Parachutes are hard. They're super complicated. They'll figure it out, but this will always be tough.

I'm surprised to hear this. I've not heard much about parachute failures in Soyuz landings, except Soyus-1 in the 60's. Nasa had a good track record with parachutes too before they started using the space shuttle.

Are there technical challenges unique to SpaceX or Boeing that other systems didn't have to deal with?

No US orbital crew fatalities have ever occurred due to parachute failure, but parachute failure has occurred on at least one of the Apollo missions (Apollo 15). One parachute failure out of 61 parachutes for the US[0] versus one (or two, counting the reserve) parachute failures out of 143 (144) parachutes for Russia/USSR. The statistics here are effectively indistinguishible in any meaningful measure.

The challenge is these are new, pre-operational crewed spaceflight systems being developed from the beginning. New systems ALWAYS have a higher rate of failure for complex things like this, and also because there are not yet actually crew on board, there's a little bit lower level of mission assurance (which I would argue is optimal!). Nothing in particular special about SpaceX or Boeing.

And in many ways, we got lucky that there weren't more parachute-related fatalities. We understand the dynamics significantly better now than in the past.

[0](1 parachute on each Mercury and Gemini mission, 3 parachutes on each Apollo capsule)

That's a 50+ years ago flight on a system which was being debugged - unfortunately, too hastily. Parachutes subsystem underwent major rework after that catastrophe, and the follow-up flight history attests to it.

One can call it "142:143" only as a first approximation.

https://en.wikipedia.org/wiki/Aerobraking#Aerodynamic_brakin...

But even if it didn't do that, it would need a much smaller chute than a capsule of the same weight because gliding greatly increases distance traveled through the atmosphere, which enables the vehicle to bleed off a lot more kinetic energy as drag.

You’re packing (by hand) a large area of fabric and cord into a very small volume. You’re coating that fabric and cord with a variety of anti-stick substances, which have to be stable with extreme temperature and radiation levels, and huge vibrations.

Parachutes are deployed in several ways - springs, hydraulics, compressed gas, explosives, drogues, and combinations thereof.

For flight tests, parachutes are typically pre-stressed as though they’ve been to orbit and back. This wasn’t always the case.

So - there’s a lot of surface area to go wrong purely around the problem of getting it to eject and unfurl, before you even start to think about the parachute itself.

They spent a bit of time talking about this on a documentary about a Mars lander. Supersonic wind tunnels are spendy.

The Crew Dragon abort test anomaly was caused by a problematic valve leaking oxidizer "backwards" into the helium tubes which are used to pressurize the system right before ignition. The second they pressurized, it sent a huge amount of oxidizer into the engine where there should have only been helium at the time which caused the explosion.

The AMOS-6 anomaly was caused by LOX pooling and working it's way into the liner of a COPV inside the LOX tank. The LOX got into the fibers, and a small amount of friction ignited the oxygen and caused the "boom".

They may seem similar in that they are both related to the oxidizers getting somewhere they shouldn't and igniting, but a rocket is pretty much just a tube of carefully controlled fuel and oxidizer and a nozzle to shoot it out.

Of course most problems are probably going to result in fuel or oxidizer getting somewhere it shouldn't, and when that happens they are going to explode. For laypeople the exact reason why the fuel and oxidizer mixed at the wrong time isn't really important, but don't fall into the trap of thinking that the 2 are related.

You mentioned that fueling system issues have been a recurring theme in failures, and I just wanted to point out that it's not really correct. Even though the 2 failures looked somewhat similar from the outside, they actually had basically nothing in common.

I'm not trying to argue or get in internet fights here, I just like talking about space stuff.

I too like talking about space stuff, I just think it's deconstructive to call out some random poster on the internet as pedantic lol

SpaceX would have had to do their own launches and landings to verify the propulsive landing system, but they wanted to test it out on "production" cargo missions they were already doing for NASA.

I thought that was the bigger reason for the retro rockets.

https://www.space.com/16878-mars-rover-landing-sky-crane-gui...

It takes takes ~6.400 m/s of dV to slow down, and do a powered landing on Mars.

Thanks to the tyranny of the rocket equation, it takes ~5x more fuel to do a powered landing on Mars, than it does on the Moon. For the entire mission. That's five Saturn V rockets, if you want to get a similar payload to Mars and back.

Shaving most of the dV requirements of the 'land on Mars' leg of the journey will reduce that requirement, from ~5x to ~2x.

The falcon heavy and dragon were almost definitely up to the task, given that SpaceX was for a short period of time actively looking for customers.

Source on the 99.9% is this talk (about starship, but I doubt red dragon would have been substantially different in terms of delta v): https://www.youtube.com/watch?v=bysu8XN5OfY

A capsule doing a simpler landing generally needs to get rid of about 400m/s using other methods, based on NASA's past missions.

