Europa Clipper’s launch date dependent on SLS Mobile Launcher readiness

[Chris Bergin]

https://www.nasaspaceflight.com/2017/11/europa-clippers-launch-dependent-sls-ml-readiness/

By Chris Gebhardt.

With cool L2 renders via Nathan Koga.

Other Europa (and mainly Europa mission on SLS) articles:
https://www.nasaspaceflight.com/?s=Europa

[rockets4life97]

Wow. I didn't realize the schedule had such a dour outlook. One option that wasn't discussed in the article was using the same configuration for EM-1 to launch Europa Clipper. Is this possible or is the Exploration Upper Stage needed for its performance?

[DreamyPickle]

Any estimates for when the probe itself can be ready?

I remember reading that it's being designed so that it fits on smaller launches and what the SLS provides is a faster trajectory. This might be nullified if it has to wait several years for SLS to be ready.

There is also a lot of risk in launching a 2B flagship mission on a new launcher config.

[ChrisGebhardt]

Wow. I didn't realize the schedule had such a dour outlook. One option that wasn't discussed in the article was using the same configuration for EM-1 to launch Europa Clipper. Is this possible or is the Exploration Upper Stage needed for its performance?

SLS Block 1B w/ EUS is the only thing that can inject Europa Clipper into the desired direct trajectory to Jupiter with no gravity assists.

[ChrisGebhardt]

Any estimates for when the probe itself can be ready?

I remember reading that it's being designed so that it fits on smaller launches and what the SLS provides is a faster trajectory. This might be nullified if it has to wait several years for SLS to be ready.

There is also a lot of risk in launching a 2B flagship mission on a new launcher config.

Well, right now Europa Clipper can ready for launch on 4 June 2022 or the TIM wouldn't have set that as the target launch date.   History tells us that the probe's readiness will slip, but right now it's on track to be ready for launch in the June 2022 window.

Due to U.S. Federal laws written by Congress, SLS is the only vehicle that can launch Europa Clipper unless the law is changed.

As for the added risk, that's the "need to add additional testing to the payload and the SLS Block 1B design if Europa Clipper is indeed the first mission to fly on the SLS Block 1B" referenced in the article.

[Coastal Ron]

Great article!

It would be interesting to understand what the factors are driving the 33 months to do the conversion, because that is a long time. As a comparison it took 6 years from starting to dig the foundation of the world's tallest building, the Burj Khalifa, until it opened - so is the SLS ML only half as complicated as the Burj Khalifa? It would seem to be far less complicated, but they have different functions so maybe that is a factor.

Is it money?

Is it that the ML has to be disassembled and then reassembled?

[AncientU]

Great article!

It would be interesting to understand what the factors are driving the 33 months to do the conversion, because that is a long time. As a comparison it took 6 years from starting to dig the foundation of the world's tallest building, the Burj Khalifa, until it opened - so is the SLS ML only half as complicated as the Burj Khalifa? It would seem to be far less complicated, but they have different functions so maybe that is a factor.

Is it money?

Is it that the ML has to be disassembled and then reassembled?

It is processes.

[AegeanBlue]

So, if I understand correctly a study will follow to see if the current launcher arm can be modified to a cargo only version for Block 1B that will allow it to be within the weight limits, while a new crew only version of the mobile launcher would need to be built so as to fit the weight limit. Were it not for Senator Shelby I would say 2022 is out of the picture just from the launcher side. Then again people in the know in the robotic part of this forum say that it is possible that the payload may slip 2022 anyway. If 2022 is to be pursued is the kind of decision that the NASA administrator needs to consult with the national space council and the Vice President. If Brindestine is approved, which looks likely right now, this may be his very first big decision.

[UltraViolet9]

Due to U.S. Federal laws written by Congress, SLS is the only vehicle that can launch Europa Clipper unless the law is changed.

The FY 2016 approps language is contingent on both the orbiter and lander launching in 2022 and on the Administration providing a five-year budget for the same.  The former was highly unlikely before MLS schedule issues, and the latter was almost certainly never going to happen.

The Administration will have to decide how it wants to unpack and deal with this in its FY 2019 budget deliberations (currently ongoing).  Then Congress/Culberson will have to decide if they're still interested in funding Clipper (or not) after the Administration performs its surgery.

[TaurusLittrow]

So NASA needs "33 months of work for ML conversion from Block 1 to Block 1B once the EM-1 mission has launched."

