Sample Images
from the PRE-FLIGHT calibration data.
Sample Images
from the PRE-FLIGHT calibration data.
The lightweight (55 pound) SWUIS experiment operates from inside the Shuttle mid-deck cockpit, and looks out of the Shuttle through an optical-quality quartz window on the port side of the Orbiter.
The miniaturized SWUIS space observatory is designed to take maximum advantage of humans in the Shuttle to assemble, operate, and evaluate experiments while on orbit. By taking advantage of the Shuttle crew capabilities, SWUIS's designers believe they have achieved a $5-$10M flight experiment for just over one-half million dollars. (Functional Schematic and Comparison to some other Instruments)
SWUIS is based around a rugged, 18-cm (7-inch) diameter Maksutov-design UV telescope and a UV-sensitive, image-intensified CCD camera that frames at video rates. By combining the video data in a computer on the ground, scientists can obtain sensitive measurements of astronomical targets observed by SWUIS; the video-rate framing also freezes out the motion of the Shuttle, thereby eliminating the need for the expensive pointing control platforms many Shuttle astronomy payloads have used in the past. Telescope focal length changes can be made during each SWUIS operation to allow its field of view to range from 0.1 to 0.6 deg.
The characteristic angular resolution of the SWUIS instrument is approximately 3 arcsecomds, or about 1/1000th of a degree. Special-purpose comet imaging filters are being carried on the August STS-85 mission to make observations in the OH (0-0) band, the CS (1-0), and the CN (0-0) molecular emission bands, as well as in the UV reflectance continuum, and in a host of visible channels covering the major C2, C3, and H2O+ emissions so prominent in comets.
SWUIS was originally conceived and developed under the direction of Dr. Alan Stern, a planetary scientist, Assistant Director of SwRI's Space Science Department, and manager of SwRI's Boulder Extension Office. After laboratory development in 1992, SWUIS was first flight tested in 1993 aboard a NASA SR-71 Blackbird aircraft flying at Mach 3.3 and 86,000 feet out of Edwards Air Force Base. In 1996, NASA accepted proposals to fly the innovative, low-cost imager on three flights of the Shuttle, beginning with the STS-85 mission to study comet Hale-Bopp. Dr. Stern is the Principal Investigator for these missions; Dr. David Slater of SwRI is the SWUIS Project Manager. Stern and Slater have teamed with colleagues Dr. Michael A'Hearn (University of Maryland), Paul Weissman (JPL), Martha Hanner (JPL), and Larry Paxton (Applied Physics Lab) to study comet Hale-Bopp with SWUIS.
SWUIS's unique attributes are its low development and operations cost (near $600K, about half the cost of a typical sounding rocket experiment), its wide field of view (having lower resolution, but over 500 times the sky coverage area of the Hubble Space Telescope), and its rapidly reconfigurable nature (which allows the astronaut operating it to respond in real time to the data being collected so as to optimize the experiment, much as one would at a groundbased observatory). SWUIS also boasts the capability to observe science targets as close as 20 degrees to the Sun; in contrast, the Hubble Space Telescope and most other space observatories are not allowed to point closer than about 45 degrees to the Sun. These capabilities make SWUIS ideal for studying comets, the inner planets, and a variety of other sources.
On STS-85, astronaut mission specialist Dr. Steve Robinson will operate SWUIS, while his crew mate, mission commander Col. Curt Brown points the Shuttle Discovery to view the comet. In a daring and innovative move to shield the Shuttle window through which SWUIS will view Hale-Bopp from the Sun, mission specialist Dr. Jan Davis will position the Shuttle's Remote Manipulator System (RMS) arm to cast a shadow over the observing window.
SwRI personnel on the ground at Mission Control in Houston, assisted by Dr. Weissman, will advise the astronauts in the Shuttle on the quality of the data being obtained and make recommendations to optimize each of the four planned comet observing runs. Additionally, Dr. Stern will be taking an infrared-sensitive version of SWUIS to altitudes as high as 50,000 feet aboard a NASA high-performance WB-57 aircraft operated out of JSC's Ellington Field to make additional observations complementing the Shuttle's UV measurements during the flight.
Following its first flight on STS-85 this August, SWUIS is scheduled to fly again twice aboard the Shuttle in 1998 and 1999 to make observations of other solar system and astronomical targets.