tag:blogger.com,1999:blog-3596550435682943926.post2444409543697601513..comments2024-03-21T17:50:42.377-07:00Comments on Hop's Blog: One Legged StoolsHop Davidhttp://www.blogger.com/profile/12923433894475072056noreply@blogger.comBlogger9125tag:blogger.com,1999:blog-3596550435682943926.post-15270184609947394272014-03-05T02:50:07.271-08:002014-03-05T02:50:07.271-08:00Have you seen this?
David Weaver:
NASA is develop...Have you seen this?<br /><br />David Weaver:<br /><i>NASA is developing an ambitious human spaceflight mission to Mars using a stepping stone approach that will take us beyond the Moon, to an asteroid and ultimately to the Red Planet.</i><br /><a href="http://blogs.nasa.gov/weaverblog/2014/02/27/nasa-on-track-for-deep-space-missions/" rel="nofollow">http://blogs.nasa.gov/weaverblog/2014/02/27/nasa-on-track-for-deep-space-missions/</a><br /><br />Granted, it is not quite an elaborate statement (and could mean very little in reality), but it makes me at least a little bit hopeful.Tony Machhttps://www.blogger.com/profile/14823430729798784689noreply@blogger.comtag:blogger.com,1999:blog-3596550435682943926.post-663869852433875092014-01-01T11:43:15.199-08:002014-01-01T11:43:15.199-08:00Interesting pdf, thanks Warren. It does indeed loo...<a href="http://www.fas.harvard.edu/~planets/sstewart/reprints/papers/48_Weiczorek_etal_2012_Science_SPA.pdf" rel="nofollow">Interesting pdf</a>, thanks Warren. It does indeed look like there's a Sudbury near Aitken.Hop Davidhttps://www.blogger.com/profile/12923433894475072056noreply@blogger.comtag:blogger.com,1999:blog-3596550435682943926.post-8245689424893605972014-01-01T07:04:43.347-08:002014-01-01T07:04:43.347-08:00Re: prospecting for the remains of metallic astero...Re: prospecting for the remains of metallic asteroids on the Moon, it's easy: just look for magnetic anomalies. We already have maps of these.<br /><br />http://www.fas.harvard.edu/~planets/sstewart/reprints/papers/48_Weiczorek_etal_2012_Science_SPA.pdf<br /><br />The point about impacting reducing concentrations of metals is well taken, but there may be concentration mechanisms on the Moon that can concentrate precious metals in polar craters, as the LCROSS results seem to indicate. If accepted at face value, we're looking at concentrations of 5 ppt (5,000 g/t)which is simply phenomenal--nothing on Earth comes close. Depending on the crustal composition and number and size of metallic impactors, such concentrations are within the realm of possibility. Such deposits could function as a metaphorical "one-legged" stool--a killer app that can survive on its own without dependence on other "legs". After all, one-legged stools actually work just fine, you just have to maintain balance.Warren Plattsnoreply@blogger.comtag:blogger.com,1999:blog-3596550435682943926.post-59877993883544923422013-09-27T10:54:21.429-07:002013-09-27T10:54:21.429-07:00I can add a few more thoughts since my group and I...I can add a few more thoughts since my group and I have been thinking about this and simulating it for a while now. Technically you don't even have to give up the free return by launching directly into a lunar polar azimuth, depending on how much fuel and time you have. But then the trajectory become more dependent upon launch location. If you make the plane change during boost and TLI you can launch ONCE A DAY, whenever your position phases into your desired trajectory. We happened upon this by assuming that in the future ALL side mounted boosters will be reusable and that you can more or less use as many as you want to boost a large hydrogen powered core stage that carries all your payload as fuel. A bunch of new options open up when you consider rocket fuel as expendable and time and vehicle hardware as precious commodities. In simulation the only constraint is the lack of SSME restart capabilities. A cluster of smaller restartable engines closes the architecture almost completely. If anybody has anything else to add I would love to hear about it. As I said, a technical discussion of these trajectories is long overdue.Thomas Lee Elifritzhttp://cosmic.lifeform.orgnoreply@blogger.comtag:blogger.com,1999:blog-3596550435682943926.post-542139358392623012013-09-27T10:47:35.951-07:002013-09-27T10:47:35.951-07:00A lot of great stuff in that pdf. Thanks, Thomas.A lot of great stuff in that pdf. Thanks, Thomas.Hop Davidhttps://www.blogger.com/profile/12923433894475072056noreply@blogger.comtag:blogger.com,1999:blog-3596550435682943926.post-17278059429651562492013-09-27T10:10:42.419-07:002013-09-27T10:10:42.419-07:00The original reference I used was here. The entire...The original reference I used was <a href="http://www.applieddefense.com/wp-content/uploads/2012/12/2005-Carrico-Comparison_Of_Lunar_Landing_Trajectory_Strategies.pdf" rel="nofollow">here.</a> The entire subdirectory is worth a look. Google 'lunar direct trajectories' and it all comes up.Thomas Lee Elifritzhttp://cosmic.lifeform.orgnoreply@blogger.comtag:blogger.com,1999:blog-3596550435682943926.post-79892065768509677472013-09-27T10:04:11.268-07:002013-09-27T10:04:11.268-07:00I can add to this, you can simply give up the free...I can add to this, you can simply give up the free return option and launch directly into the polar azimuth and all you lose is the boost from the Earth's rotation.<br /><br />Hyperbolic to parabolic arc landings incorporating LLO insertion are not for the weak of heart or mind though.Thomas Lee Elifritzhttp://cosmic.lifeform.orgnoreply@blogger.comtag:blogger.com,1999:blog-3596550435682943926.post-22045132711909366142013-09-27T10:03:08.443-07:002013-09-27T10:03:08.443-07:00Interesting. Do you know of an online description ...Interesting. Do you know of an online description of Lunar Direct? Quick Googling isn't giving me much satisfaction.<br /><br />Other routes I'd like to know more about are between halo orbits about EML1/2 and the lunar north/south pole.Hop Davidhttps://www.blogger.com/profile/12923433894475072056noreply@blogger.comtag:blogger.com,1999:blog-3596550435682943926.post-23932049524775629342013-09-27T08:30:15.816-07:002013-09-27T08:30:15.816-07:00Your last two posts were a long overdue discussion...Your last two posts were a long overdue discussion of this trajectory analysis. But if you are in a big hurry and have a load of evaporating hydrogen and oxygen necessary to actually land, you can make your plane change at a combined LEO boost and TLI and fly a weakly hyperbolic orbit directly to the pole and then land. It takes a bit more fuel but then it gets you there is as little as 36 hours. This is 'Lunar Direct'.Thomas Lee Elifritzhttp://cosmic.lifeform.orgnoreply@blogger.com