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from the sudden-outbreak-of-common-sense? dept.
https://arstechnica.com/science/2019/03/what-is-going-on-with-nasas-space-launch-system-rocket/
In a remarkable turnaround, NASA Administrator Jim Bridenstine on Wednesday said the space agency would consider launching its first Orion mission to the Moon on commercial rockets instead of NASA's own Space Launch System. This caught virtually the entire aerospace world off guard, and represents a bold change from the status quo of Orion as America's spacecraft, and the SLS as America's powerful rocket that will launch it.
[...] During a hearing of the Senate Commerce committee to assess America's future in space, committee chairman Sen. Roger Wicker opened by asking Bridenstine about Exploration Mission-1's ongoing delays. The EM-1 test flight involves sending an uncrewed Orion spacecraft on a three-week mission into lunar orbit, and is regarded as NASA's first step toward returning humans to the Moon. This mission was originally scheduled for late 2017, but it has slipped multiple times, most recently to June 2020. It has also come to light that this date, too, is no longer tenable.
"SLS is struggling to meet its schedule," Bridenstine replied to Wicker's question. "We are now understanding better how difficult this project is, and it's going to take some additional time. I want to be really clear. I think we as an agency need to stick to our commitment. If we tell you, and others, that we're going to launch in June of 2020 around the Moon, I think we should launch around the Moon in June of 2020. And I think it can be done. We should consider, as an agency, all options to accomplish that objective."
The only other option at this point is using two large, privately developed heavy lift rockets instead of a single SLS booster. While they are not as powerful as the SLS rocket, these commercial launch vehicles could allow for the mission to happen on schedule.
[...] One heavy-lift rocket would launch a fully fueled upper stage—most likely a Delta Cryogenic Second Stage or the Centaur upper stage currently used on United Launch Alliance rockets. Then, a second heavy-lift rocket would launch an Orion capsule and its service module into orbit, and these two vehicles would dock. The fueled upper stage would then inject Orion into a lunar orbit.
Bridenstine did not name rockets during the hearing, but it seems almost certain that at least one of them would be a Delta IV Heavy, built by United Launch Alliance. NASA used this rocket to launch a version of the Orion spacecraft to an altitude of 3,600km in 2014. Both United Launch Alliance and SpaceX—with its Falcon Heavy rocket—would be invited to bid on the second launch.
The SLS is the Space Launch System. It's a heavy launch vehicle that's been funded by NASA and contracted out to Boeing with more than $14 billion spent on it so far. It's been in development since 2010. If and when it's completed launches are expected to run $500 million. It's designed to be mostly an incremental improvement over the Apollo program from 50 years ago which includes no reusability as well as reliance on solid rocket boosters; A solid rocket booster uses solid fuel that—once ignited— cannot be stopped.
SpaceX's alternatives are fully reusable and rely on liquid fuel engines which can be throttled on or off at will. The Falcon Heavy is operational today and runs $90-$150 million for a launch. Their development has been almost entirely privately funded as well.
(Score: 3, Interesting) by ElizabethGreene on Friday October 25 2019, @12:41AM (4 children)
I do kind of want to see at least one Super Heavy explode...
AFAIK Starship doesn't have a launch escape system. I do not want to see the consequences of that decision.
(Score: 2) by takyon on Friday October 25 2019, @01:04AM
Pad abort with explosive Super Heavy could be tested sooner than you think™: https://www.teslarati.com/spacex-elon-musk-starship-pad-abort-capability/ [teslarati.com]
Starship escape system nowhere to be found: https://space.stackexchange.com/questions/33837/what-are-spacex-starship-bfr-proposed-abort-modes [stackexchange.com]
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 2) by Immerman on Friday October 25 2019, @02:43PM (2 children)
Starship *is* the launch escape system. Super Heavy is the high-power launch system (first stage). In event of problems Starship jets away in front of the (potential) fireball, just as the Dragon capsule would from the Falcon 9.
Now, if Starship itself blows up during a non-test flight (especially with passengers) that'd be a tragedy - but launch aborts during the second stage are generally pretty dicey on any current rocket - if they're even possible.
(Score: 2) by ElizabethGreene on Saturday October 26 2019, @03:15AM (1 child)
I'm skeptical of that. It's very different shooting a fully loaded second stage off in atmosphere than landing an almost empty stage in atmo. The turbopumps are going to be offline, the MVAC engines aren't going to be chilled, etc.
That doesn't make it impossible, just a hard engineering problem. One of the other replies mentioned that they've bandied the idea around, but aren't concrete on it yet.
(Score: 2) by Immerman on Saturday October 26 2019, @08:13PM
How long is the second stage riding inert before separation? A few minutes? I imagine most bits will be primed and waiting to go regardless. Of course - that'd be the vacuum engines, you'd probably want to keep the atmosphere engines primed too for escape. That'd also mean you could fire all six for escape, roughly doubling the available thrust during those critical first seconds, before shutting off the vacuum engines to get better control.
They're designing Starship to be able to fly fully-loaded suborbital (and maybe orbital with only a tiny payload) on its own, so it shouldn't have any problem providing the thrust needed to land safely. Especially since unlike the Falcon 9 (if Starhopper is any indication) it will be able to throttle down low enough to hover, and thus land at an arbitrarily low speed. It's hard to overstate just how huge a safe landing options envelope that creates. It could even just hover to burn off fuel if it really needed to.
And control is actually easier with a heavier vehicle - more rotational inertia means greater stability. A slower response means more time to accurately characterize and correct for any problems.