SLS versus Falcon Heavy (and Starship/SH)

[Grendal]

Here is an interesting opinion piece article pointing out the strengths of Falcon Heavy compared to the Space Launch System.

Europa or Enceladus? If NASA switches from SLS to Falcon Heavy, it won't have to choose - SpaceNews.com

 

[nwdiver]

Here is an interesting opinion piece article pointing out the strengths of Falcon Heavy compared to the Space Launch System.

Europa or Enceladus? If NASA switches from SLS to Falcon Heavy, it won't have to choose - SpaceNews.com

The first comment nailed it

FH will only win out over SLS if it brings $$$ to more congressional districts than SLS... in which case it likely won't be much cheaper. SLS is more a jobs program than for space exploration.

 

[Grendal]

FH will only win out over SLS if it brings $$$ to more congressional districts than SLS... in which case it likely won't be much cheaper. SLS is more a jobs program than for space exploration.

I liked this comment which agrees with your observation:

If NASA did not launch the Europa mission with the SLS, there is little need for the Europa mission. Congress would never approve hundreds of millions, or billions of dollars for a mission to Europa for science! Congress pushes for missions that make the SLS look useful and keeps the pork flowing for the jobs programs. And btw, no serious monies have been funded for the proposed Europa mission. It's all designed to provide good PR to continue spending serious money on SLS. In fact, by the time SLS actually flies (I bet NET summer 2021) Congress may well claim that there is no money for a Europa mission because they had to spend the funds on SLS.

 

[e-FTW]

The fact that FH has flown already and could do this mission instead of the non-existent, over-priced SLS and that this fact has not registered with NASA is nuts.
Yes, jobs program, I know. Common sense need-not apply...

So, how about BFR? That too will no doubt beat SLS to space. And it can launch big heavy things that FH cannot.

 

[Lozza12]

The first comment nailed it

View attachment 342941

FH will only win out over SLS if it brings $$$ to more congressional districts than SLS... in which case it likely won't be much cheaper. SLS is more a jobs program than for space exploration.

So a bit like digging holes and then filling them back in again?

Now I see why space flight technology from the 1960s hasn’t really evolved much until very recent times...

 

[ecarfan]

In this article A congressman’s loss clouds the future of two demanding missions to Europa it is explained that if the Europa Clipper mission flew on the FH instead of the SLS the mission would take much longer to get to Europa, and because it would involved multiple planetary flybys including one near Venus, the spacecraft would be exposed to much higher thermal loads and it would have to be designed to handle those. Currently the design does not include that level of thermal protection because the SLS has the lift capability to take a much more direct path to Europa.

But then the article says something that I did not understand. Quote:

“The breakthrough referenced by Goldstein involved the addition of a Star 48 "kick stage" to the Falcon Heavy rocket, which would provide an extra boost of energy after the rocket's upper stage had fired. With this solid rocket motor kick stage, Goldstein said Clipper would need just a single Earth gravity assist and would not have to go into the inner Solar System for a Venus flyby.”

What is a “Star 48 kick stage”? It appears to be a solid fuel third stage component used on the Delta IV Heavy. I found several references to it online, including in this article Solar probe moves into launch position at Cape Canaveral – Spaceflight Now

But the idea of incorporating a Delta IV 3rd stage into the FH, between the 2nd stage and the payload,seems a bit bizarre. That is a major change to the FH, introducing numerous potential complications and problems.

I wonder if SpaceX would agree to such a change in exchange for getting to launch the Europa Clipper mission. While the government would surely save a lot of money — NASA would have to pay for the R&D necessary to support the FH modification but that would be way less costly than one SLS launch — if something went wrong SpaceX would look bad.

 

[Grendal]

In this article A congressman’s loss clouds the future of two demanding missions to Europa it is explained that if the Europa Clipper mission flew on the FH instead of the SLS the mission would take much longer to get to Europa, and because it would involved multiple planetary flybys including one near Venus, the spacecraft would be exposed to much higher thermal loads and it would have to be designed to handle those. Currently the design does not include that level of thermal protection because the SLS has the lift capability to take a much more direct path to Europa.

But then the article says something that I did not understand. Quote:

“The breakthrough referenced by Goldstein involved the addition of a Star 48 "kick stage" to the Falcon Heavy rocket, which would provide an extra boost of energy after the rocket's upper stage had fired. With this solid rocket motor kick stage, Goldstein said Clipper would need just a single Earth gravity assist and would not have to go into the inner Solar System for a Venus flyby.”

What is a “Star 48 kick stage”? It appears to be a solid fuel third stage component used on the Delta IV Heavy. I found several references to it online, including in this article Solar probe moves into launch position at Cape Canaveral – Spaceflight Now

But the idea of incorporating a Delta IV 3rd stage into the FH, between the 2nd stage and the payload,seems a bit bizarre. That is a major change to the FH, introducing numerous potential complications and problems.

I wonder if SpaceX would agree to such a change in exchange for getting to launch the Europa Clipper mission. While the government would surely save a lot of money — NASA would have to pay for the R&D necessary to support the FH modification but that would be way less costly than one SLS launch — if something went wrong SpaceX would look bad.

