NASA - Europa Clipper updates and discussion

[ulm_atms]

Interesting clip from that article

Another vehicle that could take Europa Clipper to Jupiter’s moon is SpaceX’s Falcon Heavy—though it would do so with an asterisk attached. Falcon Heavy has already achieved three successful launches, but using the SpaceX rocket—which is less powerful than the SLS—would add at least three years of travel time to the planned two-year mission. And while using SpaceX’s rocket would save hundreds of millions of dollars on launch costs, it could add to Europa Clipper’s operations budget because of its longer cruise time to Jupiter. “It’s vital that the [Europa] Clipper be launched on the SLS,” Culberson says.

Since the FH payload to GTO is much higher than D-IVH's, it looks like SLS (and whatever delay that brings) is the only choice for a direct launch.

Isn't there a direct window to Jupiter once a year?  If they miss 2023, do they have to wait till 2025 or can they launch in 2024?

I was actually confused by that paragraph in the article as I distinctly remember it being posted in this thread that a study had been conducted by NASA to combine a FH with a STAR ‘upper stage’ to allow a more direct flight.

FH+STAR48 can do the mission in as little as 4 years with a single Earth gravity assist.

DIVH needs the 7 year Venus-Earth-Earth trajectory because it can't send the total Clipper+STAR mass of ~8000 kg to the c3=28 injection needed for EGA.

Questions I have wondered about...maybe answered, but I can seem to find it.  If they are somewhere...please point me in the right direction. 

So if FH + STAR48 can do 4 years....does that include the "usual" margins of fuel that a lot of missions have or is that full out, burn to depletion for all stages and not one iota of DV is saved?

How far off is the DV for a direct shot on published FH capacities plus STAR48?

[ugordan]

Interesting clip from that article

Another vehicle that could take Europa Clipper to Jupiter’s moon is SpaceX’s Falcon Heavy—though it would do so with an asterisk attached. Falcon Heavy has already achieved three successful launches, but using the SpaceX rocket—which is less powerful than the SLS—would add at least three years of travel time to the planned two-year mission. And while using SpaceX’s rocket would save hundreds of millions of dollars on launch costs, it could add to Europa Clipper’s operations budget because of its longer cruise time to Jupiter. “It’s vital that the [Europa] Clipper be launched on the SLS,” Culberson says.

Since the FH payload to GTO is much higher than D-IVH's, it looks like SLS (and whatever delay that brings) is the only choice for a direct launch.

Isn't there a direct window to Jupiter once a year?  If they miss 2023, do they have to wait till 2025 or can they launch in 2024?

I was actually confused by that paragraph in the article as I distinctly remember it being posted in this thread that a study had been conducted by NASA to combine a FH with a STAR ‘upper stage’ to allow a more direct flight.

FH+STAR48 can do the mission in as little as 4 years with a single Earth gravity assist.

DIVH needs the 7 year Venus-Earth-Earth trajectory because it can't send the total Clipper+STAR mass of ~8000 kg to the c3=28 injection needed for EGA.

Questions I have wondered about...maybe answered, but I can seem to find it.  If they are somewhere...please point me in the right direction. 

So if FH + STAR48 can do 4 years....does that include the "usual" margins of fuel that a lot of missions have or is that full out, burn to depletion for all stages and not one iota of DV is saved?

It can't do 4 years, at best it could do slightly under 6 years, The trajectory they were looking at for fully expendable FH+Star48BV is a 3:1 resonant one with Earth and that alone incurs a 3 year wait for the one and only Earth gravity assist.

How far off is the DV for a direct shot on published FH capacities plus STAR48?

I've done some rough calculations in this thread: https://forum.nasaspaceflight.com/index.php?topic=46338.msg1941127#msg1941127

Short answer is FH is nowhere near powerful enough for a direct injection to Jupiter. Even the FH-Star 48BV combo has some fairly tight margins for a 3:1 resonant transfer given that NASA would undoubtedly like to have some leeway in the launch period and injection C3 will vary depending from how far off the optimal day in the period you launch.

Also, any indirect trajectories EC does will also use up more fuel for deep space maneuvers, fuel that could otherwise be spent during the Jovian tour, i.e. they will impact total available mission duration for mission extensions, etc.

