As Nasa is doomed to be dismantled and sold for parts to Space X it is with sadness I ponder what could have been.
The Shuttle was the penultimate worst wrong turn of the many NASA has made, the worst being Elon Musk of course. I have puzzled for over a decade, since I became interested in space, how the Shuttle Program could have been a success instead of a failure, and a big part of that question is the LEO limitation. The Shuttle was in the class of the Saturn V but wasted most of that lift on a 737-sized glider.
The giant cargo bay of dreams, wings, landing gear, and various systems returned the engines, saved on the previously expended structure around the payload, and also carried a large crew and their life support….and massed over 70 tons, actually about twice as much as a 737. It is interesting to note a single Aerojet M-1 engine could have provided the thrust of the three engines mounted on the Orbiter. The 12 or so tons the triple RS-25 engine section massed was also why the Orbiter was side mounted, which led to the loss of the Columbia.
In hindsight the SRB’s, which caused the loss of the Challenger, should have been liquid fueled and could have used a variant of the same M-1 engine that could have been used on the Orbiter…except putting it on the Orbiter would not have been done in hindsight. Ironically, the configuration of the expendable SLS would have been ideal for the reusable Space Transportation system using liquid fuel boosters and returnable engine module at the bottom of the stack. All hydrogen would also have enabled propellent cross-feed from the boosters to the core engine module.
In regard to reusability and the ISS, the core hydrogen tank could have been the single expendable part and the LOX tank repurposed by leaving it in orbit for use as a wet workshop. Stockpiling these tanks in LEO would have provided crew compartments for approximately 100 space stations similar to the ISS….or an ISS one hundred times larger.
The Orbiter itself, at the top of the stack, without the Air Force cross-range requirement and not carrying the main engines, would have been much lighter. In reality, it would not have been worth it to just bring back a cargo bay and not much of any value was ever brought back. A large “Big Gemini” capsule with a reusable escape tower would have been the best path. And it would have flown far more often and still be flying.
Comments:
Hopefully, whatever I wrote that made this comment repeatedly unacceptable, I have managed to edit out this time:
“Mars-direct advocates correctly emphasize the urgency of becoming multiplanetary.”
Actually…” Multiplanetary”, is in my view a false pretense in that Mars and all natural bodies in the solar system other than Earth are unsuitable for colonization for the simple reason that human bodies require Earth gravity to stay healthy. Artificial habitats as envisioned by Gerard K. O’Neill, miles-in-diameter spinning hollow moons, are likely the only practical path to colonization.
“-space-based solar power for lunar use creates a comprehensive economic ecosystem.”
Space Solar Power FROM lunar resources to power civilization on Earth as the solution to Climate Change will certainly create the necessary economic engine. I doubt anything else will.
“Commercial ventures should take the lead in developing revenue-generating lunar operations and driving innovative technology development.”
Space Solar Power from lunar resources seems to be the only large commercial venture that can eventually generate revenue Beyond Earth Orbit and enable colonization. And this economic engine, like Hoover Dam and the Panama Canal, will require the government to sponsor it. Even before Space Solar becomes a public works project the government must legislate a phasing out of the burning of fossil fuels for Space Solar to become economically viable.
“-the Moon offers real partial gravity, actual deep space radiation,-“
Debilitation and dosing is the elephant in the room nobody will address, not even NASA. The “Parker Minimum” of 4 or 5 hundred tons of shielding is the basic requirement for any long duration deep space missions. The Moon will be a factory site, not a colony, and workers will likely be periodically lifted into lunar orbit to 1G space stations for rehabilitation. Or… circular “sleeper trains” providing 1G beneath the lunar surface may eventually become available. While these constructs are not so difficult to build on icy low gravity bodies, they are far more difficult on the Moon.
“The choice isn’t between lunar presence and Mars development: both are essential for America’s space future.”
Personally, I believe Mars is, like LEO, a dead end, and the Moon is the prize. This is more of a choice between the false promise of Mars and the true path to space colonization from the original prophet, Gerard K. O’Neill.