Well, by comparison, ML-3, used in 5 manned Apollo launches and 51 Shuttle launches, began construction in 1964 and was completed on March 1, 1965, a maximum of 14 months (though the swing arms were added at a later date).

Granted, different times, different budgets, different priorities, but it does make one wonder.

[oldAtlas_Eguy]

Probable realistic launch plan schedule for SLS:

EM-1   May 2020
SM-1   July 2023
EM-2   June 2024
EM-3   June 2025
SM-2   2026 (whenever the launch window in this year occurs) (plus this is the first flight of the RS-25Es, ASAP will want a unmanned flight of these engines first before a manned one) (this engine set will not be available to support a flight until this time anyway so it could not be done any earlier)
EM-4   2028 (it takes 2 years to deliver 4 RS-25Es on the current contract) (It will require a bigger budget and a new contract to  increase the build rate to deliver 4 engines per year instead of the current contract delivery rate of 2 engines per year)
Unless the engine build rate is increased there is no more launches in the 2020's.

Assumptions:
a) That ML-1 is modified to be a cargo only SLS-1B support.
b) That an ML-2 is constructed with lessons learned to make a crew version of the ML with a budget funded at a level allowing it to be constructed in 5 years starting Oct 2018. This gets a ML available to support the June 2024 EM-2 date at better than 6 months prior to launch date plus a few months of margin.
c) That EC is ready for launch by 6 months prior to its launch date in July 2023.
d) That Europa Lander is ready for launch 6 months prior to its window in 2026.

[TaurusLittrow]

Probable realistic launch plan schedule for SLS:

EM-1   May 2020
SM-1   July 2023
EM-2   June 2024
EM-3   June 2025
SM-2   2026 (whenever the launch window in this year occurs) (plus this is the first flight of the RS-25Es, ASAP will want a unmanned flight of these engines first before a manned one) (this engine set will not be available to support a flight until this time anyway so it could not be done any earlier)
EM-4   2028 (it takes 2 years to deliver 4 RS-25Es on the current contract) (It will require a bigger budget and a new contract to  increase the build rate to deliver 4 engines per year instead of the current contract delivery rate of 2 engines per year)
Unless the engine build rate is increased there is no more launches in the 2020's.

It's hard to argue with this timeline (regardless of how depressing it is). I wonder, however, if the SM-2 flight of SLS with Europa Lander (I presume) will really materialize given other heavy lift options (NG/BFR, etc.) that should be available at that time even if gravity assists are necessary.

Regardless of ASAP's opinion, the political pressure will surely favor human missions and finishing construction of the DSG with EM-4 (in place of SM-2) adding the Logistics Module in 2026 and EM-5 bringing the airlock in 2028.

[oldAtlas_Eguy]

Unfortunately the SLS schedule we have now is a direct result of the budget cutting decisions made in 2012 to make the SLS fit into a fixed yearly budget cap. This involved shortcuts that now are not that much of a shortcut nor will actually save money. A entirely new ML from ground up could have been built to meet the current actual launch schedule due to other problems in the program. This ML could have been built to meet both SSL-1A and 1B requirements only requiring arm movements. If the decision to skip the 1A and go directly to 1B had been made early enough and with enough budget the first flight would have been a 1B in 2020 with EM-2 in 2022 followed by SM-1 in June 2022. Then EM-3 in 2024. Pushing the engine build up by additional funding would get engines for EM-4 in 2025 with SM-2 in 2026 and the additional EM flights at 1 per year starting 2027 with EM-5,6,and 7.

[ncb1397]

SM-2   2026 (whenever the launch window in this year occurs) (plus this is the first flight of the RS-25Es, ASAP will want a unmanned flight of these engines first before a manned one) (this engine set will not be available to support a flight until this time anyway so it could not be done any earlier)

Unmanned test flights were never required for all the tinkering that was done during the Shuttle program.

