Solar-pumped laser power transmission, a way to dramatically decrease launch costs?
in [Physics]
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From: William Mook on 14 Feb 2010 20:49 On Feb 14, 4:29 pm, "Jorge R. Frank" <jrfr...(a)ibm-pc.borg> wrote: > Androcles wrote: > > > "William Mook" <mokmedi...(a)gmail.com> wrote in message > >news:7f4558bf-f2c5-44e9-ad08-e9f293d88557(a)q21g2000yqm.googlegroups.com.... > > On Feb 14, 1:33 pm, "Androcles" <Headmas...(a)Hogwarts.physics_u> wrote: > >> "William Mook" <mokmedi...(a)gmail.com> wrote in message > > >>news:ec69fe16-04e1-4147-82e8-4f007cb68a41(a)g23g2000vbl.googlegroups.com.... > >> On Feb 12, 5:16 pm, "Androcles" <Headmas...(a)Hogwarts.physics_u> wrote: > > >> > "William Mook" <mokmedi...(a)gmail.com> wrote in message > > >> >news:fbbddf2d-60ea-4ed3-a183-23e920219728(a)k41g2000yqm.googlegroups.com... > > >> > On Dec 18 2009, 4:43 am, "Androcles" <Headmas...(a)Hogwarts.physics_q> > >> > wrote: > > >> > > "Jonathan" <H...(a)Again.net> wrote in message > > >> > >news:p5SdndXFAKoISrfWnZ2dnUVZ_vWdnZ2d(a)giganews.com... > > >> > > >I like this idea, Relatively small mirrors would power > >> > > > the lasers, not huge solar cell arrays. The lasers would > >> > > > transmit their beams to other satellites that convert it to, and > >> > > > beam it down, as microwaves. No need for mile-size > >> > > > collectors in orbit. > > >> > > What are you babbling about? > > >> > I can't be certain, but I will say that if you move a solar collector > >> > array closer to the sun it will gather more energy for a given size. > >> > ============================================= > >> > It won't be in Earth orbit then. > > >> That is absolutely correct. It will be on solar orbit. The orbital > >> period will be 24 hours at 3 million km radius. > >> ============================================== > >> You may find it a tad warm 2 million miles from the sun. It will gather > >> rather more energy than you wanted, and having a 24-hour year it won't > >> be in sight of Earth for more than 14 hours each Earth day as it > >> disappears behind the Sun for 10 hours of that period. > > > The sun is 1.4 million km in diameter. An orbit with a 3 million km > > radius has a 6 million km diameter. So, the sun subtends only 13.5 > > degrees of the sky. > > ======================================================== > > The Sun subtends 0.5 degrees of sky, same as the moon. > > http://en.wikipedia.org/wiki/Angular_diameter > > It subtends 0.5 deg at Earth (r_orbit = 1.5e8 km). He's talking about > what it subtends at 3e6 km, 50 times closer. He's off by a factor of 2, > due to failure to multiply by 2 after taking the arcsin. > > r_sun = 0.7e6 km > r_orbit = 3e6 km > theta_sun = 2*asin(r_sun/r_orbit) = 2*asin(0.7/3.0) = 27.0 deg Correct - its 27 degrees not 13.5 degrees. Though I believe an inclination of 13.5 to 14 degrees will make the Earth visible to the satellite on the far side of the sun.
