James Webb Space Telescope Launch and Deployment

What people said

Cites user12102 · 2017-10 · Space Exploration Stack Exchange · on “What happens to JWST after it runs out of propellant?”

This Northrop Grumman video [this video] (starting at 09:31 ) illustrates JWST's orbit in a non-rotating (normal) frame. It's really in an orbit around the Sun about 1% farther than Earth's, but the weak tug of Earth pulls it along a bit faster so that it remains in 1:1 resonance with the Earth. The orbit is called a "Halo orbit" because in a rotating frame it looks like it's a ring around the L2 point. Regular, but very small station keeping propulsive maneuvers keep it in this otherwise unstable configurations. The more frequent the adjustments, the lower overall fuel consumption per year. According to this [LINK] and James Webb Space Telescope Initial Mid-Course Correction Monte Carlo Implemen

Cites notovny · 2019-01 · Space Exploration Stack Exchange · on “How will JWST maintain its elliptical orbit around L2?”

Basically, it would not be orbiting L2 in a Keplerian orbit sense. There is no mass at L2 for the spacecraft to orbit, you are correct in that sense. The JWST would be in a solar orbit in that would normally be a little longer than one year and would use the contours of the gravitational fields from the Earth and the Sun around the Earth-Sun L2 point to keep it moving around the sun in a predictable region near the L2 point, and that deliberately planned gravitational perturbation is what will keep the JWST in a 1:1 resonance with Earth around the Sun, (along with some very small mounts of station-keeping [LINK] from its maneuvering thrusters 1 [LINK] , 2 [LINK] ). As a result, when seen fro

Cites user12102 · 2019-01 · Space Exploration Stack Exchange · on “L2 point in multi-moon system”

The Earth-Moon Lagrange points are defined (I didn't use the word "exist") based on the gravity of the Earth and the Moon. If you forget all the images you've seen drawn in rotating frames and just think about the real world, all five of them are really just orbits around the Earth with a period equal to the Moon's period. They are slightly nudged and prodded by the Moon's gravity so that they stay in 1:1 resonance with the Moon, but they are truly Earth orbits. That is also true for "halo orbits", which look like they orbit the empty space where L1 and L2 are supposed to be, but in a non-rotating frame they are also just orbits around the Earth that weave up and down slightly due to the Moo

Cites user12102 · 2021-08 · Space Exploration Stack Exchange · on “What is the "mass" of a Lagrange point?”

Lagrange points... can be orbited by asteroids, satellites, and any other useful or interesting object. Assuming two-body motion however... First a quick note; the stability of a Lagrange point itself is not a predictor of the stability of an orbit associated with ("around") it. Are some Halo Orbits actually Stable? (stable orbits about unstable Lagrange points) [LINK] I'm confident that the OP knows there isn't any real mass at a Lagrange point to which objects are gravitationally attracted, but it is interesting to wonder if something like an "effective mass" can be derived. We have to keep reminding ourselves that orbits associated with Lagrange points are really orbits around the primary

Cites Schwern · 2021-12 · Space Exploration Stack Exchange · on “If we can get people to the moon and back, why are we so adamant that it's impossible to service James Webb at 4x that with a one way robotic vehicle?”

JWST is not designed to be serviceable Sending a robot to JWST is moot, it is not designed to be serviceable by human or robot. In the early days of the Webb project, studies were conducted to evaluate the benefits, practicality and cost of servicing Webb either by human space flight, by robotic missions, or by some combination such as retrieval to low-Earth orbit. Those studies concluded that the potential benefits of servicing do 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. Source: NASA [LINK] But why? JWST was designed 20 years ago, a lot has changed. JWST is already 20x over-budg

Cites Schwern · 2021-12 · Space Exploration Stack Exchange · on “Why is the speed of James Webb Space Telescope decreasing?”

JWST is like rolling a ball up a hill to have it coast to a stop at the top. Low Earth orbit is the "bottom" and the Sun-Earth L2 Lagrange point [LINK] is the "peak" at the "top". [LINK] A note about speed and distance. Speed is how much distance you're covering per unit of time. JWST's speed, as of this writing is, 0.7772 km/s. Every second it moves 0.7772 km along its path. When you're driving at 100 km/h you're moving 100 km in one hour down the road. Distance how far JWST has traveled along its curved path to L2, just how in a car your distance traveled is along the road. JWST's distance from the Earth is its "altitude". [LINK] The frame of reference for JWST is Earth's orbit around the

Cites user12102 · 2021-12 · Space Exploration Stack Exchange · on “Why does JWST need "a carefully designed series of oscillations" to avoid overheating during the 2nd stage burn? Why not rotate "rotisserie style"?”

The Northrop Grumman video James Webb Space Telescope Launch and Deployment [this video] describes the trajectory from launch to orbital insertion and illustrates several key maneuvers and incremental steps in the deployment of the telescope. After about 03:00 just after 2nd stage ignition the narrator says: The exposed telescope is delicate, and must be protected from the Sun's fierce heat. To avoid overheating and damage, a carefully designed series of oscillations are performed that provide the necessary protection. Question: Why does JWST need "a carefully designed series of oscillations" to avoid overheating during the 2nd stage burn? Why not rotate "rotisserie style"? From Spaceflight Now's

Cites Schwern · 2021-12 · Space Exploration Stack Exchange · on “How would a repair of the JWST proceed if it were ordered regardless of the cost and technical hurdles, depending on when/how it fails?”

The question is very broad covering everything from failure to launch to a stuck part requiring a gentle nudge. Someone can address all the engineering solutions to particular problems, but I'm going to address the hard reality that... Failure is always an option. Any exciting space rescue has to be cheaper, simpler, and less risky than just building a new one. "At any cost" includes building another JWST and fixing whatever went wrong before the second launch. When the Cluster mission blew up on takeoff in 1996 [LINK] , after returning what was left to the science team [LINK] , they built and flew a second one, Cluster II, in 2000 [LINK] . The explosion was considered a four-year delay. Muc

Cites user12102 · 2021-12 · Space Exploration Stack Exchange · on “Will JWST be handed over from Arianespace/ESA/CNES to NASA at some point the way Cape Canaveral handed over missions to Houston?”

@JörgWMittag yes good point! The first info from the telescope post launch will likely be via the 2nd stage to ESA's Malindi Ground Station (1st link). In the Northrop Grumman video James Webb Space Telescope Launch and Deployment [this video] it shows the telescope's own high gain antenna deploying somewhere around 15 to 20 hours after launch (hard to tell) whereas 2nd stage separation is only at 30 minutes or so. I haven't had time to check the actual launch yet (still waiting for morning coffee to kick in) but hopefully that high gain antenna will be deployed soon.

Cites user12102 · 2022-02 · Space Exploration Stack Exchange · on “How frequent are (or will be) JWST station keeping burns at L2?”

How frequent are (or will be) JWST station keeping burns at L2? 21 or 42 days I've heard mention of 'every 21 days' which at first look seems excessive but on second look may not be nuts if very brief. "How brief?" would be an excellent follow-up question! It's exactly this high cadence that helps keep the station-keeping delta-v budget so low. Halo orbits are exponentially unstable so making the cadence substantially longer would dramatically increase the budget. Also with all the variation in torque due to solar photon pressure on the giant reflective sunshield, these scheduled propulsive maneuvers include momentum unloading as well as trajectory station-keeping. From this answer to What h