The entire NASA budget is rounding error compared to the FY2022 US$728.5B of the Department of Defense. But in terms of space exploration, uncrewed planetary and Earth surveillance missions provide a vast scientific yield for a fraction of a penny on the dollar compared to crewed missions. A single year of the crewed program would provide enough funding for a couple of outer planets exploratory missions, or the interplanetary communications and telemetry system desperately needed for any serious expansion of space exploration beyond Lunar orbit. That doesn’t feed into anyones’ Congressional district, though.
Eh, you can argue it in either direction, but ultimately hydrogen propellant demands huge tankage volume, and the only way to accomplish that efficiently is with a low aspect ratio. The SERV took that to an extreme, but any hydrogen-only vehicle would be the same. The Delta IV is pretty squat as it is and it’s not even that strong a launcher.
Once you’ve settled on a low aspect ratio, it makes sense to get as much from that design as you can, and that enabled the capsule-stye reentry mode.
Of course the “Lego” thing is a mild joke, but the entire document is filled with nonsense about saving money via reusing existing components and says essentially nothing about massive integration costs.
DIRECT – Safer, Simpler and Sooner
Minor Modifications for Loads
Uses Existing Tooling
Uses Existing Factory
Uses Existing Transportation
Jupiter Restores Orion’s Safety, Capability while Speeding up Development and Lowering Cost thru Reusability
Jupiter will Lower the Cost to Orbit Significantly over STS
Proven Thrust Oscillation Mitigation
Proven SRB Staging
Proven Dynamic Environment
Yay! Look at all the “existing” and “proven” stuff in there. And it makes no mention of any other possible integration issues, so all this stuff must be easy, right?
Maybe some of this extra information is contained within the
1000+ pages detailing how to the utilize the existing infrastructure for an Inline design
You think anyone in Congress read those 1000+ pages, or any other detailed papers, when they signed the SLS authorization that demanded that NASA use Shuttle-origin components and facilities whenever practiable?
For BLEO, you need either 3+ stages or orbital refueling for decent performance. Obviously I’m a supporter of the latter, which has the advantage that you get a vehicle multiplier effect–if you refuel N times, it’s like having a 3-stage vehicle of N-times the mass.
But if you’re not going that route, and aren’t just going to LEO, then you pretty much need three stages. There’s just too much dead mass in the second stage. Mass fractions only get so good (particularly for hydrolox).
Ok, another alternative would be to launch your vehicle to LEO and use some other propulsion system to go from there to wherever. But that’s just a repackaged third stage and I wouldn’t say that’s fundamentally different.
The Delta IV core stage is 5 meter diameter and 60 to 72 meters in length, giving it an L/D of 12 to 14.4. That is “pretty squat” compared to the liquid ICBM heritage of Thor-Delta and Titan (although less than the SM-65 ‘Atlas’ at an L/D of 8.5) but launch vehicles can certainly have a larger sectional aspect without much efficiency loss. SERV was not of such large diameter because it it used liquid hydrogen (as specified by the NASA proposal) but because they wanted a squat capsule shape as a base-plug aerospike and for reentry performance. We can agree that hydrogen is a poor fuel from a volumetric standpoint and for ground launch its benefits of high vacuum specific impulse (due to low molecular weight of the exhaust products) are dwarfed by the low specific thrust performance and larger amount of tankage structure, in addition to all of the other problems with cryogenic hydrogen as a fuel.
There is a cost saving from reusing existing components…provided that they aren’t changing the design such that it requires substantial modification to handling and ground support equipment and requalification of flight hardware. Since that slide deck is trying to promote the advantages of reuse it is glossing over the fact that the STS/Shuttle system was expensive to operate (in no small part because of the low volume of flights that was largely driven by maintenance and refurbishment of the Orbiter Vehicle) but the intent was a rapid return to flight with a minimum amount of rework or retraining. The SLS has evolved to become very much its own development program with full requalification of many previously qualified components for little reason other than to show new work, and obviously has not satisfied the primary intent to be a rapidly developed system for interim use. That there are no plans for any future replacement system, and that the flight rate is so low that per-launch costs are beyond that for STS is frankly inexplicable, but again, those are decisions beyond even the NASA Administrator’s office.
I’m not sure what BLEO is, but when we refer to ‘stages’ of the booster it is generally referencing those in the booster stack necessary to achieve Low Earth Orbit, and further stages for apogee or trans-planetary injection are referred to as “upper stack”. Saturn V was a bit of a special case because the S-IVB was both a third stage of the booster stack and the trans-Lunar injection stage because of the Lunar Orbit Rendezvous mode. Regardless, two stages to orbit is generally recognized as being the optimum for a ground-to-LEO vehicle (or “stage and a half” in the case of something like a spaceplane) and if we were designing a Saturn V-class vehicle today it would be a larger than S-IC first stage and something like the S-IVB second stage, with higher structural coefficient. In fact, that is the configuration for the S-I and S-IB, and their first stages actually had terrible structural coefficients by any modern standard.