With generous reserves, I guess. The speed on a low Moon orbit is about 1700 m/s, Apollo's LEMs had about (less than?) 2500 m/s delta-V for landing.

> It takes takes ~6.400 m/s of dV to slow down, and do a powered landing on Mars.

Seems too generous. Escape velocity for Mars is 5.027 km/s, so low orbital speed is about 3.6 km/s; more importantly, there is atmosphere - which maybe too thin to land safely on parachutes, but it definitely is going to reduce speed from orbital to some extent.

Now imagine this happening under supersonic conditions. Recovery would be almost impossible.

This is why skydivers wear multiple chutes.

Seems like even a big gust wouldn't make much difference at supersonic speeds in thin atmosphere.

The "more modern" alternatives would be heavier and depend upon more systems. Even if dealing with futuristic assumptions like say electromagnetic in atmosphere flight and battery density/reactors good enough to handle reentey braking for a reduction of net reaction mass a parachute would have a place as a backup plan.

* The additional risks of a relatively untested system * Starship development had begun, which would make Dragon obsolete

Propulsive landing of Dragon was therefore scrapped (and [Red Dragon](https://en.wikipedia.org/wiki/SpaceX_Red_Dragon), a plan to send uncrewed Dragons to the surface of Mars, along with it.)

Q: Are thrusters programmed as backup if chutes fail to deploy properly?

A: Most likely, but this is contingent upon NASA review & approval

https://twitter.com/elonmusk/status/1104510803313487872?lang...

The LES parachute(s) will be firing at quite low speeds, so they don't need to be too strong. The LES parachute(s) also don't need to be nearly as reliable or give nearly as soft a landing.

Ejection seats in combat aircraft show the same tradeoff -- it's considered acceptable to have ejection seats that fail sometimes and sometimes cause a landing injury. Hopefully you never have to use it, and so even if it fails or injures you say 10% of the time, it's much better than certain death in a pad explosion or similar.

The right solution is probably the ballute. SpaceX, Rocket Lab, Armadillo Aerospace, and Copenhagen Suborbitals have all been investigating ballutes in recent years.

https://en.wikipedia.org/wiki/Ballute

> Since the design of Boeing’s parachute system is so similar to NASA’s, the company had to perform fewer tests to demonstrate the system’s safety compared to SpaceX.

This doesn't seem like a good habit for Boeing.

While I like to bang on Boeing for being fucking dumb about 737MAX, the habit of copying an existing well-tested, approved design is something that should NOT be discouraged.

Re-use of existing validated solutions / components leads to faster development cycles and increased agility (financially) . This is achieved by making more critical components COTS (Commercial Off The Shelf - not one-off / custom) and re-usable as self-contained "modules" or "packages".

Reinventing the wheel for reinventing the wheel's sake is in most cases not a good use of resources.

That said, if the original design has issues, my above commentary is invalidated somewhat - you need to modify the design to fix the root cause, which should trigger a fresh round of validation and testing at the original specification levels or greater. And of course, you should always do fully integrated tests, even if all of the components were previously validated and approved. You pretty much always find stuff (maybe only in solution-integrated combination) - I believe that's what happened in this case.

Boeing reused the 737 design to produce the 737 Max; however, because it was a reused design, Boeing did not go through the same certification process or testing that would have been done for a new airplane. Skipping testing because you have a reused design is the bad habit he is referring to.

As for later programs like Apollo that are more comparable, I'm not sure. Maybe they were comfortable with heavier systems or worse safety margins. Also, I expect that working out the parachutes for Apollo was not easy.

Using pre-existing proven designs for components is essential for building safe systems.

The rocket equation is cruel.

Probably better to use km/h, especially for space related coverage.

I don't really believe that. American public schools have been teaching the metric system to middle schoolers for a few decades now. Every American I talk to understands the metric system. In some cases, particularly units of volume, they understand the metric system better than the imperial units (liters are easy, but I can never keep quarts/pints/cups/floz/etc straight in my head.) Coca Cola sells sugar water to Americans in liter-oriented packaging (.5, 1, an 2 liter bottles are ubiquitous), and Americans certainly don't balk at that. They drink it up.

Also, 24H time system is something people often don't get, and only know about it as "military time", due to army actually using it.

Anyway, my point in all of this is that if a pop-sci publication like Wired uses units like kilometers, it is unlikely that their American readers will be confused. They'll probably walk away from such an article with a casual understanding of the subject that is reasonably close to the casual understanding they'd have if the article used miles instead.

Speed was easy, relatively. Even weight/height was alright, though Aussies tended to use imperial for those often anyway, including the whole 'stone' thing that threw me off at first.

Pardon me, the ignorant American... but this is who I am :D