To Dr. Griffin

[skywalker01]

Dr. Griffin<br /><br />From what I have been able to find out about the Moon/Mars architecture studies it appears that there is a cash flow problem concerning the operating funds for a growing exploration program and having enough funds left over to develop the hardware necessary for the following steps.<br />As I understand it the current ‘Return to the Moon’ plans consist of developing; <br />1) a Crew Exploration Vehicle with Propulsion Module, CEV + PM, <br />2) a Shuttle Derived CEV Launch Vehicle, SDCEVLV, <br />3) a Shuttle Derived Heavy Launch Vehicle, SDHLV, <br />4) a Trans Lunar Insertion Stage, TLIS, <br />5) a Lunar Lander, LL, <br />6) and all the Lunar surface equipment for the LUNOX plan.<br />Followed by the ‘Onward to SEL-2’ plan, the NEO plan, and then Mars.<br />All of which is built on the foundation of the SDHLV and its cost to LEO and the TLIS and its cost to escape velocity.<br /><br />My suggestion is that somewhere in the plan there needs to be a new lower cost way of getting to LEO plan added into the mix as well as a new lower cost way of getting to escape velocity in order to solve this cash flow problem.<br /><br />There are a number of ideas out there for ways on how to do this for both of these steps that you may not have included in your architecture studies. <br />Ideas such as;<br />a) 6g ground accelerators for reducing the mass ratio requirements of the Earth to orbit launch vehicle while increasing the payload fraction at the same time, <br />b) payload only ground accelerators,<br />c) adding an ion propulsion system and a downward pointing graphite tether to the ISS and moving the ISS into a higher orbit so that sub-orbital launch vehicles (ground accelerator launched, air launched, or regular VTO rocket) can dock with the lower end of the graphite tether which is moving at less than orbital velocity for its altitude,<br />d) adding an ion propulsion system and an upward pointing graphite tether to the ISS for launching payloads to escape veloci

 

[spacefire]

I didn't know Griffin posted here. what's his username, kmarinas86? <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>

 

[skywalker01]

I am new here. Who is kmarinas86?

 

[earth_bound_misfit]

Well I don't know if Mike posts here, but I wouldn't be surprised if he has read some of these posts. SDC seems fairly high on google lists when searching space stuff. <div class="Discussion_UserSignature"> <p> </p><p> </p><p>----------------------------------------------------------------- </p><p>Wanna see this site looking like the old SDC uplink?</p><p>Go here to see how: <strong>SDC Eye saver </strong>  </p> </div>

 

[john_316]

I hear it on good accord that several NASA managers and some engineers do skim our posts once in awhile and I also hear that some other famous engineers do as well...<br /><br /><img src="/images/icons/smile.gif" /><br /><br />So its safe to say Mike might listen in here once in awhile.....<br /><br />

 

[gunsandrockets]

http://www.affordablespaceflight.com<br /><br />I've looked over some of the numbers for the earth orbiting elevator, and though an intriguing idea it does not seem a practical choice for near term space flight. The investment cost is steep and the break-even point is too far down the road. NASA's limited resources would be better spent in other areas first such as nuclear power and ISRU.<br /><br />Even if NASA were to build the elevator, construction at the ISS orbital inclination of 51 degrees would not only increase the investment cost of the elevator it would decrease the benefit derived from the operational system. Launch vehicles cannot lift as much to 51 degrees as they can lift to lower orbital inclinations. Sending payloads from ISS to other places of interest such as geosynchronous orbit or the moon also incurs a penalty for the orbital plane changes.<br /><br />Now I will give my reasons for these conclusions. First a description of the Earth Orbiting Elevator, then my analysis of it's operational benefits and costs.<br /><br />The Earth Orbiting Elevator is a baby version of the science-fiction orbital space tower, and has many differences.<br /><br />The science-fiction space tower, connected to the Earth, lifts a payload from the ground until the elevation of the payload puts it into a location with an orbital velocity or even escape velocity. Since you can't get something for nothing the energy the payload gains comes from the transfer of rotational momentum from the Earth itself. The elevated payload speeds up quite a bit relative to the surface of the ground below while the rotation of the Earth slows infinitesimally thus maintaining the conservation of rotational momentum. Obviously a space tower must be built along the equator and could only lift payloads to an equatorial orbital plane. The tower itself is in a balanced equatorial orbit.<br /><br />The Earth Orbiting Elevator (EOE)

 

[skywalker01]

I am impressed!! You did read up on the EOE in depth.<br /><br />And yes, thinking of the EOE as a reusable ion powered upper stage is valid.<br /><br />Regarding the cost and method of construction.<br /><br />Yes the mass of the EOE could all be sent up by HLLV if you had an unlimited budget.<br />A better way would be to send up the first 200 kilometers of cable (two 100 km long strands) plus an initial ion propulsion system via the Shuttle or Progress, deploy that cable and then start making all future delivery flights to the bottom of the cable. This way as the cable grows it is possible to start taking advantage of the cost savings almost from the beginning. And while the savings in the beginning are small they get better and better as the cable gets longer and longer.<br />Think of it as a foot path that can gradually be grown into a freeway. The example you gave is closer to the freeway then the inial foot path.<br /><br />Another idea for an initial system is to use a cable and reel system for boosting payloads to near escape velocity (or some percentage of escape velocity). Since the cable would only be reeled out to launch the payload it would only have to be sized to support the payload mass which would make it much lighter than a permanent cable with an endpoint station and a cable crawling elevator. Add into that the savings in upper stage mass and cost and this typle of initial system could pay for itself very quickly as part of the MtM program. (By the way, since the flight rate for going to the Moon has been stated to be around two flights per year it won't take a very large ion propulsion system to meet that need.)<br />This reel system could also be used to deorbit ISS garbage while getting a slight orbit boost from the garbage as well as provide practice for the docking of arriving spacecraft. <br />Also, think of the savings in ISS re-boost propellant.<br /><br />Regarding the current orbital inclination and orbital altitude of the ISS.<br />If the init

 

[spacefire]

kmarinas86 is our good friend from the Phenomenon forum <img src="/images/icons/smile.gif" /><br /><br /><br /><br /> <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>

 

[spacefire]

<font color="yellow">I hear it on good accord that several NASA managers and some engineers do skim our posts once in awhile and I also hear that some other famous engineers do as well... </font><br /><br />good.<br />then, hear me out, ye famous managers and engineers:<br />Ditch the shuttle, sack the CEV and build a lifting body scramjet RBCC SSTO! <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>