Hi Marshall, On 05/12/2018 05.39, tme_at_asteroidinitiatives.com [mpml] wrote: > They have apparently put out NOTAM type restrictions for the launch : > > 1815-1834 UTC - Long March 3B/E carrying Chang'e 4 lunar lander and > rover to the far side of Luna! > > https://twitter.com/LaunchStuff/status/1070197596596129793 > > Regards > Marshall Thank you. I'm not having any real success in getting ephems for this launch. The Chinese space program is something of an enigma wrapped in mystery inside a cloak of invisibility. However, I've not given up hope. Cees Bassa pointed out some characteristics of the Chang'e 5T1 orbit, which look to be quite similar to those for Queqiao and Chang'es 2 and 3. (Though my data for those last two is pretty rough; we didn't start observing them until after the hardware had passed the moon.) In each case, the trajectory was an eminently sensible one : launch due east with things timed so that you enter your transfer orbit to the moon exactly at a point opposite where the moon will be at your apogee. This uses the least necessary amount of fuel. That point is roughly at longitude W 179, latitude -1, and occurred about 13 minutes after launch for Queqiao. Your inclination is then roughly the latitude of the launch site. Queqiao's was 28.57 +/- 0.01; the launch site is at 28.15 N. Once we've got a more exact launch time, I'll come up with an orbit with perigee 13 minutes later, just above that spot near the international date line, with inclination 28.57 degrees, and tweak the apogee distance to result in the object encountering the moon about four days later (possibly constrained if I can get data on when it's "officially" supposed to reach the moon). The lunar approach will ideally be prograde, and I think coming in from below the lunar equator (the landing is supposed to be near the south pole). Given this, we may at least get ephems suitable for finding spacecraft and booster. Or not, since it'll probably be at a low elongation from the sun, and it's not a given that anybody will even look. -- Bill _______________________________________________ Seesat-l mailing list http://mailman.satobs.org/mailman/listinfo/seesat-lReceived on Wed Dec 05 2018 - 10:39:04 UTC
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