COUNTING DOWN TO THE LAUNCH OF POPACS

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1 COUNTING DOWN TO THE LAUNCH OF POPACS (Polar Orbiting Passive Atmospheric Calibration Spheres) Gil Moore Utah State University Walter Holemans Planetary Systems Corporation Jin Kang U.S. Naval Academy

2 A project to measure the effects of solar flares and coronal mass ejections on the density of Earth s upper atmosphere during Solar Cycles 24 and 25

3 Program Status Six 10-cm-diameter hollow spheres have been machined from 6061-T6 Aluminum These spheres have been filled with sand and Bismuth shot to make them weigh 1 kg, 1.5 kg and 2 kg, respectively

been polished Four lightweight Aluminum spacers have been

4 The spheres have been welded shut, three of them have been coated with space-proven AZ-93 flat white paint, and three have been polished Four lightweight Aluminum spacers have been designed by Drexel University to support the spheres during launch into orbit

launch and deploy it into orbit Utah State University has purchased a 3U CubeSat

5 Planetary Systems Corporation has provided one of its newly developed 3U Canisterized Satellite Dispensers (CSDs) to support this 6 kg payload during launch and deploy it into orbit Utah State University has purchased a 3U CubeSat slot on a SpaceX Falcon 9 that will be launched from Vandenberg AFB during Solar Maximum 24

The spheres and spacers will be deployed from the CSD aboard the Falcon 9 into an initial 325 km x 1500 km orbit, inclined 80 degrees to the earth s equator, with a 104 minute period The lightweight,

6 The spheres and spacers will be deployed from the CSD aboard the Falcon 9 into an initial 325 km x 1500 km orbit, inclined 80 degrees to the earth s equator, with a 104 minute period The lightweight, high-drag spacers will de-orbit, due to atmospheric drag at perigee, and be consumed within a few months, while the much more dense spheres will orbit for approximately 10, 12.5 and 15 years, before de-orbiting and being consumed

8 Each sphere will be tracked by the Space Surveillance Network (SSN) Phased Array radars and GEODS optical sites of the U.S. Strategic Command s Joint Space Operations Center (JSPOC),

10 Atmospheric drag at perigee will cause the spheres orbits to decay at different rates, due to their different masses and, thus, their ballistic coefficients The JSPOC will periodically publish Two Line Element sets (TLEs), similar to those below, that define each sphere s orbital elements at the start of a given epoch U 98067A

An international network of amateur and university observers who own Go-To telescopes with built-in GPS receivers, computers and drives will use those TLEs to track the spheres during visible passes

11 An international network of amateur and university observers who own Go-To telescopes with built-in GPS receivers, computers and drives will use those TLEs to track the spheres during visible passes over their individual locations Using digital recorders attached to their telescopes, the observers will record frames of each sphere s position at a given moment within the background stars. They will then use a digitized star catalog and pattern recognition software to measure the sphere s right ascension and declination at the precise time of the observation.

13 The optical observers will use the Internet to share their measurements of sphere right ascension, declination and time, plus longitude, latitude and altitude of their own site, with other observers all over the world. They will then calculate each sphere s orbit, using the angles-only method of LaPlace or the Gooding method, and compute their own TLEs As the spheres orbits shrink, over time, due to atmospheric drag, the observers will be able to compute the density of the earth s upper atmosphere at the altitude, latitude and longitude of each sphere s perigee pass, using software provided to the POPACS project by Analytical Graphics, Inc. They will measure the global variations in Earth s upper atmospheric density before, during and after the occurrence of solar flares and coronal mass ejections

14 The optical teams will forecast atmospheric density variability in response to future solar stimuli during Solar Cycles 24 and 25 and compare their results with solar- terrestrial scientists of the U.S. Naval Research Laboratory (NRL), who use TLEs from thousands of satellites and an efficient fast algorithm to construct a database of atmospheric density The POPACS project will award periodic prizes to the individual observers whose sphere right ascension and declination measurements consistently come closest to those provided by the AFSPC using reference orbits derived from their radar and GEODS optical sites

15 The authors would like to thank the student team at Drexel University, Dr. T.S. Kelso and Wes Bradley of Analytical Graphics, Inc., Bruce Bowman of the Air Force Space Command, Dr. Judith Lean of the Naval Research Laboratory, Machine of Colorado Springs, CO, Petersen, Inc. of Ogden, UT, Dr. Jan Sojka and Joseph Jenkins of Utah State University, Dr. Alan Thurgood of the Space Dynamics Laboratory and Dustin Doud of SpaceX for helping us get this project started. If you have constructive suggestions for this work in progress and/or would like to become an observer, please contact Gil Moore, POPACS Project Director at or (cell)

COUNTING DOWN TO THE LAUNCH OF POPACS (POLAR ORBITING PASSIVE ATMOSPHERIC CALIBRATION SPHERES)

SSC12-X-3 COUNTING DOWN TO THE LAUNCH OF POPACS (POLAR ORBITING PASSIVE ATMOSPHERIC CALIBRATION SPHERES) Walter Holemans Planetary Systems Corporation 2303 Kansas Ave., Silver Spring, MD; 301-495-0737;