N-Prize

[Paul1684]

Hi all,
A quick reply to some of the points raised. Re piggybacking on a larger launch vehicle - sadly against the rules. Re cannon launches - I'm not convinced this is the way to go, but I do think a balloon start from about 50km is the likeliest option. Re useful electronics in a 20 gram package - ever bought one of those pennyweight remote helicopters? Tell me you can't put a transmitter in 20 grams; and the aim isn't utility - it's doabilty; how much luggage did the Wright brothers carry? Re drag/heating [Urwumpe] - are you basing this on a ground-level launch?

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[simonpro]

A transmitter from one of those remote helicopters would most likely not function in orbit. The radiation environment absolutely kills stuff up there, particularly small pieces of electronics. That's why spacecraft still use "old" computers from the 1990's (or earlier): Modern ones have their components closer together and are thus more likely to experience problems from cosmic radiation.

The best way to go with transmitters is to add something really simple that doesn't involve modern electronics at all. Just a transmit signal timed by a capacitor or something: Sputnik style.

 

[Urwumpe]

Re drag/heating [Urwumpe] - are you basing this on a ground-level launch?

No, 10000m altitude.

 

[bujin]

Re piggybacking on a larger launch vehicle - sadly against the rules.

Damn. So that means I can't just buy a golf ball for less than a quid and give it to the crew of STS-124 then?

 

[reverend]

I'm not sure about the feasibility of a balloon start from extremely high altitude. Even by avoiding the thick lower atmosphere, the task still remains to get the required ~7.7km/s velocity for orbital insertion. This is still going to require a massive rocket, which would mean a balloon would need to be really massive. We're probably talking the proportions of a zeppelin, and being that the air gets thinner as you rise, there would likely be a max altitude attainable with such a massive rocket...

The best chance would likely be an airplane launched liquid fueled rocket.

 

[cjp]

The US army has recently become really serious in developing electric cannons. I guess they're only interested in re-usable cannons, so I guess it's possible to make something like that. If the vehicle doesn't make contact with the gun while being accelerated (e.g. because it uses magnetic levitation), then the only thing that stops you from gaining huge velocities is the switching speed of high-voltage circuits, and, of course, air.

You can avoid the air mostly by lifting up the cannon with helium balloons. Things are getting really huge here, but luckily you don't need the energy to accelerate the big thing: you only need to launch the small thing.

Now, if you launch something with a gun from a balloon at, say, 60km altitude, then you still need an orbital insertion burn, so you need to have a rocket engine on board that can survive the huge accelerations in the gun. Or maybe it's enough to put an explosive charge in the center, and radio emitters on both sides of it. With some luck, one of both sides will enter a stable orbit when you let the charge explode at apogee.

As an alternative, maybe there is an altitude that can be reached with balloons, and that doesn't immediately de-orbit a sufficiently aerodynamic satellite. However, the small mass of the satellite might be a problem here.

I'm still quite sceptic, however. Especially on the budget part.

 

[Paul1684]

No, my point wasn't to use part of a toy helicopter in a satellite (the helicopter doesn't have a transmitter anyway - it has an IR receiver). My point was that you can put a lot into 20 grams.

In terms of radiation hardening - it is not a major problem for short-duration exposure at that altitude. My personal favourite is to devote 10 grams to a solar panel, 5 grams to a simple timer and 5 grams to a small xenon tube; just accumulate power for 5 minutes, then flash three times; then accumulate again and flash. No attitude control - just let the thing tumble and accept suboptimal solar collection. Easily detectable at 100km by a decent ground-based telescope if you know roughly where to look, and very robust.

Think simpler, guys. Space is closer than some people have jogged.

A transmitter from one of those remote helicopters would most likely not function in orbit. The radiation environment absolutely kills stuff up there, particularly small pieces of electronics. That's why spacecraft still use "old" computers from the 1990's (or earlier): Modern ones have their components closer together and are thus more likely to experience problems from cosmic radiation.

The best way to go with transmitters is to add something really simple that doesn't involve modern electronics at all. Just a transmit signal timed by a capacitor or something: Sputnik style.

 

[reverend]

Now, if you launch something with a gun from a balloon at, say, 60km altitude, then you still need an orbital insertion burn, so you need to have a rocket engine on board that can survive the huge accelerations in the gun.

I wouldn't approach it this way, I would lift a rocket with the cannon on top. The rocket+cannon would accelerate to close to orbital velocity, say 1/2, or 3/4ths. Then wait for apogee. The firing of the projectile would be the final orbital insertion itself.

 

[tl8]

No, my point wasn't to use part of a toy helicopter in a satellite (the helicopter doesn't have a transmitter anyway - it has an IR receiver). My point was that you can put a lot into 20 grams.

In terms of radiation hardening - it is not a major problem for short-duration exposure at that altitude. My personal favourite is to devote 10 grams to a solar panel, 5 grams to a simple timer and 5 grams to a small xenon tube; just accumulate power for 5 minutes, then flash three times; then accumulate again and flash. No attitude control - just let the thing tumble and accept suboptimal solar collection. Easily detectable at 100km by a decent ground-based telescope if you know roughly where to look, and very robust.

Think simpler, guys. Space is closer than some people have jogged.

Remember we all think we are rocket scienctists :dry:

 

[ijuin]

I wouldn't approach it this way, I would lift a rocket with the cannon on top. The rocket+cannon would accelerate to close to orbital velocity, say 1/2, or 3/4ths. Then wait for apogee. The firing of the projectile would be the final orbital insertion itself.

A rocket big enough to put the cannon high and fast enough would probably exceed the financial budget restriction.

 

[simonpro]

In terms of radiation hardening - it is not a major problem for short-duration exposure at that altitude.

Unfortunately that's not the case. Without proper protection even something as simple as a capacitor can be ruined by a cosmic ray, if you're unlucky enough to be hit by one.
So, you either have to provide some hardening, or you have to accept a relatively high chance that your electronics will fail at some point during the 9 orbits.

My personal favourite is to devote 10 grams to a solar panel, 5 grams to a simple timer and 5 grams to a small xenon tube; just accumulate power for 5 minutes, then flash three times; then accumulate again and flash. No attitude control - just let the thing tumble and accept suboptimal solar collection. Easily detectable at 100km by a decent ground-based telescope if you know roughly where to look, and very robust.

10g would provide (assuming optimum solar lighting at normal) 4W of power, based on the specifications of the most lightweight solar cell I know of. This doesn't include the related structures, just the cell mass itself.
You can also simplify the idea by removing the timer, to gain the necessary voltage you need capacitors, so just charge a capacitor until full and then it'll set off the xenon flash. BEcause of radiation a lot of the flashes will be set of prematurely, but you should be able to get 10 or 20 good flashes per minute.

(edit) I still prefer radio transmitters though, easier to see if you don't have a telescope

 

[thomasantony]

Sorry I must have misunderstood this
USD 0.6 million was charged for the nano satellites

Yes, the total weight of all the nanosats combined was 50kg. 0.6 million was the total amount charged from all the sats combined.

~
Thomas

 

[Dark_Fox]

What about hyperbolic fuels, like that used in the ME-263 rocket plane? that would get you to 30,000 feet, at least, now, for the rest of the way..... the problem isn't even cost yet, but sheer feasibility of the physics. look at sputnik, the rocket that launched that thing wasn't very little at all.

another (albeit remote) possibility is beamed power, i saw a documentary of a small, reflective rocket that when hit laser, vaporized the air behind it, acting as a thruster, no propellant on the vehicle but you need a whole power station the run the laser. at least to get orbital speed outta it

just a thought

 

[adamb193]

Railgun.