Death In Space

[Jeff M. Hopper]

Does the absence of gravity affect rigor mortis? Seeing how you can figure out the approximate time of death based on how much blood has pooled in the gravity facing side of the body, how does lower gravity or even the absence of gravity affect this?

I'm just thinking about murder mysteries in space and the possibilities they hold.

 

[Enoki]

I would assume things are different on several issues.

While rigor mortis would still set in at the same rate decomposition would be quite different. This could range from none in a vacuum to very quick given the right set of conditions.

In Zero Gravity everything tends to move to center mass if that helps.

 

[Lycanorukke]

Does the absence of gravity affect rigor mortis? Seeing how you can figure out the approximate time of death based on how much blood has pooled in the gravity facing side of the body, how does lower gravity or even the absence of gravity affect this?

Well, no grav means no blood pooling. A side effect of this is you wouldn't get the 'pale/flush' colours on the upper and lower sides of the body due to pooling. If the person was shot in zeroG, any blood which leaked out would form globules and float around, making an absolute mess of the room.

Rigor would work as normal as it is an internal metabolic function. Though again, if the body was floating around the room it could be bent into funny shapes (due to ship movement, air currents, etc) before stiffening.

 

[CosmicGamer]

Does the absence of gravity affect rigor mortis? Seeing how you can figure out the approximate time of death based on how much blood has pooled in the gravity facing side of the body, how does lower gravity or even the absence of gravity affect this?

I'm by absolutely no means an expert on any of this.

I believe the blood pooling and discoloration, both paleness in areas the blood has left and blue in the areas the blood pooled, is Livor mortis or postmortem lividity. Rigor mortis is a biochemical reaction in the muscles. Algor mortis, postmortem temperature, is also a method of determining time of death. I think all of these are only effective for a short period of time, like only a few days.

There are many other methods of determining a time that require an autopsy. A medical professional obviously would be able to make a good determination by studying the biochemical activity, or lack thereof, in different organs. Even an investigator with much experience discussing these things with forensic pathologists might be able to cut up a body and make some determination. For example, if you know when the person last ate you can cut open the digestive track to make a determination of time of death if someone has told you in the past how long certain digestive activity takes. Perhaps even a Traveller with access to a medical library and medical tools and instruments could make some determination.

 

[Fritz_Brown]

Yes, I don't think 0-G would affect rigor mortis. I think vacuum might - at least on the bits closest to the surface. You probably would have blood pooling, but (as mentioned) it would be center of mass in 0-G. In a vacuum, you might get a flushing of the skin due to capillaries bursting. The big difference would be the dessication that would begin immediately if it were exposed to vacuum - the only decomposition that would happen would be in the very interior. I think it would mummify (excepting a few spots that pop because of the pressure differential).

 

[BytePro]

...You probably would have blood pooling, but (as mentioned) it would be center of mass in 0-G.

I'd think internal gravitational attraction would be too weak to overcome other forces - the blood would collect, as such, where nature normally assisted against gravity (cardiovascular design, not just heart) and physically easiest - i.e., head and torso primarily - or, where condition of death allowed it to...

Strong external forces could result in blood positioning internally and externally in such a way as to be useful in determining time and conditions of death.

Blood not pooling due to significant gravity could also prove useful forensically - such as helping identify site and degree of trauma.

 

[Jeff M. Hopper]

What about the air? Would breathing a higher or lower pressure of air, or even a different gas mixture affect decomposition? (Like when an astronaut needs to wear a low tech vacc suit and must breath a near pure oxygen mix because the pressure in the vacc suit is lower and has a different gas mixture than the spacecraft or station.)

By forensic examination of the lungs and hemoglobin in the blood, can you determine what the victim was breathing and at what pressure?

 

[BytePro]

Breathing different mixtures to reduce Nitrogen in the blood (my layman's knowledge) would surely then show up in the blood and possibly even tissue samples. Assuming it didn't diffuse in/out of tissues/body too fast to be of use for that sort of forensics.

Perhaps useful to tell if the body was moved after death?

 

[Carlobrand]

Does the absence of gravity affect rigor mortis? Seeing how you can figure out the approximate time of death based on how much blood has pooled in the gravity facing side of the body, how does lower gravity or even the absence of gravity affect this?

I'm just thinking about murder mysteries in space and the possibilities they hold.

Rigor mortis refers to the stiffness of a body brought on by chemical changes in muscles after death. Nothing about gravity changes that; the deceased's body would stiffen up in whatever position it held while floating. Rigor starts setting in about 3 hours after death and peaks about 12 hours after death; after a couple of days the body loosens up again.

The blood pooling you're referring to is called livor mortis. Without the beating of your heart, the blood settles in gravity - or any steady force - to the "low" parts of the body. No gravity, no low parts. That's actually a better indication of the position of the body after death; the blood congeals in the low parts a few hours after death, and if the body is moved after that, it can be a giveaway that the body was moved.

