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View Full Version : Polar orbit: A very brief question



Zvezdichko
2009-Jun-01, 02:44 PM
It just came into my mind...

Have NASA and Russia ever operated manned spacecraft in polar orbit?

djellison
2009-Jun-01, 02:51 PM
No.

I believe ISS / Mir is the highest inclination flown. The loss of Challenger put the idea of launching STS into polar orbits (with new composite SRB's) from Vandenberg firmly to bed.

KaiYeves
2009-Jun-01, 03:19 PM
Yeah, the shuttle was supposed to do polar orbit missions, but it never did.

GeorgeLeRoyTirebiter
2009-Jun-05, 12:49 AM
I'm not an astrophysicist, but I'll take a stab at the question anyway.

Actually, all of the Apollo missions launched to an orbital inclination of 28.5. This is both the latitude of the launch site (thereby maximizing the payload with a due-East launch) and the approximate inclination of the Moon's orbit (thereby eliminating the need for a costly orbital plane change). Launching in this manner merely required waiting until the plane of the Moon's orbit passed through the launch site (not counting other considerations).

Antarctica is visible in the famous Apollo 17 "blue marble" photo because when it was taken the spacecraft was at a high altitude and at the southernmost part of its orbit.

The Soviets had to use a different approach for their lunar missions because of the location of their launch sites. Their southernmost launch site (Baikonur) is at about 45 N latitude, but allowable drop zones for spent stages limited the southernmost possible inclination to 51.5. To get from that orbit to the Moon required waiting until the Moon itself (not just its orbital plane) would intersect the higher-inclination orbit. This put the Zond (and Luna, and Lunkhod) craft in near-polar lunar orbits (71 inclination), instead of the nearly equatorial retrograde orbits of the Apollo spacecraft.

I haven't tried modeling one of these orbits, so I don't know for sure, but I suspect that the polar Earth return trajectory was done deliberately with a plane change during the Earth-return burn in order to ensure that the spacecraft would re-enter over Soviet territory.

JMV
2009-Jun-05, 08:48 PM
Apollo 17 had a high orbital inclination; the crew got a good view of Antarctica after TLI. Am I correct to say, that of the Apollo missions, Apollo 17s was the highest inclination?
Apollo 17's translunar trajectory at TLI had an inclination of 28.466 degrees. Apollo 16 had the highest inclination at 32.511 degrees.

You're probably remembering your old question in the New Apollo Quiz Game thread. Anyway this (http://www.bautforum.com/space-exploration/19610-new-apollo-quiz-game-21.html#post765194) is the answer I gave you three years ago.

JonClarke
2009-Jun-06, 02:47 AM
Vostok and Voskhod were launched in 65 degree orbits. STS 77 flew the highest inclination US mission, to 62 degrees.

matthewota
2009-Jun-06, 04:54 AM
Launches from the United States that send payloads into polar orbits all originate from Vandenburg AFB in California. Range safety rules prohibit launches due south from the Kennedy Space Center Florida because the vehicles would overfly land and populated areas.

At one point the USAF was going to launch Space Shuttles from VAFB, but the project was canceled after the Challenger accident. Vandenburgh AFB allows for due south trajectories, as they are over ocean.