I think that was the RHU easing; basically you need the whole approval chain
still for RTG quantities but radioisotope heaters (MUCH smaller) are head of
agency.
-George
Sent from my iPhone
On Mar 1, 2021, at 7:32 PM, William Claybaugh <wclaybaugh2@xxxxxxxxx> wrote:
All:
On 20 August 2019 the rules for radioisotope space launch were modified to
allow “Tier 1” and “Tier 2” materials (as defined) to be launched with
permission of the head of the sponsoring agency, or the Secretary of
Transportation, if commercial.
“Tier 3” materials (basically, large amounts) still require Presidential
authorization although that can be delegated to the head of OSTP. So far as
I can tell, the list still includes Am 241 and Pu 239 but I’m checking w/ a
friend who was responsible for the rules change.
Bill
On Mon, Mar 1, 2021 at 7:16 PM William Claybaugh <wclaybaugh2@xxxxxxxxx>
wrote:
Mike:
I clearly recall a list of material that required the full OSTP/NSC review
w/ Presidential authorization that I have evidently conflated w/ SNM’s.
I’ll go look for that list tomorrow.
Bill
On Mon, Mar 1, 2021 at 7:03 PM William Claybaugh <wclaybaugh2@xxxxxxxxx>
wrote:
Mike’s right; my error.
Handling requirements for both might have changed in the past decade but my
previous experience is that neither AM 241 nor Pu (in any form) can be
launched w/o the full nuclear rigamarole, including permission of the
President.
Bill
On Mon, Mar 1, 2021 at 6:50 PM Michael Kelly <dmarc-noreply@xxxxxxxxxxxxx>
wrote:
Oh, and AST has set up a working group to deal with rules for commercial
launch of nuclear materials. The staff are all of the people I would have
picked if I were still there. So a private project is getting more, not
less, realistic.
One thing I should have clarified in my response to Bill. Am-241 is NOT a
special nuclear material.
On March 1, 2021 at 8:46 PM, "Michael Kelly"
<dmarc-noreply@xxxxxxxxxxxxx> wrote:
Yep. I have a friend who is a (very senior) nuclear engineer who is
plugged into the Am-241 supply chain, and I was surprised to find out how
readily available it is - in quantity.
On March 1, 2021 at 8:12 PM, Rand Simberg <simberg@xxxxxxxxxxxxxxx>
wrote:
Yes, in this case, the UK government. Since they are making RTGs, I
don't know any reason that they wouldn't be amenable to selling them.
On 3/1/21 4:45 PM, William Claybaugh wrote:
Mike:
Am 241 is a special nuclear material; if one has to use an RTG, one
has to deal with a government.
Bill
On Mon, Mar 1, 2021 at 5:04 PM Michael Kelly
<dmarc-noreply@xxxxxxxxxxxxx> wrote:
Northrop Grumman makes a whole range of pulse-tube cryocoolers for
space applications, and have been developing them as electric
generators when run in reverse. They have no moving parts (well, no
parts that move very far), and last forever.
https://rps.nasa.gov/internal_resources/160/
And, yes, Americium 241 is back in production (big time). It would
provide a more level power output in RTG applications, given a
half-life ~> 5 times that of Pu 238.
On March 1, 2021 at 10:47 AM, William Claybaugh
<wclaybaugh2@xxxxxxxxx> wrote:
Rand:
Yep, but that does not justify ignoring the best answers.
Bill
On Mon, Mar 1, 2021 at 8:24 AM Rand Simberg
<simberg@xxxxxxxxxxxxxxx> wrote:
Bill, you're the one who started this topic as a "home-built space
mission."
On 3/1/21 7:18 AM, William Claybaugh wrote:
Rand:
They don't last as long and NASA Gleen's Stirling power systems are
(ground) qualified for 20 years.
Bill
On Mon, Mar 1, 2021 at 8:02 AM Rand Simberg
<simberg@xxxxxxxxxxxxxxx> wrote:
You could buy one from the UK. They've started making them out of
Americium.
On 3/1/21 6:55 AM, William Claybaugh wrote:
Rand:
I think an efficient RTG is required and that will mean USG
involvement in what likely wants to otherwise be a privately
funded activity.
Bill
On Mon, Mar 1, 2021 at 7:47 AM Rand Simberg
<simberg@xxxxxxxxxxxxxxx> wrote:
That begs the question of why it would be either big budget, or
done by
NASA. :-)
On 2/28/21 10:00 PM, Henry Spencer wrote:
On Sat, 27 Feb 2021, Robert Steinke wrote:
imparting about... 15km/s if the back of my envelope is
correct. That's a whole lot for a chemical rocket...
That close to the sun it should be easier to do high thrust
solar
thermal.
Wikipedia says Isp up to 1000 seconds so the mass ratio would
need to be
~4.5. Use a drop tank for boiloff so the burn starts out
with a full
tank.
Unfortunately, that Isp requires LH2, and after circa a decade
in
space (out to Jupiter and back), almost certainly it will all
be gone.
There are ways of storing LH2 for years, in principle, e.g.
active
refrigeration, but it's beyond today's state of the art, and I
believe
Bill is hoping for a relatively low-cost mission.
(A big-budget planetary mission isn't going anywhere unless
you can
convince a Decadal Review to make it their first priority,
which isn't
going to happen for this. Smaller efforts can sometimes do
end runs
around the traditional process, but ill-defined costs and
risks from
techological pioneering are just what you don't want if you're
trying
to convince people to stick their necks out in support.)
Henry