Mars: Dry, desolate planet, 2nd smallest in the solar system and 4th from the sun; can one day be our next home. The planet is also called the Red planet because of the surface color imparted by high iron oxide level in soil.
Scientists speculate that billion years ago Mars did have favorable condition to harbor primitive life forms; but over the course of time it turned into dusty dead planet. Living on Mars can be as harsh as living atop the Mount Everest peak; honestly saying Everest top could be even better.
Handful of studies suggests that few billion years ago Mars used to have thick atmosphere with liquid water. The powerful magnetic force field which creates magnetosphere kept atmosphere intact; which in turn resulted in liquid water and stable warm temperature; free from most harmful radiations. But study of its geological features and atmosphere revealed a dark past; its magnetosphere got snatched. Continuous bombardment of strong solar winds and cease of plate tectonic activity is what caused its magnetosphere to fade. Atmosphere collapsed, most air flew away from the planet including water vapors. Very cold areas on planet’s pole though continued to retain water and carbon dioxide as ice.
With all favorable conditions gone, planet became dead. But scientists are not losing hope; they want to revive it back. They are already planning the settlement and tons of research is being conducted for the same. Out of the many issues regarding the settlement, human health is always of Primary concern. Though there are many heath issues that need addressing; as an optometrist I will be reviewing on problems our eyes can face. I want to inform all the readers that everything written would be as far as my knowledge and may not include problems entirely.
Here is the list of few things we need to be concerned about:
Microgravity during space travel and Low Mars Gravity
Gravity plays an important role on our body physiology. In conditions of microgravity or low gravity the flow of blood is more towards the head region; similar is with Cerebrospinal Fluid. This raises intracranial pressure. Normal ICP in a healthy person in upright position is around 5-10mm of Hg, which increases up to 15 mm of Hg during supine position. Few studies have found that astronauts at international space station have average ICP of 13 mm of Hg. So, why is ICP of major concern? It’s not about 15 or 13; it’s about for how long you are subjected to raised ICP. Raised ICP causes disc edema causing blurred vision. Edema for long duration may cause permanent damage to the nerves causing blindness. Space flight for more than 1 month may have such affect. But Mars; it takes around 8-9 months to reach there. Medications targeting CSF secretion, Cerebral blood volume, volume of aqueous humor (eg: acetazolamide ) may be of some help. Physical devices that increases IOP, decreases ICP such as pressurized goggles or lower body negative pressure could be relevant.
Long Duration mission in space may cause Spaceflight Associated Neuro-Ocular Syndrome (SANS). Prolonged stay at microgravity causes your choroid and retina to shift forward; it results in hyperopic shift. Astronauts at International Space Station (ISS) frequently complain of seeing earth blurry after few months of stay. Moreover situation might get worse; choroid develops folds, optics nerve sheath distends. Some end up with permanent vision loss while others may takes as long as 6 months to recover.
Gravity on Mars is 3.71 m/s2, which is nearly one third of the Earth’s Gravity (9.8 m/s2). It’s hard to tell the how much it will affect our eye since no person has been there. But concern still remains and we need more studies.
Low atmospheric Pressure:
Our Intraocular pressure is (770-780) mm of Hg which is countered by atmospheric pressure of 760 mm of Hg. The result would be (770/780)-760 equals 10-20 mm of Hg which is our normal measured IOP. Mars has an atmospheric pressure of around 6 mm of Hg; hence our IOP would be as high as 774 mm of Hg (780-6). You can imagine the consequences.
Moreover, water boils at 100 degree Celsius on earth; but on Mars it’s just 10 degrees. Our body temperature of 37 degree Celsius will probably make our blood and aqueous boil.
Extreme temperature fluctuation
Temperature fluctuation on Mars is from 20 degree Celsius during peak hot day to -70 degree Celsius at night in the equator. At poles temperature can go as low as -125 degrees. Even if you wear thick body clothes, your cornea will still freeze; tears will freeze. Blood vessels will constrict. Overall, it will affect your vision and permanently damage to your eyes.
Mar’s atmosphere primarily consists of consist of 95.32 % carbon dioxide and only 0.174% oxygen. Humidity is equivalent to the driest part of Atacama Desert in Chile i.e. low but still enough for survival of few life forms. Your cornea gets most of its oxygen from atmosphere but in Mars, hypoxia may cause severe corneal edema. Less humidity means severe dry eye. You may need goggles with humidifier and oxygen chamber.
Human beings in developed nations are exposed to an average of 0.62 rad per year. Studies have shown that we can withstand radiation dose up to 200 rads without permanent damage. But again it’s about duration of the exposure. On Mars exposure to radiation will be around 20 rads per year which may cause various kinds of skin cancer. That simply means skin around your eyes is not safe as well.
Carbon dioxide in atmosphere of Mars can absorb all UV radiation of 190nm and below. But UV-C (200-280nm), UV-B (280-320 nm) and UV-A (320-340 nm) remains totally unchecked. This may affect most of our ocular structures. We will need expensive glasses that cut off all sort of radiation.
It seems Mars settlement and daily living comes with high expenses and many health problems. Concept of air tight house and air tight tube channels for travel could be one way to settle on Mars. But one thing is clear; you cannot stroll free and feel the air of the planet. With ongoing studies on various aspects, it is essential for an optometrist to get involved, conduct experiments and resolve issues around eye and vision for extra planetary missions.
Author Rupesh Poudel, M-Optom Tilganga Institute of Opthalmology