On the non-Hohmann cycler the main takeaway I got from the Friedlander et al. article, which I ripped off, is that a regular cycler from point A on an orbit to point B with Free-Return often runs into the angles being off on the return. For Aldrin, Friedlander & Co. this was 1/7 of a pizza; or if you're THAT much of a nerd, a bit less than a radian (2π/7 to be exact). Venus and Earth align again even further out: -0.8π radians.
As a result, Aldrin's cycler from Earth to Mars demanded a close approach to Earth, starting its second leg, to yank ("rotate") it to whither Mars is likely to be (please ignore Wiki here; stick with Friedlander). The Earth-Venus-Earth "EVE" cycler, if my numbers be right, also requires close approaches to one or the other planet.
With EVE, both planets are high(ish) gravity, so the close approach is better-tweakable, from either side, than a Mars-assisted cycler would be. In fact I don't think Mars is going to be doing gravity assists for any cycler. When you add Mars' eccentricity I'm really wondering if the Stinky CyclerTM is ever going to happen between Mars and any other planet.
As for the EVE cycler, its "VEV" sister will need to get closer to Venus than any Earth-assisted cycler would get to Earth, on account of solar interference and that Venus' mass is that bit lighter. Also, from a look at the semi-major axes for any of the EVE orbits - someone's getting a sunburnt cornhole.
We might also consider cyclers between Earth and Venus' L4; or between Venus and either of Earth's Libration points. Since there's nothing at a Libration point, beyond the narrow plateau fore and aft of it, those cyclers don't have a gravity-well to bother them or to be used.
VISIT-1, Venus can dock every (short) Venerean year to dock here at Earth every four of our years. VISIT-2, Earth can dock every other year to dock at Venus on that 13th Venerean, so every eighth of ours. Either way Venus will see things in synodals, 1.5987 years. In that light VISIT-1 comes to Venus (or to L4) with freight every 4 / 1.5987 = 2.5 synodics; VISIT-2 comes - at all - every 13 * 0.615 / 1.5987 = five.
Now: consider that Venus and L4 (both) can get one-way Hohmann cargo every synodic. Also consider the P.I.T.A. of boarding and leaving a cycler. Add to that, VISIT-1 is 2:1 with Venus and VISIT-2, 1:2 with Earth. 2:1 is a Kirkwood resonance - unstable. I'm not seeing who on Venus and Earth will even fund this boondoggle. No good!
I haven't calculated the offset in the TerraVenerean synodal year starting 21 October 2224. For such, I'll let someone else do the maths. Bring sunscreen and Aloe.
SCREW IT 12/9 - After looking at the Kirkwood thing, I give up on this trajectory. It Stinks, to rip off Jon Lovitz this time. So let's stick it right after the Saturday piece (which I was mulling over posting at all, also backdated) and call it a waste of a Sabbath. May G-d forgive me.
The Walter Hollister Earth-Venus cycler, proposed 1969(!), holds up better. Or just the Hohmann.
No comments:
Post a Comment