What should NASA actually do with SLS?

[Vahe231991]

Alexw, the rest of us define it by the number of launches required. No gray areas there.

Did anyone put out proposals for asteroid defense?

I know that we have already some coordinated efforts to identify potentially threatening objects; is there any possibility about doing something with 70MT to orbit, and maybe propellent depots? This is blue sky, and we'd better not need it before 2017, but still, is there anything we reasonable do about it with SLS capability?

This thread may be old, but with respect to the first two questions, but in January 2012 a near pass-by asteroid 2012 BX34 prompted the publication that year of a paper titled "A Global Approach to Near-Earth Object Impact Threat Mitigation" by researchers from Russia, Germany, the United States, France, Britain, and Spain, which dealt with the "NEOShield" asteroid defense project. The DART spacecraft was proposed in the mid-2010s and it was launched in November 2021 and successfully hit the asteroid Dimorphos on September 26, 2022.

Links:
https://www.space.com/14370-asteroid-shield-earth-threat-protection-meeting.html
https://web.archive.org/web/20150607004851/http://www.esa.int/Our_Activities/Space_Engineering_Technology/NEO/Asteroid_Impact_Deflection_Assessment_AIDA_study

[spacenut]

Back in 2010, they thought SLS would be cheaper and more sustainable.  Today, it is not.  It has become too expensive to launch more than once a year.  Solids are expensive and not reusable.  They cost as much to refurbish as new ones.  Hydrogen is not a good booster fuel.  Is expensive and only good for upper stages.  All the new rockets are using methane, Starship/superheavy, Vulcan, New Glenn, and some small startups.  Clean, more power than hydrogen, and is great for reusable engines as there is no coking like kerosene.  SpaceX has proven you can land a booster which is the largest and most expensive part of getting to orbit.  Now we have to reuse upper stages/spacecraft.  NASA did not go this route because of congress who appropriates the money. 

[TrevorMonty]

Back in 2010, they thought SLS would be cheaper and more sustainable.  Today, it is not.  It has become too expensive to launch more than once a year.  Solids are expensive and not reusable.  They cost as much to refurbish as new ones.  Hydrogen is not a good booster fuel.  Is expensive and only good for upper stages.  All the new rockets are using methane, Starship/superheavy, Vulcan, New Glenn, and some small startups.  Clean, more power than hydrogen, and is great for reusable engines as there is no coking like kerosene.  SpaceX has proven you can land a booster which is the largest and most expensive part of getting to orbit.  Now we have to reuse upper stages/spacecraft.  NASA did not go this route because of congress who appropriates the money.

RLV wouldn't have made sense then given they were unknown and expected flight rate for BLEO missions was too small. Any RLV would've required in orbit refuelling another new technology and probably new engine. That is 3 new things with RLV being very high risk and likely to over budget and schedule. Delays and cost overruns from all 3 would've added up as they needed to be built consecutively. RLV needs engine and in orbit refuelling operational RLV.

[Robotbeat]

Thing is… NASA needs orbital refueling (or at least cryo management) for Artemis and Mars *anyway*. The typical Artemis or Mars reference design makes extensive use of cryogenic propellants, Artemis required refueling as part of the sustaining missions for Artemis HLS.

The smart thing would’ve been to build the architecture around an unflinching embrace of refueling (since it’s needed anyway), and then not start with an RLV at all but with proven EELVs. Develop the RLV(s) on the side in parallel, not on the critical path.

[Coastal Ron]

Back in 2010, they thought SLS would be cheaper and more sustainable.

I don't know who "they" is, but it would be hard for anyone to think that building an "Ares IV" type launcher would be significantly less than the Ares V Congress was cancelling - because it was too expensive.

The reality is that Congress didn't care about cost, otherwise they would have asked NASA to provide a budget estimate and not funded the SLS. Not long after Congress did fund the SLS there was this article talking about development costs for a variety of heavy launchers, including one that is close to what the SLS turned out to be. Here is the article:
https://nasawatch.com/cev-calv-lsam-eds/the-hlv-cost-information-nasa-decided-not-to-give-to-congress/

Congress didn't care to reassess their assumptions, and now most of that development cost is already "water under the bridge" so to speak. But the operational costs and operational limitations of the SLS are still around.

