Author Topic: NASA returning to the moon  (Read 1236 times)

Offline apollo16uvc

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Re: NASA returning to the moon
« Reply #15 on: February 17, 2019, 02:07:29 PM »
Progression died when NASA stopped using hasselblad camera's.
Ultraviolet light photography rules!
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Offline cjameshuff

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Re: NASA returning to the moon
« Reply #16 on: February 17, 2019, 02:23:52 PM »
Firt NASA has to build and test fly the SLS, and that is taking a long time for an expendable rocket.  Not to change the design, but perhaps NASA should start embracing the fully reusable rocket?

It's clear the "repurpose Shuttle hardware to reduce costs and speed development" strategy was as spectacular a failure at those goals as the Shuttle itself was (what a surprise). Changing direction to a reusable system would require more than a change in the design though, there's no quick fix for the lack of liftoff thrust or excess landing thrust and insufficient throttle control due to the propellant and engines used by the first stage.

Also, reusable vehicles are only even being discussed because private companies have stepped up to do what NASA should have been doing in advancing the state of the art in reusable vehicles. NASA shouldn't now be trying to compete with them, they should be providing them with contracts to encourage the development of those capabilities. They instead seem to be sticking their heads in the sand and ignoring what's going on. (the analogy to a flightless bird seems particularly appropriate here...)

Offline bknight

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Re: NASA returning to the moon
« Reply #17 on: February 17, 2019, 04:30:36 PM »
I wouldn't call it competing, but more in the line of stretching resources.   Yes I agree that design changes would be difficult, but not impossible.
The Shuttle program wasn't thought out, frozen insulation for example.   Placement of the orbiter might have been different.   It does seem like NASA does stick its head in the sand or proceed with blinders.   Here I complain from the outside, but it seems like they could do better.
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Offline cjameshuff

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Re: NASA returning to the moon
« Reply #18 on: February 17, 2019, 05:09:25 PM »
I wouldn't call it competing, but more in the line of stretching resources.   Yes I agree that design changes would be difficult, but not impossible.

The core can't launch without boosters, it can't re-light its RS-25s and land on them. Salvaging and rebuilding the boosters was never particularly close to "reuse", and the new ones burn longer and reenter faster and further downrange, making things worse. The core needs higher thrust to get rid of the boosters, it needs to perform multiple burns in flight, and it needs to be able to reduce thrust by nearly an order of magnitude and still throttle rapidly and precisely over a wide range for landing.

This would be very difficult to achieve with hydrogen propellant, can't be done with the RS-25, and would realistically best be approached by clustering 7 or more engines using a hydrocarbon fuel...like Falcon 9, New Glenn, and Starship do. Changing the propellant to something denser drastically changes the dimensions of the tanks. The core will need its own avionics making it capable of independent flgiht and landing. It'd also have to stage much sooner to reduce reentry stresses, with the second stage providing much more of the launch delta-v.

Practically every detail of the design of SLS works against reuse. The changes to make it even partially reusable would constitute a complete redesign, discarding most of the Shuttle-derived technologies. At most you'd reuse some of the tank design, but even that would need major changes to insulation, etc.

Offline Echnaton

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Re: NASA returning to the moon
« Reply #19 on: February 17, 2019, 08:47:12 PM »

You are supporting your point of view based on a 50 year old incident. I am supporting mine based on current statistics.

For the time being, rocket development is a make work program for the aerospace industry that may, eventually produce something the the government may eventually, want to use.  That doesn't have much political pull to it. I can't image either party wanting to fund this.
« Last Edit: February 17, 2019, 09:03:57 PM by Echnaton »
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Offline ka9q

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Re: NASA returning to the moon
« Reply #20 on: February 17, 2019, 09:04:34 PM »
I consider myself pretty liberal in most ways, and I'm obviously a supporter of space exploration.

