It is one of the weirdest, wildest moments in Star Wars history. Han Solo picks up Luke Skywalker's lightsaber and slices open the belly of his dead tauntaun and stuffs Luke in to to warm him up and save his life.
But is this scene at all realistic? If you were freezing, would jumping inside the dead body of a giant animal really help you stay warm in this situation? According to our highly scientific examination of this topic, the answer is a shocking "no." Here's why.
Nights on the icy planet of Hoth are brutally cold. Since the tauntaun is dead, it is no longer generating heat. In time, the interior of the animal will become a death trap for Luke. How much time does Han have to find shelter and save his friend who is also one-third of an ongoing love triangle? First things first . . .
How did the Tauntaun die?
This question is the key to determining how long Luke can survive. Tauntauns are denizens of Hoth, acclimated to average temperatures of -61° Celsius on the planet. While the beasts of burden are accustomed to extremely low temperatures, they often seek shelter at night in order to survive. Echo Base is located near the equator, with nighttime temperatures averaging around -60 °C (-76 °F).
Han Solo does not appear to have any problems with the tauntaun that would denote symptoms of hypothermia during his travels. Based on this fact, I am going to say that the tauntaun dies of overexertion/exhaustion and not hypothermia. This allows us to set the tauntaun's body temperature at the time of the death to be 37° Celsius (98.6 °F for those on the Farenheit scale). This decision, of course, is made with the the assumption that tauntauns operate at a core body temperature similar to mammals on Earth.
When a Tauntaun becomes a deathtrap
Using Newton's Law of Cooling, we can estimate the time it takes for the tauntaun's body temperature to reach levels detrimental to Luke's survival. Luke is swimming in a sea of blood, bodily fluids, and organs during his time inside the tauntaun.
This is essentially a liquid-like environment, one that will transmit the body temperature of the tauntaun well. To best model this scenario, merging Luke's body with the tauntaun becomes necessary, creating a one body system.
Forensics teams use Newton's Law of Cooling to estimate the time of death of a newly discovered body. Dead bodies will acclimate to the surrounding temperature of the room as the bodies no longer metabolize nutrients or generate heat. By measuring the rectal temperature of the cadaver and temperature of the room, the time since blood circulation ceased (i.e., death) can be calculated. Let's just let the idea of obtaining a Tauntaun's rectal temperature sit with you a moment.
The calculated values we will discuss assumes a particular body temperature for the Tauntaun/Luke sandwich, and then back-calculates the amount of time it would take to achieve that temperature in a cold climate. Hoth commonly reaches temperatures of -60 °C at night, and we will use that temperature to establish the frigid "room" temperature.
Whether Luke is completely inside of the tauntaun plays a role as well. Tauntauns are a little over two meters tall. This makes the fetal position necessary in order for Luke to be entirely enclosed within the belly. Any part of Luke that is hanging out of the tauntaun will cool faster than rest of his body inside the tauntaun, as the starting point for cooling would become Luke's own body temperature. The open wound is a problem as well, but one that is not easy to model. For the sake of Luke's survival and simplicity, we will assume Luke is completely within the interior of the tauntaun carcass.
What is Luke's condition?
Luke's body temperature at the time Han rescues him is likely below normal body temperature of 37 °C (98.6 °F). Luke recently fought a wampa, spoke to a vision of Ben Kenobi, and is seen shivering and confused.
Admittedly, wampa-fighting is not a symptom of hypothermia. But hallucinations, impaired movements, and confusion — three symptoms Luke exhibits — are useful for diagnosis of Luke's physiological state.
Hypothermia comes in a variety of forms - mild, moderate, and severe. Mild hypothermia begins once the core body temperature drops to 35.0 °C (95.0 °F), a temperature at which the human body's metabolism and organ systems begin to be affected. In mild hypothermia, the the body begins to shiver and one's heart rate increases in an effort to conserve heat. One might suffer some confusion in this state too.
Moderate hypothermia begins at 32.0 °C (90.0 °F), with the symptoms of mild hypothermia worsening and the extremities beginning to turn blue. Severe (and deadly) hypothermia sets in once the core body temperature reaches 28 °C (82 °F). This state is characterized by speech difficulties, amnesia, puffy blue skin along with the joy of organ failure. Limb loss and death comes soon if this stage persists.
How much time does Luke have?
