Lightning strikes on spacecraft

Discuss the Traveller RPG and its many settings
phavoc
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Lightning strikes on spacecraft

Postby phavoc » Tue May 28, 2019 1:56 pm

Here we see a lightning strike on a Soyuz rocket that recently launched. The article mentions lightning striking an Apollo Saturn V twice during launch and knocking out some primary electrical systems. Backups were activated and everything went fine.

Gas giant refueling, or even travel through terrestial weather systems can also bring about lightning strikes. We know that aircraft can get hit by lightning and be ok, though there is apparently a limit on just how much/powerful the strikes can be before they can start causing damage.

Does anyone use these sorts of things during their adventures or as a plot device to disable a ship?

https://www.dailymail.co.uk/sciencetech ... aunch.html
Moppy
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Re: Lightning strikes on spacecraft

Postby Moppy » Tue May 28, 2019 3:32 pm

Maybe in gas giants it could happen? But there's already rules for damage/difficulty when skimming, and I suppose the GM could rule the damage comes from lighting instead of buffeting.

On Earth I can't remember the last time a plane was lost to lighting. I can't imagine it being a problem at TL 9 on an Earth-type world, and at TL 12 there's weather control. I regard current space vehicles as experimental prototypes at best. An 8% failure rate is not very good and I'm not surprised they have problems with.

edit: Having done some google work the last airliner to crash as a result of lighting was in 1976. A few light planes have been lost since then, but nothing new or heavy. Lightning strikes when noticed can cause a plane to land to check the damage as a safety precaution because aviation is heavily regulated (they say pilot's discretion, but that obviously also includes airline standing orders), and the planes can be damaged but are designed in a way to enable them to continue to operate. The average Traveller and their complete disregard for safety procedures like backup flight computers means they won't land until the drive falls off. Space craft can fly over storms, so it'll probabaly only be an issue during takeoff or landing.

https://www.boeing.com/commercial/aerom ... 2012_q4/4/

I'd be interested to hear what an aviation expert has to say on this topic.
phavoc
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Re: Lightning strikes on spacecraft

Postby phavoc » Tue May 28, 2019 8:12 pm

Agreed that jetliners don't crash that much. According to this Scientific American article (https://www.scientificamerican.com/arti ... redirect=1) the average jetliner gets struck about once a year. But airliners also try to avoid storms when possible, and for most cruising fly above storm clouds.

For the most part lightning strikes are not common, and usually just a single strike. What made me ask this question was something else I had read recently about a supernova a few million years ago supercharging the atmosphere to cause more lightning strikes and forest fires, having man do more walking out of the forests. With so many more worlds to choose from in Traveller, planetary environments with more electrical activity could be a challenge for spacecraft. And we really have no meterological data on how common lightning storms are in gas giant atmosphere's.

One item the article talks about is fuel and lightning strikes causing explosions. In this case a ship that is skimming will have open fuel scoops and lightning could potentially strike the open scoops, and hydrogen in the presence of oxygen is quite combustible. It could be an interesting hazard for skimming ships.
Moppy
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Re: Lightning strikes on spacecraft

Postby Moppy » Tue May 28, 2019 11:32 pm

I believe Traveller hulls are armored or considerably stronger than current aircraft. If they have problems with lighting then I'd expect it to be from electricity zapping the electronics rather than blowing holes in the hull. A fib computer might be resistant, or they might have a "damper" using magic fields.

Now this is speculation but I think that if lighting would randomly explode atmospheric hydrogen, then it happens regularly and the planet's atmosphere would have stabilised? But maybe you got caught in a surprise storm, or maybe the environment is still stabilising? In any case it requires a specific ratio of oxgen and hydrogen to cause an explosion, otherwise it will "merely" catch fire; I haven't a clue what that does to a space craft.
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Re: Lightning strikes on spacecraft

Postby AnotherDilbert » Tue May 28, 2019 11:53 pm

I would assume a spacecraft that can survive the particle sleet at 0.5 c would not have any problem with terrestrial lightning.
Moppy wrote: Now this is speculation but I think that if lighting would randomly explode atmospheric hydrogen, then it happens regularly and the planet's atmosphere would have stabilised?
I think you can safely assume that no atmosphere will have both noticeable amounts of pure oxygen and hydrogen (or anything else burnable like methane).
Condottiere
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Re: Lightning strikes on spacecraft

Postby Condottiere » Wed May 29, 2019 5:12 pm

Would assume that a hull optimized for micrometeor strikes should be insulated against electrical discharges, we're certainly paying enough for it.

