David A. Hinkley

CubeSat communications transceiver for increased data throughput

CubeSat communication links require small size, low power, and low cost transceivers. Link parameters resulting from the satellites Low Earth Orbit (LEO) can impair transceiver performance, degrading mission data throughput. This paper describes the characteristics and control of a new CubeSat transceiver. The new transceiver provides an estimated 300% increase in data throughput for a typical 45-degree maximum elevation angle LEO pass over the Aerocube-2 transceiver.

Single-frequency low-threshold continuous-wave 3-μm periodically poled lithium niobate optical parametric oscillator

A low-threshold (350-mW) stable single-frequency continuous-wave optical parametric oscillator was demonstrated. Tunable idler output up to 450 mW was obtained near 3 μm by resonating both the signal wave and a single-frequency 1.06-μm Nd: YAG pump laser in a periodically poled lithium niobate optical-parametric-oscillator ring resonator. Tunable output wavelengths from 2.9 μm to 3.25 μm were also demonstrated. By inserting an etalon, we achieved an absolute midinfrared single-frequency stability of +/-0.01 nm.

A linear mode photon-counting (LMPC) detector array in a CubeSat to enable earth science LiDAR measurements

Work is underway to demonstrate a new linear mode photon counting (LMPC) detector in Earth orbit inside a 3U Cubesat. The detector is 16 pixel (2×8) HgCdTe electron Avalanche Photodiode (e-APD) array developed by DRS Technologies, C4ISR Group, Infrared Sensors and Systems (ISS). It has ~70% quantum efficiency and single photon level response at wavelengths from 0.4 to 4 microns. The detector will be mounted in a small integrated detector cooler assembly that operates the e-APD at 80K. The LMPC CubeSat is planned for launch into a 450 km × 820 km × 99 degree inclination orbit in July 2016. In space measurements are planned at 1.06, 1.57 and 2.06 microns using internal sources and with ground-to-space experiments.

Efficient collection and manipulation of laser diode output using refractive micro-optics

The collection efficiency and collimation ability of high numerical aperture circular and cylindrical GaP lenses were evaluated using single index-guided and gain-guided laser diode emitters. Comparisons were made between 200 micrometers focal length cylindrical lenses (NA equals 0.75) fabricated by an accurate repetitive step-wise etching method and 70 micrometers focal length cylindrical lenses (NA > 1) fabricated by a simple resist reflow technique. Lens arrays (200 - 300 micrometers fl, 0.5 - 0.75 NA) fabricated by the repetitive resist-etch method were used to collimate the output of a diode bar consisting of 100 index-guided elements. Refocusing of the collimated light with a macro-optic (for pumping a Nd:YVO4 laser) produced a spot that was on average 2 - 3 times larger than the diffraction limit and contained up to 88% of the total bar output. The deviation from the theoretical limit was examined in terms of lens fabrication accuracy and alignment tolerances between the diode and lens arrays, which were shown to be on the order of 1 - 2 micrometers .

Single photon HgCdTe avalanche photodiode and integrated detector cooler assemblies for space lidar applications

A linear mode photon counting HgCdTe avalanche photodiode (APD) focal plane array (FPA) detector was developed for space lidar applications. An integrated detector cooler assembly (IDCA) was manufactured using a miniature Stirling cooler. The HgCdTe APD demonstrated a greater than 60% photon detection efficiency from 0.9 to 4.3 μm wavelength and a dark count rate less than 250,000/s. The IDCA cooled the FPA to 110K from ambient room temperature at a total electrical power of 7 W. The IDCA has passed environmental tests, including vibration, thermal cycling and thermal vacuum tests.

On-orbit characterization of space solar cells on nano-satellites

The Aerospace Corporation has been building, testing, and flying miniature satellites in the pico-and nano-satellite class for over a decade. Significant advances have been made to the bus avionics unit and other satellite subsystems during this time. The advances have enabled various on-orbit tests and experiments, one of which has been to host space solar cell experiment payloads. Recent solar cell flight experiments on Aerospaces CubeSats (AeroCubes) demonstrated several subsystems can simultaneously operate to obtain precise measurements of space solar cell performance. Low cost, rapid return CubeSat missions can be valuable development tools for advancing the readiness level of space technologies.

Flight of the pico satellite solar cell testbed (PSSC Testbed) space experiment

The PSSC Testbed flight data confirmed that the picosatellite can be used for measuring I–V characteristics of solar cells. Continuing monitoring of the I–V measurement will allow determining the actual degradation of the solar cells due to exposure to the space environment. Mission success for the initial low earth orbit (LEO) space flight provided proof of concept for the PSSC Testbed. Subsequent mission will fly in a geosynchronous transfer orbit (GTO), in which a 450-day radiation exposure of the solar cells will be equivalent to that of 15 years radiation exposure in geosynchronous orbit.

Solar cell calibration for the Pico Satellite solar cell testbed (PSSC Testbed) space flight experiment

The results of this preflight calibration of the measurement electronics and the individual solar arrays will allow corrections to be made to flight data for determining the actual degradation of the test solar cells as a result of exposure to the space environment.