Difference between revisions of "Talk:Lander"

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(Pasted in from an e-mail.)

Revision as of 15:07, 22 August 2008

ubject: Re: Launch Vehicles From: Gary Snyder Date: Fri, 22 Aug 2008 14:11:33 -0600 (MDT) To: Terry Wilson

Hi Terry, I'll try to answer some questions in-line:

> > Gary, > > > > Paul expresses that we are going to use the same lander type for all five > > missions to save on development. I don't think this is possible because > > they ask for requirements across an enormous scale (about two orders of > > magnitude.)

Yep and nope. I've spent the last couple of days crawling (figuratively and literally) around the Micro-Space lander equipment. The is still much work to be done but the progress made is significant. The current reference design is a vehicle that can land 300 lbs (cargo) on the surface of the moon from LLO. Its dry/MT mass is about 50 lbs, 650 wet/loaded. This is assuming the Vac Isp delivered to be 300 sec. This motor spec is doable but not done. The tanks are in hand.

A 300 lb payload for mission one is to large. (1) It would be about right for exploration/sample return mission. (2-3) It would require a Rendezvous (baselined) for a manned mission. (4) All bets are off on the Mission 5

> > The mission I have the best information on is "Mission 5", > > the human one.

which, unfortunately is the least defined at this stage. You win it  :) Seriously, bringing passengers to the moon is a different game. The equipment in development is assuming a motivated pilot alone.

> > Assuming, reasonably, that taking off from the moon, landing on > > the moon, and TLI, each multiply the mass of the next stage by three,

Really dependent on performance. current tanks are *Very* good. Looks like a factor of two for LLO->LS or back. rendezvous in LLO for an additional 300 lbs would get it home to earth. The GTO to LLO stage is a 2x multiplier also. How to get to GTO from the surface of the Earth is launch vehicle question. I am trying to see what proportion strap on tanks I will need to extend the GTO -> LLLO stage to make up assorted DeltaV needs from the launch vehicle. IE if we start an LEO we need Xlbs of payload, for every extra Y m/sec we can loose Z lbs of payload.

> > even a > > minimal human mission gets very large by the standards of Mission 1. > > Assuming the returning entry mass is 300lb (the astronaut, his suit, an > > inflatable heatshield, parachute and survival kit), the mass that needs to > > ascend from the moon is 900lb,

I do not,out of principle, agree with lunar Direct. I helped zubrin and know the (poor)logic.

and the mass that needs to be sent > > translunar > > is 2700lb (Delta II level performance), with an equivalent LEO mass of > > 8100lb (also Delta II performance). So, Mission 5 is well beyond the > > capabilities of Falcon 1e. > >

I see a bare minimum of 1500 lbs in LLO. which is 3klbs in GTO. much more than a Falcon. There is the matter of cost also. Speaking of cost, we are trying to get some grant money in the next 2-6 weeks, (Nasa-USAF). I apologize for not putting more up on the wiki. just a little swamped.

> > Paul says it's your department. I'm always in need of help. It's all our project, It's all our departments.

> > > > IMHO, the best plan for Mission 1 is to start with a single day rover > > (i.e. > > sunrise to sunset with overnight survival a secondary objective) landed on > > an overhead lander. The primary objectives would be to deliver the rover, > > have it depart and roam, and then have it come back to the lander and > > re-integrate. The lander would then hop west to a new landing site and > > extend the day the rover can operate. This would prove almost all the > > functionality required for the larger "PEZ candy" lander, which can then > > be > > scaled up from the original overhead lander (longer tanks, more motors.) > > The multiple rover mission would also add overnight survival as an > > objective. Multiple rover/sample return could then be built on the human > > lander architecture, which would need to ascend on a larger booster.

I think we are already building on the human mission. The one thing the pez idea has is some mesh networking possibilities. The hopper with pez dispenser will rapidly hit multiple locations. (make hast while the sun shines, because the night is cold and long)

> > > > If we're stuck with launch vehicles too large to bother with a single > > rover > > lander, we can put up a relay satellite to ease the communications > > problems > > on the same launch (a bit like Japan's *Hiten*). That relay would still > > be > > operational for the larger multi-rover and sample return landers, and > > hopefully long enough for even the human mission. The relay satellite > > would > > be bigger, and possibly could test the propulsion gear for the human > > mission. If that gear doesn't work, perhaps more than one Mission 1/Relay > > type launch would be required.

Yea, Another idea that has been brought up with excess launch capacity is a test of the inflatable reentry vehicle. This would be a better test if done from GTO due to the higher loads.

> > > > Anyway, I'd like to get a thread started on this.

Here or on the wiki ? I think paul might like the wiki.

(I'll see if I can hit the wiki today.)

> > > > Terry > >

On an aside: I'm not a very authoritarian person and I hope I don't sound like that in my typing. I appreciate and value your input. I think If we kick stuff around like this we may: a) change the plan -or- b) understand the plan better -or- c) which we could do a or b  :)

later, Gar,

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