Atmospheric Reentry?


General Discussion


No, this hasn't come up in a game but I just was kind of curious.

Let say you go out of your starship on a EVA. And someone comes along and decides to blow up your starship. Are there any kind of items or class abilities that allow for you to just guide yourself towards the planet and reenter the atmosphere? Normally that sort of thing would result in blacking out and dying from heat without special shielding to help you.

However, humans have done juumps "from space" and survived. And all of our combat armor is basically super tough space suits.

So do we have any armor upgrades or anything that deals with reentering a planet's atmosphere without using a space ship?

I mean I guess with force soles or a jet pack you could just control your movement back into the atmosphere. It might just take you a while to get back on your feet. Since it's like 60 miles from Earth's surface to "space". So you need some sort of system to make a controlled fall, and then gain complete control before you splat.


Jet pack or jump jets should do it.

Thermal capacitor

Life bubble + Resist fire


How in depth are we looking to get here?

Like, I think most of the heat from re-entry is the craft using the atmosphere to slow down, either by presenting its undercarriage or taking a long, oblique trip through said atmosphere. So, do you want to figure out how hot it gets if you just nose-dive from space, or do you want to say "Air-brake = hot, nose dive = not?"

After that... by RAW, a fall from atmosphere deals 20d6 damage. If we're using that, pretty much any character over level 10 doesn't even care about the landing. I assume we'll not be using that rule?

I'd say anything that lets you fly or something like a slow (or feather) fall would do it. I don't think force soles would work, if we're going to all the trouble to even slightly model falling from space, then force soles would be the equivalent of landing on your feet in the street from a fall at terminal velocity, and I can't see how that's any good for you.


I think the phrasing "most of the heat from re-entry is the craft using the atmosphere to slow down" is a bit of a misunderstanding. The heat generated is because the speed the vessel enters the atmosphere compresses the atmosphere so much that it rapidly heats up. It's not to purposefully slow down, although it does also cause that.

European Space Agency wrote:

If the entry angle is too steep, deceleration forces (the braking effect due to atmospheric friction) will become too large and the spacecraft can break up. Additionally, the steeper the entry angle, the higher the heat flux. This is a measure for the amount of thermal energy absorbed by the heat shield every second. If the heat flux is higher than what the heat shield material can take, the heat shield will fail – most likely it will burn through.

Conversely, if the entry angle is a bit too shallow, other unpleasant things can happen.

Firstly, the deceleration then will be too low, so the spacecraft will travel much farther than it is supposed to. It might end up landing on land or even in rugged terrain (which is disastrous if it was designed to land only in water), on inhabited regions or in busy shipping lanes. Also, although the heat flux – like the deceleration – would be lower than expected, there may still be thermal problems, because the heat shield will be exposed to the flux for a much longer time, so the total heat load may be a lot larger. At some point, all of the protective insulation will have been burnt away, or heat might begin to seep through the shield and temperatures inside the spacecraft might become too high.

So your long oblique trip can actually be as bad or worse than the the nosedive through the atmosphere, at least with our current technology. The heat shield is designed from ablative material specifically to minimize heat transfer, break away, and not burn up.

I was mostly just wondering if there were any items that specifically addressed the situation.

As far as I know we don't have rules for what happens if you try to do this, so we can just kind of pretend that "hey there's fall damage and fire damage" and if you find a way to mitigate those you avoid it.

I was just hoping for something more concrete.

I was mostly thinking about the scene from Mass Effect where Sheppard falls through the atmosphere and dies.


I think the biggest issue then is finding a way to prevent yourself burning up, which I suppose depends if you are falling at orbital velocity, or if you just jumped from a science fantasy starship that can fly where it pleases, when it pleases, and doesn't need to go 25x the speed of sound relative to the ground in order to stay in space.

So, are we talking 3d6/round, or 10d6+?


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Pantshandshake wrote:

How in depth are we looking to get here?

