Evans Optical, Systems, Design, & Software Engineering  

About Evans Engineering


Dennis Charles Evans

Evans Engineering; Independent Consultant

Has sixty years of successful technical participation, leadership, and management of short and long range science and engineering development and applications programs. Engineering development and science research in space sciences, systems engineering, and technical management, are the primary fields of experience. Has experience with project management, product development, systems engineering, computer applications, science research, and engineering development and application. The experience includes: engineering, science, and management of satellite and sounding rockets systems for stellar, planetary, and solar research; photometry and spectrophotometry from the extreme ultraviolet through submillimeter infrared; photographic instrument design; computer applications systems implementation and programming; hardware and software evaluation and specification; robotic systems; relativity; non-Euclidean geometries; philosophy; religion-theory of God; and cosmology - theory of creation.


Bachelor of Science

  • Geology: Geophysics, Engineering Mathematics;
  • California Institute of Technology, 1960.

Graduate Studies

  • Geology and Geophysics, University of Oregon, 1960.
  • Geophysics and Planetary Science, UCLA 1961-1963.


  • Cosmic Background Explorer Mission won 2006 Nobel Prize for Physics - Cobe Team Participant 1/1500th!!
  • NASA Exceptional Achievement Medal for outstanding creativity, productivity, and dedication in optical work for the Instrument Synthesis and Analysis Laboratory - 2006
  • Instrument Systems and Technology Division Engineering Excellence Award for outstanding support to the Instrument Synthesis and Analysis Laboratory - 2005
  • Outstanding Teamwork Award – Instrument Synthesis and Analysis Laboratory Team - 2003
  • Customer Service Excellence Award – Triana Project – 2002
  • Peer Nomination, Instrument Technology Center Annual Excellence Award as a contractor supporting the Instrument Synthesis & Analysis Laboratory, August 2000
  • Advance Geosynchronous Studies (AGS) GSFC Imager Instrument Optical Design – Customer Service Excellence Award – Individual 1999
  • AGS GSFC Imager Instrument Team – Customer Service Excellence Award – Team 1999
  • Total Ozone Mapping Spectrometer (TOMS) Design Audit Team Award, 1993
  • Presidential Award for Design Excellence (IUE Team), 1988
  • Exceptional Performance Award, Goddard Space Flight Center's highest employees award, 1982 - For sustained contributions to the advancement of spaceflight instrument engineering for technical innovation and leadership provided in the development of the International Ultraviolet Explorer
  • Member, American Scientific Affiliation, 1986
  • Member, The Planetary Society, 1984
  • Member, Society for Photo-optical Instrumentation Engineers (SPIE), 1984
  • President, Goddard Computer Club, 1983
  • Constitutional Author, Goddard Bible Club
  • Listed "American Men and Women of Science", Edition 14, Vol. 2, 1979 and following, 1979
  • Apollo XI Award in appreciation of support for the Lunar Landing Mission, July 20, 1969



Dozens of Technical Publications, Numerous Technical Memoranda & Reports


  • 1982 - Present; Evans Optical, System, Design and Software Engineering, Independent Consultant.
  • 2010 - 2019; SGT, Inc., 7515 Mission Drive, Suite 300, Seabrook, MD 20706 - Principle Optical Engineer
  • 2009 - 2019 Goddard Space Flight Center, Principle Optical Engineer Emeritus - 8800 Greenbelt Road, Greenbelt, MD 20771
  • 2009 - November 30; Retired from NASA, Federal Service
  • 2001 - 2009 Goddard Space Flight Center, Principle Optical Engineer supporting Instrument Design Laboratory
  • 1993 - 2001 See Evans Optical, System, Design and Software Engineering above
  • 1988 - 1993 Advanced Technology & Research Corporation, Manager, Instruments Systems Division. Columbia MD
  • 1986 - 1989 Space Exploration & Development Corporation, President.
  • 1984 - 1988 Sachs/Freeman Associates, Inc. (SFA, Inc.), Director of Space Sciences. Landover MD (Sotera Defense Solutions)
  • 1964 - 1984 Goddard Space Flight Center, Senior Systems Engineer.
  • 1961 - 1963 Douglas Aircraft Company, Santa Monica, California.

Typical Tasks

Since 1993 more than 200 tasks for more than 100 different satellite projects have been supported. This includes proposal studies, optical design, stray light analysis, photometric analysis, systems engineering, and integration support.

