Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

James Webb telescope reaches its final destination in space, million miles away

npr.org

Post reply on HN
Print view View original

21–30 of 350 posts

Re: James Webb telescope reaches its final destination in space, million miles away

#21

Post by sgt101 »

PinkMilkshake wrote: post #3

I'm a little embarrassed to say this and I don't know exactly what I pictured in my head, but I had no idea these telescopes were so big[1]. I guess I never saw one pictured next to a human. I've only seen pictures of satellites being worked on so I expected something more human sized? It seems so stupid now, especially since earth telescopes are huge. [1] https://svs.gsfc.nasa.gov/vis/a010000/a013500/a013522/JWST_v.…

The JWST at 6.5m is larger than the largest terrestrial telescope in my childhood.

Keck was the first one bigger - 1989.

The next one Keck 2 was 1997.

https://en.wikipedia.org/wiki/List_of_largest_optical_reflec...

Re: James Webb telescope reaches its final destination in space, million miles away

#23

Post by readthenotes1 »

PinkMilkshake wrote: post #3

I'm a little embarrassed to say this and I don't know exactly what I pictured in my head, but I had no idea these telescopes were so big[1]. I guess I never saw one pictured next to a human. I've only seen pictures of satellites being worked on so I expected something more human sized? It seems so stupid now, especially since earth telescopes are huge. [1] https://svs.gsfc.nasa.gov/vis/a010000/a013500/a013522/JWST_v.…

The human is not to scale if that's the Webb telescope.

Re: James Webb telescope reaches its final destination in space, million miles away

#24

Post by entrep »

mabbo wrote: post #18
EMM_386 wrote: post #9

This was an absurdly teeth-clenching deployment. And no back-up, even if the Ariane launch failed. No back-up. Congrats to everyone across the board for getting this amazing telescope right where it needs to be. Now all we need is the mirror alignment and we're in for some seriously incredible science.

Mirror alignment was done in the days leading up to insertion, wasn't it? Afaik, all that's left is testing and cooling- the cold side is still around 63K and needs to get down to 50K (-223C).

Mirror deployment was done before insertion, moving the 18 mirrors up from their locked position by 12.5 mm. Now, 3 months of mirror alignment will follow. They will align with a reference star having to first move one mirror a little bit to identify how the mirror affects the alignment, then calculate the alignment and move the mirror. Each mirror's position can be controlled at 10 nm resolution.

Re: James Webb telescope reaches its final destination in space, million miles away

#25

Post by LeonM »

pfdietz wrote: post #12

I'd be happier in a world where individual universities, or at least consortiums, could have their own space telescopes.

The JWT is famous for costing over 10b USD to develop. AFAIK it's the most expensive object ever to be launched into space.

I don't think universities should (or could) spend that kind of money on research equipment.

Re: James Webb telescope reaches its final destination in space, million miles away

#26

Post by amelius »

PinkMilkshake wrote: post #3

I'm a little embarrassed to say this and I don't know exactly what I pictured in my head, but I had no idea these telescopes were so big[1]. I guess I never saw one pictured next to a human. I've only seen pictures of satellites being worked on so I expected something more human sized? It seems so stupid now, especially since earth telescopes are huge. [1] https://svs.gsfc.nasa.gov/vis/a010000/a013500/a013522/JWST_v.…

Did you ever see images like these?

https://www1.udel.edu/udaily/2009/may/cool051509.html

Then it should not be surprising that a telescope is about that size.

Re: James Webb telescope reaches its final destination in space, million miles away

#27

Post by vermontdevil »

inamberclad wrote: post #13
PinkMilkshake wrote: post #3

I'm a little embarrassed to say this and I don't know exactly what I pictured in my head, but I had no idea these telescopes were so big[1]. I guess I never saw one pictured next to a human. I've only seen pictures of satellites being worked on so I expected something more human sized? It seems so stupid now, especially since earth telescopes are huge. [1] https://svs.gsfc.nasa.gov/vis/a010000/a013500/a013522/JWST_v.…

The space shuttle blows my mind every time I see one. It's huge - the size of an airliner - and would glide back at Mach 25. It's a humbling level of accomplishment.

To show the comparison (737 for example here)

https://icdn2.digitaltrends.com/image/shuttle-948x1500.jpg?v...

Re: James Webb telescope reaches its final destination in space, million miles away

#28

Post by pfdietz »

LeonM wrote: post #25
pfdietz wrote: post #12

I'd be happier in a world where individual universities, or at least consortiums, could have their own space telescopes.

The JWT is famous for costing over 10b USD to develop. AFAIK it's the most expensive object ever to be launched into space. I don't think universities should (or could) spend that kind of money on research equipment.

If launch costs are 1% or less per mass of the Ariane 5, mass budgets could be greatly increased, and engineering could become easier. I see no reason ultimately why space telescopes should be much different in cost than terrestrial telescopes. Ultimately I see telescopes being maintained and upgraded in space much as terrestrial telescopes are.

Re: James Webb telescope reaches its final destination in space, million miles away

#29

Post by danbruc »

readthenotes1 wrote: post #23
PinkMilkshake wrote: post #3

I'm a little embarrassed to say this and I don't know exactly what I pictured in my head, but I had no idea these telescopes were so big[1]. I guess I never saw one pictured next to a human. I've only seen pictures of satellites being worked on so I expected something more human sized? It seems so stupid now, especially since earth telescopes are huge. [1] https://svs.gsfc.nasa.gov/vis/a010000/a013500/a013522/JWST_v.…

The human is not to scale if that's the Webb telescope.

I measured the mirror - top to bottom - as 304 pixels and the human as 86 pixels. This makes the human 1.83 meters given a mirror diameter of 6.5 meters. So it is to scale.

Re: James Webb telescope reaches its final destination in space, million miles away

#30

Post by [deleted] »

Denvercoder9 wrote: post #19
ainiriand wrote: post #16

Earlier quoted context omitted.

Then you can use football fields as measurement unit, following that argument. Or bananas.

There's a reason things like football fields are commonly used as measurements in science communication: it actually helps the average person to get a sense of scale.

[deleted]
Post reply on HN