Lightning rods should keep random sparking from finding it's way into the scoops.
phavoc
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Re: Lightning strikes on spacecraft

Postby phavoc » Wed May 29, 2019 7:28 pm

We already know Traveller hulls are made of magical materials - they can shrug off impacts at fractional-C speeds with no issue, but can take damage from the explosive effect of a small man-portable missile (i.e. the standard missile). These two issues are at direct odds with one another. But, it's a game, so we let things like this slide.

As far as lightning strikes, a Traveller ship would be a giant attractor of potential lightning since it's more metallic than current aircraft. And, as was pointed out, terrestial craft statistically get struck once a year while doing their best to avoid flying through storm clouds.

Electrical strikes can be debillitating to aircraft, and Traveller electronics are still, at the end of the day, electronics and subject to the same potential for disruption. A single, or even a few, strikes should probably be shrugged off. Flying into an electrical storm with constant strikes should be disruptive, possibly damaging or even dangerous.
Moppy
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Re: Lightning strikes on spacecraft

Postby Moppy » Wed May 29, 2019 8:11 pm

The missile is engineered to break the hull, with specific knowledge of the hull's construction, as part of the arms race. The hull is engineered for the lightning and the lightening doesn't evolve.

Computers without fib might indeed be vulnerable depending on how the hull shields the electronics. Anything coming along an expected path should trip a fuse (they can react quickly enough) or be routed around the computer - but there's always the possibility of a design fault, manufacturing error, or improperly repaired damage (quite likely given most PC ships). I'd expect fib comptuers to not care as this (too much electricity where you don't want it) is exactly what they're designed to stop.

If a space craft wanted to avoid a storm I'd expect it to be hit much less than an aircraft. The atmospheric performance of 1-G vertical climb exceeds a fighter jet, and with no fuel issues, hypersonic speed and orbital+ altitude, they can re-route how they wish, or spend less time in a storm.

edit: Selected jets can match the climb speed for a minute or so.
phavoc
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Re: Lightning strikes on spacecraft

Postby phavoc » Thu May 30, 2019 10:19 pm

A missile has an explosive payload which would be detonating either by contact or proximity (no different than aircraft - if the target is evading you want to do your best to hit it with something rather than miss). HEAT/HESH warheads are designed to penetrate armor on contact, but not proximity-based, as they are defeated via reactive armor. So there's a logical hole here. Otherwise we'd need to assume it's just a standard HE warhead and it's relying upon fragmentation to do damage. In space, without an atmosphere to help with the pressure wave, nearby hits aren't nearly as deadly. Again, we've got a logical hole. But we'll run with it.

A subsidized merchant going hypersonic in an atmosphere? Um... I'd still have to say no to this. A vehicle that is capable of hypersonic needs to be VERY aerodynamic - most Traveller starships aren't. At least not aerodynamic as established by today's current standards. The faster you move through an atmosphere the more pressure you build up in front of you. So ensuring a smooth flow through it is essential. You generate vast amounts of heat and instability trying to do so. I realize where they are trying to come from with the estimates for starships traveling in-atmo, but they are wildly optimistic at best. It's more realistic to assume the ships travel at a few hundred KPH for 1-G in-atmo (though I wouldn't automatically scale that up per G-rating). This has been a perennial problem with many versions.
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Re: Lightning strikes on spacecraft

Postby Linwood » Fri May 31, 2019 2:47 am

It might be more important to consider how a spacecraft might dissipate a static charge buildup as it travels through an atmosphere. After all lightning is typically generated by a difference in potential.
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Re: Lightning strikes on spacecraft

Postby Moppy » Fri May 31, 2019 12:44 pm

Linwood wrote:
Fri May 31, 2019 2:47 am
It might be more important to consider how a spacecraft might dissipate a static charge buildup as it travels through an atmosphere.
The same way aircraft do it? :-)
phavoc wrote:
Thu May 30, 2019 10:19 pm
A subsidized merchant going hypersonic in an atmosphere? Um... I'd still have to say no to this... This has been a perennial problem with many versions.
It's not a problem for me as I assume FTL means current physics is somehow wrong, and therefore a wizard enchants the space ships.

However, I'm assuming we agree that a Traveller ship is much less vulnerable to terrestrial lightning than an airplane?

An airliner spends its entire life in atmosphere and is struck once a year almost always inconsequentially. (Lighter planes are more vulnerable).

A typical Traveller ship is going to be in atmosphere for much less time, has a stronger hull, and computers so reliable/protected they don't install backups on civilian craft. Even if you don't believe it out-performs an Airbus in the sky, it's still less vulnerable.

