In a NTR, can you adjust your ISP and thrust value by changing your working fluid? For example, could one working fluid optimize your thrust, while another optimizes your ISP?
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wick07":24evs69m said:
Antimatter or laser propulsion is the only way.No one wants a nuclear rocket liffting off from earth and nuclear rockets may have higher ISP so can take off and land 2 or 3 times not like chemical rocket that uses up the fule on one shot to get into space.
One problem is nuclear rockets are very big.
nec208":il9lrm62 said:
The cost to make Antimatter is way to high right now if it can be done. ( 1999 NASA gave a figure of $62.5 trillion per gram of antihydrogen )
This is a lot more danerous then Nuclear rocket.
nec208":67nkoxhy said:
Dude how man times have we said it!
Nuclear rockets WON'T TAKE OFF FROM EARTH SURFACE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Nuclear rockets are for space ONLY!
The thought of nuclear rockets operating in earths atmosphere is part of the reason that stupid people who think space is a "pristene" enviroment keep misunderstanding and freaking out.
A NERVA type engine or any other like it is simply for going from one place to another then another vehicle departs and enters atmosphere area etc.
Nuclear rockets or something similar are essentual for our advancement into space as a species. Solar and others just arent going to cut it. The future of space lies in multiple technologies. Nuclear should be a core of these.
And you do realise a chunk of antimatter the size of a marble would destroy new york right? Yea im EVERYONE would be ok with that flying over there heads near florida.
Antimatter when we learn how to produce it in sufficent quantities should be moved off earth to a safer area for production.
But remember nec-Nuke rockets not planned for atmosphere work.
May be now!! But I was only saying that do to chemical rockets are like going in space in raft that is like a crack addict on fuel and cost too much.
If we really want to start to go in space we must get of chemical rockets .
May be laser propulsion to get in space and nuclear rockets or antimatter use in space.
A spaceship running on antimatter can lift off from earth to take stuff up and stuff back down will have enough fuel for a life time if chunk of antimatter the size of a marble is that powerful!! They would never have to get more fuel .Has for safety there would have to be some thing put in place..
nec208":3b7wmru6 said:
The fuel for a Rocket isnt the really expensive part. Its all the people, infestructure, etc. Thats what drives up cost.
No one would build a spaceship to take off in atmosphere on antimatter. If even a small, small amount survived coming out of the engine it would cause a multi kiloton explosion.........not good. Plus this would also require reactor mass (probably water) so its not a magic wand.
Antimatter/nuclear/VASMIR etc, these are all for PURE space propulsion. For surface to LEO your always looking to Rockets. Humans i doubt could survive a trip to orbit abourd a laser launched ship TO many gees.
One of the things that i always find ironic is this. After you get a good sized asteroid habitat and space stations and industry an such you have another choice. Say you need to send up 30-50 people at a time. But most of those will stay there. So say only 5 to 10 would come back. Why use a huge shuttle/pod to take em back? Eventually when people go to stay there you could build launchers that are entirely disposable.
Your launcher goes up with 40 passengers (cargo in another rocket for cheaper prices) and 2 crew. After getting to LEO it is met and hauled away by a tug to a orbital transfer station. This station has numerous tugs, orbital shuttles (no wings no frills etc just a box with life support and a attachment for a tug) which it uses to ferry people from the station to other orbital facilities. Then the original vehicle they rode up on is recycled and used as materials to contiue to expand the orbital infestructure.
People would go down on shuttles or pods. The same vehicles could carry minerals/medicenes/goods back to earth.
Just a thought.
nec208":3c2nxnx8 said:
A laser-propelled spacecraft, just from the surface to LEO, would take more power than all the earth's powerplants combined produce. The technology for it won't exist for decades, and by the time it does, a space elevator with magnetic propulsion would be better.
As for antimatter, are you even listening to yourself? The production of antimatter costs trillions of dollars, and we aren't even up to a gram yet! At most, antimatter will serve as a catalyst for interstellar missions, but not for at least a century.
