Explanation: On July 22nd this GSLV (Geosynchronous Satellite Launch Vehicle) MkIII rocket vanished from sight into a cloud bank an instant after this dramatic snapshot was taken. Launched from India's Satish Dhawan Space Centre it carried the Chandrayaan 2 mission spacecraft into Earth orbit. The spacecraft's orbiter, lander, and rover are destined for the Moon, though. In the coming weeks it will perform a series of orbit raising maneuvers, eventually transferring to <a hrf="ap090928.html">lunar orbit</a> in early September. Carrying the solar-powered rover, the lander is scheduled to separate and attempt its autonomous soft landing at high latitudes near the lunar south pole. It should arrive on the lunar nearside near local sunrise and the start of a two Earth-week long lunar day on September 7.
Interesting to see more members joining the Moon club. And a spectacular moment caught perfectly.
I notice it's getting there by a series of orbit raisings; anyone know what the advantage is of doing this, as opposed to a single TLI burn? Surely it ought to be the same total Δv requirement no matter how many times you divide it up?
Or maybe it's one of those things that only makes sense if you really are a rocket scientist...
Re: APOD: Chandrayaan 2 Launch (2019 Jul 27)
Posted: Sun Jul 28, 2019 3:53 am
by alter-ego
TheOtherBruce wrote: ↑Sun Jul 28, 2019 2:11 am
Interesting to see more members joining the Moon club. And a spectacular moment caught perfectly.
I notice it's getting there by a series of orbit raisings; anyone know what the advantage is of doing this, as opposed to a single TLI burn? Surely it ought to be the same total Δv requirement no matter how many times you divide it up?
Or maybe it's one of those things that only makes sense if you really are a rocket scientist...
Smaller engines and more efficient, but longer time. I believe the better efficiency is obtained from using the Oberth Effect which is different from the gravity assist scheme. Yeah, this is a "rocket scientist" kind of thing.
alter-ego wrote: ↑Sun Jul 28, 2019 3:53 am
Smaller engines and more efficient, but longer time. I believe the better efficiency is obtained from using the Oberth Effect which is different from the gravity assist scheme. Yeah, this is a "rocket scientist" kind of thing.
<wiki-wiki-wiki-wiki> Ahah — I've come across the Oberth Effect in various discussions, but I don't think I've read its wiki page before. Yes, that makes sense now that I can visualise what's going on.
alter-ego wrote: ↑Sun Jul 28, 2019 3:53 am
Smaller engines and more efficient, but longer time. I believe the better efficiency is obtained from using the Oberth Effect which is different from the gravity assist scheme. Yeah, this is a "rocket scientist" kind of thing.
Ahah — I've come across the Oberth Effect in various discussions, but I don't think I've read its wiki page before.
Yes, that makes sense now that I can visualise what's going on.
The first (25 July 2019) apogee raising burn raised the apogee by only ~20%
and yet it required a full 883 sec burn over ~90º of perigee longitude
"Power = Force x velocity" suggests that one should try to push the hardest only when moving the fastest.
India's Chandrayaan 2 Reveals Highest Resolution Images Of The Moon From Orbit
Chandrayaan 2 Launch
