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Conjunction Assessment Services Page

• Overview
• Qualifications
• Conjunction Analysis Data
• Outline of Services

Overview

1Earth Research is pleased to be partnering with Analytical Graphics, Inc. as a Solution Provider of satellite conjunction assessments and analyses. AGI's Center for Space Standards and Innovation (CSSI), using their space analysis tool STK, provides a list of the top 10 possible collisions between space objects, ordered by maximum probability and minimum miss distance. The list, called SOCRATES, is available at CSSI's web site, www.CenterForSpace.com. 1Earth, using STK and other customized software, offers additional comprehensive, customized, and/or recurring conjunction analyses for satellite operators.

Qualifications

Personnel at 1Earth have years of experience identifying and analyzing satellite conjunctions. Examples of the kind of work that we have done:

• Performed several on-call collision risk assessments for government and commercial satellites with space objects
• Identified and provided remedies for two satellites occupying overlapping geosynchronous slots
• Discovered a newly-launched satellite that was targeting an occupied slot
• Monitored a constellation of Low-Earth-Orbit satellites for conjunctions with defunct members.
• Monitored a constellation of Geosynchronous satellites for close approaches with other satellites and debris.
• Provided launch collision avoidance services for government satellites

Conjunction Analysis Data

A collision in space can have serious environmental, financial and national security consequences. However, the actual risk of such a collision is generally quite low. The on-going risk of collision is highly dependent on relative orbits and the local population of space objects. Estimation of this risk dependends heavily upon the accuracy with which one knows the locations of the two objects.

• Element set vs. element set: US Space Command maintains and distributes a list of satellite elements (available on the Celestrak web site). These low-accuracy but readily available data provide the basis for CSSI's list of top 10 conjunctions. Such estimates are highly useful for space awareness and monitoring, but should not be used for avoidance or maneuver planning.
• Operator data vs. element set: If one of the conjuncting objects is operated by its owner, then its ephemeris will be maintained at a higher accuracy than its corresponding element set. Further, the accuracy of the ephemeris may also be known and available. In such a case, a better estimate of collision risk may be formed using the owner ephemeris and the element set of the other object (whether debris or another operating satellite).
• Operator data vs. operator data: This case involves two operating satellites for which the owner's ephemeris is available. The operators may not have known of the conjunction, and now require a comparison of each other's predicted locations to determine the actual risk and potential avoidance maneuvers.
• Recurring conjunctions: In some cases, two operating satellites are known to occupy the same space, and it is desired to coordinate movements to reduce collision risk. Typically, operator data is compared with operator data to plan such coordinated maneuvers.

(Important note: Element sets provide predictions based only on past behavior. Owner ephemerides provide predictions which include planned maneuvers.)

Outline of Services

1Earth offers the following types of service to address the needs of satellite operators who wish to gain a deeper understanding of conjunctions between their assets and other space objects:

• Improved probability assessments
  • Maximum probability re-assessment based on owner data vs. element sets
  • Probability estimate using NASA linear probability model along with owner data, element sets, and data accuracy estimates (covariances)
  • Initiation of contact with conjuncting satellite's owner to estimate probability using their data
• Avoidance maneuver assessments and assistance
• Current and historical proximity surveys and population studies for an orbit or geosynchronous slot
• Analysis and remedy assistance for recurring satellite conjunctions between two operating satellites