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 <mailto: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/
<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 <mailto: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 <mailto: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 <mailto: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
<mailto: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