Integrated Components Trim NASA Budgets
Space exploration at the beginning of the next century will balance tight budgetary constraints against the need to understand our planetary environment. New technologies introduced in NASA's New Millennium program are designed to ensure that more science can be done with fewer dollars.
The Miniature Integrated Camera Spectrometer combines four optical sensors into a single silicon carbide structure, using one 10-cm mirror. Courtesy of JPL/NASA.
Deep Space 1, scheduled for launch in mid-October, is the first project in the program. Among the subsystems it carries are the solar concentrator arrays and the Miniature Integrated Camera Spectrometer (MICAS).
The integration saves weight, power and, consequently, cost but still provides good performance. "Technological improvements make our performance better than Voyager, and even about 85 percent of Cassini [more expensive and with a longer schedule]," said Pat Beauchamp, project leader for the camera spectrometer.
A 1024 × 1024-pixel charge-coupled device (CCD) gives 13-µrad resolution from about 500 to 1000 nm. A 256 × 256 active-pixel sensor (APS) images a portion of the same field in the same wavelength region, with 18-µrad resolution. The metal-on-silicon sensor has on-chip timing and control electronics.
Beauchamp considers this a first-generation device, with eventual improvements adding even more functionality to the on-chip electronics, further reducing the electrical power requirements. "The APS," she explained, "images like a CCD, but uses only milliwatts instead of watts."
The UV spectrometer covers 80 to 185 nm with 0.64-nm spectral resolution and 316-µrad spatial resolution from the fiber channel plate image-intensified CCD. The infrared instrument's HgCdTe detector covers 1200 to 2400 nm in 6.6-nm increments with 54-µrad spatial resolution.
This level of performance is not unusual for a planetary exploration instrument; what is unusual is its integration into a 12-kg package with no moving parts. "That leaves the instrument open to far fewer failure mechanisms, ideal for long-duration solar system investigation missions, such as a mission to Pluto," said Marc Rayman, chief mission engineer for Deep Space 1.
"In fact," Beauchamp added, "MICAS already meets the initial optical requirements for a science mission to Pluto."
The technology introduced on the integrated camera spectrometer should make it possible to achieve significant scientific goals at a lower cost, Rayman said. "It costs less, but we don't give up any capability."
Scientists hope that after its initial launch the instrument will prove the validity of its technologies on asteroid -- and possibly comet -- targets, establishing a heritage that will allow future science missions to meet cost and schedule objectives without compromising scientific accomplishments.
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