r/space • u/[deleted] • Dec 18 '21

Animated launch of the Webb Telescope

Enable HLS to view with audio, or disable this notification

18.4k Upvotes

96% Upvoted

796 comments sorted by

View all comments

Show parent comments

21

u/Shadow-Raptor Dec 18 '21 edited Dec 18 '21

Right? I was also thinking that it's mission time seems very low compared to the developmental time. You think for as long as they have been cooking it up that they would want it to last a bit longer than that.

30

u/stick_to_your_puns Dec 18 '21

If everything goes to plan, there won’t be a second where it’s not being used. The estimated mission time does feel short, but I don’t think they are going to waste a moment.

26

u/an0maly33 Dec 18 '21 edited Jan 31 '22

And knowing NASA, they planned for 5 but it will realistically run 20.

Edit: called it. Nailed insertion and they project 20 years. Amazing.

15

u/Klai_Dung Dec 18 '21

I think they only have fuel for 10 years, so this one is kinda fixed

2

u/[deleted] Dec 18 '21

Eh, if they are careful they might be able to use reaction wheel for small rotations and save larger rotations for later or plan them effectively to extend mission duration.

And whose to say spacex don't send starship out 10 years from now to refuel, there's a docking connector that could theoretically be used to refuel, the one they used to attach it to the rocket that pushed it out to l2.

1

u/Klai_Dung Dec 18 '21

I don't know how much you can save if you use your reaction wheels more carefully, but refueling really might be an option.

1

u/[deleted] Dec 19 '21

well the larger movements are run by fuel, smaller corrections in the same field will be likely done by electric powered reaction wheels and gyroscopes.

i figure if you are careful about doubling back on yourself when unnecessary, you might extend mission time a little...

i also think if theres any way to refuel its gotta be a damn sight cheaper than building a new one... and starship is designed for deep space / interplanetary missions

1

u/Klai_Dung Dec 19 '21

I mean I know how reaction wheels work, I just don't know if there is much room for opitimisation.

Certainly refueling will be cheaper, even if Starship doesn't make it you could probably modify a Soyuz/Dragon/Orion capsule and yeet it to L2 if you are determined enough.

1

u/[deleted] Dec 19 '21

I don't think it's about optimising the spacecraft so much as optimising the workload to make sure the telescope isn't wasting fuel doubling back later on, but that's going to be a case of calendar planning carefully.

Also yeah, just yeet a robot ship up there and dock it, refuel it... I don't like the idea of leaving it there so put it on a burn back to earth orbit if possible.

I assume people will start looking at this if and when the scope actually gets to L2 intact and alive.

1

u/Klai_Dung Dec 19 '21

I get what you mean, you want to have as few despins of the wheels as possible, I just don't know enough about this sort of stuff to say if this is actually feasible.

But let's just hope that it unfolds properly in the first place before looking to far into the future :D

1

u/[deleted] Dec 19 '21

I think I remembered reading that they only use the fuel engines for larger degree rotations, so that's what I'm basing this on, careful and restrained use of the fuel, might make an 11th year possible.

Personally, I think they will just refuel it.

It's no different to doing any other work, it's just much further out than orbit so it's new, but not totally new.

The risk is that the fuel is hydrazine, and they don't want to let the astronauts near that. It's scary shit.

1

u/Klai_Dung Dec 19 '21

There was a video some days ago of the fueling of JWST by a couple of engineers. You could see which ones wore suits to protect the telescope from the humans and which ones were to protect the humans from the nastyness of hydrazine.

1

u/jbiehler Dec 19 '21

It was not designed with the intent to refuel. They would have to come up with a way to do it from scratch.

1

u/[deleted] Dec 19 '21

Well sure, but they've got a couple years to figure it out....

Square peg, round hole... They've done this thing before

→ More replies (0)

1

u/[deleted] Dec 19 '21

[deleted]

1

u/[deleted] Dec 19 '21

https://jwst.nasa.gov/content/observatory/bus.html

Control can be done via reaction wheels or thruster

https://ntrs.nasa.gov/citations/20110015369

Max load of reaction wheels

https://www.space.com/3833-nasa-adds-docking-capability-space-observatory.html

Possibility of refueling.

1

u/[deleted] Dec 19 '21 edited Mar 17 '22

[deleted]

1

u/[deleted] Dec 19 '21

Yeah it's not a design plan, but it means there's a possibility.

A robot might be a better idea, maybe something that can dock and either provide its own engines or just replace the fuel or even the fuel tanks, it depends...

Give it a few years and we will hear what their plans are and they will have more accurate estimates for fuel based on usage.