Chemical and nuclear are the only options in the short term and medium term (i.e., next 50 years, with solar sails serving in the inner solar system possibly). Chemical has been proven reliable since WWII. The US has only lost 7 people in chemical rocket failures (and no fatalities on liquid rocket failures) in the entire manned spaceflight program, going back to the X-15 in the 1950s. Chemical is the only system that produces enough thrust to get off the surface.
In the vacuum, the near-term options are solar sails (best used within Jupiter orbit, and only now in the test phase), nuclear thermal (tested in the sixties, with on-off NASA studies into the late 80s), and nuclear electric (VASIMR). Nuclear thermal is the most feasible option for flights to Mars and Moon, if you were to develop it, because it can fly within a decade. Nuclear electric is better for cargo flights to the Moon, Mars transits, and voyages to the outer solar system (Jovian moons, Saturn, etc). Solar sails can be used best for cargo and flights within Jupiter orbit.
The best thing about chemical rockets (besides that they're a tried and proven system) is their versatility. With chemical, you can make any rocket. You can make small SSTOs (Lockheed-Martin is bringing back X-33 proposals from what I heard), medium-heavy rockets (Falcon, Delta, Atlas), and super-heavies (everything from N-1 and Energia to Sea Dragon and a 1968 study for 4 Saturn Vs lashed together for 500 tonne payload to LEO).
Laser propulsion won't be ready for decades. If you're seriously proposing that we wait decades to expand into space, we may as well give up now. If Columbus wanted to wait for 747s before going to the New World, Spain certainly would not have become a major power. Likewise, if we wait to build something like the Starship Enterprise, we'll be sitting on earth with our thumbs up our arses when the asteroids, or the gamma ray bursts, or the alien colonizers show up.
The problem with Chemical rockets is it cost too much and payload problem.Really there was nothing wrong with the space shuttle or a new better space shuttle but cost is a big factor .On less we get off Chemical rockets on to some better system or make Chemical rockets better the US,China,Russia and may be the UK are going to be the only countries that can put people in space.
sorry I do not know of the problems with Laser propulsion or antimatter propulsion .
sorry I do not know of the problems with Laser propulsion or antimatter propulsion .
Any rocket able to orbit 2 tons of payload could obviously put a manned capsule in orbit. Since rockets are for sale, any country or organization could do it. Italy, South-Africa or Venezuela could perfectly put a man in space. It would only be expensive and not very useful.nec208":2pamm6n2 said:
Besides, countries like Costa-Rica, Syria, Afghanistan and many others have had astronauts flying into space.
Even tourists have been buying space trips...
The UK's first cosmonaut, Helen Patricia Sharman, did fly on the Russian Soyuz TM-12.
http://en.wikipedia.org/wiki/Timeline_o ... ationality
The problem why we do not have 8 or 10 countries in the world or more putting people in space is not of smarts but cost.Even the 3 countries in the world are under major lobby for the government to go with space probes and not putting people in space.Really in the 60's it was pride a country can put people in space and going in space was big fad and every kid was into rockets .Now it is dumbing down science and intellectual.Look at the schools and look at TV tank overhaul ,monster truck ,ice road truckers ,ice pilots ,forensic ,murder and crime , fixing up cars, so on.
People are obsessive with crime,,forensic,war and militay and reality TV and that is what takes up most of the learning channels on TV now.It hard to get science and intellectual stuff on TV.
Again 8 or 10 countries in the world or MORE could put people in space if they really wanted to give the money.Countries want to put money in space probes not put money to put people in space,
Look at Canada do you really think Canada is going to spend millions of dollars to make a space shuttle to put people in space and spend millions of dollars to keep it going every year when the militarty is so out of date from the 70,s and long wait times in the ER.And the UK has even longer wait times in the ER.
It money money money meony.They cannot even inprove the long wait times in the ER or give money in social programs for the needy and they are going to cough up money to put people into space.
