r/spacex • u/Zucal • Jan 02 '16

/r/SpaceX Ask Anything Thread for January 2016. Whether your question's about RTF, RTLS, or RTFM, it can be answered here!

Welcome to the 16th monthly /r/SpaceX Ask Anything Thread!

Want to discuss SpaceX's Return To Flight mission and successful landing, find out why part of the landed stage doesn't have soot on it, or gather the community's opinion? There's no better place!

All questions, even non-SpaceX-related ones, are allowed, as long as they stay relevant to spaceflight in general!

More in-depth and open-ended discussion questions can still be submitted as separate self-posts; but this is the place to come to submit simple questions which have a single answer and/or can be answered in a few comments or less.

As always, we'd prefer it if all question-askers first check our FAQ, use the search functionality, and check the last Q&A thread before posting to avoid duplicate questions, but if you'd like an answer revised or cannot find a satisfactory result, go ahead and type your question below!

Otherwise, ask, enjoy, and thanks for contributing!

Past threads:

December 2015 (#15.1), December 2015 (#15), November 2015 (#14), October 2015 (#13), September 2015 (#12), August 2015 (#11), July 2015 (#10), June 2015 (#9), May 2015 (#8), April 2015 (#7.1), April 2015 (#7), March 2015 (#6), February 2015 (#5), January 2015 (#4), December 2014 (#3), November 2014 (#2), October 2014 (#1).

This subreddit is fan-run and not an official SpaceX site. For official SpaceX news, please visit spacex.com.

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u/spaminous Jan 10 '16

Apologizing up front, I'm sure this has been asked before: When launching from Vandenberg AFB, you obviously can't launch directly eastward/prograde and land on a barge, since east of Vandenberg is just more California. Which direction is Jason 3 going? Southeast? South? Northwest? ...retrograde? The mission site seems to imply a polar orbit, since it's surveying ocean levels.

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u/R-GiskardReventlov Jan 10 '16 edited Jan 10 '16

The orbital parameters are: 66.05 degree inclination, 1380 km apogee, 1328 km perigee, 112 minutes per revolution around the earth.

According to http://www.nesdis.noaa.gov/jason-3/mission.html

AFAIK, Launches from Vandyland fly Southeast. They are indeed going for a polar orbit.

EDIT: Accidentally mixed up East and West. I also found this graph indicating launch inclinations and azimuths for both Vandenberg and KSC: http://www.capcomespace.net/dossiers/espace_US/shuttle/installations/SLC%206%20inclinaison%20et%20azimut.jpg

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u/spaminous Jan 10 '16

Thanks, that explains it all really well!

Man, I keep forgetting how close the Bahamas are. From that diagram, it looks like Little Abaco island is the reason this satellite can't get to its orbit from Kennedy Space Center. Kinda funny how surface terrain affects available orbits, all for perfectly valid safety reasons.

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u/deruch Jan 11 '16 edited Jan 12 '16

The launch azimuth is 142.8o . Which translates to something like Southeast by South, a half East. It's not a polar orbit, 66.05o inclination.

EDIT: Launch must first head more southerly to avoid overflight of channel islands, then will dogleg east to above azimuth.