Joseph Scott Stuart

PRE-DISCOVERY OBSERVATIONS OF DISRUPTING ASTEROID P/2010 A2

Solar system object P/2010 A2 is the first-noticed example of the aftermath of a recently disrupted asteroid, probably resulting from a collision. Nearly a year elapsed between its inferred initiation in early 2009 and its eventual detection in early 2010. Here, we use new observations to assess the factors underlying the visibility, especially to understand the delayed discovery. We present pre-discovery observations from the LINEAR telescope and set limits to the early-time brightness from SOHO and STEREO satellite coronagraphic images. Consideration of the circumstances of discovery of P/2010 A2 suggests that similar objects must be common, and that future all-sky surveys will reveal them in large numbers.

Design of volume hologram filters for suppression of daytime sky brightness in artificial satellite detection

We present a design methodology for volume hologram filters (VHFs) with telephoto objectives to improve contrast of solar-illuminated artificial satellites observed with a ground-based optical telescope and camera system operating in daytime. VHFs provide the ability to selectively suppress incoming light based on the range to the source, and are used to suppress the daylight background noise since signal (satellite) and noise (daylight scatterers) are located at different altitudes. We derive the overall signal-to-noise ratio (SNR) enhancement as the system metric, and balance main design parameters over two key performance considerations--daylight attenuation and spectral bandwidth--to optimize the functioning of VHFs. Overall SNR enhancement of 7.5 has been achieved. Usage of multi-pixel cameras can potentially further refine this system.

Performance assessment software for the EO-1 Advanced Land Imager

The performance assessment of the EO-1 Advanced Land Imager (ALI) requires software for processing data collected during sensor integration and test, ground calibration, and on- orbit operations. This paper describes the software developed for performance assessment processing and analysis of data collected on the ground during ALI and ground calibration. This involves various characterizations and calibrations of the ALI, including functional test, focus, MTF, radiometric response, spectral response, functional image reconstruction, and internal calibration lamp data processing. Processing examples are given, including results. Also, each section describes the use of this software to support the analysis of data collected on-orbit during mission operations, as well as the types of data to be collected and processed. The interface between MIT Lincoln Laboratory and the EO-1 Mission Operations Center at NASA Goddard Space Flight Center is also described.

Automated ground data acquisition and processing system for calibration and performance assessment of the EO-1 Advanced Land Imager

The calibration and performance assessment of the Earth Observing-1 (EO-1) Advanced Land Imager (ALI) required a ground data system for acquiring and processing ALI data. In order to meet tight schedule and budget requirements, an automated system was developed that could be run by a single operator. This paper describes the overall system and the individual Electrical Ground Support Equipment (EGSE) and computer components used. The ALI Calibration Control Node (ACCN) serves as a test executive with a single graphical user interface to the system, controlling calibration equipment and issuing data acquisition and processing requests to the other EGSE and computers. EGSE1, a custom data acquisition syste, collects ALI science data and also passes ALI commanding and housekeeping telemetry collection requests to EGSE2 and EGSE3 which are implemented on an ASIST workstation. The performance assessment machine, stores and processes collected ALI data, automatically displaying quick-look processing results. The custom communications protocol developed to interface these various machines and to automate their interactions is described, including the various modes of operation needed to support spatial, radiometric, spectral, and functional calibration and performance assessment of the ALI.

Detection of Artificial Satellites Using Optimized Volume Hologram Filters

We design and optimize volume hologram filters with telephoto objectives to mitigate the daytime sky background noise in the detection of solar-illuminated artificial satellites. Overall signal-to-noise ratio enhancement of 7.5 has been achieved.