James Webb is Super Cool!

[Scientist]

Strange. Maybe it took a wrong turn or someone at NASA found an error in the distance calculation. The distance to L2 is going down again

[NukeML]

I’ve been plotting the distances and speeds since launch, mainly to settle a debate with my daughter. The total distance suddenly jumped by 12,000 miles

The debate is whether the speed is slowing as a polynomial or exponentially.

[gatto]

@NukeML

distance suddenly jumped by 12,000 miles

maybe there’s someone to ask on the twitter verse? one of the scientists or something?

it’s eventual orbit is just wild…

maybe since its destination isn’t a fixed point - more of a path - it could be getting further while also getting closer? ( to l2 and its injection point, respectively )

i know nothing of physics tho, and maybe it could just be a data error or some sort of update lag… is that an app you’re using or a website? ( id guess an app could have lag or sync issues, while a website with an explicit refresh probably wouldn’t )

[NukeML]

It looks like an error, or adjustment. The total distance for the trip had not changed since day 2, when all of a sudden it jumped by over 12,000 miles.

Also, this is the site

Where Is Webb? NASA/Webb

[nosaj]

From the teeny tiny bit I know about orbital mechanics, I’m gonna guess “polynomially”. T^2/R^3 = k, and all that. My non-rocket-scientist brain has dumbed this down to a verrrry eccentric orbit, so it’s not actually decaying in my mind, just doing the normal approaching-apogee slowdown?

My kids are about 5 years away from being able to make those kinds of arguments. I’m happy with their steps towards it, though.

Keep us posted!

[jerwin]

Note the loop. (It’s known as Trajectory Correction 2)

But L2 is moving, earth is moving, jwst is moving, so maybe there’s a vantage point where the loops are minimized.

some papers with math.

MID-COURSE CORRECTION CONTINGENCY ANALYSIS FOR THE JAMES WEBB SPACE TELESCOPE

L2 STATION KEEPING MANEUVER STRATEGY FOR THE JAMES WEBB SPACE TELESCOPE

SEASONAL VARIATIONS OF THE JAMES WEBB SPACE TELESCOPE ORBITAL DYNAMICS

The JWST is also restricted on how it can maneuver-- the sunshield will move it around, and it can’t directly move towards the sun (since it has no thrusters next to the heat sensitive optics)