ឆ្នាំនេះ សាស្រ្តាចារ្យរបស់រាជស្ថាប័នបុណ្យណូអែល រកមើលនៅក្នុងបញ្ហាប្រឈមនៃការហោះហើរអវកាសរបស់មនុស្សនិងអ្វីដែលវាត្រូវការដើម្បីបោះមនុស្សចូលទៅក្នុងការប្រកួតវគ្គផ្តាច់ព្រ័ត្រព្រំដែននៃការរុករករ៉ែនៅលើដំណើនាវាចរណ៍.
ក្នុងនាមជាគ្រូពេទ្យម្នាក់ខ្ញុំបានចំណាយពេលច្រើនជាងមួយទសវត្សរ៍បានធ្វើដំណើរទៅវិញទៅមករវាងចក្រភពអង់គ្លេសនិង Nasa បាន មជ្ឈមណ្ឌលអវកាសចនសុន នៅហ៊ូស្តុន, ការធ្វើការជាអ្នកស្រាវជ្រាវដែលមកទស្សនានៅលើគម្រោងចាប់ពីការសិក្សាលើឥទ្ធិពលនៃបរិស្ថានអវកាសនៅលើប្រព័ន្ធភាពចាស់សរីរវិទ្យាទំនាញសិប្បនិម្មិត. នៅពេលជាមួយគ្នានេះខ្ញុំបានបញ្ចប់ការបណ្តុះបណ្តាពេទ្យយុវជនរបស់ខ្ញុំនៅក្នុងការប្រើថ្នាំសន្លប់និងការថែទាំយ៉ាងយកចិត្តទុកដាក់. វាជាសេសព្យាយាមដើម្បី splices ជីវិតទាំងពីររួមគ្នា. ធ្វើការនៅលើបន្ទប់ថែទាំពិសេសពេញមួយយប់, ធ្វើដំណើរទៅព្រលានយន្តហោះនៅចុងបញ្ចប់នៃការផ្លាស់ប្តូរនេះ, ចាប់យកការដេកលក់មួយចំនួននៅលើយន្ដហោះបាន, ហើយបន្ទាប់មកបានមកដល់នៅថ្ងៃបន្ទាប់នៅក្នុងបន្ទប់ប្រជុំមួយនៅ Houston, ដែលជាកន្លែងដែលមនុស្សត្រូវបានគេអង្គុយនៅជុំវិញនិយាយអំពីរបៀបក្នុងការបញ្ជូនមនុស្សទៅភពព្រះអង្គារដោយសុវត្ថិភាព.
ប៉ុន្តែរឿងដែលបានតភ្ជាប់ទាំងពីរនាក់នេះគឺជាបញ្ហាប្រឈមនៃជីវិតនៅខ្លាំងនេះ. នៅក្នុងមន្ទីរពេទ្យខ្ញុំត្រូវបានគេសម្លឹងមើលខ្លាំងនៃជីវិតពេលដែលជំទាស់ដោយជំងឺនិងការរងរបួស. នៅឯណាសាខ្ញុំត្រូវបានគេសម្លឹងមើលការគំរាមកំហែងចំពោះសរីរវិទ្យាមនុស្សដោយខ្លាំងនៃពិភពលោករាងកាយនិងសកលលោក.
នៅពេលដែលយើងនិយាយអំពីបរិស្ថានខ្លាំងយើងអាចទទួលបានជាគំនិតលំបាកមួយនៃការរឹតត្បិតរបស់ខ្លួនដោយការវិនិច្ឆ័យថាតើរយៈពេលយូរពួកគេនឹងគាំទ្រដល់ជីវិតមនុស្សដែលមិនបានការពារនិងមិនបានគាំទ្រ. ដោយចន្លោះវិធានការនោះគឺជាការធ្ងន់ធ្ងរចុងក្រោយ: តែមួយគត់ដែលមានអរិភាពនឹងសរីរវិទ្យាមនុស្ស, វាផ្ដល់ការគាំទ្រសម្រាប់ជីវិតមនុស្សអ្វីទេ. មិនមានការការពារការធ្វើដំណើរអវកាសរស់នៅក្នុងបរិស្ថាននេះនឹងគ្រាន់តែសម្រាប់ពីរដែលមានមួយចំនួនតូច.
