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