There has to be a driver, an engine, and a destination. The driver is Climate Change, the engine is Space Solar Power, and the destination is the resources on the Moon that can be exploited without generating greenhouse gases on Earth. This is the Green New Space Deal that can transform the world and create the Next America. Because, in case you have not noticed, the old America ended on election night. Oligarchy is only about enriching oligarchs and unless there is a popular uprising as powerful as the civil rights and anti-war movements of the 60’s, we are entering an ever more oppressive era of autocracy that will be increasingly harder to escape.
There is ice on the Moon…but it is not an ocean of water and that is what is needed. I would say creating “catch shafts” on the Moon, that ice from the outer solar system can fly down into and be captured, is the best path. Using lunar ores to mass produce miles-in-diameter spinning hollow moons will excavate large spaces under the lunar surface that can be filled with this water from the outer solar system. In a century or so there will be large underground reservoirs. In several centuries the hundreds of millions of tons of lunar material will be replaced with these underground living seas.
I would like to see these robot spacecraft designed to send large chunks of ice at the Moon.
It is amazing how NASA took such a great concept, a Saturn V class launch vehicle that only expended a single tank of propellants and executed it in the worst way possible. And how Musk has done essentially the same thing with a two stage VTVL concept. At least it proves that the miracle of entrepreneurship is a myth. Both the government and private entities can mess up a concept equally badly.
1) Some concepts are pursued before the technologies to make them a reality exist. Pursuing them may foster development, but the failures may hinder future progress. For example, it may be that Starship would work fine with Rotating Detonation Rocket Engines with an Isp of over 500 and made out of super-alloys lighter than aluminum and stronger than steel. Both of these are being developed but do not “exist.” Starship does not look like it is going to succeed in it’s present form because the rocket equation says so.
2) Some technologies exist but are not available, not feasible, due to their inherent risk, cost, or effect on the environment. For example, Nuclear Pulse Propulsion is by far the most powerful and efficient technology available to lift immense masses off the Earth and travel to the outer reaches of the solar system and back at fantastic speeds. But lifting off from the Earth is not acceptable. And presently not even operating in deep space is an available option due to cost and lack of vehicles that can send components like multi-thousand-ton plates Beyond Earth Orbit.
3) Some consequences, predicted as a possibility or unintended, even if technology is available, make many goals not worth pursuing due to their problematic nature and near certainty of negative, and in some cases, catastrophic results. For example….Megaconstellations.
In the center, being pulled from these three sides of concepts, technology, and consequences, are the goals in space exploration well worth pursuing. Evaluating these goals are the place to start.
What are these end goals? To get rich? To survive as a species?
We could solve Climate Change and provide a western standard of living to 10 billion human beings. We could remove the nuclear arsenal to months away in deep space on human-crewed spaceships and thus end the launch-on-warning nuclear threat to civilization. We could build miles-in-diameter artificial hollow moons to colonize space with and eventually travel to other stars. We actually have the technology to do this.
It does not appear these first two goals complement each other and in fact are the opposite. This is my problem with NewSpace….it is the wolf pack pleading with the flock of sheep to trust their good intentions.
I would cite 2 other sources for my comments:
https://www.verneh2.com/news-article/verne-and-lawrence-livermore-national-laboratory-achieve-cryo-compressed-hydrogen-storage-record-demonstrating-first-system-suitable-for-heavy-duty-transportation
and
https://web.archive.org/web/20160303181821/http://www.la.dlr.de/ra/sart/publications/pdf/2003-4597.pdf
The best replacement for the SLS-SRB’s, in my view, would be partially pressure-fed boosters using cryo-compressed liquid hydrogen storage and expander-bleed cycle engines. These would be essentially scaled-up versions of the Japanese LE-9 331,000 pound thrust engines, in the 2 million pound thrust range. These boosters, each mounting 2 engines and four per pair, might also offer propellent cross-feed to the SLS core and would be ocean-recovered like the original Shuttle boosters. Along with the RPAM concept at the top of the page, with a dual side mount, this would drop 4 items per launch into the ocean to be recovered by a ship off the coast of Florida. While the RPAM data provided cites a weight of approximately twice the lift of our current heavy lift helicopter (CH-53K), a twin RS-25 derivative RPAM able to be helo-captured might be feasible.
I believe this would make the SLS into what the Space Shuttle was intended to be.