Moon-to-Earth: Eavesdropping on the GRAIL Inter-Spacecraft Time-Transfer Link using a Large Antenna and a Software Receiver
- Creators
- Esterhuizen, Stephan
Abstract
NASA's twin GRAIL [1] spacecraft (Ebb and Flow) arrived at Earth's Moon on New Year's Day, 2012. GRAIL's primary mission is to create a high-resolution map of the Moon's gravitational field by measuring very precisely the change in distance between the two spacecraft [2]. Each spacecraft transmits two signals to the other spacecraft, a PRN code modulated on a 2 GHz carrier (S-band), as well as an unmodulated carrier at roughly 33 GHz (Ka-band). Since it's not feasible to synchronize the two GRAIL spacecraft's clocks via GPS (as was done with GRACE), the S-band signals are used as a time-transfer link to synchronize either Ebb's clock to Flow or vice versa. As an independent measure to determine the clock offset of the GRAIL ultra-stable oscillators to UTC(NIST), an experiment was conducted where our JPL team used a large antenna on Earth to eavesdrop on the inter-spacecraft time-transfer link.
Additional Information
© 2012 California Institute of Technology. Government sponsorship acknowledged. The work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. Thanks to Kamal Oudrhiri for overseeing this experiment. Thanks to Dong Shin, who designed the L-band to IF assembly and helped install this experiment in the DSS24 pedestal. Thanks to Gerhard Kruizinga and his team for producing oneway light time models used to generate the absolute timing offset plot. Thanks to Danny Kahan for helping with scripting of the PRSR. dc.date.issued 2012-09-20.Additional details
- Eprint ID
- 43346
- Resolver ID
- CaltechAUTHORS:20140113-140929184
- Created
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2014-03-03Created from EPrint's datestamp field
- Updated
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2019-10-03Created from EPrint's last_modified field