Goddard Space Flight Center, Greenbelt, Maryland 20771
ENGINEERING COLLOQUIUM
Monday, February 27, 2012 / 3:30 PM, Building 3 Auditorium
John Hagopian
"Development of Multiwalled Carbon Nanotubes for Space Flight Instrumentation"
ABSTRACT -- Observations of the Earth are extremely challenging; its large angular extent floods scientific instruments with high flux within and adjacent to the desired field of view. This bright light diffracts off of instrument structures and invariably contaminates measurements, sometimes rendering up to 40% of the scene unusable. Astrophysical observations also are impacted by stray light that obscures very dim objects and degrades signal to noise in spectroscopic measurements. Stray light is controlled by using low reflectance structural surface treatments on baffles and stops to limit this background noise.
In 2007 NASA Goddard Space Flight Center researchers discovered that Multiwalled Carbon Nanotubes (MWCNTs) are exceptionally good absorbers, with potential to provide order-of-magnitude improvement over current surface treatments and a resulting factor of 10,000 reduction in stray light when applied to an entire optical train. Development of this technology provides numerous benefits including: a.) simplification of instrument stray light controls to achieve equivalent performance, b.) increased observational efficiencies by recovering currently unusable scenes in high contrast regions, and c.) enabling low-noise observations that are beyond current capabilities. Our objective was to develop and apply MWCNTs to instrument components to realize these benefits.
Over the next four years we addressed the technical challenges to advance the technology by tuning the MWCNT geometry using a variety of methods to provide a factor of 10 to 40 improvement over current surface treatments. We have achieved average hemispherical reflectance of less than 0.5% from 200 nm to 100 microns in wavelength on silicon substrates using single formulation. In addition, we have developed formulations for use on stainless steel, titanium and silicon nitride to accommodate a variety of components. Techniques are being developed to apply the optimized geometry to typical instrument components such as spiders, baffles and entrance apertures. In addition, candidate geometries have been tested and optimized for robustness to survive integration, testing, launch and operations associated with space flight hardware. The benefits of this technology extend to space science where observations of extremely dim objects require suppression of stray light. We have recently optimized carbon nanotube formulations for use in the Mid to Far Infrared portions of the spectrum out to 100 microns wavelength where standard processes are ineffective. Our latest process has attained the highest emissivity ever measured by NASA, providing a new material that can be applied to small instrument radiator surfaces. We are also exploring the application of this enhanced carbon nanotube formulation for use as improved FIR detector absorbers and high efficiency near ideal calibrators and radiators.
SPEAKER -- John G. Hagopian is a Senior Optical Physicist at the Goddard Space Flight Center in the Optics Branch. He served as alignment and test engineer for the Far Infrared Spectrometer on the Cosmic Background Explorer (COBE), Lead on the Broad Band X-Ray Telescope and Composite Infrared Spectrometer (CIRS) on Cassini mission to Saturn, the Corrective Optics Space Telescope Axial Replacement (COSTAR) for the HST repair mission and contributed to the Energetic Gamma Ray Telescope, Tropospheric Emissions Spectrometer, and IRMOS. Mr. Hagopian served as the Integrated Science Instrument Module (ISIM) and Mission Optical Systems Lead for the James Webb Space Telescope. His area of expertise is optical alignment, integration, and test. He has developed novel technologies in detector calibration, acoustic testing, micro-stability testing, laser engineering, contamination control, and nanotechnology. He is currently working on several technology and instrument development programs at GSFC. Mr. Hagopian holds patents relating to nanotechnology, optical test and optical communications. He has BA's in Physics and Astronomy and a MA in Nuclear Engineering from the University of Virginia and has been at GSFC since 1982.