[Star One]

Interesting clip from that article

Another vehicle that could take Europa Clipper to Jupiter’s moon is SpaceX’s Falcon Heavy—though it would do so with an asterisk attached. Falcon Heavy has already achieved three successful launches, but using the SpaceX rocket—which is less powerful than the SLS—would add at least three years of travel time to the planned two-year mission. And while using SpaceX’s rocket would save hundreds of millions of dollars on launch costs, it could add to Europa Clipper’s operations budget because of its longer cruise time to Jupiter. “It’s vital that the [Europa] Clipper be launched on the SLS,” Culberson says.

Since the FH payload to GTO is much higher than D-IVH's, it looks like SLS (and whatever delay that brings) is the only choice for a direct launch.

Isn't there a direct window to Jupiter once a year?  If they miss 2023, do they have to wait till 2025 or can they launch in 2024?

I was actually confused by that paragraph in the article as I distinctly remember it being posted in this thread that a study had been conducted by NASA to combine a FH with a STAR ‘upper stage’ to allow a more direct flight.

FH+STAR48 can do the mission in as little as 4 years with a single Earth gravity assist.

DIVH needs the 7 year Venus-Earth-Earth trajectory because it can't send the total Clipper+STAR mass of ~8000 kg to the c3=28 injection needed for EGA.

Questions I have wondered about...maybe answered, but I can seem to find it.  If they are somewhere...please point me in the right direction. 

So if FH + STAR48 can do 4 years....does that include the "usual" margins of fuel that a lot of missions have or is that full out, burn to depletion for all stages and not one iota of DV is saved?

It can't do 4 years, at best it could do slightly under 6 years, The trajectory they were looking at for fully expendable FH+Star48BV is a 3:1 resonant one with Earth and that alone incurs a 3 year wait for the one and only Earth gravity assist.

How far off is the DV for a direct shot on published FH capacities plus STAR48?

I've done some rough calculations in this thread: https://forum.nasaspaceflight.com/index.php?topic=46338.msg1941127#msg1941127

Short answer is FH is nowhere near powerful enough for a direct injection to Jupiter. Even the FH-Star 48BV combo has some fairly tight margins for a 3:1 resonant transfer given that NASA would undoubtedly like to have some leeway in the launch period and injection C3 will vary depending from how far off the optimal day in the period you launch.

Also, any indirect trajectories EC does will also use up more fuel for deep space maneuvers, fuel that could otherwise be spent during the Jovian tour, i.e. they will impact total available mission duration for mission extensions, etc.

Do you consider the FH the best alternative from a cost vs performance basis as compared to SLS?

[ugordan]

Do you consider the FH the best alternative from a cost vs performance basis as compared to SLS?

If the referenced "DeltaV Earth Gravity Assist 3-Minus" trajectory option closes from a performance margin standpoint, then yes.

However, based on historical NASA LSP mission assignments split between ULA and SpaceX (ULA invariably snatching the higher value payloads), I'm not inclined to believe NASA would be willing to actually fly Clipper on a FH. I can see them "falling back" to a Delta IV Heavy and just living with the worse thermal environment of a Venus flyby trajectory. The one obvious problem there is the availability of an additional DIVH vehicle, it would have to be ordered right now basically.

Clipper is kind of stuck between a rock and a hard place, on one hand the uncertainty of availability of even the nominal SLS vehicle, on the other hand it's happening right during the changing landscape of available U.S. LVs. Delta is going away, Atlas is going away, Vulcan and New Glenn will probably not be available by the time LV selection needs to be made  which is Pretty Soon Now (TM).

[Star One]

Do you consider the FH the best alternative from a cost vs performance basis as compared to SLS?

If the referenced "DeltaV Earth Gravity Assist 3-Minus" trajectory option closes from a performance margin standpoint, then yes.

However, based on historical NASA LSP mission assignments split between ULA and SpaceX (ULA invariably snatching the higher value payloads), I'm not inclined to believe NASA would be willing to actually fly Clipper on a FH. I can see them "falling back" to a Delta IV Heavy and just living with the worse thermal environment of a Venus flyby trajectory. The one obvious problem there is the availability of an additional DIVH vehicle, it would have to be ordered right now basically.

Clipper is kind of stuck between a rock and a hard place, on one hand the uncertainty of availability of even the nominal SLS vehicle, on the other hand it's happening right during the changing landscape of available U.S. LVs. Delta is going away, Atlas is going away, Vulcan and New Glenn will probably not be available by the time LV selection needs to be made  which is Pretty Soon Now (TM).