From: William Mook on 14 Feb 2010 20:59 On Feb 14, 6:01 pm, Fred J. McCall <fjmcc...(a)gmail.com> wrote: > William Mook <mokmedi...(a)gmail.com> wrote: > > :On Feb 14, 2:00 pm, "Scott M. Kozel" <koze...(a)comcast.net> wrote::> "Androcles" <Headmas...(a)Hogwarts.physics_u> wrote: > > :> > :> > "William Mook" <mokmedi...(a)gmail.com> wrote in message > :> > :> > That is absolutely correct. It will be on solar orbit. The orbital > :> > period will be 24 hours at 3 million km radius. > :> > ============================================== > :> > You may find it a tad warm 2 million miles from the sun. It will gather > :> > rather more energy than you wanted, and having a 24-hour year it won't > :> > be in sight of Earth for more than 14 hours each Earth day as it > :> > disappears behind the Sun for 10 hours of that period. > :> > :> It would take an enormous amount of energy to put a satellite that far > :> down into the Sun's gravity well. > :> > :> It has been difficult enough to get a satellite into the same orbit as > :> Mercury, which is 35 million miles from the Sun. > : > :Solar sails are ideally suited for this mission. I am considering > :fully reusable vehicles capable of putting 1,000 metric ton payloads > :on orbit for very little cost per ton. This sort of vehicle is > :required to build any sort of orbital or lunar or Martian > :infrastructure. Its well within our capacity to build it. > : > :http://www.scribd.com/doc/24390383/mokaerospace-3 > : > > There is a BIG difference between a few line drawings and some web art > and an actual, working vehicle. So, you are proposing that we proceed without any calculations drawings or visualizations? Why? > : > :There are 10 million millionaires in the world and they control $40 > :trillion of the world's $58 trillion in liquid wealth. Selling 5,000 > :tickets to 0.05% of them for $200,000 raises $10 billion - enough to > :build a fleet of ships. > : > > For a very small fleet numbering something less than one. You aren't getting it. Money buys things. At $10 million per metric ton for hardware $10 billion buys 1,000 metric tons of hardware. With MEMS based rockets T/W of 1,000 have been achieved. Structural fractions of 5% are achieved with this T/W which mean a vehicle 20.0x the mass of the structure. So, this is 20,000 tons of vehicle. A 5% launch weight to payload weight on orbit means 20,000 puts up 1,000 tons of payload - for $10 billion non-recurring cost. With 1,000 flight cycles this is amortized at $100 million per flight - or $100,000 per ton - which is very inexpensive. > : > :Once built, reusable vehicles are useful for a variety of missions. > : > > Quite true. The 'trick' is getting past that handwavium first part > that assume you can build them for next to nothing and have negligible > operating costs. I've used figures developed for a cost analysis course at MIT. $10 billion is not next to nothing. > -- > "Ordinarily he is insane. But he has lucid moments when he is > only stupid." > -- Heinrich Heine You must be a really sad person Fred to be so abusive. The town isn't taking any risk with a contingent purchase agreement. A five year development cycle and a monthly report of progress will give them - and the risk taking VCs - a clear idea of progress as it occurs.
From: Scott M. Kozel on 14 Feb 2010 21:56 William Mook <mokmedi...(a)gmail.com> wrote: > > "Scott M. Kozel" <koze...(a)comcast.net> wrote: > > "Androcles" <Headmas...(a)Hogwarts.physics_u> wrote: > > > "William Mook" <mokmedi...(a)gmail.com> wrote in message > > > > That is absolutely correct. It will be on solar orbit. The orbital > > > period will be 24 hours at 3 million km radius. > > > ============================================== > > > You may find it a tad warm 2 million miles from the sun. It will gather > > > rather more energy than you wanted, and having a 24-hour year it won't > > > be in sight of Earth for more than 14 hours each Earth day as it > > > disappears behind the Sun for 10 hours of that period. > > > It would take an enormous amount of energy to put a satellite that far > > down into the Sun's gravity well. > > > It has been difficult enough to get a satellite into the same orbit as > > Mercury, which is 35 million miles from the Sun. > > Solar sails are ideally suited for this mission. I am considering > fully reusable vehicles capable of putting 1,000 metric ton payloads > on orbit for very little cost per ton. This sort of vehicle is > required to build any sort of orbital or lunar or Martian > infrastructure. Its well within our capacity to build it. The orbital velocity of a 24-hour circular orbit 2 million miles radius from the center of the Sun -- (3.14 * 4,000,000) / 24 = 523,333 miles per hour. That is the velocity you would have to attain.
From: Greg D. Moore (Strider) on 14 Feb 2010 23:31 Fred J. McCall wrote: > "Androcles" <Headmaster(a)Hogwarts.physics_u> wrote: > >> >> When usenet posts get interrupted by gmail users, in this case Mook, >> it prevents Microsoft's Outlook Express from automatically inserting >> the indent markers, >> > > No. It's when people post through GOOGLE GROUPS (not Gmail) and then > you reply with OUTLOOK EXPRESS that the problem arises. If you can't > be convinced to use a real newsreader instead of the POS you currently > employ, why don't you just fix your Outhouse Distress installation so > that it doesn't mishandle what comes out of Goggle Gropes? > > http://home.in.tum.de/~jain/software/oe-quotefix/ BTW, Fred, thanks for this link. This is exactly what I had been looking for and had previously failed to find. Excellent. Thanks. -- Greg Moore Ask me about lily, an RPI based CMC.
From: Pat Flannery on 15 Feb 2010 04:00
Fred J. McCall wrote: > Venture capitalists > are smarter than to hand money to someone like you. I don't know about that; remember the Moller Flying Car that's been "entering production later this year" for around twenty years now. Wait till you see their new one, that must be made for Nick Fury and SHIELD to replace the flying Porsche 904's that Stark Industries made for them back in the 1960's: http://www.moller.com/index.php?option=com_content&view=article&id=128&Itemid=105 Heck, they'll have that thing flying by next week. Even if it can't get airborne it will make the ultimate riding mower. :-D Pat |