The SLS, and the Orion (which is the only payload the SLS is assigned to carry), can't be the cornerstone of NASA's expansion into space because they 1) cost too much on a Person/$ ratio, and 2) can't support a robust amount of people in space continuously. Sure, they can be used for limited missions, but the U.S. has to decide what it wants for the long term, and then start putting that in place. And the SLS is not part of that.

[TomH]

Back in 2010, they thought SLS would be cheaper and more sustainable.

That is patently not true. No one ever thought that. Senators Hatch, Shelby, Nelson, and Hutchison supported SLS solely for the pork it would bring into their states. They proscribed technical specifications so precise that only obsolete shuttle parts, made in their states, could be utilized in this beast. They then allocated roughly 85% of the funds necessary to develop this albatross at a reasonable pace, so that its development would drag on for many years, allowing even more money in toto to flow into their states as corporate welfare.

As for what NASA should do with it? Cancel it and replace it with this:

[Vahe231991]

At the current time of writing, proposed SLS cargo variants remain deferred when it comes to near-term prospects of being approved for full-scale development. Nonetheless, they would make good launch platforms for a new generation of unmanned spacecraft designed to explore the gas giants and Kuiper belt, even a notional nuclear-powered space probe for exploring not just Uranus, Neptune, and Pluto but also other objects in the Kuiper belt.

[Jim]

.... they would make good launch platforms for a new generation of unmanned spacecraft designed to explore the gas giants and Kuiper belt, even a notional nuclear-powered space probe for exploring not just Uranus, Neptune, and Pluto but also other objects in the Kuiper belt.

no, it doesn't.  it is too expensive for those missions.

[VSECOTSPE]

Acoustic and vibration environments for payloads may also preclude, if Europa Clipper is anything to go by.

[woods170]

Acoustic and vibration environments for payloads may also preclude, if Europa Clipper is anything to go by.

There are technical solutions possible for quite a lot of those problems. Jim correctly identified the primary problem: nobody, not even NASA, is going to pay $2B+ for a launch, unless it is part of Artemis.

[Vahe231991]

Acoustic and vibration environments for payloads may also preclude, if Europa Clipper is anything to go by.

The Europa Clipper is only intended to explore Europa and make flybys past Jupiter. the Pioneer 10 and 11 as well as the Voyager 1 and 2 along with the New Horizons that have explored deep space have a launch mass which far less than that of the Europa Clipper.

[VSECOTSPE]

The Europa Clipper is only intended to explore Europa and make flybys past Jupiter. the Pioneer 10 and 11 as well as the Voyager 1 and 2 along with the New Horizons that have explored deep space have a launch mass which far less than that of the Europa Clipper.

It’s not a question of how far SLS can throw these scientific spacecraft.  It’s a question of whether these spacecraft, especially their more sensitive instruments and deployables, can survive a launch on SLS.

[butters]

Transition Michoud to the production of 8.4m pressurized modules for 9m payload bays.

[Zed_Noir]

Transition Michoud to the production of 8.4m pressurized modules for 9m payload bays.

The 8.4m PCM concept will not be able to competed with a 9m PCM. The proposed Michoud product is likely to be too pricey.

Maybe a better idea is to produced 8.4m cryogenic (e.g. liquid hydrogen) storage tanks for orbital depots.

[Vahe231991]

The Europa Clipper is only intended to explore Europa and make flybys past Jupiter. the Pioneer 10 and 11 as well as the Voyager 1 and 2 along with the New Horizons that have explored deep space have a launch mass which far less than that of the Europa Clipper.

It’s not a question of how far SLS can throw these scientific spacecraft.  It’s a question of whether these spacecraft, especially their more sensitive instruments and deployables, can survive a launch on SLS.

