Doesn't need to be a city burner to be good propulsion. In fact, that
would be counterproductive if it burned up the sail, which it would. You
want enough power density to get good thrust without heating it beyond
its heat-rejection capability.
On 2/26/21 3:04 PM, William Claybaugh wrote:
Rand:
So far, there ain’t no city burning lasers in orbit.
I’m interested in what might be accomplished today, or in the next few years.
Bill
On Fri, Feb 26, 2021 at 4:01 PM Rand Simberg <simberg@xxxxxxxxxxxxxxx <mailto:simberg@xxxxxxxxxxxxxxx>> wrote:
Not sure I have the bandwidth to do that, but I'd ask John
Carrico, if you know him. He does that sort of thing for
recreation. It certainly doesn't seem implausible to me. That's
the sort of thing that it would be nice to have a laser in orbit
or on the moon that could push a sail. That would get it there a
lot sooner.
On 2/26/21 2:52 PM, William Claybaugh wrote:
Rand:
I’d be real interested as to whether your independent
astrodynamic analysis—at the spreadsheet level—could confirm that
60 klicks per second will catch it in about 20 years and that a
plane change at Jupiter followed by a solar gravity assist and
some makeup electric propulsion would allow a flyby.
Bill
On Fri, Feb 26, 2021 at 3:35 PM Rand Simberg
<simberg@xxxxxxxxxxxxxxx <mailto:simberg@xxxxxxxxxxxxxxx>> wrote:
I think there is scope for a lot of private missions in the
solar
system. Is Milner still planning an Enceladus mission?
On 2/26/21 2:29 PM, William Claybaugh wrote:
> Since we are not talking about homebuilt rockets, I was
wondering if
> we might talk about homebuilt space missions:
>
> A top level analysis suggests it would take about 60 Km /
sec to catch
> Oumuamua in about 20 years.
>
> Another very top level analysis suggests that a gravity
assist at
> Jupiter (solely to turn the plane from near ecliptic to
near that of
> Oumuamua; near to but less than 90 degrees) followed by a
50 solar
> radii assist at the Sun (Parker is doing 10 radii as I
recall but it
> carries way too much heat shield for this mission) can pretty
> certainly get to 50 km / sec.
>
> One of NASA Glenn’s Stirling cycle RTG’s tied to an existing
> commercial electric thruster appears capable of making up the
> difference with a big fuel tank.
>
> Assuming a New Horizons-like spacecraft, but much smaller,
a flyby
> seems possible based on this very top level analysis.
>
> I’d be real interested in helpful comments.
>
> Bill