# Did InSight take a “mean left” turn on its way to Mars? Is it an out-of-plane maneuver?

In the NASA JPL video NASA Launches InSight to Mars (part 1) after about 14:30 (currently) NASA's new Chief Scientist Jim Green (better photo here) explains:

Vandenberg is great for putting spacecraft into polar orbit. We fire straight south, and that way it goes over the ocean, goes under the south pole, comes up on the other side of the earth and then takes this &mean left*, and heads on out to Mars.

Was there a significant out-of-plane maneuver with respect to its orbit and is this what the "mean left" refers to? Would that vary depending on the launch time within the 2 hour launch window?

• Not a dupe of [Insight mission broken-plane maneuver needed? ](space.stackexchange.com/q/25825/12102) as that asks about a mid course plane correction. – uhoh May 6 '18 at 4:33
• Yep, Jim's comment is puzzling. The Atlas V 401 had plenty of launch capacity for InSight, but out-of-plane components are a bad way to waste ∆V if you don't need them. Instead of making a "mean left", just waiting an hour or so later to launch would have the same effect. As it was, the 2nd Centaur burn put the departure V∞ vector almost aligned (in azimuth) with Earth's orbit velocity vector, with a declination south of equatorial, maybe not too far from the ecliptic. I'll ask some of my JPL trajectory buddies about it next week. – Tom Spilker May 6 '18 at 6:10
• I just thought ... if you have a 2-hr launch window to a near-polar orbit, then coming over the N pole boost to a departure orbit more or less aligned with Earth's orbital velocity vector, it might be that launching at the center of that launch window orients the orbit for an ideal escape orbit injection maneuver, i.e. no out-of-plane component. But if you lauch as that window opens, 1 hr early, there's a 15° misalignment between the orbit plane and the departure V∞ vector, requiring a "mean left". Launching 2 hrs later requires a "mean right". – Tom Spilker May 6 '18 at 22:35
• @TomSpilker that's what I'm wondering too. Actually in the title I should probably change the two words "Was there..." to "Is it..." because that's what I'm really asking. In fact, I'll do that now (and fine-tune the last two sentences), thanks for helping me visualize this in 3D! – uhoh May 7 '18 at 0:34
• Good point @uhoh, I'll write a quick answer based on my comment above. – Tom Spilker May 7 '18 at 1:49