From what you’ve said above makes a good case for why I think they will go for the FH. The idea of higher value payloads always being given to ULA has to be shaken up at some point.

[baldusi]

Higher value payloads require higher rated LV. Until recently only ULA had Cert 1. And still to this days only Atlas V is nuclear-payload certified. At least as far as I understand it.

[Star One]

Higher value payloads require higher rated LV. Until recently only ULA had Cert 1. And still to this days only Atlas V is nuclear-payload certified. At least as far as I understand it.

Is there any major barriers standing between FH achieving this other than paperwork?

[russianhalo117]

Higher value payloads require higher rated LV. Until recently only ULA had Cert 1. And still to this days only Atlas V is nuclear-payload certified. At least as far as I understand it.

Once 39A has its MST installed it will be eligible as it's a late install item.

[whitelancer64]

Higher value payloads require higher rated LV. Until recently only ULA had Cert 1. And still to this days only Atlas V is nuclear-payload certified. At least as far as I understand it.

Is there any major barriers standing between FH achieving this other than paperwork?

As I understand it, becoming nuclear certified requires a special panel to convene, to perform a study on the worst case scenarios with respect to radioactive contamination in the event of a failed launch. Basically they have to prove that the Falcon Heavy exploding won't crack open the RTG fuel cask.

[Norm38]

If we’re being honest about it, both the CRS-7 failure, and the IFA, go a long ways towards proving that the payload won’t be obliterated by a launch failure.

The RTG is more likely to crack from ocean surface impact than it is from a stage failure.

[Star One]

Higher value payloads require higher rated LV. Until recently only ULA had Cert 1. And still to this days only Atlas V is nuclear-payload certified. At least as far as I understand it.

Is there any major barriers standing between FH achieving this other than paperwork?

As I understand it, becoming nuclear certified requires a special panel to convene, to perform a study on the worst case scenarios with respect to radioactive contamination in the event of a failed launch. Basically they have to prove that the Falcon Heavy exploding won't crack open the RTG fuel cask.

They could hold that panel and probably still see a cost saving on the FH.

[Star One]

If NASA did select FH would they likely require one made up of all unused cores?

[192]

I'm a little confused by all of this discussion about nuclear-rating Falcon Heavy, I thought Europa Clipper was solar powered?

https://spacenews.com/42121europa-clipper-opts-for-solar-power-over-nuclear/
https://fas.org/nuke/space/heritage.pdf

[baldusi]

I'm a little confused by all of this discussion about nuclear-rating Falcon Heavy, I thought Europa Clipper was solar powered?

https://spacenews.com/42121europa-clipper-opts-for-solar-power-over-nuclear/
https://fas.org/nuke/space/heritage.pdf

It isn’t really. Someone pointed out that ULA took all expensive payload launches from NASA/DoD. I pointed out it was due to lack of Cat 1 certification and nuclear-payload certification. It kinda snowballed from there. But I was referring to the lack of big payload wins rather than Clipper’s particular case.

[zubenelgenubi]

FYI, I opened a splinter thread re: special order launch vehicle for Europa Clipper.
Falcon Heavy/Centaur/Europa Clipper?

[redliox]

One point and a question come to mind since the last sets of posts in February....

A) FH is going to launch Psyche plus 2 co-missions.  While a Flagship mission isn't something to idly change options for, the fact several definite science missions will have flown Falcon by 'Clipper's time will only verify the rocket can do a great job.

B) A large Deep Space Maneuver seems to be a major concern for the route 'Clipper could take via FH.  What options are available that could lessen the size of this maneuver?  Could adjusting/eliminating a 3rd stage or using 2 flybys (say either Earth or Mars) adjust the DSM needs?

[ugordan]

B) A large Deep Space Maneuver seems to be a major concern for the route 'Clipper could take via FH.  What options are available that could lessen the size of this maneuver?  Could adjusting/eliminating a 3rd stage or using 2 flybys (say either Earth or Mars) adjust the DSM needs?

Mars is not really of significant use as a gravitational assist body and trying to work it into your trajectory would drastically restrict your launch period options. You'd be going back from basically a 2 body system (Earth-Jupiter) where the same rough alignment occurs what, every 13 months to one where it's probably years between similar arrangement when Earth-Mars-Jupiter align for Mars to produce any useful assist.

