"Breakthrough propulsion systems"?

[cymrych]

So after watching, then reading, the President's remarks at KSC last week, I get the strong impression that Obama really wants something innovative and new in a HLV for NEO, Mars and beyond, not just a rehashing of DIRECT or a reconfigured Constellation derivative. He used terms like "groundbreaking" and "breakthrough" several times, which suggests, to me anyway, he really wants something exceptional to come out of NASA for the next stage in American manned spaceflight.

My question is: what does he have in mind? It seems to me that chemical rocket motors can only be so efficient, and beyond a certain point, it wouldn't matter how much money you toss into R&D, your rate of increase in efficiency will stagnate. Thrust and ISP can only be raised so far.

So either he expects a radical next-generation in chemical rocket motors, or something else? Any thoughts?

Also, I guess I'm having trouble with the math involved in the plan and hoped someone can help me out. The Obama plan is to spend $3 billion on designing a new HLV for final approval by no later than 2015. But, we've already spent what, $9 billion on Constellation, which is supposedly the best that NASA could come up with given the constraints of the anticipated federal budgets.

I know I'm a product of the Pennsylvania public school system, so correct me if my logic has failed horribly somewhere: if $9 billion gave us Ares utilizing more-or-less existing technology, how the devil is $3 billion supposed to give us "breakthrough" or "groundbreaking" technologies plus the vehicle to utilize these technologies on?

Please note, I don't want to open up the whole argument for or against Obama's plan again; it's already been done on other threads. I'm just interested in what some of these breakthrough advances may entail. Because it seems to me that NASA and others have been working on the problem of moving beyond chemical rockets for quite some time, and the results are, thus far, very slow to realization.

 

[2552]

One of them is VASIMR, with which a trip to Mars can be done in 39 days. Others are Nuclear thermal propulsion, and Solar/Nuclear Electric propulsion. These are listed on page 341 of this NASA PDF. VASIMR is listed as "plasma prupulsion"

 

[Ark]

Those three, VASIMR in particular, are critical to a real revolution in space travel. However, none of them are viable as components of an HLV. So that $3b for HLV development will probably go to something cheap, proven, and conventional.

 

[tblaxland]

My little baby: Electrical momentum exchange tethers?

Some more info here: http://www.nasa.gov/vision/universe/roboticexplorers/tethered_spacecraft.html

A proof of concept Orbiter addon I made with Nomad23 for lunar transfers here: [nomedia="http://www.orbithangar.com/searchid.php?ID=3399"]Ananke Tether-Sling v0.2[/nomedia]

 

[garyw]

http://en.wikipedia.org/wiki/Breakthrough_Propulsion_Physics_Program

Too bad the above office was closed in budget cuts and I don't see Obama planning on opening it again.

 

[cymrych]

Those three, VASIMR in particular, are critical to a real revolution in space travel. However, none of them are viable as components of an HLV. So that $3b for HLV development will probably go to something cheap, proven, and conventional.

I guess this is where my imagination with the new plan fails me.

According to the most recent DRM, the TMI would have utilized some form of nuclear-based propulsive means anyway (be it an NTR like Triton or some other bi-modal system, or NEP like VASIMR), launched atop the Ares V stack. We're still going to need an HLV to lift the masses we'll require for any realistic TMI, and getting to LEO still seems best done using chemical rockets. Plasma drives have extraordinary fuel economy but extremely low thrust rates, and NTR's look like they still fall well short of the thrust/weight ratios of chemical rockets unless you use a gargantuan reactor, which would pretty much negate an NTR's advantage of not requiring an oxidizer mass anyhow.

I know of course that there are alternatives to the Ares family of rockets for getting the hardware into LEO, but none of them seem to be a radical leap forward in either total lift capability, or in efficiency. And I have to believe that Obama wants first and foremost to make any plan cheaper and simpler than Constellation; and an "easy" way to do this would be an HLV that could carry much more than the 150mT or so that Ares V could. Less launches for a Mars mission equals less complexity and costs.

But a rocket on the ground can only get so large, right? Eventually you start reaching structural limits on total mass, so the only real option is to increase thrust and Isp. And both of those variables, based on rocket motors over the last couple decades, seem to have already reached some sort of limiting threshold for chemical motors.

And THIS is where I fail to see what 3 billion can provide for us which the 9 billion already invested in Constellation cannot. What to do? How do we proceed?

 

[anemazoso]

As I understand it they want to design a modern hydrocarbon based motor, like an updated F-1. What I don't understand is why. I realise there is a trade-off between LH2 and Hydrocarbons, the former is more energetic and the latter is more dense requiring less tankage and therfore makeing the vehicle lighter.

In addition to the new motor they want to increase motor monitoring to be able to maximize motor optimization.

There won't be any revolutionary new technology but there are several tricks that can be employed like duel bell methods, one that slides over the first as it reaches higher altitudes allowing the motor to be more efficient as it accends. Another capability is deep throttling. If a motor can throttle down as it uses fuel and gets lighter it could be a lot more efficient as well. The $64 billion questions: Can this happen with the money given? Not if it's cost-plus contracting.

For me I think NASA should use the new 5-seg SRB but buy them at a standard rate and not cost plus. Those combined with the improvments mentioned above should lead to a pretty nice and cheaper HLV. And there might be some movment on this. It seems congress is seriously considering continuing 5-seg testing to keep the capability while these other developments take place.

 

[SiberianTiger]

I believe this may be a part of the answer:

http://www.nasa.gov/home/hqnews/2010/mar/HQ_C10-017_Technology_Awards.html

NASA has awarded contracts to five companies to provide space propulsion systems technologies in support of research and technology development activities at the agency's Glenn Research Center in Cleveland.

Each of the five indefinite-delivery, indefinite-quantity contracts provide for fixed price, cost share and cost reimbursement competitive tasks with a maximum value of $50 million over the next five years.

The companies selected are Aerojet of Sacramento, Calif.; ATK Mission Systems of Ronkonkoma, N.Y.; Northrop Grumman Aerospace Corporation of Redondo Beach, Calif.; Orbital Technologies Corporation of Madison, Wisc.; and Pratt & Whitney Rocketdyne Inc. of Canoga Park, Calif.

The selected companies will perform work in six disciplines: propulsion system design and trade studies; non-toxic chemical propulsion systems; hypergolic propulsion systems; propellant systems; electric propulsion and rocket-based combined cycle propulsion systems.

The work will provide for the development of advanced space propulsion technologies to enable missions with higher performance, reduced cost, improved reliability and improved safety.

Technical challenges addressed include alternate propellants, thruster performance, novel concepts, thermal control, cryogenics, propellant and combustion product properties, chemistry, fluid dynamics and advanced concept fabrication.

http://www.orbitec.com/propulsion.html