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Planets at near stars?

Posted by: JonHogan - Sat Nov 02, 2013 12:23 am
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Planets at near stars? 
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Post Re: Planets at near stars?   Posted on: Fri Dec 13, 2013 3:55 am
Sigma, the premise underlying this thread is that proven practical technology could be used to acquire high-resolution images of extrasolar planets. Light-gas guns are routinely used experimentally to accelerate small masses to extremely high velocities, but I am unaware of any project using a light-gas gun or any other type of linear mass accelerator which has successfully launched any ballistic object of any size even to low Earth orbit, let alone the moon. It’s not for lack of trying. Experiments with light-gas guns began many decades ago shortly after the second world war.

The only guns actually built that might have even been considered for “rocketless” orbital launches were not even light-gas guns at all, but experimental specially lengthened and modified conventional artillery. In 1966, using a gun 119 ½ feet long, Project High Altitude Research Program (Project HARP) fired a 185-pound dart-like projectile called a Martlet 2C to an altitude of 590,000 feet (~112 miles or ~180 km) in a non-orbital vertical launch from the Kofa firing range at the U.S. Army’s Yuma Proving Ground near the city of Yuma in southwestern Arizona. That record stands to this day.

In the smaller Project HARP guns, the experimental projectiles had to endure accelerations as high as 35,000 times the force of gravity. In the biggest guns, launch accelerations were “only” as high as 15,000 gravities. That means the structural design of a one-pound non-orbital payload would have to be strong enough to support 7 ½ tons of its own weight during launch. Most of the mass of an actual orbital satellite would have to be devoted to surviving the launch, with little left over for useful work in space. Rocket propulsion, on the other hand, is a proven well established method of space transportation which can reliably carry delicate payloads (such as astronomical optics) to orbit and beyond with accelerations as low as three gravities.

Launching satellites to orbit from big guns is theoretically possible, but we use rockets because it turns out rockets are so much simpler.


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Post Re: Planets at near stars?   Posted on: Fri Dec 13, 2013 7:07 pm
A very long track would mean a small amount of acceleration,

A very high exit point would mean that it would not be subjected to thick atmosphere,

if the payload is smaller than 1 foot in radius, I believe oil pipes could be used to accomplish the building of the gun,

Now as far as a "engine" that accelerates the projectile, linear acceleration has come a long way recently, (rail guns, coil guns etc.

However you are accelerating, if you can launch the craft 1 after another,
you may be able to "ride" the slipstream behind the last projectile.

I know that the infrastructure involved is much more costly initially,
this could be compensated by the fact that everything is reusable, and not marooned in space.
however, the "Cannon" style launch could add escape velocity to a rocket bearing craft.

So stage 1 - Cannon - (not high acceleration)

stage 2 - Rocket motor.

This allows for a rocket of less weight, to go further and faster.

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Post Re: Planets at near stars?   Posted on: Mon Dec 16, 2013 2:14 am
Sigma, as others have emphasized earlier, theoretical technical feasibility is not enough. The dominant factor in the development of any public work is public support.

A very long track would mean a very long list of angry residents and conservationists opposing construction. To avoid excessive accelerations, the track or tube would have to be at least several miles long, too long to be acceptable.

A very high exit point would require construction in the mountains of the southwestern United States, which are popular vacation destinations for millions of voting citizens going to great expense to have homes or holidays where they can get away from industrial bustle and noise and relax in the beauty and quiet of the great outdoors.

A typical angle of launch proposed for these systems is only about 25 degrees above horizontal. In addition, nearly all of these ideas assume sub-orbital “muzzle” velocities and so rely on projectiles with rocket-propelled second and even third stages. That translates into hypersonic flight paths of hundreds or in some cases even thousands of miles through the airspace of the United States. Supersonic commercial air service over land was prohibited by lawmakers in the U. S. because of public opposition to the effects of sonic shock waves. Those same concerns would drive votes solidly against hypersonic vehicles being routinely launched over populated areas.

If the payload is smaller than one foot in radius then traditional launch facilities using conventional rockets would have to be maintained anyway for delivery of larger payloads. A single huge central launch facility delivering only small payloads greatly restricts launch flexibility and greatly increases vulnerability to natural disasters or sabotage.

All of the arguments against gigantic space guns in general apply to electromagnetic accelerators in particular, with the additional fact that none of the experimental launchers have demonstrated reliable large-scale feasibility. The greatest potential for space transportation using linear accelerators lies in space-based mass drivers launching material from the moon or from asteroids, not from Earth.