អ្នកអាចស្រមៃថានឹងមានច្រើនសម្រាប់គ្រូពេទ្យម្នាក់ដើម្បីធ្វើ - ថានៅពេលដែលវាមកដល់ការរុករករ៉ែអវកាសរបស់មនុស្ស, មនុស្សដែលយល់និងអាចរៀបចំសរីរវិទ្យាមនុស្សនឹងបានឈានមុខគេនៃកិច្ចខិតខំប្រឹងប្រែងដែលថា. ប៉ុន្តែវេជ្ជបណ្ឌិតលេងវីយ៉ូឡុងលើកទីពីរក្រីក្រអ្វីដែលលើសលុបវប្បវិស្វកម្មមួយ - ហើយជាមួយនឹងហេតុផលល្អ.
ការហោះហើរអវកាសគឺមាននៅក្នុងគោលការណ៍សាមញ្ញ disarmingly ដែលរាងកាយ. ដូច្នេះសាមញ្ញមួយនៅក្នុងការពិតដែលថាញូតុនបានចាប់ផ្តើមដើម្បីឱ្យយល់ពីសក្ដានុពលដែលគាំទ្រដល់វាជិត 400 ប៉ុន្មានឆ្នាំកន្លងមក. ការចាកចេញពីផែនដីនិងបញ្ចូលគន្លងមួយដែលនៅជុំវិញវា, ដំបូងអ្នកត្រូវការដើម្បីបោះវត្ថុនៅទូទាំងពិភពលោកមួយយ៉ាងខ្លាំងថាគន្លងរបស់ខ្លួនបានពង្រីកហួសពីការយល់ដឹងរបស់ផែនដី - ការលំបាកដូច្នេះវាអាចត្រូវបានធ្វើឡើងដើម្បីធ្លាក់ចុះនៅក្នុងរបៀបមួយដែលវាមិនជាថ្មីម្តងទៀតបានរកឃើញដី.
ដូច្នេះហើយដើម្បីដាក់វត្ថុដែលបានចូលទៅក្នុងតារាវិថីជុំវិញផែនដីដែលអ្នកមានដើម្បីផ្តល់នូវវាជាមួយយ៉ាងច្រើននៃថាមពល. នៅក្នុងលក្ខខណ្ឌទូលំទូលាយលឿនជាងមុនដែលអ្នកបានចូលទៅកាំធំនៃគន្លងដែលអ្នកសម្រេចបាននូវ; ដើម្បីទទួលបានរថយន្តមួយដើម្បីសម្រេចបាននូវគន្លងមួយដែលធំទូលាយគ្រប់គ្រាន់ដើម្បីទទួលបានវាដើម្បីនឹកទាំងពីរផែនដីនិងស្រទាប់ខាងលើនៃបរិយាកាស, ដើម្បីដាក់អ្នកនៅកម្ពស់ដូចគ្នាជា ស្ថានីយអវកាសអន្តរជាតិ មួយចំនួន 250 ម៉ាយល៍ពីលើយើង, អ្នកត្រូវការធ្វើដំណើរនៅជុំវិញ 17,500mph.
ដែលតម្រូវឱ្យរថយន្តជំរុញដោយម៉ាស៊ីននិងធុងប្រេងមានសមត្ថភាពផ្ទុះនៃអាវុធនុយក្លេអ៊ែរតូចមួយ. ការធ្វើដំណើរនេះ, ពីផ្ទៃខាងលើនៃផែនដីចូលទៅក្នុងគន្លងផែនដីទាប - ជិះនៅលើយានអវកាស Soyuz - ត្រូវចំណាយពេលបន្តិចជាងប្រាំបីនាទី. ដូច្នេះហើយមូលហេតុដែលនៅឯណាសាដែលបានបណ្តុះ, និងទីភ្នាក់ងារអវកាសនៅទូទាំងពិភពលោក, ចាក់ឫសគល់យ៉ាងរឹងមាំត្រូវបានដូច្នេះក្នុងការទាមទារនៃវិស្វកម្មជាជាងអ្នកដែលនៃជីវសាស្ត្ររបស់មនុស្សគឺដោយសារតែនៅក្នុងរយៈពេលខ្លីប៉ុន្តែអំពើហិង្សាដែលថាមានស្ទើរតែគ្មានអ្វីអាចផ្តល់ជូននូវថ្នាំសម័យទំនើបនៅក្នុងវិធីនៃការការពារ. ក្នុងអំឡុងពេលនៃការចាប់ផ្តើម, វិស្វកម្មធ្វើការទាំងមនុស្សគ្រប់គ្នារស់នៅនិងការ, ឬវាមិននិងមនុស្សគ្រប់គ្នារលួយខូច.