Like, I think most of the heat from re-entry is the craft using the atmosphere to slow down, either by presenting its undercarriage or taking a long, oblique trip through said atmosphere. So, do you want to figure out how hot it gets if you just nose-dive from space, or do you want to say "Air-brake = hot, nose dive = not?"

After that... by RAW, a fall from atmosphere deals 20d6 damage. If we're using that, pretty much any character over level 10 doesn't even care about the landing. I assume we'll not be using that rule?

I'd say anything that lets you fly or something like a slow (or feather) fall would do it. I don't think force soles would work, if we're going to all the trouble to even slightly model falling from space, then force soles would be the equivalent of landing on your feet in the street from a fall at terminal velocity, and I can't see how that's any good for you.

You use Force Soles to walk down to the planet surface from space. You’re never falling.

The level 3 Cloudy Blue Rhomboid Aeon Stone (Flight 1 once per day) solves your impact issues. Use an extra to bleed off orbital velocity and atmospheric damage, if necessary.


There are lots of variables:
- Planet gravity
- Planet atmosphere or absence of it
- Initial speed (if you are in orbit, you'll stay in orbit unless you find a source of propulsion)

It's very DM dependant in my opinion. Bringing a heat resistant armor, a jetpack and being able to cast Flight I is the most you can do.


Pathfinder Starfinder Roleplaying Game Subscriber

Its important to note that people have skydived from "space", they have *not* skydived from *orbit*. Being in orbit isn't about height, its about speed. Most of the difficulty in coming down from orbit is figuring out how to lose the velocity, which even for geostationary orbit is about 3.7 kilometers per *second*.

So, can a person in Starfinder deorbit in a space suit? Sure. . . so long as they have suit add-ons that provide flight capability similar to a space ship. If you can just fly up to orbit from the ground on your own, or fly from one stellar body to another? You are fine, you can deorbit just like a spaceship can.

If you *don't* have that kind of propulsion? Well, you might still be able to de-orbit. . . but you'd better have what amounts to physical invulnerability, and hopefully you don't overly care about anything near to your landing site. At geostationary orbital velocity, you'll hit with roughly the impact of 150 kilograms of TNT detonating.


Pathfinder Maps, Pawns Subscriber; Pathfinder Roleplaying Game Superscriber; Starfinder Charter Superscriber
Metaphysician wrote:
If you *don't* have that kind of propulsion? Well, you might still be able to de-orbit. . . but you'd better have what amounts to physical invulnerability, and hopefully you don't overly care about anything near to your landing site. At geostationary orbital velocity, you'll hit with roughly the impact of 150 kilograms of TNT detonating.

ಠДಠ

So cool!

Second Seekers (Luwazi Elsbo)

Lights up
Jumps out of airlock naked

"Wheeeeeeeeeeeeee "


Ehhh...assuming you don't just burn up trying to reenter the atmosphere you wont exert anywhere near that much force.

You will achieve terminal velocity because the atmosphere will slow you down, assuming you're not trying to make the biggest crater possible.

Remember folks F = M * A, force = mass * acceleration.

In the end, the mass of humanoids is typically pretty tiny relative to other things. I would expect a human sized thing to exert a force well short of a ton of tnt.

560m/s^2 * 90 kg, which comes out to be about the force of 1 kg of TNT. which is still kind of impressive.*

*Lots of assumptions made


Claxon wrote:

No, this hasn't come up in a game but I just was kind of curious.

Let say you go out of your starship on a EVA. And someone comes along and decides to blow up your starship. Are there any kind of items or class abilities that allow for you to just guide yourself towards the planet and reenter the atmosphere? Normally that sort of thing would result in blacking out and dying from heat without special shielding to help you.

However, humans have done juumps "from space" and survived. And all of our combat armor is basically super tough space suits.

So do we have any armor upgrades or anything that deals with reentering a planet's atmosphere without using a space ship?

I mean I guess with force soles or a jet pack you could just control your movement back into the atmosphere. It might just take you a while to get back on your feet. Since it's like 60 miles from Earth's surface to "space". So you need some sort of system to make a controlled fall, and then gain complete control before you splat.

