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Space Science Technology

Cambridge N-Prize Team To Build Balloon-Assisted Rockets 93

Rob Goldsmith writes "Earlier this week we heard that Cambridge University Spaceflight would be entering the N-Prize competition. The N-Prize is a competition to stimulate innovation directed towards obtaining cheap access to space. Most importantly, the launch budget must be within £999.99. Cambridge University Spaceflight plan to win the prize using a balloon and a rocket. They have now opened up an official forum where the public can track their progress." The linked story has images from a test flight of July 23, and an interview with a member of the team, Ed Moore.
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Cambridge N-Prize Team To Build Balloon-Assisted Rockets

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  • Inflation (Score:3, Insightful)

    by circlingthesun ( 1327623 ) on Sunday July 27, 2008 @04:29PM (#24360825)
    What if someone did it for just under £999.99 but then the price of say rocket fuel goes up?
  • by fyoder ( 857358 ) * on Sunday July 27, 2008 @04:47PM (#24360941) Homepage Journal

    I, for one, welcome our new balloon rocket overlords.

    Otherwise known as BOC and Cambridge Precision [ucam.org] .

    I can see the usefulness of sponsorship by private enterprise, and it's reasonable to expect the sponsor to want their name on the craft, but this is ridiculous.

  • Re:Inflation (Score:5, Insightful)

    by Anonymous Coward on Sunday July 27, 2008 @05:07PM (#24361077)
    To mod as Insightful the person who mentions "What if fuel prices increase?" while modding down as "Offtopic" the person who discusses why they have and might increase is contradictory, at best. They are either both offtopic or both insightful. I think sometimes moderators forget that "Offtopic" and "Troll" are not synonymous with "I disagree" and "I don't like what that guy said but I won't try to refute it".
  • Re:Inflation (Score:5, Insightful)

    by causality ( 777677 ) on Sunday July 27, 2008 @05:28PM (#24361223)

    To mod as Insightful the person who mentions "What if fuel prices increase?" while modding down as "Offtopic" the person who discusses why they have and might increase is contradictory, at best. They are either both offtopic or both insightful. I think sometimes moderators forget that "Offtopic" and "Troll" are not synonymous with "I disagree" and "I don't like what that guy said but I won't try to refute it".

    This was a politely worded post. You worded this in a non-inflammatory manner and explained why you feel the way that you do, did not use invectives or name-calling and did not even take a very controversial position, and yet you were still modded as Troll. This is one of the better statements on the recent quality of Slashdot moderation that I've seen in a while. You point out that they were not applying the moderating guidelines and they respond by failing to apply them some more, without ever explaining why they disagree with you because they probably realize they would not have a leg to stand on. I'm fully expecting to get modded to -1 myself for pointing this out, but that's okay. I have karma to burn and I'll feel better for having done it since I believe this sort of bullshit needs to be called out wherever it occurs.

  • by TimeTraveler1884 ( 832874 ) on Sunday July 27, 2008 @05:41PM (#24361329)

    I always thought that the way orbit worked was that you got far enough away that you could equalize the reduced pull of the earths gravity with your forward momentum to achieve a stable relationship.

    Achieving orbit is not about how far away you are away, it's all about your angular velocity. You could theoretically achieve orbit at sea level, but atmospheric drag keeps that from happening on earth.
    As satellite orbits the Earth, it is constantly accelerating, not because its speed is increasing, rather because it is constantly changing direction (speed + direction = velocity, change in velocity = acceleration).

    The acceleration of gravity is 9.8m/s, so if you can achieve an acceleration of 9.8m/s in the opposite direction, you will be in constant free fall and establish an orbit.

    It takes a lot of energy (32MJ/kg) to sustain this acceleration on Earth and maintain an orbit. However, you are correct that it takes less energy to enter into a geo-synchronous orbit than other types of orbits from different latitudes. Sorry I can't find a reference for it at the moment though.

  • by GameMaster ( 148118 ) on Sunday July 27, 2008 @06:28PM (#24361635)

    It seems to be an attempt to open up space launch capability to the little guy. Sure, when you look at the numbers, those big launch vehicles seem to be down-right cheap per lb., but good luck getting your 1lb. hobby project onto one of those launches. The organizations responsible for launching those rockets are, most likely, working exclusively with companies and fellow governments that need to launch 100lb+ payloads. Even if they'd work with an individual/small business, the red-tape and per-project overhead would destroy those per-lb. price numbers. Is it a good idea to make it possible for any average Joe to launch micro-satellites into space? I don't know, but that seems to be the goal of the N-Prize.

  • by MarkusQ ( 450076 ) on Sunday July 27, 2008 @07:18PM (#24362021) Journal

    The "burn most your fuel close to the ground" only applies to big rockets that are having to use early fuel to get later fuel up to altitude.

