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During 2014 and 2015, NASA's Neutron star Interior Composition Explorer (NICER) mission proceeded successfully through Phase C, Design and Development. An X-ray (0.2{12 keV) astrophysics payload destined for the International Space Station, NICER is manifested for launch in early 2017 on the Commercial Resupply Services SpaceX-11 flight. Its scientific objectives are to investigate the internal structure, dynamics, and energetics of neutron stars, the densest objects in the universe. During Phase C, flight components including optics, detectors, the optical bench, pointing actuators, electronics, and others were subjected to environmental testing and integrated to form the flight payload. A custom-built facility was used to co-align and integrate the X-ray \concentrator" optics and silicon-drift detectors. Ground calibration provided robust performance measures of the optical (at NASA's Goddard Space Flight Center) and detector (at the Massachusetts Institute of Technology) subsystems, while comprehensive functional tests prior to payload-level environmental testing met all instrument performance requirements. We describe here the implementation of NICER's major subsystems, summarize their performance and calibration, and outline the component-level testing that was successfully applied.

We present a new and innovative near-infrared multi-band ultraprecise spectroimager (NIMBUS) for SOFIA. This design is capable of characterizing a large sample of extrasolar planet atmospheres by measuring elemental and molecular abundances during primary transit and occultation. This wide-field spectroimager would also provide new insights into Trans-Neptunian Objects (TNO), Solar System occultations, brown dwarf atmospheres, carbon chemistry in globular clusters, chemical gradients in nearby galaxies, and galaxy photometric redshifts. NIMBUS would be the premier ultraprecise spectroimager by taking advantage of the SOFIA observatory and state of the art infrared technologies. This optical design splits the beam into eight separate spectral bandpasses, centered around key molecular bands from 1 to 4 microns. Each spectral channel has a wide field of view for simultaneous observations of a reference star that can decorrelate time-variable atmospheric and optical assembly effects, allowing the instrument to achieve ultraprecise calibration for imaging and photometry for a wide variety of astrophysical sources. NIMBUS produces the same data products as a low-resolution integral field spectrograph over a large spectral bandpass, but this design obviates many of the problems that preclude high-precision measurements with traditional slit and integral field spectrographs. This instrument concept is currently not funded for development., Comment: 14 pages, 9 figures, SPIE Astronomical Telescopes and Instrumentation 2012

We present results of a study of a deployable version of the Advanced Technology Large-Aperture Space Telescope (ATLAST), designed to operate in a Sun-Earth L2 orbit. The primary mirror of the segmented 9.2-meter aperture has 36 hexagonal 1.315 m (flat to flat) glass mirrors. The architecture and folding of the telescope is similar to JWST, allowing it to fit into the 6.5 m fairing of a modest upgrade to the Delta-IV Heavy version of the Evolved Expendable Launch Vehicle (EELV). We discuss the overall observatory design, optical design, instruments, stray light, wavefront sensing and control, pointing and thermal control, and in-space servicing options.

The Landsat Data Continuity Mission (LDCM), a joint NASA and USGS mission, is scheduled for launch in December, 2012. The LDCM instrument payload will consist of the Operational Land Imager (OLI), provided by Ball Aerospace and Technology Corporation (BATC) under contract to NASA and the Thermal Infrared Sensor (TIRS), provided by NASA's Goddard Space Flight Center (GSFC). This paper outlines the design of the TIRS instrument and gives an example of its application to monitoring water consumption by measuring evapotranspiration.

Spherical primary telescopes are cost effective for large segmented apertures. The SPOT segments are cast in pyrex and shaped to allow radius of curvature control. This paper discusses design, fabrication and performance of SPOT segments.