Since the proposed SLS Block 2 cargo variant is seen as the most likely launch platform for the proposed Interstellar Probe, it'd be interesting to see if the Interstellar Probe could survive a launch on the SLS Block 2 cargo version, especially given that the Interstellar Probe weighs only 1,900 pounds and is thus far lighter than the Europa Clipper. Since NASA decided that the Falcon Heavy's lack of SRBs was the chief reason to pick the Falcon Heavy as the launch platform for the Europa Clipper, it may decide that the New Glenn could be the launch platform for the Interstellar Probe because it too does not have SRBs, also sparing the Interstellar Probe from any vibrations generated by solid-rocket boosters.

[Robotbeat]

The Europa Clipper is only intended to explore Europa and make flybys past Jupiter. the Pioneer 10 and 11 as well as the Voyager 1 and 2 along with the New Horizons that have explored deep space have a launch mass which far less than that of the Europa Clipper.

It’s not a question of how far SLS can throw these scientific spacecraft.  It’s a question of whether these spacecraft, especially their more sensitive instruments and deployables, can survive a launch on SLS.

Since the proposed SLS Block 2 cargo variant is seen as the most likely launch platform for the proposed Interstellar Probe, it'd be interesting to see if the Interstellar Probe could survive a launch on the SLS Block 2 cargo version, especially given that the Interstellar Probe weighs only 1,900 pounds and is thus far lighter than the Europa Clipper. Since NASA decided that the Falcon Heavy's lack of SRBs was the chief reason to pick the Falcon Heavy as the launch platform for the Europa Clipper, it may decide that the New Glenn could be the launch platform for the Interstellar Probe because it too does not have SRBs, also sparing the Interstellar Probe from any vibrations generated by solid-rocket boosters.

The main reason FH was chosen is because it’s an order of magnitude lower cost and SLS has extremely low availability. If you want to have the mission fly, I’d pick any launcher OTHER than SLS. Starship, Falcon Heavy, New Glenn, Vulcan. Any of those would be better. Expendable Starship, especially with a kick stage, could push the probe to any delta-v SLS could. Refuelable Starship could launch an order of magnitude larger probe and will be ready far before SLS Block 2.

[VSECOTSPE]

Since the proposed SLS Block 2 cargo variant is seen as the most likely launch platform for the proposed Interstellar Probe,

Interstellar Probe’s challenge is not a launcher but endorsement by a heliophysics decadal survey.  A  fast mission to the interstellar medium has been around as a concept since at least the mid 70s. (It’s nearly as old as I am.) The APL/Ralph McNutt version has been around since at least the late 90s.
A mission to the interstellar medium has never ranked well against other heliophysics mission concepts.  The science is too low priority, the return too far in the future, and the cost too high compared to other missions.  Could change this time around, but I would guess not given the multi-decade history on this.

[Jim]

Since the proposed SLS Block 2 cargo variant is seen as the most likely launch platform for the proposed Interstellar Probe, it'd be interesting to see if the Interstellar Probe could survive a launch on the SLS Block 2 cargo version, especially given that the Interstellar Probe weighs only 1,900 pounds and is thus far lighter than the Europa Clipper. Since NASA decided that the Falcon Heavy's lack of SRBs was the chief reason to pick the Falcon Heavy as the launch platform for the Europa Clipper, it may decide that the New Glenn could be the launch platform for the Interstellar Probe because it too does not have SRBs, also sparing the Interstellar Probe from any vibrations generated by solid-rocket boosters.

No.   Interstellar Probe is not an approved mission, therefore there is no likely "launch platform".  It is only a proposal.  There is no guarantee that it will ever go forward and become a funded project.  Also, lighter weight has no bearing on the capability of a spacecraft to handle vibrations.

[woods170]

Acoustic and vibration environments for payloads may also preclude, if Europa Clipper is anything to go by.

The Europa Clipper is only intended to explore Europa and make flybys past Jupiter. the Pioneer 10 and 11 as well as the Voyager 1 and 2 along with the New Horizons that have explored deep space have a launch mass which far less than that of the Europa Clipper.

You seem to lack the fundamental understanding that payload mass has nothing to do with a payload's capability to withstand certain acoustic and vibration environments.

[Vahe231991]

This recent development is of utmost relevance to the question posed by the title of this thread:
https://arstechnica.com/space/2023/09/nasa-finally-admits-what-everyone-already-knows-sls-is-unaffordable/