Traveler JTAS 11 did have a Atmospheric Re-entry Kit which had an inflatable ablation shield plus a deorbiting booster which you strapped your self into - you then deorbited and made the last stage as a normalish parachute jump

https://members.tip.net.au/~davidjw/tavspecs/maint/ar-kit.htm


It highly depends if you use anti gravity or not.
Without anti gravity you need a lot of forward momentum to stay in orbit and this momentum is what causes the heat buildup.
So you either need to be immune to fire damage and somehow have a way to steer yourself into the atmosphere so its starts slowing you down. And you need something to reduce falling damage.

If you have anti gravity (or at least the ship had), you would not have needed the forward momentum mentioned above, so you would just be falling towards the planet with the normal falling rules when you turn it off. When you have some way to slow down falling you should be able to stay slow enough for the heat to not be a problem.
But anti gravity opens another can if worms...

In the end, better to just teleport to the planet. Much less of a hassle.


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I highly doubt this is going to be the one issue where starfinder goes all hard science so you CAN"T do an orbital drop


Pantshandshake wrote:
if we're going to all the trouble to even slightly model falling from space, then force soles would be the equivalent of landing on your feet in the street from a fall at terminal velocity, and I can't see how that's any good for you.

Here's an extremely strange piece of trivia: If you have to land on a hard surface from a potentially lethal height, landing on the balls of your feet and basically "crumpling" through your joints bending is the best shot you have of surviving.

It's not a good shot, but if you can't hit something softer it's your best shot.


Pathfinder Starfinder Roleplaying Game Subscriber
Claxon wrote:

Ehhh...assuming you don't just burn up trying to reenter the atmosphere you wont exert anywhere near that much force.

You will achieve terminal velocity because the atmosphere will slow you down, assuming you're not trying to make the biggest crater possible.

Remember folks F = M * A, force = mass * acceleration.

In the end, the mass of humanoids is typically pretty tiny relative to other things. I would expect a human sized thing to exert a force well short of a ton of tnt.

560m/s^2 * 90 kg, which comes out to be about the force of 1 kg of TNT. which is still kind of impressive.*

*Lots of assumptions made

Yes, but it won't matter, because all that energy still had to go somewhere. The 150 KG of TNT is the total amount of kinetic energy a geostationary object of about 100 KG possesses, *just* from velocity. This is not counting potential energy ( which would be non-trivial, geostationary orbit is very high ). One way or another, that energy has to go away, and if its not going away via counterthrust, its going away as heat. So instead of 150 KG of TNT in impact yield, you get it in thermal heating. Not exactly an improvement.

Ablative heat shields and air braking can disperse this energy, yes, but that requires actually *having* an ablative heat shield and/or the ability to engage in ( continent spanning ) reentry maneuvers. If you don't have that? Sucks to be you.


Pathfinder Starfinder Roleplaying Game Subscriber

Also, regarding anti-gravity. . . my inclination is to say that even with anti-gravity, most ships most of the time still place themselves into an orbit. It costs energy to reach orbital speed, sure, but if you are going to be flying around from planet to planet, you obviously have energy to spare and are going to need to accelerate a lot, anyway. All of which is made massively easier by the presence of anti-gravity and power sources at least equivalent to fusion ( if not far better ), which collectively mean you can more or less turn your power straight into velocity, without any need for reaction mass.

All this soft science also means that, whenever its convenient and desirable, Starfinder ships *can* enter all kinds of weird funky not-really-orbits, with their altitude sustained purely through anti-gravity thrust. Or, things only go Kerbal when its actually useful for the plot, otherwise spaceflight just works.


Bypassing reality might be a lot easier. A tiara of translocation costs a bit, but has other uses too.


Pathfinder Starfinder Roleplaying Game Subscriber
avr wrote:
Bypassing reality might be a lot easier. A tiara of translocation costs a bit, but has other uses too.