“Drafting” at Mach 10 doesn’t work quite as well as drafting on a bicycle or in a car. Furthermore, if the public would not even support supersonic passenger aircraft flying overhead, they certainly will never support a gigantic aerospace “machine gun” firing hypersonic projectiles one after an other.

Your last point is a genuinely viable option, although not for a lunar optical telescope. Using a gun as the first stage of small rocket-propelled vehicles is the most likely practical application of the “space gun” concept. The guns can be small enough (although still really, really big) to be located away from populated (or popular) areas. No gigantic installation is necessary. The technology is compatible with private operations delivering the smaller payloads that larger outfits would rather not handle and profits can be realized quickly enough to satisfy investors.

The ongoing commercialization of space transportation is already driving down the cost of rocket launches and can reasonably be expected to continue to do so. Rocket propulsion using “big dumb boosters” is still the only proven space transportation technology that could be put to work “today” delivering the components necessary to capture high-resolution images of extrasolar planets.


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Post Re: Planets at near stars?   Posted on: Tue Dec 17, 2013 9:03 am
Can't do anything about the payload size or G forces from a gun but the sonic booms could be mitigated by site selection. In the late 50s and 60s I lived in the Los Angeles suburbs and as a kid I thought they were 'cool'.

Today I live about a hundred miles outside of Los Angeles and 75 miles south of the military's supersonic flight corridor and cannot hear the sonic booms unless I'm at the FAR site that sits in the flight corridor. At other military bases in the area they fire off munitions all the time that aren't heard. I don't think it would be hard to find an area in the southwest with mountains that could support a 'gun' for space shots. Just don't know why one would choose to do so since we currently have rockets that do it better.


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Post Re: Planets at near stars?   Posted on: Tue Dec 17, 2013 9:23 pm
Sound pollution is the least a project like this would have to overcome. I'd say its a non-starter in the US or anywhere in the "developed" world from a litigative perspective. Which is just as well because you'd want it on the equator anyway. Probably the best bet is a proposal Sigma or Box suggested, a seamount somewhere the "gun tube" sections along or buried with in it.

Will never happen of course because the "rocket mafia/lobby" has far too much vested interest...


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Post Re: Planets at near stars?   Posted on: Tue Dec 17, 2013 11:00 pm
Seamounts have the added complexity of dealing with salt water, divers, submersibles, and the other problems with working underwater. A platform could also be built to keep station above the seamount but it would be easier to do it on a deserted island and bring in revenue for some of those island countries near the equator strapped for cash.


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Post Re: Planets at near stars?   Posted on: Wed Dec 18, 2013 2:22 am
Rockets are clearly the way to go for the foreseeable future, but what kind of rockets? That question was actually answered all the way back in the 1960s with the Minimum Cost Design (MCD) concept, also known as “big dumb rocket” or “big dumb booster” (BDB). Arthur Schnitt helped to develop the concept while working as an engineer for the Aerospace Corporation, a federally funded nonprofit “think tank” for the U.S. Air Force among others. Schnitt tirelessly championed MCD as the best way forward for the American space program, but his words fell on deaf ears at NASA, in the Congress and in the aerospace industry. Instead of following the least expensive path, the military, the industry and the government all hand-in-hand headed off in the opposite direction to produce the most expensive system ever devised to send cargo to space, the outrageously bloated and (literally) fatally flawed space shuttle program.

Arthur Schnitt’s Minimum Cost Design concept was proven to be practical by independent researchers decades ago. Now that the free market is finally beginning to influence the business of space transportation, Schnitt’s model is effectively a blueprint for success for commercial aerospace companies. The first company to adopt MCD as their operating principle will be able to outbid any other competitor. Then the race will be on and transportation costs will plummet to a fraction of what they are today. At that point, mass-deploying the mass-produced primary reflectors of a very-large-array optical telescope becomes a reasonable financial consideration.

All the necessary proven practical technology really does already exist to build the components of a lunar observatory and to build the “big dumb rockets” that can deliver the goods to the moon at a price we can afford.


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Post Re: Planets at near stars?   Posted on: Mon Jan 06, 2014 10:31 pm
Having Kepler fail was a major blow for planet research. Even though it will take years to research the data they collected. More would have been better.

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Post Re: Planets at near stars?   Posted on: Tue Jan 07, 2014 5:40 am
Agreed. Even though we know every observatory we send into space will eventually fail, it’s always a disappointment when an instrument as extraordinary as the Kepler Mission satellite finally ceases to function. Still, with original observations of more than 3500 candidate planets and confirmation of 199 independent observations of extrasolar planets at last count, Kepler must be considered a resounding success. Plus, there’s hope for the satellite yet. Only the stabilization system has been compromised. All of the sensory equipment is still in perfect working order.

