SpaceX Unveils Plan for World's First Fully Reusable Rocket

[n2doc]

By Mike Wall and SPACE.com | September 30, 2011 |

The private spaceflight firm SpaceX will try to build the world's first completely reusable rocket and spaceship, a space travel method that could open the gates of Mars for humanity, the company's milionaire CEO Elon Musk announced Thursday (Sept. 29).

A fully reusable rocket would dramatically decrease the cost of lofting cargo and humans to space, making the exploration and colonization of other worlds such as Mars more feasible, Musk said in a speech at the National Press Club in Washington, D.C.

Musk did not guarantee success, acknowledging the daunting task his SpaceX team has taken on. SpaceX released a video animation of its proposed reusable rocket and space capsule system to illustrate how it would work.

[bananas]

1. Video here:"Elon Musk Outlines Grand Plans In Speech (Video)"

Elon Musk Outlines Grand Plans In Speech (Video) http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=228x84043

[sofa king]

2. What a nifty idea.

But the problems must be enormous. Some thoughts:

The overall efficiency of the system must necessarily be lower than a fully expendable launch system. Extra mass will have to be devoted to the landing gear and for a return fuel reserve. Complexity, which SpaceX routinely seeks to avoid, will go up considerably even though the ascent and descent will probably use the same engine and control system.

On the other hand, a partially-pressurized SpaceX stage probably has about the overall density and flight characteristics of a beer can with a swig left in the bottom. I'm sure they're easiest to control and land when they're nearly empty.

Some of that extra mass could be avoided by using the downrange velocity of the launch to send the expended stage on a more natural low-energy parabolic path toward a recovery barge at sea. (It would also allow them to avoid the environmental complications that landing an RP-1 fueled rocket will necessarily entail.) That of course would make the overall system weather-dependent in multiple locations, requires naval resources to return the vehicle, and so on.

The return-to-facility option avoids all that, but a flaming gasoline truck hurtling over populated areas while belching out a rush-hour's equivalent of petroleum emissions is probably not going to be well accepted by all. That would almost certainly require a separate H2/LOX system for public approval, or a complete conversion to that fuel option.

Still another option would be to "re-use" the upper stage by fitting it with comparatively small and light solid rockets and giving the empty stage the remaining energy needed to boost it into LEO to a collection facility, where the tanks can be used for storage, construction material, or future missions beyond LEO. Residual fuel from the tanks can be used to maintain orbit, as hydraulic fluid (if it's still RP-1), and as breathing oxygen for future human missions. Multiple rockets could be detached, mounted in a stage-shell, and reentered from the facility in a way similar to that depicted in the film, while some are reserved for deep-space launches from LEO.

Anyway, I have to say I really like the success and imagination SpaceX is showing.