Satellite Orbital Conjunction Reports Assessing Threatening Encounters in Space
Top 10 Conjunctions by Maximum Probability
Top 10 Conjunctions by Minimum Range
As a service to the satellite operator community, the Center for Space Standards & Innovation (CSSI) now offers SOCRATES—Satellite Orbital Conjunction Reports Assessing Threatening Encounters in Space. This service will provide regular information on pending conjunctions on orbit over the coming week. Because of the potentially catastrophic consequences of such conjunctions going unnoticed, it is hoped that this service will help satellite operators avoid undesired close approaches through advanced mission planning.
Twice each day, CSSI runs a list of all satellite payloads on orbit against a list of all objects on orbit using the catalog of all unclassified NORAD two-line element sets (TLEs) releasable to the public to look for satellite conjunctions over the next seven days. The reason for limiting the search to conjunctions with payloads is to give satellite operators an opportunity to plan—or obtain planning services—to move their satellites out of harm's way (if their satellite is maneuverable), or to take other appropriate measures. Since there currently is no way of knowing which payloads are still active, all payloads are considered.
The runs are made using, STK/CAT—STK's Conjunction Analysis Tools—and the SGP4 propagator in STK. STK/CAT is set to look for all conjunctions which are within 5 km at time of closest approach (TCA) and reports both minimum distance and maximum probability for the conjunction. Because the minimum distance method ignores position covariance information and can lead to an exaggerated assessment of the true risk, CSSI believes the maximum probability method provides a more reasonable (although still conservative) assessment of the true risk. For more details on the maximum probability method, see Dr. Sal Alfano's paper titled "Relating Position Uncertainty to Maximum Conjunction Probability" (2,493,912 bytes).
For more information on SOCRATES, see the papers, briefings, and animations on "Satellite Orbital Conjunction Reports Assessing Threatening Encounters in Space (SOCRATES)" presented at the 15th AAS/AIAA Space Flight Mechanics Conference, the Fourth European Conference on Space Debris, and the Sixth US-Russian Space Surveillance Workshop.
STK/CAT allows users to examine conjunctions of interest in further detail. For those users seeking additional comprehensive, customized, and/or recurring conjunction analyses, CSSI has partnered with 1Earth Research, LLC to provide these services. Please contact analysis@1EarthResearch.com for further details.
|TLE Data||Space Data|
Dr. T.S. Kelso
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