To they get off Chemical rockets on to some better system or make Chemical rockets better the 3 countries are going to be the only countries that can put people in space and with major lobby for the government to go with space probes and not putting people in space.Not to say launching rockets take along time of getting the rocket and launch site ready.And no where do we have weekly launches or 3 or 4 launch every month.
People are obsessive with crime,,forensic,war and militay and reality TV and that is what takes up most of the learning channels on TV now.It hard to get science and intellectual stuff on TV.
Again 8 or 10 countries in the world or MORE could put people in space if they really wanted to give the money.Countries want to put money in space probes not put money to put people in space,
Look at Canada do you really think Canada is going to spend millions of dollars to make a space shuttle to put people in space and spend millions of dollars to keep it going every year when the militarty is so out of date from the 70,s and long wait times in the ER.And the UK has even longer wait times in the ER.
It money money money meony.They cannot even inprove the long wait times in the ER or give money in social programs for the needy and they are going to cough up money to put people into space.
To they get off Chemical rockets on to some better system or make Chemical rockets better the 3 countries are going to be the only countries that can put people in space and with major lobby for the government to go with space probes and not putting people in space.Not to say launching rockets take along time of getting the rocket and launch site ready.And no where do we have weekly launches or 3 or 4 launch every month.
Polishguy":1mjizu6v said:
hmm I don't know about that. In 2000, they launched a small object 233 feet with a pulsed laser. I think it was like 50 grams or something...I would point to the Lightcraft Technologies, Inc., page, but they are under construction. Here's the wikipedia:
Wikipeda Lightcraft section of Beam powered propulsion article
Wikipedia separate Lightcraft article.
From the above articles:
wikipedia":1mjizu6v said:
So, 1 MW for 1 kg. 25,000 kg orion capsule would take 25 GW, hardly comparable to the power output of all humanity :-O According to wikipedia, the total energy generation for the whole world in 2006 was 15.8 TW (terawatts, each of which is one thousand megawatts)!!!
So the power to launch an orion capsule with a laser would be 1/1000th of all of humanity's power over the period of one year.
--Brian
I definitely think nuclear energy will power many spaceships in the future. Propulsion, beyond the range of the Sun, will probably be plasma rockets powered by nuclear reactors. I think you will some solar sails for long distance also, as long as it involves known trade routes, say, between the Sun and the nearest star with planets on it.
--Brian
--Brian
neutrino78x":16r2f1f8 said:
Ah, this is an interesting article. But lightcraft do have their own problems. It is much easier to sabotage a launch by a lightcraft than a chemical launch. If one were to sabotage the Space Shuttle in flight, for example, you'd need to launch an ASAT missile. For a lightcraft, one must only set off a smoke grenade near the laser.
And 1/1000 of all humanity's annual power usage may not seem like a lot...until you calculate what it really means. If 1 kilogram = 1 megawatt of power, and a single Orion capsule, fully loaded, weighs 25 tonnes, then you need 25 gigawatts to send a single Orion capsule into Low Earth Orbit. Assuming humanity produces 25 terrawatts a year (rounded up from current estimates to match what we'll be around when laser propulsion takes off), then we are indeed at 1/1000 humanity's annual energy use. However, this becomes a problem because 1/1000 of our use in 365 days is equal to our energy use every 8.75 hours. That's globally. And it's compressed into the time it takes to launch the object. So, 25 gigawatts is needed. This adds up to $50,000 to launch it. It's actually a lot; Hoover Dam produces just 2 gigawatts at maximum capacity. However, higher amounts of energy have been compressed into lasers before. However, chemical rockets still have 50 years of reliability behind them.
Don't get me wrong. I'm all for experimentation with laser launches. But they're an unproven technology with energy requirements higher than chemical, even if costs end up lower. It needs research, but it's hardly worth cutting funding for new chemical rockets for. In fact, it sounds very promising (2.5 billion initial investment sounds good).
As for making launches accessible for all nations, is this really desirable? Do you want to give Iran or North Korea the ability to place kinetic weapons into LEO?