Thanks to the diagnostic criterion of blue extremities and puffy skin, we can likely rule out Luke as being in the stages of moderate or severe hypothermia. Luke's bewildered state and sluggish pace places him in the mild stage of hypothermia, placing the upper limit of his core body temperature at 35.0 °C (95.0 °F). This is also a reasonable starting point for the temperature of the tauntaun carcass, as it has been dead for several minutes.
With Luke's body temperature decided, we can now determine how long it takes for the Jedi to plunge into severe hypothermia and with it, death. If Luke enters the tauntaun in a state of mild hypothermia, Han only has 17 minutes and 48 seconds to remove Luke, clean off the fluids from his face, and move him to warm shelter before moderate hypothermia sets in. The bigger scare here is the possibility of severe hypothermia, limb loss, and death, with Han having the extremely short window of 47 minutes and 26 seconds to extract, transport, and warm Luke.
Even if Luke is at a normal body temperature (37 °C/98.6 °F), Solo has just under 60 minutes before Luke plunges into the deadly realm of severe hypothermia.
Real life cases
During the winter of 1860, Father Joseph Goiffon, a minister and French missionary traveling from through the Dakotas used a Tauntaun-like tactic to ward off the cold. Father Goiffon cut open his dead horse and crawled inside to seek shelter from the snow and cold. A search party found Goiffon alive, but his leg had to be amputated.
There is a spectacular medical case where a seven-year-old girl Swedish reached a core body temperature of 13 °C (55.4 °F) and survived. This is an extreme outlier, with the girl likely benefiting from the plasticity of a child's brain. For Luke to reach this temperature inside the tauntaun, it would only take two hours and twenty-two minutes.
The burden is on Han
The clock is ticking - how fast can Han Solo create a temporary shelter and warm up Luke? Pressurized pop-up tents exist in the Star Wars Universe. Mace Windu is known to carry a "wallet tent" that self assembles in seconds and can house two people.
Han Solo makes use of a similar tent in the novel The Courtship of Princess Leia. Solo pops out the tent as he explores the planet of Dathomir, a planet he won the deed to in a game of Sabacc. There is one problem however — Han explicitly keeps the tent inside the Millenium Falcon. We cannot know for sure if the tent is on his person as he explores Hoth. Luke's search and rescue mission is a quick one — Han leaves Echo Base in a hurry, likely believing it will be a short trip.
In a matter of minutes, Luke will succumb to hypothermia under our understanding of physiological limits. Can Han Solo pull a tent from his backpack and erect it within minutes? Is Han building a simple snow shanty over the course of hours? Where is the additional heat source coming from? If Han fails to act quick enough, Luke Skywalker dies from the effects of severe hypothermia, or at the very least, loses a limb or two.
Additional Dangers and caveats
The transfer of Luke from the tauntaun interior to the shelter becomes a problem as well. Any liquid on Luke's face would freeze within seconds of leaving the tauntaun, creating a solid case around Luke's mouth and nose that would need to be removed before Luke could breathe again.
What is inside the belly of a tauntaun? Feces, bile, stomach acid and more wonderful biological fluids. The wampa Luke fought in the previous scene left him with several lacerations. Any feces that comes in contact with these open wounds would make for a wonderful breading ground for infection.
As this is a tongue-in-cheek look at applying real world science to a fictional event, we should probably discuss a couple of unknown parameters and assumptions. This thought experiment assumes Luke Skywalker's physiology is the same as Earth-based humans and that his core temperature are similar to warm blooded animals. Also, Luke lacks Jedi meditation and healing skills, as the young Skywalker has yet to meet and train with Yoda.
Erring on the side of saving Luke's life (and the galaxy), we are also assuming the snow storm on Hoth did not venture outside the boundaries of temperature extremes for the planet. It very well could have due to the severity of the snowstorm at Echo Base. The effects of windchill are also neglected in this model, as well as any severe cooling of the tauntaun prior to Luke's insertion.
I want Luke to live, but there are plenty of real world hurdles to overcome for the son of Darth Vader. The bacta tank will help Luke overcome possible infections and promote limited tissue regeneration, but things don't look good for the 'ol farmboy. While this math and medicine, it's not the final verdict. Remember, it's just a movie — if Boba Fett can come back from partial digestion the depths of the Great Pit of Carkoon, Luke can fight off the effects of hypothermia.
Images from Lucasfilm and Kenner.