I think much of the problem with Apollo is that it was rightly seen as an extension of the Cold War. Its primary purpose wasn't science but to fight the Russians in the court of global opinion. Since then, space exploration has become a symbol of civilian science, technology and education, things that most (but not all) liberals approve of.

To the extent that some conservatives approve of them too, something could happen. But things are probably too polarized right now for there to be much bipartisan support. It's gotten to the point where each side automatically opposes anything supported by the other side.

Offline Peter B

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Re: NASA returning to the moon
« Reply #21 on: February 18, 2019, 08:48:17 AM »
I wouldn't call it competing, but more in the line of stretching resources.   Yes I agree that design changes would be difficult, but not impossible.

The core can't launch without boosters, it can't re-light its RS-25s and land on them. Salvaging and rebuilding the boosters was never particularly close to "reuse", and the new ones burn longer and reenter faster and further downrange, making things worse. The core needs higher thrust to get rid of the boosters, it needs to perform multiple burns in flight, and it needs to be able to reduce thrust by nearly an order of magnitude and still throttle rapidly and precisely over a wide range for landing.

This would be very difficult to achieve with hydrogen propellant, can't be done with the RS-25, and would realistically best be approached by clustering 7 or more engines using a hydrocarbon fuel...like Falcon 9, New Glenn, and Starship do. Changing the propellant to something denser drastically changes the dimensions of the tanks. The core will need its own avionics making it capable of independent flgiht and landing. It'd also have to stage much sooner to reduce reentry stresses, with the second stage providing much more of the launch delta-v.

Practically every detail of the design of SLS works against reuse. The changes to make it even partially reusable would constitute a complete redesign, discarding most of the Shuttle-derived technologies. At most you'd reuse some of the tank design, but even that would need major changes to insulation, etc.

Thank you. That was an impressive and elegant summary.

And I see the SLS currently isn't due to launch until mid-next year. Given the delays in launching any new system, I wonder when that will happen in reality...

Offline bknight

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Re: NASA returning to the moon
« Reply #22 on: February 18, 2019, 12:04:11 PM »
I wouldn't call it competing, but more in the line of stretching resources.   Yes I agree that design changes would be difficult, but not impossible.

The core can't launch without boosters, it can't re-light its RS-25s and land on them. Salvaging and rebuilding the boosters was never particularly close to "reuse", and the new ones burn longer and reenter faster and further downrange, making things worse. The core needs higher thrust to get rid of the boosters, it needs to perform multiple burns in flight, and it needs to be able to reduce thrust by nearly an order of magnitude and still throttle rapidly and precisely over a wide range for landing.

This would be very difficult to achieve with hydrogen propellant, can't be done with the RS-25, and would realistically best be approached by clustering 7 or more engines using a hydrocarbon fuel...like Falcon 9, New Glenn, and Starship do. Changing the propellant to something denser drastically changes the dimensions of the tanks. The core will need its own avionics making it capable of independent flgiht and landing. It'd also have to stage much sooner to reduce reentry stresses, with the second stage providing much more of the launch delta-v.

Practically every detail of the design of SLS works against reuse. The changes to make it even partially reusable would constitute a complete redesign, discarding most of the Shuttle-derived technologies. At most you'd reuse some of the tank design, but even that would need major changes to insulation, etc.

You are looking at what has transpired in the development of SLS, What I was referring is what seems like a shortsightedness of NASA to use inventoried RS-25's and building a complete system around them instead of designing for muscle and re-usability.  But maybe that can't ever be a product of a governmental body.

I consider myself pretty liberal in most ways, and I'm obviously a supporter of space exploration.

I think much of the problem with Apollo is that it was rightly seen as an extension of the Cold War. Its primary purpose wasn't science but to fight the Russians in the court of global opinion. Since then, space exploration has become a symbol of civilian science, technology and education, things that most (but not all) liberals approve of.

To the extent that some conservatives approve of them too, something could happen. But things are probably too polarized right now for there to be much bipartisan support. It's gotten to the point where each side automatically opposes anything supported by the other side.