    In the present case both those assumptions are violated, making their approach more sensible than it sounds. First off, for a big rocket most of the energy required will be used to 1) get up to speed and 2) gain altitude, with 1) being the biggest concern. For a small rocket, both of these will initially be swamped by 3) friction. The higher you are when you start, the less of your fuel you will waste just overcoming drag.

    Secondly, the rule only applies when you are gaining the altitude by burning fuel in the first place. When you aren't having to burn fuel to get up there, you'd always come out ahead launching from a balloon (or even a mountain top) provided you could figure out how to make it work. Heck, with a tall enough tower (hint: think GEO) based on the equator, you could launch a satellite by hand!


  • by tftp ( 111690 ) on Sunday July 27, 2008 @10:29PM (#24363481) Homepage

    But a cellphone cam might just work.

    A cell phone CCD will be about 20 grams. But you also need the decoder, the DSP, and the transmitter, and the battery. If you still manage to do all that, then what's the use of a low-res image from 400 km? I understand that it might be cool once or twice, but that's what amateur satellites are for (this includes ham [amsat.org] and non-ham [stanford.edu] ones.) These satellites don't weigh 20 grams - they are larger, but they actually work.

    Usually amateur satellites hitch a ride on some other commercial launch, for a fraction of cost. There is no need to invent yer own rocket for $2,000 - use already developed hardware that works for real. Besides, rocketry is not a safe hobby when you deal with enough propellant to lift something to an LEO. When you try to do it on the cheap things only get scarier.

    On subject of RC planes: a half a gram RC plane only needs to receive, so its power budget is not as tough as a satellite that has to have a large antenna and/or a powerful transmitter to send its status and data back to Earth. But half a gram RC plane is still an achievement, and it is useful because you can fly it and enjoy its flight. People are free to make a 20g satellite also, but it will be far less useful than a tiny RC plane.

  • Re:Good luck (Score:3, Insightful)

    by DerekLyons ( 302214 ) <fairwaterNO@SPAMgmail.com> on Sunday July 27, 2008 @11:41PM (#24363925) Homepage

    The idea behind balloon launched rockets has nothing to do with escape velocity/gravity. It has to do with aerodynamic drag. Aerodynamic drag plays a big role in eating up launch fuel at lower altitudes where the atmosphere is dense. A balloon launch bypasses that drag with a low cost, and disposable, balloon filled with hydrogen/helium without having to use expensive/heavy rocket fuel.

    There's two problems with this scheme

    1. The Hindenburg would just barely be able to lift John Glenn's Atlas booster.
    2. A disposable Hindenburg would cost tens of millions of dollars - while the few thousand gallons of fuel and oxidizer it replaced would cost a few thousand dollars.
  • Re:Hmmm. (Score:2, Insightful)

    by Ambiguous Puzuma ( 1134017 ) on Monday July 28, 2008 @03:17AM (#24365059)

    E=mc^2 would only be relevant if the payload consisted of antimatter. And producing antimatter on that scale is far beyond our current capabilities.

    I think the formula you're looking for is (1/2)mv^2 [wikipedia.org], with a high value for v.

  • Re:Good luck (Score:3, Insightful)

    by sjames ( 1099 ) on Monday July 28, 2008 @09:51AM (#24367895) Homepage Journal

    Yes necessarily. Being hundreds of thousands of tons of lifting force, it will require considerable (fairly heavy) structure to distribute that force across the lifting envelope and transfer it to the payload.

    It would require a support rail to attach the rocket. That part would be recoverable if desired. It would not require the outer skin (certainly not the iron oxide and aluminum paint!) control surfaces, engines, passenger gondola, etc.

    Sure. In the same way my pocket calculator resembles a Cray supercomputer.

    The computer I'm using now is much more powerful than a Cray from the '80s :-)

  • by Candid88 ( 1292486 ) on Monday July 28, 2008 @10:43AM (#24368815)

    "I'm not really sure what the point of this is...what is anyone going to do with 10-20 grams in orbit?"

    I couldn't disagree more. Getting anything into orbit for less than 1000 GBP has a great number of uses. Several "pico-satellites" have been put in orbit, of which the various CubeSats http://en.wikipedia.org/wiki/CubeSat [wikipedia.org] are good examples. These use relatively inexpensive equipment and the lightest of them are only a few hundred grams so I do not think it ridiculous to envisage someone developing a 20 gram satellite.

    If the launch could be done for under 1000 GBP then it raises the realistic possibility of 'personal satellites', which at the very leat sound really cool. Not to mention the numerous research and possible commercial applications of large numbers of small but inter-connected & inexpensive satellites.

Genius is ten percent inspiration and fifty percent capital gains.