When humans go to Mars, there had better be an orthopedic surgeon on the flight.
In an interview with CNBC, Elon Musk said he was “highly confident” that SpaceX
will land humans on Mars by 2026.” This is no simple feat… Mars is approximately
300 million miles away and the trip will take about 7 months to complete. And while the
scientists and engineers aboard the expedition will do everything within their power to ensure
safe arrival of the spacecraft at Jezero Crater on Mars, outer space is a hostile environment
with many variables - both known and unknown - that might jeopardize the safety of the
travellers.
NASA’s Human Research Program (HRP) is dedicated to keeping astronauts safe and productive
on extended trips through space, and has graciously made their findings available to the public.
As we examine the known effects of extended space travel on the human organism, and other
acute stressors present in space, it is clear that astronauts are at risk of various illnesses
and injuries. And while there are a whole host of things that can go wrong while in
space, for this video, we are going to focus on musculoskeletal problems only
While astronauts do receive basic medical training, and are able to perform simple tasks
such as IV administration, ultrasound scans, basic laboratory testing, many of the health
issues that arise may require more specialized care. Any team of astronauts bound for Mars
must be totally self-sufficient and capable of functioning in complete isolation. They
are too far to receive supplies from cargo flights from earth and there is a communication
delay of up to 20 minutes when transmitting to NASA’s mission control. Can you imagine
packing food and medical supplies for a dangerous multi-year expedition? And what would it be
like to have perform a complex procedure without any previous knowledge of that procedure using
only instructions that arrive by electronic transmission? Most of us can barely handle
the 1-sec delay on a Zoom teleconference call. Imagine what that delay might be like when
you are trying to perform a critical, life-saving surgical procedure. “Can you hear me now”
patois.
The human organism is precisely calibrated for life in the Earth’s gravitational field.
But on an expedition to mars, astronauts will encounter three unique gravity fields; weightlessness
while between planets, approximately ⅓ of Earth’s gravity while on mars, and our native
gravity again upon re-entry. Transitioning between gravity fields affects us in countless
ways. ​​
Notably in microgravity, the bones lose mineral density and the muscles atrophy without the
effect of gravity making them work as hard.
NASA has learned that without Earth’s gravity affecting the human body, weight-bearing bones
lose on average 1% to 1.5% of mineral density per month during spaceflight. When our team
arrives on Mars (approximately 7 months after lift-off) their weight-bearing bones will
have lost between 7% and 10.5% of their mineral density – that is a significant difference.
In fact, the rate of bone loss in astronauts is approximately 10 times that seen with osteoporosis.
After a return trip– if our space-goers ever come back, they would face a 14% to 21%
mineral density decrease on weight-bearing bones. Not to mention that it would take 3-4
years to recover this lost bone density once back on earth. It is not clear how long it
would take to recover this if they remained on Mars, but it is likely to take longer than
that, and it is probable that the full bone density would not be restored since Mars’
gravity is considerably less than on earth. And with the homeostasis between calcium intake
and excretion shifted in favour of calcium loss, astronauts are additionally plagued
by the increased likelihood of kidney stones. And if you’ve ever had one of those, you
will know that it is one of the most painful experiences possible. Not something that an
astronaut would be particularly looking forward to.
Without the proper diet and exercise routine, astronauts also lose muscle mass in microgravity
significantly faster than they would on Earth.
Resistance training is a little more complicated in space since normal gym equipment is rendered
useless in microgravity. You can’t lift a weight that is weightless… An article
by VERGE explains that “the International Space Station is equipped with three machines
designed to give astronauts that full-body workout: a bicycle, a treadmill, and a weightlifting
machine called ARED, for Advanced Resistive Exercise Device. Each machine is specially
designed for space” employing small grips, canisters, straps and pads to help generate
enough resistance for the astronaut to get a workout. In an attempt to minimize bone
loss and muscle atrophy, Bob Tweedy, the countermeasures systems instructor at NASA’s Johnson Space
Center says astronauts on the station work out six out of seven days a week for 2.5 hours
each day.
NASA is also studying several types of medication, such as bisphosphonates, that have been shown
to prevent skeletal bone loss, but none of these substances are able to fully counteract
the effect of weightlessness on the human body. Bisphosphonates are a class of medications
normally used as a first line treatment against osteoporosis. They treat osteoporosis by slowing
the rate of bone resorption through the reduction of osteoclast activity. While bones have the
appearance of being static structures, they are constantly changing through a process
called remodeling. Normally, old bone is resorbed by cells that consume bone, osteoclasts, and
new bone is laid down in response to stresses placed upon the bone by cells that produce
bone, osteoblasts. On earth, these processes are finely tuned to be in balance with one
another so that whatever is lost, is replaced. But in space, with the balance tipped in favour
of bone resorption, medication is required to equalize this disparity.
During spaceflight, if your muscles and bones exist in a weakened state– then astronauts
are more susceptible to injury, not only during the journey to Mars, but once they arrive
as well. In a study published in Aviation Space and Environmental Medicine, 219 in-flight
musculoskeletal injuries were identified. Hand injuries represented the most common
location of injuries, with abrasions and small lacerations representing common manifestations
of these injuries. Crew activity in the spacecraft cabin such as transiting between modules,
and aerobic and resistive exercise, were leading causes of musculoskeletal injuries.