Liver temperature's a better indicator of time of death, assuming normal body temperature at time of death and no unusual environmental temperatures after that. Body cools at a predictable rate; if you can get there soon enough, you can tell within about an hour or so. If you've got a body in an odd environment (such as vacuum), you might need to do some experimenting to figure how quickly a body would cool in that particular setting. Draft a few dearly departed into the cause of science and solve the riddle.

 

[Fritz_Brown]

Good points, BytePro.

 

[Spinward Scout]

Without the beating of your heart, the blood settles in gravity - or any steady force - to the "low" parts of the body. No gravity, no low parts.

Centrifugal force would move the blood to the extremities, if the body was spinning, I believe.

 

[Carlobrand]

Centrifugal force would move the blood to the extremities, if the body was spinning, I believe.

Centripetal acceleration, and yes. The degree depending on the rate of spin. Might not mean much, might be an important clue. Finding no evidence of lividity at the extremes of a body with strong spin suggests the body was set in motion several hours after the person was killed. Starts becoming an Ellery Queen mystery.

Blood spatter and bleeding would also be interesting in zero-G.

 

[Spinward Scout]

Centripetal acceleration, and yes.

CENTRIFUGAL - proceeding or acting in a direction away from a center or axis

CENTRIPETAL - proceeding or acting in a direction toward a center or axis

Gravity is centripetal - we're drawn towards the center of the gravity well.

In my example, I was talking about the victim spinning and the blood would move towards the outer body parts/extremities away from the center axis of spin. Depending on where the center of spin was, of course. But that would be centrifugal.

 

[Fritz_Brown]

My physics teacher would smack you, Spinward, and say "There's no such thing as centrifugal force!" It's simply Newton's Law in effect. Not that *I* would ever nitpick such a handy shortcut, or anything...... *whistling tunelessly*

 

[Lycanorukke]

My physics teacher would smack you, Spinward, and say "There's no such thing as centrifugal force!" It's simply Newton's Law in effect. Not that *I* would ever nitpick such a handy shortcut, or anything...... *whistling tunelessly*

A laughble claim Mr Bond....http://xkcd.com/123/

 

[Spinward Scout]

The best example I can think of for centrifugal force is when a Frisbee is wet. You throw the Frisbee and the water goes flying off of it. The force that makes the water fly off is centrifugal force. Newton's laws apply to the situation as well.

Any medical facility that owns a centrifuge would disagree with your science teacher, I would think.

 

[Vladika]

The best example I can think of for centrifugal force is when a Frisbee is wet. You throw the Frisbee and the water goes flying off of it. The force that makes the water fly off is centrifugal force. Newton's laws apply to the situation as well.

Any medical facility that owns a centrifuge would disagree with your science teacher, I would think.

There is such a thing as "centrifugal force". It is covered very well in an engineering curriculum. Particularly in Dynamics of Rigid Body's.

My physics teacher would smack you, Spinward, and say "There's no such thing as centrifugal force!" It's simply Newton's Law in effect. Not that *I* would ever nitpick such a handy shortcut, or anything...... *whistling tunelessly*

Physics teachers be damned. Engineering is Applied Physics. If the world depended solely on physics teachers nothing much would work.

Physics teachers deal in an "ideal universe" that doesn't exist. Engineers study the principles of that "ideal universe" twist them, and make things that actually work.

Spinward Scout had the correct science stated earlier, though by necessity, simplistically:

CENTRIFUGAL - proceeding or acting in a direction away from a center or axis

CENTRIPETAL - proceeding or acting in a direction toward a center or axis

Gravity is centripetal - we're drawn towards the center of the gravity well.

 

[McPerth]

Centrifugal force would move the blood to the extremities, if the body was spinning, I believe.

And also to the head...

The coroners for a crime in space must be a special team, as most what coroners look for in earth would be useless (or near so) on such a case...

The best example I can think of for centrifugal force is when a Frisbee is wet. You throw the Frisbee and the water goes flying off of it. The force that makes the water fly off is centrifugal force. Newton's laws apply to the situation as well.

The typical example I think about (and mostly while talking to wargamers and RP gamers) is a sling. Centrifugal forcé is what gies the sling Stone or bullet the speed to become a missile that damages by kinetic force.

 

[SanDragon]

I would think that after nearly 4 millenia in space all this theory would be proved or disproved...

Also, if there is still atmosphere where the body is, frictional drag of moving through that atmosphere may very well decelerate the rotating body to a stop before indicative fluids move to the extremities in sufficient amounts.

 

[Lycanorukke]

I would think that after nearly 4 millenia in space all this theory would be proved or disproved...

Sergeant: We found Dr Vladika like this. The room was in zero G, the body was standng upright and arms outstretched.

Detective: I see. And the body was slowly rotating about its axis?

Sergeant: Yes. About 30 revolutions per minute.

Detective: And a wet frisbee was sitting on his head?

Seargant: Yes. Strange that.

Detective: (looks at the Ships passenger list) Hmmm...

Sergeant: Sir?

Detective: Right. Arrest Professor Brown. It looks like another Centripital/Centrifugal arguement got out of hand. *sigh* Four thousand years...