In article ,
says...

On 2019-09-16 06:55, Jeff Findley wrote:

So, the difference is that by using a commercial launch vehicle, the US
taxpayer would save nearly $1 billion. And it would eliminate the
schedule uncertainty inherent with an SLS launch (considering this
Administration's emphasis on Artemis, which "needs" SLS).


No argument about launch uncertainty.

But in terms of saving taxpayers money, I suspect this is accounting PR
to help support buying commercial launch.

It's an acknowledgment from the NASA inspector general that SLS launches
are going to cost $1 billion each. An expendable Falcon Heavy list
price is $150 million. Double that for "NASA specific requirements" and
the off the shelf solid kick stage and you're still at about 1/3 of the
cost of an SLS launch.

But big pictures, NASA has engines for 4 SLS flights. If One of those
flights is not used for Europa Clipper, it will likely be used for
Artemis testing.

SLS flight one is the uncrewed test. The flights after that are
intended to be crewed, excepting a possible Europa Clipper launch.

And even if you were to cancel one of the 4 flights, it won't reduce the
cost of RD that is going to be spent whether you make that 4th flight or
not, and won't save on the cost of engines that have alteady been built.

You're neglecting the costs of the SRBs, core stage, upper stage,
testing, processing, launch, and etc.

So it is more than likely that the $4b spent for 4 flights will remain
$4b for 3, with each flight now costing $1.33b.

Possibly, but you're neglecting the fact that Europa Clipper was to use
SLS long before Aretmis became a thing. This was written into law by
Congress to "justify" SLS before Aretmis was around to "justify" SLS.
The fact that the NASA IG is pointing out is that Europa Clipper never
needed SLS. That was all pork politics.

If the SLS program is more of less fixed cost, then moving Europa
CLipper to a commercial launcher adds the cost of that commercial launch
to the bill sent to taxpayers. (even though the bill to the JWST
department would be much less).

Throwing good money after bad at SLS doesn't make it economical. It's
still 3x as costly for Europa Clipper than a FH with Star kick stage.
SLS will be canceled, sooner or later. The sooner the better, IMHO.

Jeff
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