Kulo nyaka ERoyal Institution sika Christmas Izinkulumo sibheke inselele komuntu indiza emkhathini futhi yini edingekayo ukuze bejikijelana abantu singene Umngcele sokugcina uhambo ukuhlola.
Njengoba udokotela ngachitha iminyaka engaphezu kweyishumi enyuka phakathi UK kanye kanye Nasa sika Johnson Space Center e Houston, ukusebenza njengoba umcwaningi evakashele kumaphrojekthi esukela ukutadisha imiphumela ye imvelo isikhala ukuguga physiology ukuze yokufakelwa amandla adonsela phansi izinhlelo. Ngesikhathi esifanayo sengizoqeda ngiyoqeqeshelwa junior wezokwelapha e yokubulala izinzwa kanye esegumbini labagula kakhulu. Okwakungahambi kahle uzama Splice kulabo izimpilo ezimbili ndawonye. Ukusebenza on an labagula olunzulu avuke engasenalo, elibangise sezindiza ekupheleni the shift, washo ubuthongo indiza, bese ifika ngosuku olulandelayo ekamelweni umhlangano in Houston, lapho abantu base ngihlezi nje bexoxa ngendlela ukuthumela abantu ngokuphepha Mars.
Kodwa into ayeyazi ezimbili kwaba inselele yokuphila at the ukweqisa. In esibhedlela ebengikufuna ngesikhathi ukweqisa wokuphila lapho esongelwa isifo nokulimala. At Nasa I ebuka usongo ukuze izitho zomzimba womuntu by obudluleleko endalweni bese universe.
Lapho sikhuluma ezindaweni ngokwedlulele sitho- umqondo olunzima austerity zabo by ukwahlulela bayohlala ukusekela isikhathi eside kangakanani ukuphila kobuntu olungavikelekile kanye engasekelwe. Ngawo lowo isikhala isilinganiso ngokwedlulele ultimate: ehlukile ephikisana physiology womuntu, it inikeza akukho ukwesekwa ukuphila komuntu leze. I olungavikelekile isikhala ngezebhizinisi babezosinda endaweni enjalo imane nje imizuzwana embalwa.
Ungase ucabange ukuthi bekuyoba khona inala udokotela ukuba enze - ukuthi uma kuziwa womuntu ukuhlola umkhathi, abantu abaqondayo futhi angalawula physiology womuntu ayeyoba iyahola ukuthi umzamo. Kodwa odokotela badlale ivayolini yesibili abampofu ukuba siyini lilidlula isiko engineering - futhi ngesizathu esihle.
indiza Space kuyinto ngokomthetho ngokomzimba disarmingly elula. Ngakho elula eqinisweni lokuthi Newton ayeseqalile ukuqonda Dynamics okusekelwe cishe zikhathi 400 iminyaka edlule. Ukuze Sihambe Emhlabeni bese ufaka i emzileni sizungeze it, wena kuqala kudingeka baphonse intfo embulungeni yonke kanzima ukuze trajectory budlulela ngalé khathizwe eMhlabeni - kanzima ukuze kungashiwo wawiswa ngendlela yokuthi baphinde nanini ithola emhlabathini.
Futhi ngakho ukubeka intfo ibe emzileni sizungeze Emhlabeni kufanele asinike omkhulu kakhulu amandla. Ngamagama abanzi ngokushesha hamba khudlwana engaba emzileni uyifinyelele; ukuze uthole imoto ukufinyelela orbit ebanzi ngokwanele ukuze uthole yona miss kokubili Earth futhi izingqimba engenhla emkhathini, ukubeka ngamazinga engamamitha efanayo njengoba International Space Station abanye 250 miles ngenhla us, udinga ukuba bahambe ngabo-17,500mph.
Lokho kudinga imoto eyayimfuqa by izinjini and uphethiloli amathangi sinekhono kuqhume isikhali encane yenuzi. Loluhambo lwekutfola, ebusweni Zomhlaba zibe ongaphakeme Earth orbit - ababegibele Soyuz mkhathi - kuthatha isikhathi esingaphezudlwana imizuzu eyisishiyagalombili. Futhi ngakho yokuthi isiko at Nasa, futhi isikhala ejensi nasemhlabeni wonke, ibizwa kanjalo ebambelela ngokuqinile okufunwa engineering kunalabo of ukwakheka komuntu kungenxa yokuthi ngaleso sikhathi emfushane kodwa enobudlova kukhona cishe lutho iqhaza kwezokwelapha zanamuhla kungaba ukunikela ngendlela sesivikelo. Ngesikhathi kwethulwa, noma lonjiniyela lisebenza futhi wonke umuntu ohlala, noma asipheli futhi wonke umuntu liyabhubha.
I ukusindiswa kwabantu kulo lonke kwethulwa akuxhomekile phezu izinqubo zokwelapha kodwa on izingqimba eyindilinga eyenziwe ukuvikelwa yokufakelwa ukuthi onjiniyela ekuklameni nasekwakheni futhi swaddle amatilosi astronaut in.
I izinjini rocket kumele axoshe ngokuphelele, kokukhulula ama nje iphuzu ilungelo ngesikhathi esifanele, waqondisa in ngokunembile indlela efanele. Amandla omkhulu ukuthi ngamandla akumelwe bavunyelwe ukuba nithintithe imoto, izinhlelo zayo noma imithwalo yayo ethambile abagibeli ahluke. Ngakho-ke kuwumsebenzi amaqembu engineering ukwenza isiqiniseko ukuthi isiqalisi imoto zenzelwe ukuba azoyidlalela umculo ubuso amabutho ukuthi zizama ukuba ayibhubhise.
Futhi aqhwakele phezu ukuthi embhoshongweni uphalafini nomoya-mpilo is a capsule encanyana, ne umthamo nedlanzana ngocingo amabhokisi, futhi umbhangqwana amathani izinto abagibeli abathathu baminyana phakathi kwabo. Lokho capsule kuyinto bubble encanyana ye yini nokusekela ukuphila kwakhe, babancwebe nyá emhlabeni futhi zigcinwe ngendlela engesiyo. Inside, namanje imishini abaletha esimweni esiwuhogelayo ne ezikuci- nokufudumala ukuze isekele ukuphila kule engenakuqonda isikhala. Uma sisinde kwethulwa, izinkinga zakho ngempela nje isiqala.
International Space Station
Akuve ukucabanga we-International Space Station njengoba hi-tech Big Brother indlu, elintantayo phezulu ngaphezu komhlaba. Kwezinye izinzwa ukuthi kuyiqiniso: izimo zokuphila abanokhahlo yinoma yimuphi ejwayelekile evamile. Kunezindawo ezimbalwa isidalwa ekunethezekeni nasekwanelisekeni kwawo ubumfihlo kancane eziyigugu. It is a ilungiselelo lokuphila bristling abanesifiso yezingxabano ezinkulu kwezenhlalo. Kodwa ngokuphawulekayo lokho ngokuyinhloko kugwenywe futhi ngo 15 zeminyaka operation kuye kwaba akukho ukuxoshwa.
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. Nakhu, 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 miles away, 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 mkhathi 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; Ngaphezu kwe 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. Ngenxa yalokhu, 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.
muva nje, 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, water, 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 futhi 30 December at 8pm. Find out more on the Royal Institution’s website and join the conversation on Twitter and Instagram by following @ri_science or searching for #xmaslectures
guardian.co.uk © Guardian News & Media Limited 2010