JWST Launch NASA Livestream | Hacker News Reader

JWST Launch NASA Livestream

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Good launch.

And over 472k viewers on the livestream. Good service by YouTube.

(I don't get to praise them often, credit where due.)

All launch events seemed precisely on schedule and trajectory.

The 2nd stage even caught the solar panel deploy on camera, which I believe was an unexpected bonus.

Now we've got 30 days of deployment events, another 300 or so SPOFs to clear. Arrival at L2 in a month.

Six months to chill and calibrate (with or without Netflix I'm not sure).

Science starts in June.

> 472k viewers on the livestream

We had about 11K on STS 82, which I still think was the high point of my career. Back in the day with capacity being what it was that put a serious strain on the internet as a whole, shortly after that we had to move to the other side of the Atlantic be able to continue to operate.

Great anecdote!

https://twitter.com/jmattheij/status/1474767067236777991

I was a little disappointed, because I'd watched the animation last night.

The only differences were in the first 4 seconds (before it hit the clouds) and after the spring launch, when we caught the solar panel deploy in the sun with earth below from the 2nd stage. At least everything went as planned!

I was surprised at the timeline and how rapidly it slows before reaching the L2 orbit. It's already fallen from 4mps to 1.7mps in the first few hours. Even though it takes 30 days to reach L2, it will be 30% of the way there in the first day.

https://webb.nasa.gov/content/webbLaunch/whereIsWebb.html

The difference: today's event relied on the animation to show planned mission phases.

And was accompanied by confirmations that those phases had in fact executed according to the plan.

The live shots of the JWST and solar array deploy were bonus.

Clear skies would've been nice. A good flight beats that though ;-)

From my limited understanding of orbital mechanics from playing Kerbal Space Program, the furthest point of the orbit (aphelion) is where you reach minimum velocity. So to leave the Earth, you accelerate a lot (the so called burn) so that your orbit grows and as you get there your speed has been decreasing the whole way, and it increases back again after passing aphelion on your way back to Earth (perihelion).

Edit: should be periapsis and apoapsis instead of perihelion and aphelion

> solar panel deploy

Seems to start pushing out at about 1:50:30 in 'Livestream'

Super exiting.

* JWST costs ~$10B, about the same as Large Hadron Collider or aircraft carrier.

* JWST has 344 single-point-of-failures (SPOF), 80% of them related to deployment.

* No ability for repair. JWST goes to orbit the Sun 1.5 million kilometers away from the Earth, almost 4 times the distance between Earth and Moon.

* Ariane 5 launch failure rate is 0.045

---

assuming 0.045 launch failure probability, and 0.0001 failure probability for each SPOF, the mission failure probability is ~8%.

  0.955×(1−0.0001)^344

> 0.0001 failure probability for each SPOF

Why did you choose this value for the assumption? Is that standard or a publicized detail?

I picked relatively high number 1/10000 as a starting point to get a ballpark. NASA has never tested deployment in the zero gravity. It's unlikely that the probability is higher.

Ariane launch failure probability dominates if you add zeros.

  0.00001  -> 4.8% 
  0.000001 -> 4.5%

This makes a 92% success rate... I'm not sure I would cross a road if I had that much chance to be hit by a car :-)

I’m much more concerned about what will happen once the telescope is in operation. We can’t send astronauts to L2 to fix it like we could send them to Hubble on STS.

We can't yet, but doing so isn't entirely out of the question. It's easier than sending anyone to Mars. The one-way trip time for astronauts to L2 might be 25 days.

https://www.wired.com/2012/04/100-day-mission-to-sun-earth-l...

JWST apparently does have some kind of docking attachment so we can service it if we get the capability between now and EOL. Servicing once could likely double its useful life. Starship and Orion could do it AFAIK. Maybe Dragon with a service module.

The docking attachment was originally planned but there's been no mention of it in the last 10 years or so and no pictures of such an attachment point. They probably de-scoped it.

I’m guessing they can’t service it by adding more fuel? That would’ve been a neat expansion to be able to expand its life

The possibility has been engineered, though the mission profile does not rely on this.

JWST does have a docking ring: https://www.space.com/3833-nasa-adds-docking-capability-spac...

Deets on station-keeping http://www.ai-solutions.com/Portals/0/AI%20Docs/Technical%20... (PDF)

NASA's official FAQ deems servicing does "not offset the increases in mission complexity, mass and cost that would be required to make Webb serviceable, or to conduct the servicing mission itself."

https://jwst.nasa.gov/content/about/faqs/faq.html#serviceabl...

Either going to be a huge, incredible, historic event, or a massive Christmas Day tragedy. Hoping for the former - good luck NASA!

E: Wow, the coverage about the hurricane causing leaks in the buildings is wild. The pictures of tarps over computer desks makes me unreasonably uncomfortable.

My hope is that if it's the latter, building a new JWST from scratch will not take as much time and money as designing the first prototype did. I hope they have kept really good notes and backups :-)

It worked!

Additional comments on the ESA livestream (posted a few minutes before this one): https://news.ycombinator.com/item?id=29681636

Anyone know why the trajectory dipped down during the second stage? To gain extra orbital velocity or something? Been too long since I played Kerbal Space Program.

Yeah I guess it was something like a partial slingshot?

I noticed Anton Petrov explained it recently: https://www.youtube.com/watch?v=_abdV-HtEJQ

It's named the Oberth effect - something like a powered slingshot.

32 minute launch window starting at 12:20 UTC (07:20 EST). When this comment's indicated age is ~30 minutes.

https://blogs.nasa.gov/webb/2021/12/21/james-webb-space-tele...

Countdown page https://jwst.nasa.gov/content/webbLaunch/countdown.html

"Webb will soon begin an approximately two-week process to deploy its antennas, mirrors, and sunshield."

https://twitter.com/NASA/status/1474724928360525827

I wonder what the Eye of God will look like through this telescope. It's much farther out than Hubble.

I had to look this one up - https://en.wikipedia.org/wiki/Helix_Nebula

From the broadcast: "Liftoff from a tropical rain forest at the edge of time itself."

What does that mean?

It was “to the edge of time itself” which I guess is some kind of reference to the telescope being able to observe the early universe? It seemed kind of cheesy.

It is 'to the edge of time' and what they mean with it is that the JWST can look very far back into our past to the earliest days of the universe with its instruments that are capable of observing severely red-shifted wavelengths.

It means that someone was paid to talk, because radio dies hard.

The idea that commentary should be informative and that content can speak for itself is (still) deeply threatening to many folks in the broadcast industry. See any sports broadcast for examples.

launch looks good!

https://jwst.nasa.gov/content/webbLaunch/whereIsWebb.html

Why there's no "narration"? Looks like nasa tv employees are out on holidays?

The event hadn't started when you looked. Check now.

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