Anyway, the lightcraft has made me curious, and I'm e-mailing the physicist in charge (Dr. Leik Myrabo) to ask about whether it has the potential to replace chemical rockets for launch to earth orbit. The main question is whether pulsed lasers, which are the only ones with a peak power that can reach the requirements of a lightcraft, can do the job.
doom_shepherd":95upbixf said:
The Orion designs were modified to only use nuclear once they had moved far enough from Earth for the radiation not to do damage. When they initially tested they were testing not just to see if a nuclear blast could propel an object into space but also to see if it could propel an object at all.
Project Orion was and still is a far better idea than anything we've done. We could design, build, and send an Orion-style space craft to meet up with Voyager 1 or 2 within 12 years, easily.
neutrino78x":187ddag9 said:
233 feet? And that is relevant to lifting something to 300 km at 7 km/sec orbital velocity exactly how?
Let's say you manage to get a small object (obviously not a satellite) to 300 km. You shut off the laser, and it accelerates at 32 ft/s/s toward the surface until it burns up in the atmosphere.
MeteorWayne":1z21qb00 said:
To get into LEO, wouldn't the laser need to accelerate it to 7 km/s anyway? Or am I missing something?
Oh, now I get it. It will have no lateral velocity to maintain orbit unless the laser also hits it in the side. Because if it remains exactly above the laser for the whole launch sequence, it is too slow in LEO to maintain orbit.
I hope you are joking...of course at 3oo km, gravity is essentially the same as on the surface.orionrider":h1es67io said:MW, at 300km the device is in the Vacuum Of Space, where there is no gravity :idea: :?
:lol:
surface (average) 9.803 m/s^2
300 km 8.9412 ms^2
Polishguy":3oe869xc said:
No you're not. Even at 384,000 km (the moon's distance) if you have no lateral velocity, you come straight down and fry.
MeteorWayne":1vi5by02 said:
To be fair, for the laser to push it up constantly in the first place, it would need to have a lateral velocity equal to the rotation of the earth (assuming an equatorial launch). So wouldn't it be capable of reaching geostationary orbit?
How do you apply a lateral velocity to an object heading straight up?
Not a problem at 233 feet. Big problem at 200 km.
Not a problem again at 36,000 km. (GEO orbit)
It's that 35,800 km in between that makes a mess of it.
Not a problem at 233 feet. Big problem at 200 km.
Not a problem again at 36,000 km. (GEO orbit)
It's that 35,800 km in between that makes a mess of it.
Well these guys are probably smart enough to put the laser head on some sort of swiveling mount. And if the craft can orient itself at an angle, there would be a differential in pressure, pushing it sideways.
Even better, like cavesofmars would say: "By 2030 the Giant Orbiting Laser Facility (GOLF) will provide escape velocity to all spacecraft climbing vertically above 100km."
Even better, like cavesofmars would say: "By 2030 the Giant Orbiting Laser Facility (GOLF) will provide escape velocity to all spacecraft climbing vertically above 100km."
Anyway, this is pretty far off topic from the subject of the thread:
nuclear rockets are very very very bad idea ??
Eh?
Let's reel ourselves back in
nuclear rockets are very very very bad idea ??
Eh?
Let's reel ourselves back in
MeteorWayne":1t8ydn3o said:
What I mean, before we bring ourselves back to the original topic, is that as long as the lasers continue to propel the object until it reaches 36,000 km, lateral velocity shouldn't be a problem. If the laser's strong enough, it'll keep the object from falling down until it cuts off. So as long as the lasers are propelling it constantly, and hitting it dead center (that's the trick at those ranges, isn't it, because hitting it off center will nudge it off course), then it shouldn't need lateral velocity. Because if the laser's still propelling it in those 35,800 km, then it should be the same, in principle, as making it hover at 200 feet.
However, if your goal is to place objects in LEO, then the lasers aren't useful. And if your lasers should fail at any point during the procedure, you're screwed.
It doesn't work like that. By the the time the "object" get to GEO, you will have completed several day and night cycles, during most of which the sat would not be visible in the sky.
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