The loss of the second reaction wheel was terrible news for the Kepler Mission, but very clever engineers at Ball Aerospace & Technologies Corporation and the Laboratory for Atmospheric and Space Physics who are responsible for the care and operation of the satellite have figured out how to “sail” Kepler using solar wind to stabilize the satellite sufficiently with the two remaining reaction wheels, potentially allowing observations to continue. The “Second Light” plan to give the Kepler Mission a second life (“K2”) is up for review early this year.

When Jon Hogan began this thread, he specifically alluded to the ability of existing space-based observatories such as Kepler or Hubble to contribute to our understanding of planets orbiting distant stars. His frustration was that, despite all of the knowledge we have acquired, observations of extrasolar planets with these telescopes do not actually produce images, only reams of data. Seeing with your own eyes has an emotional power that mere data can not match. Capturing the first high-resolution portrait of a planet looking very much like our own and only a few light years away would be one of the most transformative events in history, changing human understanding of our place in the world forever.

Jon asked if we could use existing technology to produce that image. My contention is that we can and without excessive cost or delay.


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Post Re: Planets at near stars?   Posted on: Fri Jan 24, 2014 2:58 pm
From the Space Fellowship Headlines:

Virgin Galactic Announces Successful Test Firings Of New Rocket Engines For LauncherOne

Published by Klaus Schmidt on Thu Jan 23, 2014 5:07 pm via: Virgin Galactic


“Both engines are simple, pressure-fed LOX/RP-1 systems built with a low part-count design.”


This is practically the definition of the Minimum Cost Design (MCD) protocol, also known as “Big Dumb Rocket” or “Big Dumb Booster,” first promoted in the 1960s. But even if you are using “small dumb rockets” to do it, drastically reducing the cost of delivering payloads to orbit seems like a smart idea to me.

I am thrilled to see Virgin Galactic welcoming the wisdom of MCD within their business model and leading the way to truly low-cost commercial space transportation. With Virgin Galactic’s success, other aerospace companies will have no choice but to follow their example or fail. The low-cost space transportation revolution has begun!


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Post Re: Planets at near stars?   Posted on: Fri Jan 24, 2014 9:53 pm
USJay wrote:
From the Space Fellowship Headlines:

Virgin Galactic Announces Successful Test Firings Of New Rocket Engines For LauncherOne

Published by Klaus Schmidt on Thu Jan 23, 2014 5:07 pm via: Virgin Galactic


“Both engines are simple, pressure-fed LOX/RP-1 systems built with a low part-count design.”


This is practically the definition of the Minimum Cost Design (MCD) protocol, also known as “Big Dumb Rocket” or “Big Dumb Booster,” first promoted in the 1960s. But even if you are using “small dumb rockets” to do it, drastically reducing the cost of delivering payloads to orbit seems like a smart idea to me.

I am thrilled to see Virgin Galactic welcoming the wisdom of MCD within their business model and leading the way to truly low-cost commercial space transportation. With Virgin Galactic’s success, other aerospace companies will have no choice but to follow their example or fail. The low-cost space transportation revolution has begun!


I read somewhere it was only 5% cheaper than regular space rockets.

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Post Re: Planets at near stars?   Posted on: Fri Jan 24, 2014 10:54 pm
My interest is in the engines, not the launch system. “Small dumb rockets” are not as cost effective as “big dumb rockets,” but Virgin Galactic’s use of these very simple pressure-fed engines is a step in the right direction. If other companies want to compete they will have to develop even cheaper launch systems. Even a 5% difference is enough to drive a price war. That’s good for customers and good for space exploration.


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Post Re: Planets at near stars?   Posted on: Thu May 15, 2014 8:20 pm
From the Space Fellowship Headlines:

Giant telescope tackles orbit and size of exoplanet

Published by Klaus Schmidt on Thu May 15, 2014 4:47 pm via: Lawrence Livermore National Laboratory

“The Gemini Planet Imager snapped an amazingly clear and bright image of the gas giant Beta Pictoris b after an exposure of just one minute.”

http://spacefellowship.com/wp-content/u ... 00_Big.jpg

No Earth-based telescope is likely to produce an image of an exoplanet much more “amazingly clear and bright” than this. The 8-meter Gemini South optical telescope in Chile using the adaptive optics system of the Gemini Planet Imager is about as cutting edge as it gets. Keep in mind the report states Beta Pictoris b is “at least four times the size of Jupiter.”

Space is the only place big enough for building optical telescopes big enough to give us detailed images of Earth-like extrasolar planets.


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