TOPIC: S4 Exploration of the Universe Beyond Our Solar System

S4.01 Sensor and Detector Technology for Visible, IR, Far IR and Submillimeter
S4.02 Detector Technologies for UV, X-Ray, Gamma-Ray and Cosmic-Ray Instruments
S4.03 Cryogenic Systems for Sensors and Detectors
S4.04 Optics Manufacturing and Metrology for Telescopes
S4.05 Data Analysis Technologies for Potential Gravity Wave Signals
S4.06 Terrestrial Balloon Technology

The Universe division of the NASA/GSFC is charged with exploring the universe beyond the solar system - out to its very edges. To do this requires ever more sophisticated instruments (surpassing Chandra, Spitzer, and Hubble) with larger and better optics and more sensitive detector systems. Future mission may include spacecraft in formation-flyin; optics that fold and deploy and can be assembled on orbit; as well as larger arrays of detectors: bolometers, microcalorimeters, and room temperature semiconductors. Some of these arrays may contain billions of pixels. Our missions cover the full range of the electromagnetic spectrum (from sub-mm to gamma-rays) and gravitational waves. Some of our major science goals are to identify dark matter, to understand dark energy, to produce a census of black holes, to image material in the accretion disks around black holes and to measure gravitational waves from a wide range of sources. In addition, we are exploring new technologies for terrestrial sub-orbital platforms including long duration balloons, tethered balloons, and airships. We are soliciting ideas and concepts in six areas covering optical systems, UV, visible, IR and sub-mm detectors, x-ray and gamma-ray detectors, lasers for gravitational wave measurements, and sub-orbital platforms. The subtopics in this area are described in detail in each subtopic section.

• Large (4 meter), lightweight, deployable antennas for frequencies between 180 to 660 GHz. Reflectors for such antennas with surface densities of 10 kg/m² or less.
  
• Broadband (> 2 GHz, 4 GHz preferred), modest resolution (10 MHz), low power (< 5 watt) digital spectrometers for submillimeter spectroscopy. This may include enabling technologies such as:
  
  • Efficient FPGA firmware for spectral analysis including polyphase filterbanks;
    
  • High speed, low power, space qualifiable digitizers with analog bandwidths of > 5 GHz and preferably up to 18 GHz, sample rates > 5 Gs/s, 4 to 6 bit resolution, and simple interface to present FPGAs;
    
  • Hardware (ex. ASICs) for low power implementation of digital signal processing.
    
• Broad bandwidth, low power, flight qualifiable spectrometers. Band of interest is 6 to 18 GHz or higher with ~200 MHz resolution.
  
• Reliable, tunable, spurious free, and flight qualifiable local oscillators for SIS mixers covering 190 to 270 GHz and 600 to 660 GHz.
  
• Broadband cryogenic isolators covering 6 to18 GHz.
  

• The next generation of gravitational missions will require greatly improved inertial sensors. Such an inertial sensor must provide a carefully fabricated test mass, which has interactions with external forces (i.e., low magnetic susceptibility, high degree of symmetry, low variation in electrostatic surface potential, etc.) below 10^-16 of the Earth's gravity, over time scales from several seconds to several hours. The inertial sensor must also provide housing for containing the proof mass in a suitable environment (i.e., high vacuum, low magnetic and electrostatic potentials, etc.);
  
• Advanced Charged Couple Device (CCD) detectors, including improvements in UV quantum efficiency and read noise, to increase the limiting sensitivity in long exposures and improved radiation tolerance. Electron-bombarded CCD detectors, including improvements in efficiency, resolution, and global and local count rate capability. In the X-ray, we seek to extend the response to lower energies in some CCDs, and to higher, perhaps up to 50 keV, in others;
  
• Significant improvements in wide band gap (such as GaN and AlGaN) materials, individual detectors, and arrays for UV applications;
  
• Improved microchannel plate detectors, including improvements to the plates themselves (smaller pores, greater lifetimes, alternative fabrication technologies, e.g., silicon), as well as improvements to the associated electronic readout systems (spatial resolution, signal-to-noise capability, and dynamic range), and in sealed tube fabrication yield;
  
• Imaging from low-Earth orbit of air fluorescence, UV light generated by giant airshowers by ultra-high energy (E >1019 eV) cosmic rays require the development of high sensitivity and efficiency detection of 300 - 400 nm UV photons to measure signals at the few photon (single photo-electron) level. A secondary goal minimizes the sensitivity to photons with a wavelength greater than 400 nm. High electronic gain (~106), low noise, fast time response (< 10 ns), minimal dead time (< 5% dead time at 10 ns response time), high segmentation with low dead area (< 20% nominal, < 5% goal), and the ability to tailor pixel size to match that dictated by the imaging optics. Optical designs under consideration dictate a pixel size ranging from approximately 2 x 2 mm² to 10 x 10 mm². Focal plane mass must be minimized (2 g/cm² goal). Individual pixel readout. The entire focal plane detector can be formed from smaller, individual sub-arrays.
  

• Superconducting electronics for cryogenic X-ray detectors such as SQUID-based amplifiers and their multiplexers for low impedance cryogenic sensors and superconducting single-electron transistors and their multiplexers for high impedance cryogenic sensors;
  
• Micromachining techniques that enhance the fabrication, energy resolution, or count rate capability of closely-packed arrays of X-ray calorimeters operating in the energy range from 0.1 - 10 keV; and
  
• Surface micromachining techniques for improving integration of X-ray calorimeters with read-out electronics in large-scale arrays.
  

• Low-power ASICs and the associated high-density interconnects and component arrays to interface them to detector arrays;
  
• Superconducting tunnel junction devices and transition edge sensors for the UV and X-ray regions. For the UV, these offer a promising path to having "three-dimensional" arrays (spatial plus energy).
  

• Techniques for fabrication of close-packed arrays, with any requisite thermal isolation, and sensitive (SQUID or single electron transistor), fast, readout schemes and/or multiplexers;
  
• Arrays of CZT detectors of thickness 5 - 10 mm to cover the 10 - 500 keV range, and hybrid detector systems with a Si CCD over a CZT pixelated detector operating in the 2 - 150 keV range.
  

• Large format (4 K x 4 K and larger); high quantum efficiency;
  
• Small pixel size;
  
• Large well depth;
  
• Low read noise;
  
• Fast readout;
  
• Low power consumption (including readout);
  
• Intrinsic energy and/or polarization discrimination (3D or 4D detector);
  
• Active pixel sensors (back-illumination, UV sensitivity); and
  
• High-resolution image intensifiers, UV and EUV sensitive, insensitive to moisture.
  

• Highly efficient coolers in the range of 4 - 10 Kelvin as well as at 50 milli-Kelvin and below, and cryogen-free systems, which integrate these coolers together;
  
• Highly reliable, efficient, low-cost Stirling and pulse tube cooler technologies in the 15 Kelvin and 35 Kelvin regions;
  
• Essentially vibration-free cooling systems such as reverse Brayton cycle cooler technologies;
  
• Highly efficient magnetic and dilution cooling technologies, particularly at very low temperatures;
  
• Hybrid cooling systems that make optimal use of radiative coolers; and
  
• Miniature, MEMS, and solid-state cooler systems.
  

• Innovative concepts for trajectory control and/or station keeping for effectively maneuvering large terrestrial balloons in either the horizontal latitude or vertical altitude plane or both;
  
• Innovative floatation systems for water recovery of NASA's scientific payloads;
  
• Innovative guided or gliding parachutes systems for use in thin atmospheres.
  

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