Engineering topics

Sandusky, John V.

Publications and source records attributed to Sandusky, John V..

4 records

DOE OSTI2024

helioLuna: Prospect for cislunar spacecraft and near-earth asteroid detection using heliostat fields at night

We experimentally and computationally investigate a proposed frequency-domain method for detecting and tracking cislunar spacecraft and near-earth asteroids using heliostat fields at night. Unlike imaging, which detects spacecraft and asteroids by their streak in sidereally-fixed long-exposure photographs, our proposed detection method oscillates the orientation of heliostats concentrating light from the stellar field and measures the light’s photocurrent power spectrum at sub-milliHertz resolution. If heliostat oscillation traces out an ellipse fixed in the galactic coordinate system, spacecraft or asteroids produce a peak in photocurrent power spectrum at a frequency slightly shifted from the starlight peak. The frequency shift is on the scale of milliHertz and proportional to apparent angular rate relative to sidereal. Relative phase corresponds to relative angular position, enabling tracking. A potential advantage of this frequency-domain method over imaging is that detectivity improves with apparent angular rate and number of heliostats. Since heliostats are inexpensive compared to an astronomical observatory and otherwise unused at night, the proposed method may cost-effectively augment observatory systems such as NASA’s Asteroid Terrestrial-impact Last Alert System (ATLAS).

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2017

Massively parallel diffuse optical tomography

Diffuse optical tomography systems and methods are described herein. In a general embodiment, the diffuse optical tomography system comprises a plurality of sensor heads, the plurality of sensor heads comprising respective optical emitter systems and respective sensor systems. A sensor head in the plurality of sensors heads is caused to act as an illuminator, such that its optical emitter system transmits a transillumination beam towards a portion of a sample. Other sensor heads in the plurality of sensor heads act as observers, detecting portions of the transillumination beam that radiate from the sample in the fields of view of the respective sensory systems of the other sensor heads. Thus, sensor heads in the plurality of sensors heads generate sensor data in parallel.

36 MATERIALS SCIENCE↗

NASA NTRS2000

Overview of the Preliminary Design of the Optical Communication Demonstration and High-Rate Link Facility

Tlis paper presents an overview of the preliminary design of both the flight and ground systems of the Optical Communication Demonstration and High-Rate Link Facility which will demonstrate optical communication from the International Space Station to ground after its deployment in October 2002. The overview of the preliminary design of the Flight System proceeds by contrasting it with the design of the laboratory-model unit, emphasizing key changes and the rationale behind the design choices. After presenting the preliminary design of the Ground System, the timetable for the construction and deployment of the flight and ground systems is outlined.

Sandusky, John V.↗

NASA NTRS1999

Design of a 2.5 Gbps Optical Transmitter for the International Space Station

A high data rate laser transmitter assembly (LTA) has been designed as the source for an optical free-space communication link between the International Space Station and the 1-meter Optical Communication Telescope Laboratory (OCTL) to be built at the Table Mountain Facility (IMF, Wrightwood, CA). The transmitter design concept uses a fiber-based master oscillator power amplifier (MOPA) configuration with an average output power of 200 made at a 1550 nm transmit wavelength. This transmitter source is also designed to provide a signal at 980 nm to the Silicon-based focal plane array for the point-ahead beam control function. This novel integration of a 980 nm boresight signal allows the use of Silicon based imagers for the acquisition/tracking and point-ahead functions, yet permits the transmit signal to be at any wavelength outside the Silicon sensitivity. The LTA, a sub-system of the Flight Terminal, has been designed to have a selectable data rate from 155 - 2500 Mbps in discrete steps. It also incorporates a 2.5 Gbps pseudo-random bit sequence (PRBS) generator for complete link testing and diagnostics. The design emphasizes using commercial off the shelf components (COTS).

Ortiz, Gerardo G.↗