This reminds me of some thoughts.

So, strictly speaking according to real world physics, teleportation from ground to orbit or vice versa would be *really hard*, even beyond the actual physics of some achieving teleportation in the first place. The problem is potential energy. A person at orbital altitudes has a *lot* more potential energy than a person on the ground, and vice versa. That energy still has to be supplied, or dispersed, even if you relocate via some exotic method, lest your teleportation machine also be a perpetual motion machine.

This is why basically every sci fi setting with teleportation just ignores the whole issue. I think Traveler is the only one to bring it up with some precursor supertech. Most every other setting hard enough for it to be an issue, either doesn't have teleportation at all, or at least only has it at sufficient god-tech levels where the relevant potential energy can be ignored as a rounding error for the tech involved.

So, how is this relevant for Starfinder? Well, by and large, its not an issue. The laws of physics and magic are such that it never comes up, thanks to various properties of the Astral Plane through which all teleportation works. The gods specifically patched reality so that it would never cause problems.

. . . because they found out that it could cause problems, in the beta version of reality: the First World. And to this day, there are regions in the First World where you actually *can* get into trouble via teleportation, because the local laws of reality *don't* have the necessary patches to prevent potential energy/perpetual motion problems.

Sovereign Court

I'm intrigued by the idea that teleporting from one moving frame of reference (a planet) to another one (a ship, a different planet) is hard because you have to compensate for that in the spell. Because it also suggests that if you can actually get the speeds similar enough, teleporting becomes easier.

So you could have a starship combat where the pilot and science officer are working together to try to exactly match the speed of an enemy ship so the technomancer can teleport in a boarding party.


Ascalaphus wrote:

I'm intrigued by the idea that teleporting from one moving frame of reference (a planet) to another one (a ship, a different planet) is hard because you have to compensate for that in the spell. Because it also suggests that if you can actually get the speeds similar enough, teleporting becomes easier.

So you could have a starship combat where the pilot and science officer are working together to try to exactly match the speed of an enemy ship so the technomancer can teleport in a boarding party.

The rules explicitly forbid that use of teleportation spells, per the Teleporting Between Starships box on page 326 of the Core Book.


I think it was not meant as a rules statement, but an exploration of thought about how things could work with a different version of a teleport spell.

Sovereign Court

Nerdy Canuck wrote:
Ascalaphus wrote:

I'm intrigued by the idea that teleporting from one moving frame of reference (a planet) to another one (a ship, a different planet) is hard because you have to compensate for that in the spell. Because it also suggests that if you can actually get the speeds similar enough, teleporting becomes easier.

So you could have a starship combat where the pilot and science officer are working together to try to exactly match the speed of an enemy ship so the technomancer can teleport in a boarding party.

The rules explicitly forbid that use of teleportation spells, per the Teleporting Between Starships box on page 326 of the Core Book.

Yes, and if you read what's in that rule box, you see what I'm getting at:

CRB wrote:

TELEPORTING BETWEEN STARSHIPS

Starships in combat are constantly in motion, so it is impossible for a
PC to cast a spell with the teleportation descriptor to travel between
vessels. Even if a spellcaster has seen the inside of the target
starship, the relative speeds between two moving vessels mean that
the destination has changed before casting the spell is complete. PCs
can teleport only between stationary starships.

This is sci-fantasy, not "we take No for an answer". The improbable we do today, the impossible takes a little longer. We've been talking in a lot of threads about how nice it would be if there were more different things to try in starship combat. This is an example.

Also, consider that the explanation given in that box text is a bit of a fib. Interplanetary teleport moves people from one moving planet to another moving planet. What this box is really about is "oh please don't split the party between a space combat and a regular combat". If only because you can't fit both maps on the table at the same time. GM responsibly :P


Ascalaphus wrote:


This is sci-fantasy, not "we take No for an answer". The improbable we do today, the impossible takes a little longer.

Not that's its relevant, but your quote made me think of the song "Crazy He Calls Me".