Orbital refueling has its advantages but only if you are able to get your fuel from some space resource (and can figure out all of the complexities that come with handling large fluid volumes in freefall where there is no net force to settle it); otherwise you are just spending more launches to loft the fuel in orbit with terrible overall efficiencies. The only way it really makes sense is if you have a transit vehicle that would be prohibitively large to launch all up, and was the reason that NASA ultimately went to the Lunar Orbit Rendezvous mode for Apollo. Of course, you’d have to do this for a crewed Mars mission, or a to support a Lunar base, but then that argues for the need to develop an space infrastructure to extract and utilize space resources in-situ using automation as an on-ramp to a larger human presence rather than carting every kilogram of consumable resource from the surface of the Earth at enormous cost.
Those are different senses of “reuse”. The document is arguing for reuse of developed systems such as the SRBs. However, it (i.e., Jupiter/SLS/whatever) is still an expendable rocket.
The slide deck is IMO a clear demonstration of how Shuttle-derived designs were sold to those that held the purse strings: an overemphasis on using existing components (still uses the factories in my state!), while downplaying the costs of modification and integration.
The critics called these Lego rockets or dial-a-rocket or whatever, and while they were being euphemistic, they were right in the essentials. I’m sure the actual engineering leadership understood the costs but they were not the ones making the funding decisions.
Sorry, “Beyond Low Earth Orbit”. Catch-all term for lunar, etc. missions. Say, anything with a positive C3.
Yes, agreed with that. IMO, this is something like an “impedance match” problem. The delta V of a stage should be between 1x and 2x its exhaust velocity, ideally somewhere close to the middle. Kerolox gets you ~3 km/s exhaust velocity; LEO is ~9 km/s. A single stage is not great (if even possible), but 3 stages is overkill. However, if you need 12+ km/s, then you really want 3 stages.
Yes. But that’s no small thing. A single Starship launch ends up with ~150 t prop and a ~120 t vehicle in LEO. That same vehicle, refueled, has 1200 t prop. The only way to conceivably launch that is with some absurdly large “Ultra Heavy” booster. That’s unreasonable–Starship is big enough as it is–but with refueling you get the same effect. And if the launcher itself is even partially reusable, then you get better amortization of your fleet.
Falcon 9 boosters are already hitting 12 uses, with no end in sight. I see no reason to believe that Starship won’t achieve that at an absolute bare minimum (i.e., upper stage reuse is a total fail and booster reuse is far smaller than expected). That’s nevertheless a huge win compared to some hypothetical ultra-rocket that launches just once in the same timeframe.
Please explain the “desperate need” for a “serious expansion of space exploration.” As compared to, like, you know, the desperate need for homeless shelters and hospitals.
Your profile pic is of a cat in a guitar case. Please defend your funding of pets and music instead of donating to homeless shelters.
Or, just maybe, society can and should spend some money on things which are of no immediate value, but make life worth living.
As for your specific questions, space-based Earth surveillance is the best way of understanding climate change. We would know almost nothing about it without satellites.
Well, for one is unambiguous confirmation and quantification of the progression and consequences of global warming and climate effects, which is only observable on the global scale from the high vantage of orbital space. Climate monitoring and modeling is actually one of the main missions of NASA, apparently unbeknownst to most of the public.
There are, of course, enormous amounts of scientific knowledge about the larger universe and our place in it, and while you may not personally value basic science for its own sake, it is this knowledge that has allowed every advancement in human civilization in often wholly unexpected ways.
False dichotomy; the United States is an extremely wealthy nation that could provide homeless shelters, universal health care, and social protections as a tiny fraction of its budget. That it does not is not an indication of spending priorities of space exploration vice social welfare but a deliberate philosophical choice not to do so because being poor or vulnerable is a moral failing in the view of many people.
You have misquoted me; what I said was
…the interplanetary communications and telemetry system desperately needed for any serious expansion of space exploration beyond Lunar orbit.
The “desperate need” for an interplanetary communication system is in the context of supporting the far flung exploration missions and hypothetical crewed missions to Mars and elsewhere promoted by people who believe that the only important thing is to get people and probes to their destination and figuring out how to communicate is something that will just happen in the course of a mission. Of course, if you do not think any space exploration is necessary, then obviously communication is also not necessary. But these efforts would employ engineers and technicians otherwise engaged in the development of military systems to a more fruitful (or at least less harmful) result.