I understand that many of the problems with recovering the two pieces of the Falcon 9 fairing deal with the weird aerodynamic patterns of the descent. It is by no means an aerodynamically sound object when split in half and therefore is subject to unpredictable wind conditions.

(Additional reading and possibly related questions...)


My main question here is, could the fairing be separated, and then reconnected before its descent to earth?

The main considerations that I would like to address are:

  • With what force are the two fairings ejected from each other?
  • What is the weight of each fairing pieces.
  • What is the required tensile strength of a tether(s) to bring the two pieces back together?
  • Does this tensile strength exceed our current material science understanding?
  • If it is possible, is it even remotely useful?

I would like to ignore: Potential collisions due to reconnect- assume the reconnect occurs long after the rocket has engaged the next stage, and that the tether(s) is designed in such a way that it avoids collision with the payload/next stage.


I figure, if the fairings are jettisoned and there is a tether(s) between the two objects with enough strength to resist breaking it could reconnect, is there a gap in my thinking? Could the two pieces could be reunited on a sub-orbital trajectory, then have the clamps re-engage to make the fairing more aerodynamic and predictable? In this manner they only need capture a single object as well-- instead of 2.

Am I over-simplifying this? If I'm not-- it seems a hinged fairing that opens and jettisons tangential to the payload may suffice (if indeed maintaining the original shape is even remotely beneficial).

  • One fairly large gap in your thinking is that the tether would likely smash the two halves into each other, damaging them beyond repair. – SF. Aug 2 at 21:49
  • Perhaps the carrier rocket could have a payload bay with doors that open to release the payload. Of course, that would increase the weight, and you might have to add wings to help recover the system. If only we had something like that. – Organic Marble Aug 3 at 0:17
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    The gap in your thinking may be that you're assuming the payload fairing is deployed between stages. Instead it's deployed while the 2nd stage is still firing. I've updated my answer a bit. – Schwern Aug 3 at 3:47
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    The fairing separates when aerodynamic heating drops below ~1 kW/m^2, so there's still significant air resistance when that happens. The fairing doesn't float away slowly on separation, it drops away quickly. – Hobbes Aug 3 at 7:01

...is there a gap in my thinking?

...assume the reconnect occurs long after the rocket has engaged the next stage...

I think there's the gap.

The payload fairing is typically deployed while the second stage is still firing. See this example during the first Falcon Heavy flight.

...and that the tether(s) is designed in such a way that it avoids collision with the payload/next stage...

There's a substantial length of still accelerating rocket which must pass through the deployed fairing. This cannot be hand-waved away.

Here's a SpaceX fairing test in a vacuum chamber. Note the tethers, presumably only for this test. The fairing isn't much wider than the rocket itself. The still firing second stage of the rocket must pass between the fairing halves. Tethers risk being snagged. Hinges risk the fairing not separating cleanly and impacting the second stage. Either puts the mission at risk.

With what force are the two fairings ejected from each other?

I don't know, but I do know it's pneumatic and it's a pretty light push to reduce shock on the payload.

The two halves of the fairing are fastened by mechanical latches along the fairing vertical seam. To deploy the fairing, a high-pressure helium circuit releases the latches, and four pneumatic pushers facilitate positive force deployment of the two halves. The use of all pneumatic separation systems provides a benign shock environment, allows acceptance and preflight testing of the actual separation system hardware, and minimizes debris created during the separation event.

Source: Falcon 9 Launch Vehicle Payload User’s Guide rev 2 section 2.3

What is the weight of each fairing pieces.

I don't know, but I do know its dimensions and what it's made of.

The fairing is 13.1 meters (43 feet) high and 5.2 meters (17 feet) wide. It consists of an aluminum honeycomb core with carbon-fiber face sheets fabricated in two half-shells.

The Falcon 9 Launch Vehicle Payload User's Guide says...

The SpaceX fairing is 5.2m (17.2 ft) in outer diameter and 13.2 m (43.5 ft) high overall. Fairing structures and dynamics result in a payload dynamic envelope with a maximum diameter of 4.6 m (15.1 ft) and a maximum height of 11m (36.1 ft).

I figure, if the fairings are jettisoned and there is a tether(s) between the two objects with enough strength to resist breaking it could reconnect...

A payload fairing is designed to be as light as possible. Any weight you can shave off the fairing is extra payload you can carry. It's also designed to be as reliable as possible, if the fairing fails to deploy or strikes the payload the mission is a wash. Making the fairing as simple as possible helps with both weight and reliability.

If that were solved, the tethers themselves would add weight. The tethers would have to be wound back in requiring a winding mechanism, adding weight, complexity. The mechanism would require an independent power source adding weight and complexity. You'd have to reliably realign the latches and latch them securely, adding weight and complexity. If you miss the alignment, you risk being unable to correct that.

When you tug on the tethers, either deliberately or simply because the fairings drift too far away, in atmosphere there's air drag to slow them down. In the near-vacuum when they've separated there's nothing to prevent them from possibly crashing into each other.

Rejoining them safely and reliably would be tricky.


Instead SpaceX uses attitude-control thrusters and a steerable parachute. The thrusters are probably cold-gas or monopropellant for simplicity and reliability. The thruster helps keep the fairing's orientation on reentry. The steerable parachute slows it and keeps it on course for landing.

Weight and complexity is why SpaceX doesn't land rockets with parachutes. However, it does use them on the fairing. Presumably the much lighter fairing requires a much lighter parachute.

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