Comparisons tell a stark tale. A round trip to the Moon could be achieved in a week and, in the event of a problem, rescue would just about be possible. A round trip to Mars would take close to four years and rescue would be impossible.
If the Earth is a basketball, Mars is an orange several hundred metres away, and both are moving so that distance and direction is constantly changing.
Our spaceship is smaller than a speck of dust that must leave Earth at just the right moment with just the right speed and in just the right direction towards an empty point in space where our computers tell us Mars will be eight and a half months from now.
Getting off the Earth takes a lot of fuel and we need fuel to slow our ship as it approaches Mars, but we cannot carry enough to make significant course changes. Most of the trip is powered by gravity which is out of our control; one small error could see our ship miss totally.
If our angle of approach is too shallow, we skip off the Martian atmosphere and finish in orbit around the Sun with no hope of rescue. If our angle of approach is too steep, we smash into Mars at 70,000km/h - 50 per cent of unmanned missions to Mars have either crashed or missed.
We leave Earth and our calculations are correct for the rendezvous, but what about the journey? Once we are into deeper space, the radiation level is much higher than on Earth and we are going to be in that environment for at least 16 months, while measurements by robots show levels of ultra violet radiation on Mars much higher than expected.
So we voyagers will have significantly increased risk of cancer and we should have our children before the trip as the chance of birth defects afterwards will be increased.
How many people could you stand to be with every day for almost four years? Your partner, your kids ... yes - but then it gets tricky. What if that proximity is about the size of a campervan. A crew composed of people who hate each other would end in disaster. Psychological aspects of long spaceflight are far from understood.
We have reached Mars without killing each other. To escape the radiation, we will probably be living in a hole in the ground. After eight months in weightlessness our muscles will have lost a lot of strength, making physical work harder.
How long should we stay? As with the time for leaving Earth we must wait for the planets to be in the right places. Earth and Mars will not be placed to make the journey possible for 26 months, so after eight and a half months in a campervan with five other people you now spend over two years with the same people with their same sweaty socks and annoying whistling living in a hole in the ground.
At the end of this ordeal we cram back into our campervan and, if the engine has not been damaged on landing and if the computer gets the calculations right, we leave Mars at the right moment and splash down somewhere in the Pacific Ocean eight and a half months later.
The technology is possible but who would pay for it?
The cost of getting men to the Moon was largely a political gesture by the United States - there was no financial gain.
Entry-level Martian expeditions come in at US$500 billion ($715 billion). There would be no financial profit.
Robotic mining of asteroids for valuable minerals will happen in the next 20 years but there is nothing on the surface of Mars that would turn a buck for investors.
The technology of this mission should not be seen as a step to the stars. Going to the stars, if the technology is possible, means you are probably not coming back.
It may be that your children get there, not you, the times and distance are so huge. The question we need to answer above all about going to Mars, is why?
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Frank Gibson is a semi-retired teacher of mathematics and physics who has lived in the Whanganui region since 1989