Future space telescope programs need to assess in-space robotic assembly of large apertures at GEO and ESL2 to support ever increasing aperture sizes. Since such large apertures will not fit within a fairing, they must rely on robotic assembly/deployment. Proper assessment requires hardware-in-the-loop testing in a representative environment. Developing, testing, and flight qualifying the myriad of technologies needed to perform such a test is complex and expensive using conventional means. Therefore, the objective of the ALMOST program is to develop a methodology for hardware-in-the-loop assessment of in-space robotic assembly of a telescope under micro-gravity conditions in a more cost-effective and risk-tolerant manner. The approach uses SPHERES, currently operating inside ISS, to demonstrate inspace robotic assembly of a telescope that will phase its primary mirror to optical tolerances to compensate for assembly misalignment. Such a demonstration, exploiting the low cost and risk of SPHERES, will dramatically improve the maturity of the guidance, navigation and control algorithms, as well as the mechanisms and concept of operations, needed to properly assess such a capability.

The Single Aperture Far Infrared (SAFIR) observatory - a concept design for a 10m-class spaceborne far- infrared and submillimeter telescope, has been proposed for development, and given high priority by agency strategic planners. SAFIR will target star formation in the early universe, the chemistry of our interstellar medium, and the chemical processes that lead to planet formation. SAFIR is a telescope that, with passive cooling at Earth-Sun L2, achieves temperatures that allow background-limited broad-band operation in the far infrared. This observatory is baselined as being autonomous in deployment and operation, but consideration has been given to understanding the enabling opportunities presented by Exploration architecture. As this architecture has become better defined, these opportunities have become easier to understand.We present conceptual strategies that would use modestly enhanced Exploration architecture to service and maintain SAFIR, allowing extended duration, lower risk and hardware cost, and performance enhancements linked to the steep development curve for sensor technology. These efforts, which would rely on both human and robotic agents, presume routine operations at Earth-Sun L2, and servicing at an Earth-Moon L1 jobsite. The latter is understood to be easily accessible to a lunar-capable Exploration program. This study bridges the interface between Exploration technology and astronomical space observatory technology. Such an Exploration-enhanced version of SAFIR can be seen as a strawman for more ambitious far future work, in which much larger science instruments that cannot be packaged in a single launch vehicle are not only serviced and maintained in space, but also constructed there.

SPIRIT is a candidate NASA Origins Probe mission. It is a spatial and spectral interferometer operating at 4 K with an operating wavelength range 25 - 400 microns. This paper describes the various components of the candidate optical system, including telescopes, pointing and tracking optics, along with their functions. Some of the tradeoffs involved in selecting various components, with their particular characteristics, are described.

The Space Infrared Interferometric Telescope (SPIRIT), a candidate NASA Origins Probe mission, is a cryogenic 6-36m variable-baseline imaging interferometer operating at 25 - 400 μm. SPIRIT utilizes dual, meter-class, telescopes which translate along opposed deployable booms. The collimated beams from the telescopes are combined in a central instrument module operating at 4K and lower. Mission-enabling mechanisms include the large, optical delay line scan mechanism, the afocal collector telescope trolley drives, and the boom deployment mechanisms. This paper provides an overview of the mechanical aspects of the conceptual design created to meet the challenging instrument requirements.

We report results of a recently-completed pre-Formulation Phase study of SPIRIT, a candidate NASA Origins Probe mission. SPIRIT is a spatial and spectral interferometer with an operating wavelength range 25 - 400 microns. SPIRIT will provide sub-arcsecond resolution images and spectra with resolution R = 3000 in a 1 arcmin field of view to accomplish three primary scientific objectives: (1) Learn how planetary systems form from protostellar disks, and how they acquire their inhomogeneous composition; (2) characterize the family of extrasolar planetary systems by imaging the structure in debris disks to understand how and where planets of different types form; and (3) learn how high-redshift galaxies formed and merged to form the present-day population of galaxies. Observations with SPIRIT will be complementary to those of the James Webb Space Telescope and the ground-based Atacama Large Millimeter Array. All three observatories could be operational contemporaneously., 20 pages, 12 figures, accepted for publication in J. Adv. Space Res. on 26 May 2007

We report results of a recently-completed pre-Formulation Phase study of SPIRIT, a candidate NASA Origins Probe mission. SPIRIT is a spatial and spectral interferometer with an operating wavelength range 25 - 400 μm. SPIRIT will provide sub-arcsecond resolution images and spectra with resolution R = 3000 in a 1 arcmin field of view to accomplish three primary scientific objectives: (1) Learn how planetary systems form from protostellar disks, and how they acquire their chemical organization; (2) Characterize the family of extrasolar planetary systems by imaging the structure in debris disks to understand how and where planets form, and why some planets are ice giants and others are rocky; and (3) Learn how high-redshift galaxies formed and merged to form the present-day population of galaxies. Observations with SPIRIT will be complementary to those of the James Webb Space Telescope and the ground-based Atacama Large Millimeter Array. All three observatories could be operational contemporaneously.