Gas giants? Sure, why not? Who knows?
phavoc
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Re: Lightning strikes on spacecraft

Postby phavoc » Sun Jun 02, 2019 7:39 pm

Gas giant weather is for sure an unknown. I dont think any crew would willingly fly ino a massive storm system, but since we really know nothing about it, it's a possible plot point. Today aircraft very rarely get struck, then again aircraft try to avoid the storms. No aircraft has been made of steel and is a giant flying lightning rod either. So a hundred strikes is something that would take down a modern aircraft. Might not do the same to a Traveller starship, but it could destroy sensors, disrupt them, cause all kinds of havoc, etc, etc.

And then there are going tobe planets with different atmospheres, so a planet that has a highly charged atmosphere could just be waiting for a metal hull ship to slide through it to discharge a lot of energy into.

So maybe those same magicians who make all this possible have left a little curveball for the unlucky pilot or crew to find.

If nothing else it's a way to inject the unknown into a session and start the crew on a path to survival and escape. Who knows, maybe there's some treasure at the end of the bolt?
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Re: Lightning strikes on spacecraft

Postby Moppy » Sun Jun 02, 2019 10:42 pm

Weird weather damage in a gas giant would be an interesting plot point.

I'm not sure what the aircraft aren't giant steel lighting rod comment means (Traveller crystaliron is iron?) but aluminium is a better conductor than iron or steel. If only it didn't like being on fire so much, it would be great lighting rod that didn't rust so much.

Edit: Aluminium lightning rods are legal here. I would never have guessed. I guess they don't care about fire risk. Now I need to find a civil engineer and ask why.
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Re: Lightning strikes on spacecraft

Postby phavoc » Mon Jun 03, 2019 4:51 am

True, aluminum is a better conductor than iron, though conductivity isn't that much of an issue since the ship has nowhere to conduct the energy to. I would assume crystaliron shares more with iron than crystals. And two of the chief concepts behind lightning rods are height and location. A ship in the upper atmosphere will fulfill both requirements for a possible lightning strike.

I used to live in a house that had aluminum wiring (built in the 70s), but with plugs and fuse box made for copper wiring. The wiring itself wasn't an issue, but the plugs and fuse box had issues with interfacing between copper and aluminum (they both conduct electricity, but not quite the same way) was a known cause of house fires. You could put your hand on them and feel them being warm. Then again we also had wood shingle roofs, so hey, it was a house fire waiting to happen. :)
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Re: Lightning strikes on spacecraft

Postby Moppy » Mon Jun 03, 2019 9:43 am

On Earth it usually conducts from the -ve charged cloud to the +ve charged ground, through the air, into the plane and back into the air. The plane is like a conductive wire briding some part of the distance between the charged cloud and the ground.

If the plane wasn't conductive, it wouldn't get hit by the lighting at all.
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Re: Lightning strikes on spacecraft

Postby Linwood » Mon Jun 03, 2019 11:00 am

Lightning rods offer a low-resistance path to ground for lightning strikes. Aluminum could work fine but needs to be sized accordingly for the current carried.

From reading thru the links some of the others on this thread have provided, when lightning strikes an aircraft (or a spacecraft presumably) it conducts along the vehicle’s skin to an exit point, usually behind the wing or near the tail. The more metal in the skin the better; aircraft with large amounts of carbon-fiber panels in the skin have to take additional steps to protect themselves. Entry and exit points are prone to localized damage, including actual holes in the skin; charge density will be much stronger at sharp edges and protrusions so those points are more likely to be damaged.

The links also indicate aircraft are much more likely to be struck by cloud-to-cloud lightning than other types. As Moppy said the aircraft is apparently acting as a bridge between areas with differing potential. There’s also evidence that above a certain altitude chances of being struck by lightning go down, which likely has more to do with atmospheric density - the less air, the less charge it can hold for potential discharge. The discharges that result will likely be far less powerful and more localized.

Note that the chief protection is conductivity of the hull. If the hull is less conductive - or, worst case non-conductive - a lightning strike seems far more likely to find a path thru the aircraft’s internal systems. I don’t know if lowering hull conductivity reduces the risk of a lightning strike occurring, but I think if it should occur it would be far more destructive.
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Re: Lightning strikes on spacecraft

Postby Moppy » Mon Jun 03, 2019 11:32 am

Yes the most conductive thing will be hit, and you want that to be the plane skin, and not the computer, so you want a conductive skin.

But when I said it would be best if the plane wasn't conductive, I mean "perfect" insultation, which means it won't get hit at all. It's not possible to engineer such a plane currently.
phavoc
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Re: Lightning strikes on spacecraft

Postby phavoc » Mon Jun 03, 2019 1:09 pm

Actually the newer planes are trending in that direction with more carbon-fiber instead of aluminum. They will probably never be metal-free, but the wings, tail and body are becoming more and more that way.

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