Author Topic: NASA's realigning dual Mobile Launcher plan targets extra SLS Block 1 missions  (Read 13223 times)

Online Chris Bergin

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Offline envy887

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Nice summary.

I think this plan makes more sense than launching either crew or the Europa Clipper on an untested EUS. Also, being able to ramp up flight rate earlier helps mitigate the overall program expense on a per-flight basis... although exactly what those flights will launch is unclear.

I'd note that a FH for Clipper would likely cost about $180 million rather than "just over $100 million", based on the $150M for expended FH and $30M increase in government required paperwork noted by Musk.

Also, I'm used to "mirror" meaning "opposite to", not "the same as".

Offline Jim

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There is more than just Falcon Heavy in play

Online oldAtlas_Eguy

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There is more than just Falcon Heavy in play
Yes, a Vulcan ACES with distributed launch would have near or even better BEO capability than a SLS 1B.

There is also possible BO’s NG which would have close to same or better capability than a SLS for a BEO mission.

Then there is always a Atlas V (551).

Offline dror

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Which Europa Clipper would get there first,
Launched on Block 1  or on Block 1b later ?
Space is hard immensely complex and high risk !

Offline envy887

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Which Europa Clipper would get there first,
Launched on Block 1  or on Block 1b later ?

There is at least 3 years difference in launch date. I don't think the differnece in performance from Block 1B to Block 1 is that large. Even going to a Atlas V 551 shouldn't add more than 3, maybe 4, years to the flight time.

There is more than just Falcon Heavy in play
Yes, a Vulcan ACES with distributed launch would have near or even better BEO capability than a SLS 1B.

There is also possible BO’s NG which would have close to same or better capability than a SLS for a BEO mission.

Then there is always a Atlas V (551).

ACES isn't planned to be available until 2024. Neither is Orbital's Omega XL.

The choices for 2021 or 2022 launch are:

Omega 500 series, if selected for EELV
Atlas V 551
Delta IV Heavy (would require ULA to build another set of cores over what's currently planned)
Vulcan Centaur V, if selected for EELV
Falcon Heavy
SLS Block 1
Ariane 5 or 64, if ESA wants in on the project

Offline redliox

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Well this is a definite kink in the lines.  Whether or not this is good or bad for NASA I'm unsure.  2 separate MLs at least mean the respective SLS blocks won't be competing with each other.  Assuming the Europa Clipper team has no qualms, flying on the Block 1 instead of 1B isn't an impossible stretch although I will admit Block 1 against Falcon Heavy would lose if the concern comes down to cost.  Feels like mixed news, but it is at least progress instead of false hope that NASA's had to survive on for years.
"Let the trails lead where they may, I will follow."
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Offline butters

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Is ICPS human-rating going to happen or not?

Offline Sam Ho

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Which Europa Clipper would get there first,
Launched on Block 1  or on Block 1b later ?
There is at least 3 years difference in launch date. I don't think the differnece in performance from Block 1B to Block 1 is that large. Even going to a Atlas V 551 shouldn't add more than 3, maybe 4, years to the flight time.
There are 3 Europa Clipper trajectories baselined.  You can substitute launchers with similar high-energy capability, of course.

Direct, SLS, 2.7 years.
EVEEGA, Atlas V 551, 7.4 years
∆v/EGA, Delta IV Heavy, 4.7 years

https://sites.nationalacademies.org/cs/groups/ssbsite/documents/webpage/ssb_172023.pdf

Offline TaurusLittrow

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Kudos for a nice article that clarifies some of the key decision points, timelines, and options.

What I find incomprehensible, and indefensible, if not surprising, is the fact that "due to Orion readiness, it is unlikely both missions [EM-1 and -2] will close the previous multi-year gap by any notable margin."

Three years to human rate ICPS and make Orion suitable for astronauts!? Oh, how things have changed since the flights of Apollo IV and VIII. Somewhere, Gilruth, Low, Kraft, and von Braun are shaking their heads.  :-\

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Is ICPS human-rating going to happen or not?

It will probably have to be.
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Offline redliox

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Is ICPS human-rating going to happen or not?

It will probably have to be.

That will be a headache.  Although they could just as easily do something like send up the Gateway modules aboard Block 1 ahead of the Orion flights on Block 1B to give SLS something productive to do.
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Offline AncientU

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Is ICPS human-rating going to happen or not?

It will probably have to be.

As will the SLS software.
Last report wasn't optimistic that was even possible without starting over.
"If we shared everything [we are working on] people would think we are insane!"
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Offline butters

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Is ICPS human-rating going to happen or not?

It will probably have to be.

As will the SLS software.
Last report wasn't optimistic that was even possible without starting over.