Ascalaphus wrote:
CRB wrote:

TELEPORTING BETWEEN STARSHIPS

Starships in combat are constantly in motion, so it is impossible for a
PC to cast a spell with the teleportation descriptor to travel between
vessels. Even if a spellcaster has seen the inside of the target
starship, the relative speeds between two moving vessels mean that
the destination has changed before casting the spell is complete. PCs
can teleport only between stationary starships.

This is sci-fantasy, not "we take No for an answer". The improbable we do today, the impossible takes a little longer. We've been talking in a lot of threads about how nice it would be if there were more different things to try in starship combat. This is an example.

Also, consider that the explanation given in that box text is a bit of a fib. Interplanetary teleport moves people from one moving planet to another moving planet. What this box is really about is "oh please don't split the party between a space combat and a regular combat". If only because you can't fit both maps on the table at the same time. GM responsibly :P

I mean, fair, but you've also just pointed to some of the very good game design reasons for the rule. Trying to make it work would probably just be a lot of work to not have an especially good time, and it runs the risk of being a bell you can't un-ring.

Sovereign Court

Nerdy Canuck wrote:
Ascalaphus wrote:
CRB wrote:

TELEPORTING BETWEEN STARSHIPS

Starships in combat are constantly in motion, so it is impossible for a
PC to cast a spell with the teleportation descriptor to travel between
vessels. Even if a spellcaster has seen the inside of the target
starship, the relative speeds between two moving vessels mean that
the destination has changed before casting the spell is complete. PCs
can teleport only between stationary starships.

This is sci-fantasy, not "we take No for an answer". The improbable we do today, the impossible takes a little longer. We've been talking in a lot of threads about how nice it would be if there were more different things to try in starship combat. This is an example.

Also, consider that the explanation given in that box text is a bit of a fib. Interplanetary teleport moves people from one moving planet to another moving planet. What this box is really about is "oh please don't split the party between a space combat and a regular combat". If only because you can't fit both maps on the table at the same time. GM responsibly :P

I mean, fair, but you've also just pointed to some of the very good game design reasons for the rule. Trying to make it work would probably just be a lot of work to not have an especially good time, and it runs the risk of being a bell you can't un-ring.

It's the sort of thing you do as a plot device in a scenario, or in a home campaign. Definitely not something you'd put in the core rules. But the game was never intended to be limited to the out of the box rules; look at all the scenarios that have an odd subsystem just for this time.

In practice this could be something like: an odd kind of starship battle where you try to maneuver around a capital ship and match its speed and heading, while fending off some fighters. So it's a starship combat with complications. Then, when you've got things all lined up, the whole party teleports over to the enemy ship, does some critical sabotage, and then gets out again. Meanwhile, their NPC junior officers keep watch on the PCs ship. It really requires that the GM and players are grownup enough to not get hung up on the fact that all the PCs should go on the away mission together for OOC reasons.


Ascalaphus wrote:
Nerdy Canuck wrote:
Ascalaphus wrote:
CRB wrote:

TELEPORTING BETWEEN STARSHIPS

Starships in combat are constantly in motion, so it is impossible for a
PC to cast a spell with the teleportation descriptor to travel between
vessels. Even if a spellcaster has seen the inside of the target
starship, the relative speeds between two moving vessels mean that
the destination has changed before casting the spell is complete. PCs
can teleport only between stationary starships.

This is sci-fantasy, not "we take No for an answer". The improbable we do today, the impossible takes a little longer. We've been talking in a lot of threads about how nice it would be if there were more different things to try in starship combat. This is an example.

Also, consider that the explanation given in that box text is a bit of a fib. Interplanetary teleport moves people from one moving planet to another moving planet. What this box is really about is "oh please don't split the party between a space combat and a regular combat". If only because you can't fit both maps on the table at the same time. GM responsibly :P

I mean, fair, but you've also just pointed to some of the very good game design reasons for the rule. Trying to make it work would probably just be a lot of work to not have an especially good time, and it runs the risk of being a bell you can't un-ring.

