Why then did NASA go with a traditional Pu RTG for the current Mars rover
that just landed last week? NIH?
Ken
On Mon, Mar 1, 2021 at 4:04 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:to be
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
full~4.5. Use a drop tank for boiloff so the burn starts out with a
believetank.
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
Bill is hoping for a relatively low-cost mission.isn't
(A big-budget planetary mission isn't going anywhere unless you can
convince a Decadal Review to make it their first priority, which
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