Eliminating a Star-48BV would only increase the DSM requirements as IIRC, FH alone cannot launch Clipper to a L+3 resonant orbit, only to a Juno-like L+2 resonant one where the DSM would likely be even greater (I'm not really sure how DSM magnitude scales with aphelion velocity, if it's linear or whether there's some nonlinearity due to also changing the flyby geometry).

[su27k]

From https://www.gao.gov/products/GAO-20-405:

The Europa Clipper project entered the implementation
phase and established its cost and schedule baselines
in August 2019. The project set a baseline life-cycle cost
of $4.25 billion and a launch date of September 2025.
This is $250 million above the top end of the project’s
preliminary cost estimate and more than 2 years after
its preliminary launch readiness date of July 2023.
According to the Consolidated Appropriations Act, 2020
the project shall use SLS as its launch vehicle. The NASA
HEO Mission Directorate informed the Europa Clipper’s
Mission Directorate that the earliest an SLS launch vehicle
would be available for the Europa Clipper project is 2025.
According to the NASA officials, before that date, all SLS
launch vehicles would be required for use by the Artemis
program.

The $250 million increase above the project’s preliminary
cost estimate reflects the costs associated with this later
launch date and assumes that Europa Clipper will complete
development work in 2023 and be stored for 2 years. This
amount includes the following costs: $1 million for physical
storage; $129 million for workforce and potential staff
requirements; $96 million for mission system impact and a
change in cruise time to Europa from 2.4 to 3 years; and
$24 million in cost reserves. According to NASA officials,
it is possible that additional delays with SLS may lead to
an SLS being unavailable for use by Europa Clipper in
2025, which could require the project to reset its cost and
schedule baseline.

If I'm reading this correctly, by forcing Europa Clipper to be launched on SLS, Congress is not only wasting $250M, the spacecraft itself will be put in storage for 2 years waiting for SLS. That's exactly the opposite of what we're hearing from SLS advocates which is launching on SLS would save money and shorten the mission duration.

[su27k]

https://twitter.com/CaseyDreier/status/1255645413878583297

At this point, the difference between FH and SLS is 18 months—assuming the SLS is available on-time in 2025. SLS is great in theory but is now a burden to this mission.

[woods170]

From https://www.gao.gov/products/GAO-20-405:

The Europa Clipper project entered the implementation
phase and established its cost and schedule baselines
in August 2019. The project set a baseline life-cycle cost
of $4.25 billion and a launch date of September 2025.
This is $250 million above the top end of the project’s
preliminary cost estimate and more than 2 years after
its preliminary launch readiness date of July 2023.
According to the Consolidated Appropriations Act, 2020
the project shall use SLS as its launch vehicle. The NASA
HEO Mission Directorate informed the Europa Clipper’s
Mission Directorate that the earliest an SLS launch vehicle
would be available for the Europa Clipper project is 2025.
According to the NASA officials, before that date, all SLS
launch vehicles would be required for use by the Artemis
program.

The $250 million increase above the project’s preliminary
cost estimate reflects the costs associated with this later
launch date and assumes that Europa Clipper will complete
development work in 2023 and be stored for 2 years. This
amount includes the following costs: $1 million for physical
storage; $129 million for workforce and potential staff
requirements; $96 million for mission system impact and a
change in cruise time to Europa from 2.4 to 3 years; and
$24 million in cost reserves. According to NASA officials,
it is possible that additional delays with SLS may lead to
an SLS being unavailable for use by Europa Clipper in
2025, which could require the project to reset its cost and
schedule baseline.

If I'm reading this correctly, by forcing Europa Clipper to be launched on SLS, Congress is not only wasting $250M, the spacecraft itself will be put in storage for 2 years waiting for SLS. That's exactly the opposite of what we're hearing from SLS advocates which is launching on SLS would save money and shorten the mission duration.

It is IMO a safe bet that with interplanetary missions that are this complex, the development of the spacecraft will be severely delayed. IMO the spacecraft will NOT be ready in 2023. It will IMO suffer a delay of at least 18 months, based on performance of prior similar interplanetary missions.

As such I expect that for a 2025 flight opportunity Europa Clipper wil spend ZERO time in storage. It will likely be "just in time" for a 2025 launch date IMO.