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Pre-Coat and Stake (Left: Feb. 3, 2003 Right: Feb. 14, 2003) |
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Post-Stake and Coat (Feb. 23, 2003) |
| Mass | 117.4 grams, with conformal coat |
| Power | 48 mA @ 5V 60 mA @ 2.5V |
| Functions | Instrument timing, laser fire command, 6-channel time-of-flight measurement. Two channels are multi-stop, 15 events deep. |
| Performance | 8 Hz nominal frame rate (programmable 1, 6, 8, or 10 Hz) Time reference: spacecraft ultrastable oscillator Timing resolution approximately 380 ps |
| Design/Analysis Team | Rich Katz Igor Kleyner Rod Barto |
| PCB Layout | Banks Walker |
| Assemblers | Cindy Goode, Carol Zepp, Laura Cook, Dorrie Hall, Alice Snively, Traci Lampe |
| Polymerics | John Grondalski, Jim Cook |
| Quality Assurance | Frances Famous, Steve Himes, Stan Kirk |
A special thanks to Nick Paschalidis and Steve Jaskulek of the Johns Hopkins University/Applied Physics Laboratory for the TOF-A devices and their technical support. |
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TOF Evaluation/Burn-In Board
TOF Evaluation/Burn-In Board In Test
Instrumentation
Control Panel
Running a Time Interval Sweep, 100 ps Steps
The above article is posted courtesy of Aviation Week and Space Technology (AW&ST)
for non-commercial use. Copyright and all publication rights remain with AW&ST.
Originally published in the July 26, 2004 edition, pages 58-59.
The above article is posted courtesy of Aviation Week and Space Technology (AW&ST)
for non-commercial use. Copyright and all publication rights remain with AW&ST.
Originally published in the August 9, 2004 edition, pages 58-59.
For more information:
Messenger at the Kennedy Space Center, June 17, 2004
MESSENGER Mercury Laser Altimeter in Aerospace America's "2003: The Year in Review"
Laser Remote Sensing Branch Page for MLA
NASA Goddard Space Flight Center Applied Engineering & Technology Directorate
Two-Way Laser Link over Interplanetary Distance
David E. Smith,1 Maria T. Zuber,1,2 Xiaoli Sun,1 Gregory A. Neumann,1,2 John F. Cavanaugh,1 Jan F. McGarry,1 Thomas W. Zagwodzki1
1 NASA Goddard Space Flight Center
2 MITScience, January 6, 2006, page 53
Asynchronous Laser Transponder Experiment in Deep Space Using MESSENGER’s Mercury Laser Altimeter
G.A. Neumann1,2, D.E. Smith1, M.T. Zuber2,1 , X. Sun1, J.F. Cavanaugh1, J.F. McGarry1, T.W. Zagwodski1
1 NASA Goddard Space Flight Center
2 MITAGU Fall Mtg. 2005
G51A-0808The Mercury Laser Altimeter (MLA) aboard the MErcury Surface, Space Environment, GEochemistry, and Ranging (MESSENGER) spacecraft ranged to Earth as part of its in-flight calibration activities, while NASA’s Goddard Geophysical Astronomical Observatory (GGAO) fired laser pulses at MLA. On two separate afternoons, while MESSENGER was visible above the horizon at a distance of 24 million km, trains of 16 and 25 consecutive pulses were detected at GGAO with inter-arrival times matching those transmitted by MLA, while for 30 minutes on one afternoon at least 90 pulses from GGAO were detected by MLA. A linear fit to the MLA pulse time-of-flight revealed a 4.154 km/s Doppler shift in the nominal 8-Hz firing rate, with the majority of pulse centroid times fit to within 300 ps, and for the extended but weaker detections at MESSENGER, the majority could be fit by a quadratic curve within 2.5 ns. The ability to make such precise measurements, together with MESSENGER's stable on-board clock, allows a solution with formal covariances for two-way range, range-rate, and acceleration, as well as clock parameters. We discuss the implications of this calibration experiment for the measurement of orbital and geodetic parameters via asynchronous laser ranging.
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