It's the sort of thing you do as a plot device in a scenario, or in a home campaign. Definitely not something you'd put in the core rules. But the game was never intended to be limited to the out of the box rules; look at all the scenarios that have an odd subsystem just for this time.

In practice this could be something like: an odd kind of starship battle where you try to maneuver around a capital ship and match its speed and heading, while fending off some fighters. So it's a starship combat with complications. Then, when you've got things all lined up, the whole party teleports over to the enemy ship, does...

Definitely need to find a reason why that's not possible in the general case, though - like having some kind of anchor/beacon on the capital ship that can be used to home in on.


Ascalaphus wrote:
What this box is really about is "oh please don't split the party between a space combat and a regular combat". If only because you can't fit both maps on the table at the same time. GM responsibly :P

From what I remember of discussions that happened a while back, it's also at least in part just to promote actually using space-combat rules. After all, why do all these space combat things when you can put the ship on auto-pilot, board the enemy ship, and treat it as a (possibly somewhat time-constrained, auto-pilot isn't perfect) dungeon crawl instead.


By a quick bit of looking around, it takes about 2 to 5 minutes to fall from a low orbit. So call it 25 rounds for simplicity sake, more or less to preference. Characters take a cummulative 1d6 fire damage each round, with the increase being avoided by a DC21 Acrobatics check. If the check succeeds by 5 or more, the character only suffers half of any fire damage that round. The check is treated as a Flight check, with characters without a flight speed suffering a -10 penalty. Failure on a roll increases the difficulty on all future Acrobatics roll related to this fall by 1. Characters count as being in vacuum until after the halfway point of the fall. Impact with the ground deals the normal 20d6 damage, which may be avoided by creatures with a Fly speed as noted in the Acrobatics skill.

Yes this makes it easy to avoid taking damage if you are built for it, or even just solidly prepped for it, but this is science fantasy. A suit of sealed armor with a forcepack upgrade is all you need to survive, along with some Acrobatics training.


lightningcat wrote:

By a quick bit of looking around, it takes about 2 to 5 minutes to fall from a low orbit. So call it 25 rounds for simplicity sake, more or less to preference. Characters take a cummulative 1d6 fire damage each round, with the increase being avoided by a DC21 Acrobatics check. If the check succeeds by 5 or more, the character only suffers half of any fire damage that round. The check is treated as a Flight check, with characters without a flight speed suffering a -10 penalty. Failure on a roll increases the difficulty on all future Acrobatics roll related to this fall by 1. Characters count as being in vacuum until after the halfway point of the fall. Impact with the ground deals the normal 20d6 damage, which may be avoided by creatures with a Fly speed as noted in the Acrobatics skill.

Yes this makes it easy to avoid taking damage if you are built for it, or even just solidly prepped for it, but this is science fantasy. A suit of sealed armor with a forcepack upgrade is all you need to survive, along with some Acrobatics training.

Without actually having orbital velocity to begin with, there would not be fire damage, so it does depend a lot on starting conditions.


Pathfinder Starfinder Adventure Path Subscriber

Cast flight(1) when you get close to the ground, it kills all your momentum bc magic.


Pathfinder Starfinder Roleplaying Game Subscriber
Nathan Monson wrote:
Cast flight(1) when you get close to the ground, it kills all your momentum bc magic.

Wouldn't protect you from having already burnt to a crisp. And if you want to get really technically, at orbital velocities, there is not *that* much difference between hitting the ground and hitting the atmosphere, depending on your angle.


Metaphysician wrote:
Nathan Monson wrote:
Cast flight(1) when you get close to the ground, it kills all your momentum bc magic.
Wouldn't protect you from having already burnt to a crisp. And if you want to get really technically, at orbital velocities, there is not *that* much difference between hitting the ground and hitting the atmosphere, depending on your angle.

However, that assumes that you're at an orbital velocity, rather than merely being in space.

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