The goal of the Upper Atmosphere Research Satellite (UARS) was to understand the chemistry, dynamics, and energy balance above the troposphere as well as the coupling between these processes and between atmosphere regions. This implies an understanding of the mechanisms that control upper atmosphere structure and variability, as well as an understanding of how the upper atmosphere responds to natural and man-made causes. Together, these help define the role of the upper atmosphere in climate and climate variability. The UARS platform provided simultaneous, coordinated measurements of atmospheric internal structure (trace constituents, physical dynamics, radiative emission, thermal structure, density) and measurements of the external influences acting upon the upper atmosphere (solar radiation, tropospheric conditions, electric fields). See the figure to view measurements of temperature, pressure, wind velocity, and gas species concentrations in the altitude ranges. In addition, the combination of orbit and instrument design provided nearly global coverage. UARS was decommissioned on 14th December 2005, and fell back to Earth on Sept. 24, 2011.
The UARS mission objectives included the study of:
- Upper atmosphere energy source and sink,
- Upper atmosphere global photochemistry,
- Upper atmospheric dynamics,
- Coupling among these processes, and
- The coupling between the upper and lower atmosphere
Ten instruments on the spacecraft accomplished these specific objectives by performing measurements of chemical species composition, temperature, winds, and energy inputs of the upper atmosphere.
Four UARS instruments devoted to measurements of constituents spectroscopically determined the concentrations of many different chemical species and derived the variation of atmospheric temperature with altitude by observing infrared emissions from carbon dioxide:
Two instruments, utilizing high-resolution interferometry, studied upper atmosphere winds by sensing the Doppler shift in light absorbed by or emitted from atmospheric molecules:
An additional four investigations obtained estimates of the energy incident on the atmosphere by measuring solar ultraviolet radiation and the flux of charged particles from the Earth's magnetosphere:
NOTE: ACRIM II is not part of the UARS project. It was included on the UARS platform as an instrument of opportunity. ACRIM II data are archived at the Langley ASDC.
UARS operated 585 km above the Earth in a near circular orbit inclined 57 degrees to the equator. This orbit permitted UARS sensors to view up to the 80 degree latitude bands providing essentially global coverage of the stratosphere and mesosphere. This also permitted the UARS instrument to make measurements over the full range of local time sat all geographic locations approximately every 36 days.
The UARS system included both the flight observatory and ground based elements consisting of both mission unique and institutional elements. The institutional elements can be further broken down into communications elements on the one hand, and the ground system elements needed to support flight operations and data capture on the other.
The observatory consisted of ten science instruments, an Instrument Module (IM) including mission unique hardware, and the Multi-mission Modular Spacecraft (MMS). It provided precision pointing for the science instruments on an Earth oriented platform, periodic routine maneuvers to maintain a favorable sun orientation, and the ability to communicate through the Space Network S-band service. UARS is also compatible with the Deep Space Network (DSN) for support during emergency situations.
Flight operations are performed through Goddard Space Flight Center (GSFC) institutional mission support systems. These facilities providefor satellite command and control, definitive orbit and attitude computations, command management, and data capture.
Instrument data processing was accomplished in the mission specific Central Data Handling Facility (CDHF) at GSFC. Data analysis and theoretical studies were being conducted by members of the UARS science team through use of Remote Analysis Computers (RACs) located at the Principal Investigators' (PIs) facilities. PIs also had access to the CDHF data base archival system. Guest investigators had access to UARS data through the Goddard Distributed Information and Services Center (DISC).
Detailed Project Description
For more information about the UARS project, consult the UARS project home page or refer to the documents listed in the Reference section below.
The UARS mission data are available in two processing levels:
- Level 2
- The geophysical parameters calculated from Level 1 data, such as atmospheric temperature profiles, gas concentrations, winds, or solar spectral irradiances. Atmospheric data at Level 2 are related directly to the instrument measurement "footprint", i.e., the character of the altitude scan is determined bya given instrument's scan rate, integration time, and viewing direction, as well as the spacecraft's orbital velocity. Level 2 data also have sensor specific file formats.
- Level 3A
- Atmospheric data that reflects the geophysical information of Level 2 data transformed into a common format and equally spaced along the measurement trajectory in time ("Level 3AT", at 65.536 second centers) or latitude ("Level 3AL", every four degrees). Level 3A data have common file formats.