cloud-Aerosol Transport System (CATS) is a light detection and ranging (LiDAR) remote sensing instrument designed to provide range-resolved profile measurements of atmospheric aerosols and clouds. The CATS instrument uses a high repetition rate laser operating at three wavelengths (1064, 532, and 355 nm) to derive properties of cloud and aerosol layers including: layer height, layer thickness, optical depth, extinction, and depolarization-based discrimination of particle type. The CATS investigation is designed to provide a combination of long-term operational science, in-space technology demonstration, and technology risk reduction for future Earth Science missions; all the while adding to the continuous history of Earth atmospheric observations.
CATS is installed on the JEM-EF to enable nadir pointing of the science package sensors and instrumentation. Once CATS is connected to the JEM-EF, it is activated via the ISS command and data handling system. Mission planning and coordination for CATS is controlled via the NASA TReK system and the Marshall Space Flight Center Payload Operations Integration Center (MSFC POIC). The CATS investigation is designed to operate on the JEM-EF for at least 6 months and a maximum of 3 years. CATS is proud to be part of NASA’s Earth Right Now campaign, which includes the launches of five NASA Earth-observing missions in 12 months– more than NASA has conducted in a single year in over a decade.
An improved understanding of the makeup, structure and evolution of Earth's atmosphere can enhance spacecraft launch, landing and communications. It can also help guide future experiments investigating different atmospheres such as Mars, Jupiter, and other worlds.
CATS provides continuity for the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) that previously launched and now is in its extended phase. Long-term observations of Earth’s atmosphere are needed to help researchers model and predict climate changes.
The CATS instrumentation requires an external nadir viewing location on ISS. Power and data handling is needed to operate the investigation over long periods of time (CATS is a remote sensing instrument intended to operate continuously on-orbit, with data streaming through the Medium Rate Data Link (MRDL) interface). CATS requires no crew involvement after SSRMS installation is complete.
When on-orbit, CATS is intended for continuous, or near-continuous, operation. The investigation is commanded on and operates continuously, flowing data down through the Medium Rate Data Link (MRDL) user interface to a ground processing station at Goddard Space Flight Center (GSFC). For safety purposes the investigation (e.g., the laser) is disabled during EVA and docking events.
Ground Based Results Publications
McGill MJ, Hlavka DL, Vaughan MA, Trepte CR, Hart WD, Winker DM, Keuhn R. Airborne validation of spatial properties measured by the CALIPSO lidar. Journal of Geophysical Research. 2007 October 17; 112(D20): 27. DOI: 10.1029/2007JD008768.
McGill MJ, Hlavka DL, Hart WD, Scott VS, Spinhirne , Schmid . Cloud Physics Lidar: instrument description and initial measurement results. Applied Optics. 2002 Jun 20; 41(18): 3725-3734.
McGill MJ, Rallison RD. Holographic optics convert rings to points for detection. Laser Focus World. 2001; 37(3): 131-136.
McGill MJ, Hlavka DL, Hart WD, Welton E, Campbell JR. Airborne lidar measurements of aerosol optical properties during SAFARI-2000. Journal of Geophysical Research. 2003 July; 108(D13): 16. DOI: 10.1029/2002JD002370.
CATS web site
Earth Right Now
Schematic showing a primary component breakout of the of the CATS investigation. This investigation supports a standard JEM-EF attached payload volume.
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