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ultramegachurch | 4 years ago

I suspect the deployed structure cannot handle the acceleration required for escape velocity. That also may require much more propellant. Then on top of that, we don’t have the capability for humans to service satellites other than the ISS. So this is all a moot point.

discuss

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Mesisio|4 years ago

Interesting though.

Does that really matter without air resistance?

Depending on how high you actually bring it. Like 500km away from earth is still an orbit (I think that's Hubble's orbit) but how much force do you need or will happen?

twistedpair|4 years ago

Rockets can easily accelerate with enough force to kill a human (cargo flights and unmanned flights use different launch profiles for this reason).

The less Gs you need to design a component for, the lighter/simpler it can be, so why unfurl early and add that extra mass and complexity to the design?

MobiusHorizons|4 years ago

When rockets are firing lots of acceleration is applied that the delicate structures are only designed to handle when stowed. Think long arms on hinges. They can take acceleration in one axis, but not at 90 degrees to it.

HideousKojima|4 years ago

The parts of a ship that thrusters are directly attached to experience acceleration first, the other parts that are further out from the thrusters won't accelerate immediately and if the acceleration is too sudden or extreme could be damaged or break off entirely.

And to answer your question in the other response, many thrusters have a minimum thrust, and even that minimum may be too much for the parts when deployed.

BurningFrog|4 years ago

We had the capability in 1993, and could of course develop it again.

A broken JWT could wait a few years in orbit.

ultramegachurch|4 years ago

That may be true, but designing a mission based off that hypothetical is a bad idea. The reality is we currently don’t have the capability for humans to service satellites, and developing that capability would probably take years and cost >$100 million. And NASA can’t just decide to take on that endeavor, it would require congress and months of political bickering. JWST was designed for what is currently feasible and practical.

superjan|4 years ago

Referring to hubble? The JWT is designed to observe from the Lagrange point in permanent shadow of the earth. It won’t work from earth orbit. First parking it in orbit, and then restarting the engine after unfolding comes with a whole new set of risks and tradeoffs.

alserio|4 years ago

What about an unmanned mission to fix it? And maybe to refuel it.

ultramegachurch|4 years ago

Incredibly unlikely. First, it would have to fail in a way that’s possible to fix. We don’t have robots that can replace screws, solder joints, and polish mirrors in space. Then we’d have to design a brand new spacecraft and mission. That would take years, lots of money, and political will. NASA would likely cut its losses, document the lessons learned, and try again.

guerrilla|4 years ago

I was watching a documentary about James Webb and they claimed that NASA has plans of using unmanned robots to potentially refuel it but no mention of fixing.

nexuist|4 years ago

But who repairs the repairers?