Possible Launch Windows For Manned Mission To Mars In 1989

Can somebody find me anything on this? I'm not good with the mathematics of this, so something that would give me the launch date, travel time, landing time, Mars lift-off time, and Earth return time would be good. You can assume that the rocket used to launch the mission has twice the power of the OTL Saturn V, and that the return stage to Earth has twice the power of the OTL S-IVB. Assume that the spacecraft weight is equal to double OTL's Apollo CM and SM combined, plus 100,000 pounds for the crew's living space and supplies.

Note: These numbers are based upon some really quick research, as I haven't got any of my notes with me.
 
Actually, I was looking for a conjunction-class trajectory. I was thinking about a mission that would be somewhat similar to Mars Direct...

Err... I am NOT a rocket scientist, but I'm pretty sure a conjunction-class trajectory IS a Hohmann-type.

Someone here must know more about this than I do.
 
I have a few tables of opposition and conjunction timings, but the earliest one on the ones I have is 1997. Obviously there are ones before that, but they weren't included on these tables since they were already in the past by then. I'll see what I can dig up.
 
Last edited:
Actually, I was looking for a conjunction-class trajectory. I was thinking about a mission that would be somewhat similar to Mars Direct...

The Mars Direct Conjunction Mission is a variant of the Hohmann Orbit. Where a normal Hohmann Orbit would take 9 months (for any two objects with nearly circular orbits, a Hohmann Orbit between them is roughly equal to the mean of their orbital periods), Zubrin suggests adding less than 1km/s delta-v and shortening that to 6 months. All right there in the manual (that being, of course, The Case for Mars).

Of course, with that much mass you're talking, aerobraking into Mars orbit is impossible, so a Hohmann Transfer will prove necessary to conserve fuel.
 
Hopefully Truth is Life, Michel Van, or Methuslah will pop in.

Eh heh heh...ask me in a couple of years, hopefully by then I really WILL be a rocket scientist.

The trick with this stuff is that it's, well, tricky, unless you really know what you're doing. I haven't done celestial mechanics, I don't have any good source on me, and I couldn't do a numerical computation right now to save my life, so...yeah. I can't give you specifics. I've thought about this for my own TL, but have been eliding over it in writing and research, relying instead on what glimpses I can catch of NASA/contractor studies (where relevant), and only going into any depth with the Moon, which is far, far simpler to deal with.

Useful note though: Polish Eagle and Gridley are right, Hohmann=Conjunction. They're effectively the same thing (not technically--you can have non-Hohmann conjunction trajectories--but in practice, anything we do that doesn't involve grav assists is going to be Hohmann).

The numbers you give aren't actually too useful, though. To do a realistic mission plan, you actually really need the ISP (efficiency) of the engine, because it shows up in the rocket equation, while thrust doesn't.
 
truth is life is right about Specific Impulse. If you mean specific impulse when you say the return stage has twice the "power," then the only method for that is nuclear.

The highest chemical specific impulse is 464 seconds, for the newest RL-10. If you want something with a bit more "oomph," the SSME gets 452 seconds, and a similar engine is by no means impossible, though it would be heavier by far than a J-2 development, which would be perhaps 30%-50% lighter, but only get 430 Isp.
 
Can somebody find me anything on this? I'm not good with the mathematics of this, so something that would give me the launch date, travel time, landing time, Mars lift-off time, and Earth return time would be good. You can assume that the rocket used to launch the mission has twice the power of the OTL Saturn V, and that the return stage to Earth has twice the power of the OTL S-IVB. Assume that the spacecraft weight is equal to double OTL's Apollo CM and SM combined, plus 100,000 pounds for the crew's living space and supplies.

Note: These numbers are based upon some really quick research, as I haven't got any of my notes with me.

A little quick research shows that these launch windows occur approximately every 26 months. According to Wikipedia, Phobos 1 and 2 were launched in July 1988 (the 7th and 12th to be exact) which would seem to preclude their being a 1989 launch window being available. The next launch was that of the Mars Observer on September 25, 1992. There should have been a launch window sometime in the summer of 1990. So, for your purposes, it would seem that you would have to go in 1988 or 1990.
 
Top