Context: JWST is considered un-repairable in its current L2 location for a number of reasons:

  • Diagnosis is difficult since JWSR has no “selfie” capability. This makes planning for any repair mission (crewed or robotic) problematic.
  • Distance and radiation exposure are vastly beyond the experience of crewed missions
  • JWST was not designed to be serviceable so repair would likely be complex and require the flexible talents of a crewed mission, perhaps multiple missions.
  • Rocket exhaust could damage optical surfaces.
  • JWST cannot transfer itself closer to Earth for repair since this would mean pointing its optics towards the sun for the burn.

Proposal: Built a robotic “tugboat” with thrusters which are positioned to be safe for the optics. Have the tugboat dock with JWST using the launch mount or docking ring. The tugboat would then transfer JWST to an Earth/Moon L1 orbit. The Gateway/Artemis resources would be available for diagnosis and repair. This would avoid the expense and radiation exposure of a dedicated crewed repair mission to L2. Once repaired, the “tugboat” could reposition JWST at Sun/Earth L2, and remain with JWST in case a repeat mission is needed. The tugboat could also be used for end-of-life decommissioning, extending JWST service life.

Transfer of JWST from SEL2 to EM halo orbits or “Gateway” orbit using low-energy trajectory is within the delta-v budget of typical earth-SEL2 missions. Is the inter-manifold transfer of JWST between Sun-Earth L2 and Earth-Moon L1 within the capability of existing propulsion systems?

This proposal depends on the availability of a docking point. A docking ring was included in the early design of JWST, but I can find no reference to it after 2015. An alternative would be to use the launch mount if it is not obstructed by deployed devices.

Question: Does JWST have hardware that could be used as a docking fixture by repair spacecraft?


enter image description here

A robotic servicing arm (left) practices autonomous capture of a satellite mockup (right) in Goddard’s Robotic Operations Center. Because there is no grapple fixture, the arm will use the Marman ring, which originally attached the satellite to the rocket that launched it to space. Credits: NASA/Rebecca Roth

  • 1
    $\begingroup$ JWST has no way of actively propel itself towards earth. But it should be able to get closer by just not pushing away anymore from time to time. L2 on the axis sun-earth is like a really wide and slippery hilltop. You probell yourself towards the top with too much power, you'll slipp down on the other side (this would end the mission!). So they push to a point a bit below the top from where it will fall back eventually but really slow! Than you just give it another push (this os overly simplified, I know). $\endgroup$
    – TrySCE2AUX
    Commented Jan 21, 2022 at 6:23
  • 1
    $\begingroup$ @kruemi ---- You're right. In theory, JWST should be able to just "do nothing" and slide home to Mama. In the real world, without course correction, it would almost certainly join an unstable manifold and end up in a random heliocentric orbit. The "tug" vehicle would likely need to supply very little delta-v to shepherd JWST to a EML1-2 orbit. $\endgroup$
    – Woody
    Commented Jan 22, 2022 at 18:22

1 Answer 1


Partial answer, too long for comments:

TL;DR: It does have a payload ring, for potential grabbing, but it is not without issues.

In 2007 it was reported by a single news source:


NASA is adding a docking ring to the James Webb Space Telescope (JWST) just in case a visit by astronauts aboard a future Orion Crew Exploration Vehicle is needed to complete deployment of the multibillion-dollar orbiting observatory. The U.S. space agency made the announcement May 10 during the unveiling of a full-scale model of the JWST on the National Mall here.

"However, what if you have a bad day when you put this thing a million miles out and everything folds out except for an antenna ... it gets stuck? Or a solar panel doesn't fold out completely, and you say, 'gee, I wish we could send an astronaut just to give it a kick'?"

Weiler said NASA Administrator Mike Griffin asked the James Webb team two years ago to examine whether it was worthwhile to design the telescope to accommodate a visit from Orion.

According to Weiler, it is.

Although this google search really confused me:

24 Dec 2021 — Ahead of launch, the James Webb Space Telescope was loaded into the ... Megan Fox's Engagement Ring Was Designed to Hurt if She Takes it Off.

And it has never been confirmed nor denied or even been in the news since. It only seems to be discussed in social media /forum circles.

Consider this:


NASA had experiments for robotic refueling in space.

NASA had experiments for robotic docking of un-cooperative spacecraft in space.

NASA actually has an office for looking at future servicing of OOS spacecraft.

NASA actually has had multiple programs over the years where they looked into various docking systems in which to capture satellites that were not cooperating, among them I've seen harpoons, engine nozzle spikes and grabbers.

OrbitFab has signed its first contract to be an in-space refueling service earlier this month.

Enter Northrop Grumman Space Systems' MEV, which operates on a very similar principle to those studied by NASA and many other companies in the last few years. It is only NG that has actually got this going that we know about (China was seen to be doing some odd maneuvers around other satellites in the GEO but I have not heard more)

Look at how MEV docks with its target:


enter image description here

enter image description here

Can you see what it is docking on to here. Something that JWST lacks.