The preservation of human life throughout launch depends not upon medical procedures but on concentric layers of artificial protection that engineers design and build and swaddle the astronaut crews in.
The rocket engines must fire perfectly, delivering just the right thrust at just the right time, directed in precisely the right way. The tremendous force of that propulsion mustn’t be allowed to shake the vehicle, its systems or its fragile cargo of passengers apart. It is the job of engineering teams to make sure that the launcher and the vehicle are designed to perform in the face of forces that are trying to destroy them.
And perched atop that tower of kerosene and oxygen is a tiny capsule, with the volume of a handful of telephone boxes, and a couple of tonnes of supplies and three passengers crammed in among them. That capsule is a tiny bubble of life support, pinched off from the Earth and maintained artificially. នៅខាងក្នុង, still more machines provide a breathable atmosphere with enough pressure and warmth to support life in the void of space. If you survive the launch, your problems are really only just beginning.
It’s tempting to think of the International Space Station as a hi‑tech Big Brother house, floating high above the Earth. In some senses that is true: living conditions are harsh by any normal standard. There are few creature comforts and precious little privacy. It is a living arrangement bristling with the potential for huge social conflict. But remarkably that is largely avoided and in 15 years of operation there have been no evictions.
But the ISS is much more than an accommodation block. When crews go to live there they are taking up residence inside a machine upon which their lives depend every second of the day. They electrolyse water to produce oxygen, employ molecular sieves to scrub waste gases out of the air that they breathe, run heating systems from vast solar arrays that can pump out 80kW of power. That solar energy also drives four huge gyroscopes, which steady and steer the station, preventing it from tumbling out of control.
The International Space Station is far from tranquil: it hums and whines perpetually; fans are running all the time. Without gravity hot air doesn’t rise and cold air doesn’t sink. There is, as a consequence, no convection and without that it’s hard to get air to move or mix. That in turn causes problems, leaving astronauts prone to headaches in poorly ventilated areas, where exhaled carbon dioxide can build up. Hence the constant drum of motors churning air. The draughts on the ISS, like almost everything else that the crews depend upon for healthy living, are artificial. All of this effort just to maintain that bubble of life support in an outpost just 250 miles above our heads. The challenges involved are legion and we haven’t even started to talk about leaving low Earth orbit yet.
Back to the moon
There is unfinished business on the moon. It is nearly half a century since the Apollo programme landed a dozen men on its surface. And while it represents a treasure trove of scientific discovery, nobody has been back since. Low Earth orbit is 250 miles away and can be reached in minutes. The moon is about 250,000 ម៉ាយល៍, takes days to get to and, in addition to isolation and the added complexity of the rocket science required, leaves crews extremely vulnerable to radiation. On Earth we’re protected from some types of radiation by the thick blanket of atmosphere above, which absorbs gamma rays, x-rays and ultraviolet radiation that would otherwise be harmful. But there’s another layer of protection that also keeps us safe: Earth’s magnetic field.
The magnetosphere filters out a particularly harmful species of radiation, which comes in the form of charged, high-energy particles – atomic nuclei spat out as a by-product of thermonuclear reactions in stars including our own. This type of radiation is particularly harmful and, during solar flares, can increase in intensity by many thousands of times. Presently we have little in the way of effective protection from the radiation that comes with the worst solar flares.
