Via Reynolds: Princeton reports on the two-year trip to Titan (Masters thesis pdf). This is done by the "direct" deuterium / helium-3 fusion drive - for part of the mission. Think the hybrid electric / gasoline car. At a two-year run you can see why they can't use tritium; this isn't VISTA.
It's not really news, so much as the annual report and an application thereof. Space.com floated a more meaningful report on Princeton's work last year, telling us the mass this monster could shift. They were talking 10 tonnes. They also explained the milestones, PFRC-4 being where they start prototyping. Princeton are on -2 now.
For now I note what I (still) don't hear: anything about using this to get off the launch pad. We may need a lunar base, or actual Orion, before we can get this stuff off the well. And we may need the lunar base for even sufficient helium-3 to fuel it all. [UPDATE 1/31/21: By manufacturing it, where escape-velocity is low; scraping regolith suuucks.] Indeed, they are projecting that far - the two-year Saturnine window doesn't happen 'til 2046. On that much I am unsure: our synodic period is much less, 378 days. I think they are looking at the thesis which pulls that year out of nothing. No Jovian assist, in there. Venus neither. SHADECAST 12/29: Ah, that's because they're lagging Ultra Safe's fission solution...
In the meantime, I have a better use for this DF Drive. Jupiter / Earth synod exceeds thirteen months. Hohmann then takes over two years. But what if you don't waaaanna wait a year-n-change for the next window? So: rather than send a two-year trip to Titan... I reckon very similar maths can send something up right now to take about that long to Callisto. No need for Hohmann! No need to dork around with Mars or Venus conjunctions, either.
Elsewhere we may compare Orion to Callisto: 910-day round trip to that non-radioactive Jovian. That's, what, 455 days to get there? I'd also be interested to see how this scales up, mass-wise. Orion shifts kilotonnes. I suspect Princeton is constrained by the lack of fuel.
NEUTRONS 2/6/21: Pity about the 5% wasted on neutrons, even from He-3. Can we redirect that?
No comments:
Post a Comment