Not to say that something can't be adapted and then get that to grab on to an alternative, structural piece of JWST.

Draw back of MEV is it worked well for out to GEO because it was under constant control and communication by ground support services. With the long communication delays to L2 it is likely any kind of effort would have to be mostly automated, lacking the kind of finesse that could only be provided when under constant uninterrupted supervision.

But back to JWST:

The trouble with JWST is not just lack of accessible ports for refueling (Fill/drain ports are visible on the bus, but how accessible are they?) but lack readily accessible parts for docking or otherwise grabbing on to, and certainly not without potentially damaging something.

enter image description here

JWST lacks a major engine nozzle, and lacks a clear ring for docking. It has a payload ring but I don't fancy grabbing that without doing something to those parts arrayed in and around it.

enter image description here

enter image description here

Presumably this is the launch vehicle interface ring mentioned elsewhere from when mated to the Ariane launcher but it is far more low profile than other rings seen where they cater for docking/grabbing.

Typical Payload Ring:

enter image description here

JWST actual Payload Ring:

enter image description here

Payload adapter and Marman Clamp, covering the payload ring:

enter image description here

Pretty slim without the extra parts after spacecraft separation.

NASA has a robotic gripper already developed to clamp on to them:


It looks too bulky for that ring on JWST though.

enter image description here

Just saying it is not impossible but it seems unlikely unless a major effort ,and budget to go with it, is approved.

So, Does JWST have hardware that could be used as a docking fixture by repair spacecraft?

Yes and no. For the type of operations that MEV for example uses now, no.

Could a future vehicle deal with what JWST has to offer in terms of grabbing on to something if not that ring? Possibly...

In terms of perhaps grabbing on to what JWST has now, NASA has this going on:

enter image description here


Compact Long-Reach Robotic Arm

back to JWST:

This is the view from below of the JWST bus:

enter image description here

Shows location of thrusters and payload ring, and the OSR covered parts - possibly radiators (note how the actual ring itself is covered with OSR) - arrayed around the inside of the ring.

enter image description here

If the 'future grabbing device' was gentle it could conceivably grab the outside of the ring and the inside of the (potentially) radiator segment for docking; or better yet just grab the exterior of the ring, like grabbing a jam jar top, avoiding the radiators on the interior of the ring.

And, a late edit:

I saw this before but sort of dismissed it ..because I sought a different solution.

But given the situation with the accessibility of the spacecraft separation ring / payload ring on JWST and the OP's comments, i came back to it:

enter image description here

A grip on the outside of the payload/spacecraft separation ring.

Whereas most other solutions looked at some sort of grapple of a point or part, the populated inside section of the payload ring required a look at a simultaneous multi-point grapple of the exterior of that ring.

Of course what happens after that given the shift of center of mass, etc is another thing, but perhaps with initial docking like this achieved, the rest could follow.

This comes from a joint UK and Israeli venture that was signed back in 2018. The venture was up for sale by 2020 without a single launch. It was called Space Drone but it is set to change. Astroscale, itself with a limited servicing OOS solution (could only dock with compatible satellites), bought the IP, assets and sought to hire the staff.




enter image description here

The spacecraft... uses electric propulsion to maneuver to its target satellite, attaching to the satellite’s launch vehicle interface ring.

This venture is seen as a direct competitor to (former Orbital ATK) NGS MEV which currently has two spacecraft in operation.

enter image description here

enter image description here

enter image description here

enter image description here

  • 2
    $\begingroup$ It seems that your entire answer was already covered, much more concisely, in the question itself. "A docking ring was included in the early design of JWST, but I can find no reference to it after 2015. An alternative would be to use the launch mount if it is not obstructed by deployed devices." $\endgroup$ Commented Jan 21, 2022 at 1:00
  • 2
    $\begingroup$ @blobby ----- thanks for all the info. I had not seen those renderings of the ...err... posterior of JWST post-deployment. It looks like there are no deployed items near the launch mount. The launch mount doesn't look very "docking friendly". The incoming tugboat would need to latch on with its fingernails. $\endgroup$
    – Woody
    Commented Jan 21, 2022 at 1:09
  • 1
    $\begingroup$ Couldn't really fit it in a comment so I put an answer over, such as it was! Yes, very tenuous ring hardware. As I say elsewhere, NASA was looking at other options in the past, with camera recognition software for edges, points, parts, something structural to look at. Looks difficult now but maybe in the future they can adapt. $\endgroup$ Commented Jan 21, 2022 at 1:21
  • 1
    $\begingroup$ @blobbymcblobby ---- did you come across the material the launch mount ring is made of? If it is ferritic or martensitic stainless steel, it would be magnetic. This would hugely simplify grappling. $\endgroup$
    – Woody
    Commented Jan 21, 2022 at 5:13
  • 1
    $\begingroup$ @Woody, not for JWST specifically, but for Ariane it was aluminium and/or carbon fibre reinforced polymer composite. $\endgroup$ Commented Jan 21, 2022 at 7:20

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.