The "kick stage" would fit into the fairing. It's my understanding that is what a kick stage is. So you aren't having to modify the rocket at all but just be able to fit the kick stage into the fairing section without removing too much space for the payload. The kick stage essentially becomes part of the payload. If you have a small payload, and exploration satellites usually are smaller, then adding a kick stage should be an easy add on for something with incredible LEO lift capacity.

This is the one weakness that SpaceX currently has is their second stage. The higher ISP of a hydrolox second stage gives it a lot of advantages that SpaceX has to make up with their incredible boosters.

If SpaceX was going to stick with F9 and FH then there is little doubt they would have redone their second stage and used their Raptor engine instead. A completely reusable Starship makes that unnecessary. The thought was definitely there to improve the second stage though. That is why the Air Force gave some money for the Raptor development a number of years ago.

 

[ecarfan]

Re-reading that article, I don’t see anything about who specifically had the idea to add a Star 48 kick stage to a FH. I guess it was someone on the mission team at JPL? Barry Goldstein, the Europa Clipper project manager, is the person quoted as saying "We've had a major development, and it's really relieving for the team." So “we” must refer to the JPL team.

I don’t know if SpaceX would be willing to make the changes necessary to do that. But maybe they would if NASA provided all the funding and assumed all the risk.

 

[ecarfan]

Sorry, didn’t see your post on the page until after I made my followup post and the page refreshed. Thanks for the info! Sounds promising.

The "kick stage" would fit into the fairing. It's my understanding that is what a kick stage is. So you aren't having to modify the rocket at all but just be able to fit the kick stage into the fairing section without removing too much space for the payload. The kick stage essentially becomes part of the payload. If you have a small payload, and exploration satellites usually are smaller, then adding a kick stage should be an easy add on for something with incredible LEO lift capacity.

 

[Mike1080i]

What is a “Star 48 kick stage”? It appears to be a solid fuel third stage component used on the Delta IV Heavy.

Just to add a little more background, the Star series has flown as an upper stage on various U.S. rockets dating back to the mid 60's and up to the current Delta IV, Pegasus, and Minotaur. They have flown on Shuttles as the Payload Assist Module for satellites needing a ride to a higher orbit after deployment from the payload bay.

 

[Grendal]

There is a resolution to this: SLS and ULA lost out to an expendable FH.

Falcon Heavy to launch Europa Clipper

NASA has selected SpaceX’s Falcon Heavy to launch its Europa Clipper mission, a choice that appeared likely once NASA was no longer required to use the SLS.

spacenews.com

 

[ICUDoc]

an expendable FH

No no no no no - the POINT of Falcon Heavy is to let us watch two enormous goddamn booster rockets unfold their legs in a smooth ballet of technology and land gently together like synchronised swimmers subsiding.
expendable be damned.

 

[Cosmacelf]

It was interesting re-reading all the old posts in this article lamenting the original SLS choice … and the pessimistic mid 2021 launch date for SLS

 

[ItsNotAboutTheMoney]

There is a resolution to this: SLS and ULA lost out to an expendable FH.

Falcon Heavy to launch Europa Clipper

NASA has selected SpaceX’s Falcon Heavy to launch its Europa Clipper mission, a choice that appeared likely once NASA was no longer required to use the SLS.

spacenews.com

I'm sure there was some celebration when the calculation met the criteria for the get-out clause. It might have taken some expert engineering.

 

[Cosmacelf]

I'm sure there was some celebration when the calculation met the criteria for the get-out clause. It might have taken some expert engineering.

“Well, the engineering experts said we can’t use SLS. You aren’t going to go against the experts, right?”. Who says engineers have no political power

 

[Cosmacelf]

Anyone have an idea when SLS will do its first launch? I tried to do a search for an estimate but came up empty. At this rate, Starship will beat it to orbit, negating SLS’s claim as the biggest operational rocket.

 

[favo]

Anyone have an idea when SLS will do its first launch? I tried to do a search for an estimate but came up empty. At this rate, Starship will beat it to orbit, negating SLS’s claim as the biggest operational rocket.

Artemis 1, which would be the first (uncrewed) flight of SLS, is currently NET November 22, 2021. Seems likely to slip into 2022, though.

 

[scaesare]

Anyone have an idea when SLS will do its first launch? I tried to do a search for an estimate but came up empty. At this rate, Starship will beat it to orbit, negating SLS’s claim as the biggest operational rocket.

1. Send up big wheel of cheese
2. Launch sports car in to orbit
3. Ummm.... ?

 

[Grendal]

SpaceX's first Falcon Heavy launch in two years is finally coming together

For the first time in more than two years, SpaceX’s next Falcon Heavy launch and dual-booster landing appears to be right around the corner – and it comes with a catch. In February 2018, after years of anticipation, SpaceX successfully launched its triple-booster Falcon Heavy rocket for the...

www.teslarati.com

 

[adiggs]

This one is going to be particularly fun to watch.