NASA's Surveyor, SOFIA, Cassini & WISE Projects

Optical Solutions Editorial Team

Apr 29, 2021 / 3 min read

In a prior post, we discussed NASA’s Great Observatories program, along with the contributions of Synopsys software and our engineering team. This installment discusses some of the many other NASA projects and missions that our consulting engineering team and software customers have been involved with.

ORA Beginnings and SOFIA

Optical Research Associates (ORA, the precursor to the Synopsys Optical Solutions Group) was founded by Tom Harris in 1963 as an engineering services company, not a software company. It was not until 1975 that ORA released CODE V as a commercial product. In the intervening years, early versions of what eventually become CODE V (CODE 1, CODE 2, and CODE 3; fun fact — there was no CODE 4), were used by our engineering team on a large number of projects, many associated with various NASA programs.

Darryl Gustafson, the 2nd staff member of ORA, developed the camera for the Surveyor program that landed several probes on the Moon in the mid-1960’s. NASA’s primary mission was to demonstrate the ability to soft-land a spacecraft on the lunar surface. The mission also evaluated the suitability of various landing sites for the future Apollo missions. Most recently, our engineering team designed the Mastcam-Z zoom lens for the Mars Perseverance rover

CODE V was used to design the Airborne Infrared Echelle Spectrometer (AIRES) instrument for the Stratospheric Observatory for Infrared Astronomy (SOFIA). SOFIA is a converted Boeing 747 with an opening in the fuselage for its 2.7-meter reflecting telescope. The AIRES system was designed to cover the infrared from 17 µm to 210 µm, with several cameras and several pre-disperser gratings in a carousel mount to sort orders for a large (~0.2 x 1.2 meter) Echelle.

Airborne Infared Schelle Spectrometer Model

Cassini Mission Optics

The ORA engineering services team was also involved with the Imaging Science Subsystem for the Cassini Mission. Cassini orbited Saturn for 13 years before being deorbited in 2017. The Narrow Angle and Wide Angle cameras (NAC & WAC) actually used re-purposed, spare optics from the Voyager missions.

One challenge for the Cassini mission was that the original optical design for the Voyager cameras was based on a vidicon detector. This was replaced by a CCD for Cassini, which had significantly more spectral response at longer wavelengths outside the intended color correction for the original systems. This was particularly true for the WAC, which was all refractive. As both systems used counter-rotating filter wheels for wavelength selection, the solution was to choose appropriate (i.e., different) filter substrate thicknesses to keep the cameras at best focus for each spectral band of interest. This worked spectacularly well, as demonstrated by the beautiful images that Cassini returned.

Chromatic Focal Shift

CODE V analysis output showing WAC chromatic focus shift without corrective filter thicknesses

Cassini’s view from orbit around Saturn in 2010

Cassini’s view from orbit around Saturn in 2010. Credit: NASA/JPL-Caltech/Space Science Institute

Contributions to the Wide-field Infrared Survey Explorer Telescope

Our engineering services team has contributed to many NASA projects, including the Wide-field Infrared Survey Explorer (WISE) telescope, which was launched in 2009. The WISE mission was to perform an all-sky survey at four infrared bands, ranging from 3.4 µm to 22 µm.

After its hydrogen coolant was depleted, the WISE mission was extended four months and renamed NEOWISE in acknowledgement of its search for Near Earth Objects. NEOWISE discovered over 400 new objects, many of which were a potential future threat to Earth. It also discovered several comets, including the beautiful Comet Neowise (C/2020 F3), which graced our skies last year.

In our next post, we will highlight technologies that are helping advance space-based optics, including freeform surfaces, curved detectors, and material advancements.

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