We present a conceptual design for a scalable (10-50 meter segmented filled-aperture) space observatory operating at UV-optical-near infrared wavelengths. This telescope is designed for assembly in space by robots, astronauts or a combination of the two, as envisioned in NASA's Vision for Space Exploration. Our operations concept for this space telescope provides for assembly and check-out in an Earth Moon L2 (EML2) orbit, and transport to a Sun-Earth L2 (SEL2) orbit for science operations and routine servicing, with return to EML2 for major servicing. We have developed and analyzed initial designs for the optical, structural, thermal and attitude control systems for a 30-m aperture space telescope. We further describe how the separate components are packaged for launch by heavy lift vehicle(s) and the approach for the robot assembly of the telescope from these components.

The 3m Spherical Primary Optical Telescope (SPOT) will utilize a single ring of 0.86 m point-to-point hexagonal mirror segments. The f2.85 spherical mirror blanks will be fabricated by the same replication process used for mass-produced commercial telescope mirrors. Diffraction-limited phasing will require segment-to-segment radius of curvature (ROC) variation of ~1 micron. Low-cost, replicated segment ROC variations could be almost 1 mm, necessitating a method for segment ROC adjustment & matching. A mechanical architecture has been designed that allows segment ROC to be adjusted up to 400 microns while introducing a minimum figure error, allowing segment-to-segment ROC matching. A key feature of the architecture is the unique back profile of the mirror segments. The back profile of the mirror was developed with shape optimization in MSC.Nastran™ using optical performance response equations written with SigFit. A candidate back profile was generated which minimized ROC-adjustment-induced surface error while meeting the constraints imposed by the fabrication method.

The Geoscience Laser Altimetry System (GLAS) is a laser altimeter and LIDAR instrument on the Ice, Clouds, Environment Satellite (ICESat) mission. GLAS used 3 Nd:YAG lasers with 40 Hz rep rates at 4 Watts. All 3 lasers had to fire along a common beam path. Several mechanisms and optical assemblies were developed to allow the 3 lasers to fire down a common transmit path and exit the instrument. In the receive path of the GLAS instrument altimeter, there was a primary and redundant altimeter detector. A mechanism was designed, fabricated, and tested which would divert the incoming altimeter beam path from one detector to another. This mechanism was functionally similar to the mechanisms used on the transmit path. The Solar Ozone Limb Sounding Experiment II (SOLSE2) instrument had a requirement for rotating a visible (VIS) or ultra-violet (UV) filter into the instrument optical path. Both GLAS and SOLSE2 had similar operational and survival environments and lifetime requirements. A novel, precision rotational latching mechanism was designed to fulfill the requirements of both missions. The GLAS instrument had driving stability and repeatability requirements, such that if the mechanism met these stringent requirements, it would more than surpass the required performance for the SOLSE2 mechanism. The resulting mechanism, referred to as a “select mechanism” since it allows selection between 2 positions, was successfully designed and implemented for both missions. This paper describes the transmit path optical structures and select mechanisms of the GLAS & SOLSE2 instruments.

We present a new approach to building a modular segmented space telescope that greatly leverages the heritage of the Hubble Space Telescope and the James Webb Space Telescope. The modular design in which mirror segments are assembled into identical panels allows for economies of scale and for efficient space assembly that make a 20-m aperture approach cost effective. This assembly approach can leverage NASA’s future capabilities and has the power to excite the public’s imagination. We discuss the science drivers, basic architecture, technology, and leveraged NASA infrastructure, concluding with a proposed plan for going forward.