Over the course of the Space Shuttle program, the RS-25 went through a series of upgrades, including combustion chamber changes, improved welds and turbopump changes in an effort to improve the engine's performance and reliability and so reduce the amount of maintenance required after use. As a result, several versions of the RS-25 were used during the program:[9][22][24][25][30][31][32][33][34]
FMOF (first manned orbital flight) – Certified for 100% rated power level (RPL). Used for the orbital flight test missions STS-1—STS-5 (engines 2005, 2006 and 2007).
Phase I – Used for missions STS-6—STS-51-L, the Phase I engine offered increased service life and was certified for 104% RPL.
Phase II (RS-25A) – First flown on STS-26, the Phase II engine offered a number of safety upgrades and was certified for 104% RPL & 109% full power level (FPL) in the event of a contingency.
Block I (RS-25B) – First flown on STS-70, the Block I engines offered improved turbopumps featuring ceramic bearings, half as many rotating parts and a new casting process reducing the number of welds. Block I improvements also included a new, two-duct powerhead (rather than the original design, which featured three ducts connected to the HPFTP and two to the HPOTP), which helped improve hot gas flow, and an improved engine heat exchanger.
Block IA (RS-25B) – First flown on STS-73, the Block IA engine offered main injector improvements.
Block IIA (RS-25C) – First flown on STS-89, the Block IIA engine was an interim model used whilst certain components of the Block II engine completed development. Changes included a new large throat main combustion chamber (which had originally been recommended by Rocketdyne in 1980), improved low pressure turbopumps and certification for 104.5% RPL to compensate for a 2 seconds (0.020 km/s) reduction in specific impulse (original plans called for the engine to be certified to 106% for heavy International Space Station payloads, but this was not required and would have reduced engine service life). A slightly modified version first flew on STS-96.
Block II (RS-25D) – First flown on STS-104, the Block II upgrade included all of the Block IIA improvements plus a new high pressure fuel turbopump. This model was ground-tested to 111% FPL in the event of a contingency abort, and certified for 109% FPL for use during an intact abort.

https://en.wikipedia.org/wiki/Space_Shuttle_main_engine

[oldAtlas_Eguy]

The problem is there was no alternative in the Shuttle program. You flew manned or not at all.

It could have flown unmanned but the state of the art was yet to be trustworthy for accomplishing this, hence the requirement to always be manned flights.

Since then the safety community has become more risk averse when it comes to a manned program. This not to say it could not be done just less likely in the current safety environment for manned flight.

[ncb1397]

The problem is there was no alternative in the Shuttle program. You flew manned or not at all.

It could have flown unmanned but the state of the art was yet to be trustworthy for accomplishing this, hence the requirement to always be manned flights.

Since then the safety community has become more risk averse when it comes to a manned program. This not to say it could not be done just less likely in the current safety environment for manned flight.

You could have done the 2 man crew layout that STS-1 used at the very least. All the flight tests with different versions of the SSME were done with a more normal complement of 5-7 crew. Even STS-26 directly after Challenger that was also the first flight of an RS-25A

[spacetraveler]

Amazing article.

Unfortunately it really underscored for me just how poorly thought out the whole SLS program is and why it probably will be cancelled.

I have supported it in the past, but I can't really say that cancelling it will be the wrong decision given how horribly expensive and unproductive it has become.

[spacetraveler]

Wow. I didn't realize the schedule had such a dour outlook. One option that wasn't discussed in the article was using the same configuration for EM-1 to launch Europa Clipper. Is this possible or is the Exploration Upper Stage needed for its performance?

SLS Block 1B w/ EUS is the only thing that can inject Europa Clipper into the desired direct trajectory to Jupiter with no gravity assists.

Is there something fundamentally wrong with using gravity assists? I know it takes longer, but I believe all missions to the outer planets so far have used them.

[russianhalo117]

Wow. I didn't realize the schedule had such a dour outlook. One option that wasn't discussed in the article was using the same configuration for EM-1 to launch Europa Clipper. Is this possible or is the Exploration Upper Stage needed for its performance?

SLS Block 1B w/ EUS is the only thing that can inject Europa Clipper into the desired direct trajectory to Jupiter with no gravity assists.

Is there something fundamentally wrong with using gravity assists? I know it takes longer, but I believe all missions to the outer planets so far have used them.

They want to launch direct to increase SC Life Expectancy during transit and in the Jupiter System at Europa. Also Congress said so.

[Oli]

Wow. I didn't realize the schedule had such a dour outlook. One option that wasn't discussed in the article was using the same configuration for EM-1 to launch Europa Clipper. Is this possible or is the Exploration Upper Stage needed for its performance?

SLS Block 1B w/ EUS is the only thing that can inject Europa Clipper into the desired direct trajectory to Jupiter with no gravity assists.

Is there something fundamentally wrong with using gravity assists? I know it takes longer, but I believe all missions to the outer planets so far have used them.

There are aliens on Europa and it's very important to make first contact before the Chinese do.