NASA Scientific and Technical Aerospace Reports

experience gained from the morning constellation and the planning for the afternoon constellation.
Author
Earth Observing System (Eos); Spacecraft Launching; Formation Flying; Earth Sciences
20040070758 NASA Glenn Research Center, Cleveland, OH, USA
Microgravity Environment on the International Space Station
DeLombard, Richard; Hrovat, Kenneth; Kelly, Eric; McPherson, Kevin; April 2004; 15 pp.; In English; 42nd Aerospace
Sciences Meeting and Exhibit, 5-8 Jan. 2004, Reno, NV, USA
Contract(s)/Grant(s): WBS 22-101-46-02
Report No.(s): NASA/TM-2004-213039; AIAA Paper 2004-0125; E-14473; No Copyright; Avail: CASI; A03, Hardcopy
A primary feature of the International Space Station will be its microgravity environment--an environment in which the
effects of gravity are drastically reduced. The International Space Station design has been driven by a long-standing, high-level
requirement for a microgravity mode of operation. Various types of data are gathered when science experiments are conducted.
The acceleration levels experienced during experiment operation should be factored into the analysis of the results of most
microgravity experiments. To this end, the Space Acceleration Measurement System records the acceleration levels to support
microgravity researchers for nearly three years of International Space Station operations. The Principal Investigator
Microgravity Services project assists the experiments principal investigators with their analysis of the acceleration
(microgravity) environment. The Principal Investigator Microgravity Services project provides cataloged data, periodic
analysis summary reports, specialized reports for experiment teams, and real-time data in a variety of user-defined formats.
Characterization of the various microgravity carriers (e.g., Shuttle and International Space Station) is also accomplished for
the experiment teams. Presented in this paper will be a short description of how microgravity disturbances may affect some
experiment classes, a snapshot of the microgravity environment, and a view into how well the space station is expected to meet
the user requirements.
Author
Gravitational Effects; Microgravity; International Space Station; Real Time Operation
20040071003 NASA Marshall Space Flight Center, Huntsville, AL, USA
Advanced Video Guidance Sensor (AVGS) Development Testing
Howard, Richard T.; Johnston, Albert S.; Bryan, Thomas C.; Book, Michael L.; 2004; 11 pp.; In English; SPIE Defense and
Security Symposium, 12-16 Apr. 2004, Orlando, FL, USA; No Copyright; Avail: CASI; A03, Hardcopy
NASA’s Marshall Space Flight Center was the driving force behind the development of the Advanced Video Guidance
Sensor, an active sensor system that provides near-range sensor data as part of an automatic rendezvous and docking system.
The sensor determines the relative positions and attitudes between the active sensor and the passive target at ranges up to 300
meters. The AVGS uses laser diodes to illuminate retro-reflectors in the target, a solid-state camera to detect the return from
the target, and image capture electronics and a digital signal processor to convert the video information into the relative
positions and attitudes. The AVGS will fly as part of the Demonstration of Autonomous Rendezvous Technologies (DART)
in October, 2004. This development effort has required a great deal of testing of various sorts at every phase of development.
Some of the test efforts included optical characterization of performance with the intended target, thermal vacuum testing,
performance tests in long range vacuum facilities, EMI/EMC tests, and performance testing in dynamic situations. The sensor
has been shown to track a target at ranges of up to 300 meters, both in vacuum and ambient conditions, to survive and operate
during the thermal vacuum cycling specific to the DART mission, to handle EM1 well, and to perform well in dynamic
situations.
Author
Guidance Sensors; Rendezvous Guidance; Digital Systems; Cameras; Thermal Cycling Tests; Signal Processing
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