University of Colorado Boulder ASEN 6008 Interplanetary Mission Design Spring 2015 Kate Davis Launch Considerations 1

University of Colorado Boulder  One of the most required aspects of an interplanetary mission design. ◦ Until we invent teleportation or master the control of an Einstein-Rosen bridge  From a mission design perspective, the primary three concerns we have for choosing a launch site: ◦ Availability / cost ◦ Performance (closer to the equator = more performance) ◦ Range of orbital inclinations / departure asymptotes that may be reached 2

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University of Colorado Boulder 5 Courtesy of NASA: Sergeyevsky, A. B., Snyder, G. C., and Cunniff, R. A., Interplanetary Mission Design Handbook, Vol. 1, Part 2, Earth to Mars Ballistic Mission Opportunities, , JPL Publication 82-43, 1983.

University of Colorado Boulder  As you recall: ◦ The right ascension and declination of the launch may be computed from the outgoing v-infinity vector, departing Earth 6

University of Colorado Boulder  The Departing Hyperbolae 7

University of Colorado Boulder  The Departing Hyperbolae  There are an infinite number of options. Though not all are created equal. 8

University of Colorado Boulder  The Departing Hyperbolae  One constraint: ◦ Launch vehicles may target departure hyperbolae with inclinations less than or equal to the launch site latitude without suffering performance penalties. ◦ The minimum inclination of the departure hyperbolae is equal to the declination of the launch asymptote 9

University of Colorado Boulder  The Departing Hyperbolae  Question: what coordinate frame are these vectors in? 10

University of Colorado Boulder  V is some value between and degrees, depending on the situation. ◦ Transformation from an ecliptic frame to an equatorial frame of reference. ◦ Earth’s obliquity  DLA equatorial describes the minimum inclination of a parking orbit used. ◦ If the parking orbit has a smaller inclination, then there will be launch penalties. 11

University of Colorado Boulder  In addition to desired inclination, there is another HUGE factor to consider when launching.  Allowable Launch Azimuths  Launching over inhabited regions is generally frowned upon ◦ Most people wouldn’t want an SRB landing in their front yard. 12

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University of Colorado Boulder 14

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University of Colorado Boulder 17 Question 1 Which azimuth yields the highest performance for a launch vehicle? Question 2 What is the resulting orbital inclination? Question 3 What is the range of DLA values that don’t suffer a penalty? (Equatorial)

University of Colorado Boulder Assume: Launch from Florida into 28.5 deg inclined LEO parking orbit. Observe: θ at right  If you wanted to target an equatorial DLA of 0 degrees, where would you perform the Earth-departure maneuver?  If you wanted to target an equatorial DLA of 28.5 deg, where would you perform the Earth-departure maneuver? 18

University of Colorado Boulder  How do you target RLA?  Launch at the right time!  Pay attention to your launch vehicle provider. 19 Can the upper stage re-light? Does the system require staging orbits? How many?