building a Picosatelliet for the sceince fair

[Ryan Archer]

Hi guys, my name is ryan,
i am building a Pico satellite for a Huge science fair down here in arizona, we are having trouble deciding how we'll get it up to space. we are hoping for low earth orbit. does anyone have any ideas? we could probably get it close with a weather balloon, but it would probably burst around 80,000 feet i think we need to go to atleast 100,000 feet.
any ideas?
ryan

[Lon Enloe]

Ryan,

Making a picosat with an onboard computer, power system, com system, some sort of sensor, etc., could be a very rewarding project if you don't mind simulating its journey into space (by talking to it and gathering data while it rides on a vehicle, for example).

Actually getting into space is another matter entirely. The canonical cost to LEO is $10,000 per pound, but it's availability of rides even more than cost that's the limiting factor. There are plenty of university satellite projects that end up being hanger queens for years, if not permanently.

There's an active amatuer satellite community that manages to get birds into space, but those are built by large teams of people with decades of collective experience.

I'm sorry that a ride into space it still a rarity. I hope you can scope out a successful project!

[Thermalin]

Hi guys, my name is ryan,
i am building a Pico satellite for a Huge science fair down here in arizona, we are having trouble deciding how we'll get it up to space. we are hoping for low earth orbit. does anyone have any ideas? we could probably get it close with a weather balloon, but it would probably burst around 80,000 feet i think we need to go to atleast 100,000 feet.
any ideas?
ryan

With a balloon to 80k feet... wouldn't take much (well yeah it woulid.. but you get the idea) to get it the rest of the way via solild propulsion, etc since your beyond the majority of the the gravitational pull?
Mike

[Lon Enloe]

Sorry to throw more cold water...it's true that the Earth's gravitational acceleration falls off as one over the square of the radius--but that radius is measured from the center of the Earth. 80,000 feet sounds like a lot of altitude, but it's a relatively small delta compared to the Earth's radius.

Another way to think about it--it's Earth's gravity that keeps the moon in orbit! (Although the moon is a significant enough distance away that the gravitational acceleration is greatly reduced from what we're used to here on Terra Firma.)

That's not to say that launching a rocket from a balloon is crazy--there's a blurb in the most recent Aerospace America issue noting that Van Allen did this a few decades ago--but it still won't turn a sounding rocket into something that can get into orbit.

Except that it keeps us and our breathable atmosphere from floating off into space, gravity can be a bummer.

[Accu157]

Scrap the orbital satellite, it's a little too soon, not going to happen. It will take a tripoli certification to get to around 100k feet vertical (non-orbital), and that wouldn't happen at the science fair. The smallest rocket which put a small satellite into orbit was launched from an F-15 at it's maximum flight altitude. From the ground, you're looking at a rocket that weighs 3 tons on the launch pad, it depends how small the satellite is you're launching.

You're going with a weather balloon. And the roadblocks in your way are quite minimal. Actually, balloons are somewhat a forgotten art with space research, it's really cheap, and it really works. Very reliable, and very little headache associated. Getting to 80k feet is no problem, and it will not pop assuming the correct material is used, like an under filled mylar balloon. As it climbs the gas expands as I'm sure you guessed, and it doesn't pop. Actually, there are a few balloon based observatories being used by NASA. They stay up there for a few months. You'll have to get an expert adviser if you really want to do either, get airspace clearance for you, etc. Thankfully you're in Arizona, for some reason I think that may be of benefit for you. High schools have used weather balloons before, look it up.

[billsmithjr]

Yeah but 80,000 ain't even close to being in space! Why not find an astronaut and ask them to carry it in thier pocket? Perferably one who will do a space walk so he can drop it off outside! Other option- lots and lots and lots of estes rockets? :eek: BSJ- have diaper- will travel

[trash0]

yes, there are plenty of little satellites waiting for a ride as ballast.

Even a simple satellite can turn out to be a logistical nightmare and cost many thousands of dollars.

But as mentioned, Space really isn't all that far away. Only an hour's drive, straight up ! You may find a simulated ride on amateur rockets, that will experience acceleration and vibration of launch.

Balloons are the poor man's launch platform. Weather ballons are cheap enough and filling them with helium is a little expensive, but still affordable. Hydrogen is a much better gas, but for it being flamable.
Balloons won't get you to space, but they'll get you closer. Everything is much simpler and cheaper, and quite achievable even by novice experimenters.
Even ordinary party balloons make for simple simulations of your larger efforts.

Amateur Radio operators have been playing with them for years, and even build, "Rockoons". They build their femtosats into a small rocket. The rocket is then mounted onto a remote launch platform that is carried by the balloon.
The payload is operational for the entire mission. When the balloon reaches it's maximum height, the rocket is launched and the payload recovered.

[Texas Buzzard]

Sorry to throw more cold water...it's true that the Earth's gravitational acceleration falls off as one over the square of the radius--but that radius is measured from the center of the Earth. 80,000 feet sounds like a lot of altitude, but it's a relatively small delta compared to the Earth's radius.


ABSOLUTELY !

[Dan Baldwin]

Altitude is the least of your worries. The speed an object has to be traveling to achieve low earth orbit is about 17,500 MPH.

Dan

[Lon Enloe]

Dan is correct--simply launching an object straight up (say, from the North Pole, so we can ignore the Earth's rotation) means it will come right back down, assuming you're launching at less than escape velocity.

The Earth's rotation does matter very much in real terms. For maximum payload, you'd much rather launch from near the equator, and launch to the east, so the motion you already have from sitting on the moving surface of a rotating sphere works for you. Then again, that means that the only territory you'll overfly is the equator. To see a lot more of the Earth's surface, you put yourself in a higher inclination orbit (by launching in a more northerly direction, if you're in the Northern Hemisphere) but at the cost of what you can lift.