2007 IIP Projects Awarded

Our pulsed laser approach measures the energies of laser pulses reflected from the Earth’s surface. Laser transmitters for CO2 and O2 are rapidly tuned on and off selected atmospheric CO2 and O2 absorption lines near 1572 nm and 765 nm. A laser at 1064 nm is used to measure surface height and aerosol backscatter profile. Time gating is used to isolate the echo pulses from the surface and to minimize errors from atmospheric scattering and solar background.

This proposal addresses critical aspects of the MSPI technology development that have not been dealt with in our earlier work, namely, demonstration of radiance and polarization imaging capabilities in the shortwave infrared (SWIR). Observations at 1.6-2.1 micrometers are essential for characterizing coarse-mode aerosol and cloud microphysical properties. To accommodate this requirement, we will carry out five tasks: (1) modify the existing MSPI brassboard camera to incorporate a diattenuation-compensated dichroic beamsplitter, sending UV/VNIR and SWIR light to two separate focal planes; (2) demonstrate that miniaturized spectropolarimetric filters meeting MSPI SWIR requirements can be built; (3) incorporate a commercially available HgCdTe detector array; (4) develop a focal-plane cooling approach for laboratory testing and establish a conceptual thermal engineering approach for the satellite instrument; and (5) integrate and test the upgraded brassboard camera using state-of-the-art polarization characterization equipment. Tasks 1 and 2 will bring critical components from TRL 3 to TRL 4. Tasks 3-5 will bring the entire system to TRL 5. The period of performance is 3 years, with an assumed start date of 9/29/2008.

The proposing team will apply their direct experience with the CloudSat radar design and implementation to address several areas of ACERAD. The overall radar system design will be addressed by developing a high-level conceptual design, performance requirements, a system-level block diagram, and a mechanical layout for a Ka- (i.e., 35 GHz) and W-band (i.e., 94 GHz) radar. More detailed design and prototyping is proposed for the radar front end and antenna. The proposed effort includes detailed antenna design, as well as implementation and testing of a scaled antenna prototype. We also plan to design and prototype the quasi-optical radar front end to provide various switching functions with the required low loss. Finally, we propose to undertake a study of an extremely high frequency (EHF) channel near 260-280 GHz. While not specifically mentioned in the Decadal Survey, the addition of such a channel would allow retrieval of droplet size distribution, which is requested in the Decadal Survey.

GRACE monitors the Earth gravity field using a microwave spacecraft-to-spacecraft ranging system. A laser ranging system can potentially improve performance for GRACE-II. A prototype interferometric ranging transponder was developed under a previous IIP opportunity (IIP-03-0015, 2004-2006). However it requires a requires a very stable laser frequency to improve on the GRACE performance.

A laser stabilization subsystem was not developed under the previous IIP program partly because the LISA project had been undertaking a suitable development. Early plans for the LISA project required laser frequency stability a factor of 15 better than the GRACE microwave frequency stability. Several institutions have shown that this can be achieved in a laboratory environment through use of a thermally isolated Fabry-Perot cavity (establishing TRL-4). Subsequently the LISA project has delayed development of laser stabilization as it investigates alternative signal processing schemes that can eliminate the stabilization requirement. This can be done with the three-spacecraft LISA, but stabilization is required for a two-spacecraft GRACE II.

Over a period of 36 months we will develop a prototype laser stabilization subsystem (TRL-6). We will design and fabricate a mechanical subsystem including a Fabry-Perot cavity and thermal isolation subsystems suited to the space environment while still meeting the performance requirements. We will also develop laser modulators and electronics for locking a laser to the cavity.

The proposal’s goal is to significantly enhance the readiness level of the new technologies required for SWOT, while laying the foundations for the next-generation missions to map water elevation for studying Earth. The work that we propose to reduce the risk of the main technological drivers of SWOT will address the following technologies: Ka-band radar interferometry antenna design, onboard interferometric SAR processor, and internally calibrated high-frequency (above 90 GHz) radiometer. The heritage of the radar interferometry is from the Wide-Swath Ocean Altimeter (WSOA) developed through a previous IIP-funded project under the same PI. The key personnel of the present proposal is the same as the WSOA Team. The change of Ku-band real-aperture radar for WSOA to a Ka-band SAR for SWOT will improve the spatial resolution by one to two orders of magnitude to meet the new oceanography and hydrology requirements. The first two technologies will address the challenges of the Ka-band SAR interferometry. The high-frequency radiometer will address the requirement for small-scale wet tropospheric corrections for coastal zone applications. The period of performance of the proposed effort is from June, 2008 to June, 2011. The entry TRL is 3 and the planned exit TRL is 5 for all tasks.

