Why does NASA not launch rockets from weather balloon tethered platforms?

This may have been brought up already, but wouldn't Newton's 2nd and 3rd laws come into play, here? I mean, the third law is what allows the thrust of the rocket to push itself up off of the relatively stationary surface of the earth, correct? It's the reaction of the thrust onto the unmoving earth (relatively speaking) that get the rocket up into the air--or at least helps it.

If the rocket where on a relatively stationary platform in the air, tethered to balloons (none of which seems to me like they would have the mass to counteract the thrust from the rocket), wouldn't the rocket do more to just push the platform away than to aid in pushing the rocket forward?

When we're talking about cost efficiency, here, it seems as though we would then need to produce a rocket with more fuel and a more powerful engine in order for it to achieve the same speed because it would not be accelerating as quickly because it wouldn't have a stable platform from which to launch.

Am I overthinking this?

a reply to: machineintelligence

So you are saying the Man is quite literally trying to keep us down

a reply to: SlapMonkey

Actually The rocket would be released from the platform and allowed to drop clear for a second or two before firing

a reply to: dashen

Policy is not just about what works well to achieve an objective. It also must cover unintended consequences as well. It is a factor and is unevenly considered but that is how things go.

a reply to: machineintelligence

It's just the more I consider it the more I think I can build this rig on my own.
A few hundred solar balloons.
2000 Estes rocket engines.
Or maybe one of those salami rockets like they did on Mythbusters.
Maybe a JDAM if I can get my hands on one.
Rig up some sort of air pump to the balloons to deflate or reinflate them as desired.

a reply to: dashen

We built a class M sugar rocket and made it to 36 miles. It cost more for our engineering than the rockets by a huge margin.

a reply to: machineintelligence

I'm a pretty good engineer.
want to do a science project?

a reply to: dashen

The composite rocket drops almost 60 feet per second. There is no reason for a delay of several seconds. A .5 second delay means a drop of 30 feet or less and provides more than 200 feet of horizontal separation from the lifting gas body. The lifting gas body is expended and we used hydrogen because it is cheaper. The energy cost of compressing it for reuse did not calculate out well.

a reply to: dashen

The IP contract I am under right now does not allow me to work for myself even. I can not consider IP projects outside of contract right now. I am released from my current contract in June. I will consider all options as they are presented between now and then. My current interest is in biometalic nanotechnology composites for spacecraft. We are looking at biological systems for laying down substructures which solar powered biomachines will use once in space. They locked me down while this project is in play.

a reply to: Phage

Phage, how many weather ballons would it take to support the wieght of the launch facility and platform, the rocket and fuel.

a reply to: ChesterJohn

The thing is you wouldn't want to support the force of the launch. You would want to drop the rocket and let it ignites when it is free and clear of the platform

Altitude isn't that helpful, except (as Phage mentioned) for reduced drag.

Put it this way, if we hypothetically had a balloon that could go up to incredible heights -- say 200 miles (the altitude of the space station) -- and just let a satellite go from it, that satellite would NOT just magically begin to orbit just because it is "in space"; it would actually fall back to Earth and smash to the ground due to Earth's gravity.

As mentioned by others, a satellite needs to be moving parallel to the Earth's surface at high speeds in order to stay in orbit. To achieve those high speeds parallel to the surface would still require an engine burn that is relatively not so much less than would be necessary if launched from the ground.

Getting into orbit is not all about simply getting to a high altitude.

a reply to: machineintelligence

What if you use the weather balloon that had two compartments inside the top one would have hydrogen and a secondary chamber would be used as a solar balloon.
paint the whole sucker black and make it from some sort of carbon nanomaterial.
Technically some sort of heating element could also be used to pump in warm air into the balloon

a reply to: Box of Rain

I don't think you bothered reading the rest of this thread, outside of what phage posted

originally posted by: dashen
a reply to: Box of Rain

I don't think you bothered reading the rest of this thread, outside of what phage posted

Sure I did.

I was just adding my 2 cents to proactively address the many people (perhaps not on this thread, but people I've come across on ATS before) who think all you need is to put something high into space above Earth and that thing will automatically be in orbit or be free of the effects of Earth's gravity.

There are many people who don't understand what an orbit really is.

a reply to: Box of Rain

I'm not sure anyone was saying you can put something into orbit directly with just a balloon.

originally posted by: machineintelligence
a reply to: Bhadhidar

We built a fiber composite skeletal launch tube and it was a total mass of 50 grams and was recovered intact. The first phase of the rocket was recovered. Its tether was sheared a bit but the assembly survived. The secondary assembly was not recovered. The payload made it to 36 miles at its peak altitude. It remained at altitude for more than an hour before it started to decay back to ground. It was 1476 miles down range when recovered. It did not achieve orbit. It would not have covered more than a few miles if ground launched which proved the point. Success is not enough reason to advance a program sometimes. The overall impact of the technology must be considered. In this case a downward launch from a balloon launched rocket must be considered. As a weapon it is very concerning to TPTB. It can not be used for commercial aerospace for this reason and do not waste investor or taxpayer money in pursuit of this or face losses.

I'm at work, with very limit net access until 5PM PST.

We stopped this basic line of development more than a decade ago.

Oddly, the "weaponization" scenario you mention was included in our flight permission application to the FAA/AST as part of the CATS prize.

We're probably responsible for the official "jitters" you reference!

a reply to: dashen

Right...like a missile fired from a plane.

But that doesn't answer my question.

originally posted by: dashen
a reply to: Box of Rain

I'm not sure anyone was saying you can put something into orbit directly with just a balloon.

My point is "getting something high up in altitude" is not getting it closer to orbit just because it is high up in altitude. There is still an angular velocity that needs to be reached in order for a satellite to attain an orbit, not just altitude.

I've run across people who think launch vehicles for satellites go straight up in order to put that satellite into orbit, rather than the reality of that launch vehicle having an overall trajectory that is parallel to the Earth's surface.

So it could be said that, although initially launching "up", satellite launch vehicle trajectories eventually go mostly "sideways", not "up", similar to Newton's Cannon:

The only thing using balloons will do is shorten your flight time to orbit. There is no distinct advantage of using high altitude balloons since in order to place an object of any mass into orbit around the Earth requires it to have achieved orbital velocity, and for the Earth that would be around 17,000 Mph.

Even if you had a system that could carry your payload up to 200 miles in altitude, it would not be in orbit, it would simply be something at 200 miles above the Earth.

If you desire it to orbit the Earth, you'll need to impart velocity into it.....and it takes quite a bit of energy to accelerate any thing of mass from rest to 17,000 Mph.

It also takes time. Time to accelerate something to that velocity, and while it's accelerating, the Earth's gravity will be pulling it back...and if it starts to drag in the atmosphere, you're not going to achieve orbit, but will burn up instead.

So it's not really altitude you need to get something in orbit. Hell, if you had something that could widthstand the heat of friction from the atmosphere, and can maintain the thrust, you could make something orbit the Earth at only 5 miles up....but you'd have to constantly have thrust as the drag of the air and pull of the gravity would be trying to bring it down (which is what gravity is doing to anything in orbit: pull it down. An orbit is something falling to Earth.....but missing it).

So velocity is the key, not altitude.

Now, there IS a way to get something in orbit with out having to light off a large rocket:

Space elevator.

If you could build an elevator that is anchored here on the Earth, and out to geostationary orbit (just over 26,000 miles out), you can ride it up and out of the Earth atmosphere and way out there. You could then send something into a lower (or higher) orbit, without the need for very large rockets.

However, balloons are not going to help very much in trying to put something in orbit.

What would help is: something that can accelerate a rest mass to orbital velocity.