Extra Vehicular Activity (EVA) is another common cause of injury. The astronaut exits
the spacecraft wearing a pressurized space suit that is physically restrictive and very
difficult to maneuver. EVA injuries can be divided in two different groups: contact injuries
and strain injuries. Contact injuries refer to contusions, abrasions, or hard impacts
with the spacesuit, whereas strain injuries are due to overuse, repeated movements, and
development of high muscle forces. Strain injuries can occur when astronauts are manipulating
heavy tools, working at the limit of their work envelope, or forcing the shoulder joint
against the spacesuit.
NASA’s Human Health Countermeasures Team studied EVA injuries in depth and found that
“Hand and finger injuries are the most common injuries during both training and flight,
and include onycholysis, fingernail delamination, blisters, contusions, and abrasions.” They
went on to say that “shoulder injuries typically occur during training and induce some of the
most serious harm… Most injuries that occur at the limb joints (wrist, arms, knees, and
ankles) are abrasions and contusions as a result of rubbing and impact against the soft
suit components to move the garment.”
Unfortunately for astronauts who suffer serious injuries that may require surgical treatment,
surgery in space is notoriously difficult and not yet safe to perform on a human. However
there are things that a trained surgeon can do to help treat an injury without performing
surgery.
With the available information and common sites of injury that we just covered, I would
be prepared for the following types of injuries to occur: minor sprains of the hands and elbows,
strains of the shoulders, sprains of the knees and ankles, rotator cuff tears, and even fractures
of the small bones of the hands. And I would treat them to the best of my ability with
non operative measures such as: temporary splinting where immobilization is needed (fractures
or dislocations), temporary elevation and compression to address initial swelling, progressive
movement of the injured body part, and gradual loading of the body part and surrounding joints
to restore function over time. This is a distillation of the PEACE and LOVE approach to soft tissue
musculoskeletal injuries proposed in the British Journal of Sport Medicine, which is a more
modern, nuanced replacement to the older, outdated, RICE approach previously used for
soft tissue
When our astronauts take their first steps on the surface of Mars, their muscles and
bones will be weaker. Their brains will also be calibrated to expect weightlessness, and
it will take some time to adjust their spatial orientation, hand-eye coordination, balance
and locomotion to the gravity of Mars. Although the surface gravity on Mars is only
about 38% of the surface gravity on Earth… This is a very significant change in load
for the astronaut’s muscles and bones that have had 7 months to adapt to weakened gravitational
forces. As they take their first steps in unfamiliar terrain, these astronauts will
be in immediate risk of injury. Some injuries that may occur at this time are: fractures
of the lower extremities as a result of weightbearing or falls, fractures of the upper extremities
as a result of falls, compression fractures of the spine as a result of the sudden increase
in spinal loads suddenly experienced when the osteopenic vertebrae are subjected to
the increased loads associated with the sudden return of gravitational forces. We might also
expect the astronauts to experience issues with headaches, eyesight, blood pressure regulation,
and swelling of the extremities as a result of the gravitational effects on the circulatory
system.
We must also remember that on Mars, there is not enough atmospheric pressure to sustain
life without a pressurized suit. As we begin to establish life on Mars, astronauts will
have to operate heavy machinery and vehicles, move and lift things while wearing an Extravehicular
Mobility Unit or EMU… and as we already know this creates greater risk for the squishy
human organism inside, especially in the wake of accelerated muscle and bone loss.
Now surgery in space is difficult for many reasons… on a prolonged trip like the one
to Mars must even take into consideration the weight of the surgical kit and the efficacy
of an inhaled anaesthetic in alternate gravitation. “The reality is that astronauts heading
to Mars have to face a much greater level of risk. There are striking parallels with
the limited care available during polar expeditions.” Whoever is tasked with performing surgery
for those who need it on Mars will have to be prepared for an entirely unfamiliar set
of conditions.
It would be difficult to program a robot to complete these surgeries as there are many
variables, and we cannot forecast how the human body and it’s systems will react under
⅓ earth’s gravity. A human may be better for the job as they can react in real time
to unforeseen stressors and intuit creative solutions with a patient under the knife.
But a surgeon who has undergone 7 months of space travel may require a re-learning period
to steady their hands and restore the manual dexterity necessary to perform surgical procedures
successfully. Some have also suggested a combination of a human and robotic technology is the ideal
surgeon for a space expedition: a human’s creative brain operating robotic arms that
are not susceptible to muscle and bone loss or reduced hand-eye coordination under new
gravity which would certainly be better than the alternative of a remotely-operated robot
guided by an earth-based surgeon with a 20 min turnaround for instructions…but that
is a topic for another video.
And of course, this is only considering the musculoskeletal effects of space travel to
the red planet. This does not even cover the effects of radiation, isolation, and the duration
of time associated with the sheer distance of travel. For more information on those aspects
of Mars space travel, please check out this video from Marcus house on those topics. I
will leave a link to his video in the description below. radiation, isolation and distance
Outro