Mars and beyond
In recent years the idea of putting human crews on the surface of something other than the moon or Mars has found its way into the strategy documents of the international space agencies. This mission is less science fiction than you might think. The European Space Agenecy’s Rosetta mission, which so spectacularly landed the Philae lander on the surface of a comet last year, showed us that we could find and intercept a tiny target hurtling through space hundreds of billions of miles away. This has given agencies confidence that their idea of landing a human crew on an asteroid might be realisable.
But for now it is Mars that lies at the edge of possibility, and surviving that journey presents a challenge on a different scale. With Mars, the problem is distance and time. To get to the red planet you have to traverse hundreds of millions of interplanetary miles; ច្រើនជាង 1,000 times the distance Apollo crews travelled to the moon. With existing technology it would take between six and nine months to travel from Earth to Mars and the same again on the return leg.
That’s a lot of time spent without any gravitational load on your body. Weightlessness may look like fun, but like everything else, too much of it can be a bad thing. When physiologists first considered what effect the space environment might have on the human body, before anybody had even been into space, they correctly predicted that muscle and bone would waste. Those systems are sculpted by gravity and as anyone who has ever so much as looked at a gym knows, if you don’t use it you lose it. ព្រោះតែរឿងនេះ, crews aboard the International Space Station must subject themselves to a daily programme of resistive exercise to try and prevent some of that bone and muscle loss.
Weightlessness wreaks havoc with other systems. It upsets your senses of balance and co-ordination, making it more difficult for crew members to track moving targets, creating illusions of motion and, for the first few days of flight, generally making them feel pretty queasy. With the exception of the nausea, all of these problems tend to get worse the longer you spend weightless.
បន្ថែមលើសពីនេះ, new – and potentially more worrying – problems have cropped up. For reasons that are not yet entirely clear the pressure in some astronauts’ brains appears to rise as a consequence of space flight, and this has been linked to alterations in their eyesight that sometimes persist for many years after their return to Earth. This phenomenon has only been noticed after long duration missions, which highlights the message: spending a lot of time in space isn’t great for your health.
But time also creates problems for life support systems. If you imagine the amount of food, ទឹក, oxygen and power a single person might consume in a mission set to last up to three years (if you include the surface stay), that demands quite a sizable larder. Now multiply that by a crew of four or six and it looks like you need an impossibly huge spacecraft just to keep you fed and watered.
And that does become impossible unless you are able to recycle and reuse everything you can. Already aboard the space station astronauts recycle most of their waste water, including their urine. They scrub carbon dioxide out of their exhaled air and rebreathe the remaining oxygen. You might be able to go further still, by growing crops hydroponically, as a source of food and a mechanism of removing carbon dioxide and renewing the oxygen supply. If you choose the right plants you might even recycle the nitrogen in human solid waste. Which of course is a scientific way of saying that maybe you could use your own poo to fertilise your life-supporting crops.
A system as sophisticated as that is extremely difficult to assemble, manage and maintain, and it’s likely to be a while before we see greenhouses flying through deep space. For now life support engineers will content themselves with finding ways to recycle more and more of the resources they can, and in so doing reducing the amount of payload that crews have to set aside for the things that keep them alive.
There is a simple lesson from all of this: space is hard. All frontier endeavours are. But there is plenty to celebrate here. Since the start of the 21st century there has been a permanent human presence in space. What started as a surrogate battlefield for nuclear war has become a multinational programme of science, exploration and collaboration. This is not the place to get into a discussion of why we should explore space at all. There are many benefits that derive from human space exploration but one is more important than all the rest. Human space exploration inspires children to study and pursue careers in science, technology and engineering. It does so by showing them that within the limits of human imagination anything might be possible. I know this because it inspired me and throughout the whole of my life has continued to hold my fascination.
It is an enormous honour to give the Royal Institution’s Christmas Lectures. And yes, the take-home message is that space is hard. But the real lesson for this year’s audience is that this has been my adventure and it can be yours too.
How to Survive in Space will be shown on BBC4 in three parts on 28, 29 និង 30 December at 8pm. Find out more on the Royal Institution’s website and join the conversation on Twitter and Instagram បាន by following @ri_science or searching for #xmaslectures
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