For myself I'm 50-50 and I support space programs, since they do benefit science.
Yes Apollo was a program to beat the Russians(at something in space) and only had small scientific attachments added.
Truth needs no defense.  Nobody can take those footsteps I made on the surface of the moon away from me.
Eugene Cernan

Offline Eventcone

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Re: NASA returning to the moon
« Reply #23 on: February 18, 2019, 12:49:17 PM »
(Lurker decloaking...)

It's politicians wanting their "slice of pork" that we have to thank for the deficiencies of the nation's successor to the Saturn V. What a mess.

When one thinks that NASA's most spectacular success was achieved on a philosophy of "waste anything but time", it does not inspire confidence that they will ever take us into an era of sustainable manned deep space missions.

Is it not high time that NASA stopped developing their own flight hardware, and flew their astronauts on commercially available hardware from the likes of SpaceX and others? Surely they could do so much more, for so much less, in much less time?

Offline cjameshuff

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Re: NASA returning to the moon
« Reply #24 on: February 18, 2019, 08:26:32 PM »
I wouldn't call it competing, but more in the line of stretching resources.   Yes I agree that design changes would be difficult, but not impossible.

The core can't launch without boosters, it can't re-light its RS-25s and land on them. Salvaging and rebuilding the boosters was never particularly close to "reuse", and the new ones burn longer and reenter faster and further downrange, making things worse. The core needs higher thrust to get rid of the boosters, it needs to perform multiple burns in flight, and it needs to be able to reduce thrust by nearly an order of magnitude and still throttle rapidly and precisely over a wide range for landing.

This would be very difficult to achieve with hydrogen propellant, can't be done with the RS-25, and would realistically best be approached by clustering 7 or more engines using a hydrocarbon fuel...like Falcon 9, New Glenn, and Starship do. Changing the propellant to something denser drastically changes the dimensions of the tanks. The core will need its own avionics making it capable of independent flgiht and landing. It'd also have to stage much sooner to reduce reentry stresses, with the second stage providing much more of the launch delta-v.

Practically every detail of the design of SLS works against reuse. The changes to make it even partially reusable would constitute a complete redesign, discarding most of the Shuttle-derived technologies. At most you'd reuse some of the tank design, but even that would need major changes to insulation, etc.

Thank you. That was an impressive and elegant summary.

And I see the SLS currently isn't due to launch until mid-next year. Given the delays in launching any new system, I wonder when that will happen in reality...

Late next year at the earliest:

Consequently, in light of the Project’s development delays, we have concluded NASA will be unable to meet its EM-1 launch window currently scheduled  between December 2019 and June 2020.

I wouldn't bet on it launching before 2021.

Offline Zakalwe

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Re: NASA returning to the moon
« Reply #25 on: February 20, 2019, 05:16:18 AM »

I wouldn't bet on it launching before 2021. ever

Fixed that for you, no charge.
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Offline bknight

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Re: NASA returning to the moon
« Reply #26 on: February 20, 2019, 09:41:14 AM »
The first launch will be a long time coming with tinkering with a new welding technique on the first stage tank and all.
Truth needs no defense.  Nobody can take those footsteps I made on the surface of the moon away from me.
Eugene Cernan

Offline cjameshuff

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Re: NASA returning to the moon
« Reply #27 on: February 20, 2019, 06:19:45 PM »
The first launch will be a long time coming with tinkering with a new welding technique on the first stage tank and all.

If it actually was a new welding technique, we'd at least be getting that out of this mess. It was actually just thicker metal (requiring changes to the welding tools that didn't work out as hoped) and a redesign of the welding machine to do the weld on a vertical tank. The same technique was used with a horizontal machine for the Shuttle tanks, and for SpaceX's Falcon 9 rockets (also with horizontal machines).

I wonder if experience with the welding technique, and how it scales poorly with thickness, is part of why SpaceX was so interested in using carbon fiber for larger vehicles. And now they've dropped that for stainless steel alloys that are much easier to work with.