The fundamental Earth climate driver, the long-term balance between Earth’s absorption of radiative energy from the Sun and emission of radiation to space, is addressed in the NRC Decadal Survey’s CLARREO mission intended to obtain “climate benchmarks” through on-orbit traceability of measurements to SI units. The calibration method proposed improves the SI-traceable accuracy by the factor of >10 to the required levels for the CLARREO Scientific Objective of measuring the solar radiation reflected or scattered by the Earth.
This Earth-viewing hyperspectral imager will trace its calibration on-orbit through the solar spectral irradiance recommended in the Decadal Survey as a NOAA component of CLARREO. Solar irradiance is known to better radiometric accuracy than any other calibration source available on-orbit. By cross-calibrating a hyperspectral imager with solar spectral irradiance, using techniques LASP has proven on other spaceflight instruments, the Earth-viewing imager can be calibrated, validated, and tracked on-orbit to the required accuracy and traceability levels.

A hyperspectral imager capable of cross-calibrating via direct solar irradiance measurements will be prototyped. Accurate attenuation methods allowing such cross-calibrations will be demonstrated and validated using a NIST-calibrated detector. This calibration technology will enable the creation of a climate data record that can be linked to future observations and thus establish a benchmark for detecting climate change.

GEO delivers orders of magnitude increases over existing EOS observations in terms of simultaneous measurements (from a 2-D imaging array) and high revisit rate. The challenges for GEO-CAPE are to improve precision and accuracy of existing 2.3 μm CO capability, while using this well-validated IRCR technique at GEO, nearly 50 times
farther away than the Terra orbit. The “staring” advantage of GEO allows long integration times and captures multiple samples for frame-averaging to further improve signal-to-noise ratios. This 24-month project delivers significant technology return for the ESTO investment, and enables highly time- and space-resolved measurements of CO described in the Decadal Survey for public benefit. The project advances the TRL of the system measurement from TRL 3 to TRL 5.

We focus on characterizing the 2.3 μm IRCR subsystem, although both 2.3 μm and 4.6 μm subsystems are required to obtain boundary layer CO. MAPS and MOPITT performed robustly at 4.6 μm; we have been involved in these programs from the start. The Decadal Survey refocused tropospheric chemistry goals toward the lowest layers of the atmosphere, placing new emphasis on the 2.3 μm measurements which have only recently been discussed for MOPITT. Given that GEO-CAPE mission definition is expected to occur within 3 years based on the DS time table, we suggest that the best-value focus for the near-term is this evaluation of the performance of an IRCR at 2.3 μm for GEO-CAPE.

The PanFTS IIP instrument will be a dynamically-aligned plane mirror system using an all-flexure scan mechanism. Two separate optical trains (0.26-1 micron and 1-15 micron ) will share the scan and dynamic alignment systems. The output beams will drive separate two-dimensional focal plane arrays optimized for the spectral regions. The proposed IIP instrument development will occur in phases over the 36-month period of performance: (1) definition of requirements; (2) procurement and verification of focal plane arrays (FPA’s); (3) instrument design, fabrication and integration; (4) lab verification; and (5) field testing.

PanFTS will advance two key technologies: long-life, high precision scan mechanisms (entrance TRL=4, exit TRL=6), and high performance UV-Vis-IR FPA’s (entrance TRL=3, exit TRL=4). The PanFTS team has unequaled experience in the design and use of Fourier transform spectrometers for remote sensing of trace atmospheric species from space, balloons, aircraft and the ground.

– Retiring the optics and calibration risks of the SMLS sensor design by constructing and testing an airborne prototype of the SMLS sensor and calibration system – A-SMLS – using an existing testbed, prototype sideband-separating mixers, line sources, and advanced spectrometers and calibration targets.

– Retiring the development risks of the cryogenics system by developing a flight-like cryostat and demonstrating an end-to-end prototype of the SMLS signal path from the antenna interface through the back-end electronics, and quantifing its stability, calibration accuracy, linearity, and sensitivity.

– Demonstrating, with A-SMLS, the potential science measurement capability of SMLS by measuring the concentration of upper tropospheric pollutants such as CO and ozone transported from Asia, or H2CO transported from the boundary layer by summer convective events, over the South Eastern US.

Specific important benefits to NASA include:
1. A demonstration of the key components of a highly innovative and capable instrument for GACM.
2. A quantification of the requirements for, and design of, a suitable cryocooler for SMLS.
3. An airborne instrument for advancing the TRL of millimeter-wave spectrometer technologies while conducting unique studies of chemistry and climate in the upper troposphere.

Over a two-year period of performance, Ball Aerospace will design, test, and fly on an aircraft a demonstration of the ESFL. The goal of the flight tests is to collect sufficient data over various types of vegetation that science members of the team can evaluate the ESFL for its usefulness to the proposed DESDynI mission. The effort will mature this new concept from a Technology Readiness Level (TRL) of 3 to 5.