Project: ..........Support provided     <Link to ISAL Typical Tasks>

AGSI: ............ Earth observing advanced weather satellite design study - optical design, stray light design - 3-axis stabilized.
GATES ........... Earth observing advanced weather satellite design study - optical design, stray light design - satellite scanning.
Ana Lani ........ X-Ray Sky Mapping, 9 telescope cluster, stray light control
CHyMERA....... Environmental pollution imager - refractive instrument optical evaluation and thermal sensitivity analysis.
CIRCE .......... Confusion-limited InfraRed Cosmic Explorer - Stray light design for proposal.
CIRS ............ Planetary fly-by stray light baffle evaluation and recommendations
COR-1........... Coronagraph stray light suppression study
FUSE ............ Stray light baffle consulting
GALEX ......... Design review support for optical mounting problems
GOES .......... Stray light analysis, image analysis, photometric studies, calibration, design review support
HST STIS .... Instrument stray light evaluation and miscellaneous baffle design recommendation
IRAC ........... Infrared Array Camera optical design studies and stray light analysis, image analysis, photometric analysis,
................... 3D ASAP modeling, APART analysis, GSE optical and photometric analysis, Integration image analysis, ghost image analysis
................... IRIS .... Proposal variant of IRAC
................... Astro-F Proposal variant of IRAC
IRMOS ........ TI-Digital Mirror Device micro-mirror array optical modeling for ground based instrument for NGST related instrument
Kronos ......... Optical re-packaging study
L2-Sounder .. Limb sounder from L2 orbit - optical evaluation
MAP ............ Star tracker baffle review and design change recommendations
MODIS ........ Instrument calibration study - design of equipment for calibration of integrated instrument.
NGST MIR. ...Instrument design evaluation support, Stray light studies
ORBVIEW .... Photometric performance and stray light performance instrument evaluation
REDAII ....... Optical design support for combined Earth Sciences - NGST test satellite
Resource 21.. Photometric performance and stray light proposal support for earth resources imaging satellite
Solar Stereo.. Coronagraph stray light suppression design
TOMS .......... Stray light evaluation and design review support
WFC-3 ......... Photometric analysis and stray light design studies
WIRE ........... APART stray light analysis support, Design change recommendations.

Sample tasks:

(1) evaluation of the stray light design and performance of the Wide-field Infrared Explorer;

  • Some Evans Engineering WIRE Task Results:
  • [a] [b]
  • [a] A perspective view from the entrance baffle vane of the WIRE infrared telescope. Note the convergence of the interior vanes to the right side of the image. When the vane edges were moved away from a uniform cone by a few millimeters, the stray light in the instrument was reduced about 2 orders-of-magnitude. This shows the power of 3D modeling and image rendering connected with APART/PADE and other analytical tools.
  • [b] A rendered view of the same telescope as in [4], with the primary and secondary mirrors made reflective. The detector can be seen, as desired, but some edges that should not be illuminated can also be seen. Additional baffle vanes inside the throat of the central conical baffle were recommended.

(2) radiometric calibration consultation to Goddard Space Flight Center, Optics Branch, for studying the performance of the Geostationary Observational Environmental Satellite (GOES), including primary stellar calibration measurements at Palomar Observatory and elsewhere;

(3) review of the stray light performance of the GOES Earth Sensor;

An Evans Engineering GOES Earth Sensor Assembly Task Result:

A 3D perspective view from the ESA detector showing numerous internal reflections which interfered with the performance of the device.

(4) optical design and analysis of reflective and refractive optical systems to be used by the Smithsonian Astrophysical Observatory on the Space Infrared Telescope for imaging on the Infrared Array Camera;

An Evans Engineering IRAC Task Result:

An RTL ray trace of a 10 arc-minute square field imaged onto a 256 square array infrared detector. The ray path of a dual paraboloid set has been folded in order to fit into a 30 degree sector of a 10 inch long cylinder.

(5) design advice for stray light suppression in the South Pole Infrared Array Camera operating in Antarctica;

(6) stray light evaluation and 3D model analysis of second generation instruments for infrared imaging and ultraviolet imaging spectroscopy on the Hubble Space Telescope, and

(7) consultation and advice concerning the stray light analysis and stray light suppression in the Composite Infrared Spectrometer on the Cassini mission to Saturn and the Total Ozone Mapping Satellite.

Participated in stray light design of the DIRBE instrument on the Cosmic Background Explorer and the UIT instrument (flown on shuttle Endeavor).

Developed the Ray Trace Language (RTL) optical design code for personal computers. Consulting provided for stray light evaluation of infrared satellite imaging system; for proposal development in computer sciences, optical systems, and artificial intelligence; echelle spectrograph optical design, and optical system modification for a CCD linear array, high data rate microdensitometer.

Has provided management and technical support for robotic and space-related tasks including vision processing, robot explosive ordnance disposal, optical and stray light instrument design, conceptual design and evaluation of space flight instruments (ultraviolet, visible, and infrared), space flight information management systems, acquisition and control systems. Tasks have included: the fabrication of a full scale operational mock-up of the Space Shuttle Remote Manipulator System arm.   The picture below shows the RMS simulator at GSFC being used in practice for the Hubble Servicing Mission.

International Ultraviolet Explorer

Was Scientific Instrument Manager for the International Ultraviolet Explorer (IUE) launched on January 26, 1978 and operated for almost 19 years until it was retired from operation on September 30, 1996. Participated in optical design, assembly, ground and orbital testing of the IUE as well as management of Instrument activities. While it was in operation, it was the most active astronomical observatory in existence.


US Serial Number 07/094,583; Filed September 9, 1987. Mass Relocation Inertia Controller - A low cost attitude control system for Spartan Class free flyer satellites.