That's an interesting topic because every time I've seen the SLS software problems story, it was never clear whether the software problems relate to SLS core or EUS or ICPS or the entire system. It's possible to interpret the prolonged delay of EUS as evidence that perhaps the software issues are predominantly related to EUS, and that the software for the rest of SLS is more mature because "heritage hardware." On the other hand, we also know that "heritage" only goes so far when we're talking about SLS. So I guess we'll have to wait for more breadcrumbs before we know how bad the software issues are and whether they impact Block I (or the human-rating thereof).

Offline Steven Pietrobon

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Three years to human rate ICPS and make Orion suitable for astronauts!?

Where does that information come from?

It's possible to interpret the prolonged delay of EUS as evidence that perhaps the software issues are predominantly related to EUS, and that the software for the rest of SLS is more mature because "heritage hardware."

EUS is still being designed. Any software issues are more likely due to elements that are being built now.

For those interested, Block I payload to Europa is only 2.9 t, compared to 8.1 t for Block IB. I estimate FH expendable payload for Europa (for 6,783 m/s delta-V from LEO) to be 6.5 t!
« Last Edit: 04/24/2018 06:07 am by Steven Pietrobon »
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline MATTBLAK

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That's slightly better than Cassini class!! Add a couple gravity assists to that and you'd have a good mission. I wonder if it's worth asking Elon to upgrade that upper stage a bit? ;)

Steven: do you happen to know how much Vulcan/Centaur V with 6x solid boosters could throw at Jupiter?
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Offline Steven Pietrobon

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Steven: do you happen to know how much Vulcan/Centaur V with 6x solid boosters could throw at Jupiter?

I modified the Falcon Heavy program and made a few guestimates of the Vulcan second stage. From the drawing, I got a propellant mass of 56.2 t and a dry mass of 5.0 t. Extrapolating using RL10C-1 engines, 34.9 t LEO payload and 7.1 t GEO payload, I got only a 964 kg payload to Europa! Need to either use a solid third stage, flyby's or refuelling the second stage to get better performance.

Attached is the program I used to calculate performance.

Note that the first version I posted overestimated the Vulcan second stage propellant and dry mass, giving only a 105 kg payload mass to Europa.
« Last Edit: 04/24/2018 08:07 am by Steven Pietrobon »
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline AncientU

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Is ICPS human-rating going to happen or not?

It will probably have to be.

As will the SLS software.
Last report wasn't optimistic that was even possible without starting over.

That's an interesting topic because every time I've seen the SLS software problems story, it was never clear whether the software problems relate to SLS core or EUS or ICPS or the entire system. It's possible to interpret the prolonged delay of EUS as evidence that perhaps the software issues are predominantly related to EUS, and that the software for the rest of SLS is more mature because "heritage hardware." On the other hand, we also know that "heritage" only goes so far when we're talking about SLS. So I guess we'll have to wait for more breadcrumbs before we know how bad the software issues are and whether they impact Block I (or the human-rating thereof).

The software is being developed at Marshall for SLS Block 1.  It was specifically stated that it did not have to be human rated -- if it did, they discussed starting over might be easier.
"If we shared everything [we are working on] people would think we are insane!"
-- SpaceX friend of mlindner

Offline TaurusLittrow

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Three years to human rate ICPS and make Orion suitable for astronauts!?

Where does that information come from?

Maybe a little hyperbole for dramatic effect. However, the article states, "due to Orion readiness, it is unlikely both missions will close the previous multi-year gap by any notable margin."

And, an NSF article from Sept 2017, noted, "the newly updated schedule now shows EM-2 with a launch readiness date of 1 June 2022, which – assuming a December 2019 launch of EM-1 – would represent only a 2.5 year gap between the two missions."

Three years, 2.5 or even 2 years, still represents an egregiously long interval compared to the Apollo era (Apollos IV and VIII are comparable) in my opinion. My 2 cents, anyway.

Offline AncientU

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Three years to human rate ICPS and make Orion suitable for astronauts!?

Where does that information come from?

It's possible to interpret the prolonged delay of EUS as evidence that perhaps the software issues are predominantly related to EUS, and that the software for the rest of SLS is more mature because "heritage hardware."

EUS is still being designed. Any software issues are more likely due to elements that are being built now.

For those interested, Block I payload to Europa is only 2.9 t, compared to 8.1 t for Block IB. I estimate FH expendable payload for Europa (for 6,783 m/s delta-V from LEO) to be 6.5 t!

Thanks for these spreadsheets Steven. 

So, 'Block 1' FH with a kerlox second stage is a tonne past midway between SLS Block 1 and Block 1B -- and EUS for the latter is still a year away from CDR (a paper second stage) and won't be ready until mid-2020s.  Since we are going to wait for a new second stage to be designed and built, how much can payload to Europa be raised with a methalox FH 'Block 1B' with a single Raptor vac engine?
« Last Edit: 04/24/2018 12:16 pm by AncientU »
"If we shared everything [we are working on] people would think we are insane!"
-- SpaceX friend of mlindner

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