In article , lid says...

Jeff Findley wrote:
In article ,
says...
Yet, james Web was "assigned" to Arianne 5 in 2015, so there wouldn't
have been any recent discussions of it going on SLS.

That's because James Webb Space Telescope will be launched on an Ariane
5. The program is so expensive, NASA cut a deal with ESA to launch it,
no doubt in exchange for observation time on the telescope.

While NASA is the lead agency on JWST the project has AFAIK always
been based on having major contributions from European Space Agency[1]
and the Canadian Space Agency[2].

As an example, there's four main instruments and one of these provided
via NASA, one via ESA and one via CSA with the final being a
cooperation between NASA and ESA. And arguably the FGS (that keeps
JWST on target) that CSA provides is almost an instrument so one could
almost argue they provide "1.5" instruments each :-)

Also listed in the ESA document are the launch and "part of the
operations team" (I'm assuming both before launch and operationally
afterwards).

I expect that NASA is the biggest single contributor, likely even the
majority contributor but it's hard to find any real figures (and those
figures would by necessity be very fuzzy too).

Agreed. This is not unlike how ISS is run, except that with JWST there
aren't as many contributors at an international level (you listed them
all).

https://jwst.nasa.gov/content/meetTheTeam/team.html

parity error in my memory? or is SLS still planned to use one of its
limited rockets to launch a scientific payload to somewhere?

Europa Clipper, not JWST.

IIRC it's still supposed to be launched by SLS (by senate funding
requirement) because only SLS can send it in a direct trajectory to
Jupiter.

True, but the Congress can change its mind.

There's been some recent attempts to try to move this to a commercial
launcher instead to save (lots of) money with predictable blow-back
from the senate proponents for SLS.

I think these are merely trial balloons, preparing for if (or perhaps
when) Europa Clipper is getting close to being ready and SLS isn't,
the real discussion can take place because it'll be hard to dismiss as
"mere" speculations.

More than a trial balloon. The NASA's inspector general has pretty much
recommended commercial launch because it would save the US taxpayers
nearly $1 billion.

NASA inspector general asks Congress for Europa Clipper launch
flexibility by Jeff Foust - August 28, 2019
https://spacenews.com/nasa-inspector...ss-for-europa-
clipper-launch-flexibility/

Apparently an expendable Falcon Heavy with a STAR 48BV? kick-stage can
do it with one gravity assist and Falcon Heavy and Delta IV Heavy can
do it with three gravity assists without a kick stage.

The three gravity assist version is going to be a lot slower than the
SLS direct trajectory (6-7 years vs 2-3 years depending on which
launch window used), the single gravity assist trajectory is clearly
going to be faster than the 3 assist one but I've not seen actual
timings on that trajectory.

1. https://sci.esa.int/web/jwst/-/45728-europe-s-role
2. http://www.asc-csa.gc.ca/eng/satelli...ntribution.asp

The use of Falcon Heavy with a kick stage is surely the way to go.
These kick stages are pretty much "off the shelf" and are considered
part of the payload, as far as the launch vehicle is concerned. There
are many NASA missions which have used such kick stages in the past, so
it's a proven way to provide more velocity for a mission such as this.

Jeff

--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.