Biology, Physics, Space, Spaceflight

How to Survive Spaceflight

‘To Mars!’

As both Government Space Agencies and Private Companies turn their attentions to long-haul spaceflight, plenty of problems have arisen! It isn’t just the logistics of living on the moon and mars, but getting there has provided its own plethora of difficulties to be solved!

I have already written a post about the spacecraft of the present and the future, and you can check that out here! Now, it’s time to investigate what the journey to the moon or mars would be like!

A graph showing the relationship between the cube of the distance from the centre (in this case the sun), and the square of the orbital period, featuring planets in our solar system.
Kepler’s Third Law, which explains the relationship between how far a planet is from the centre and the length of its year.

First of all, you have to launch at the right time. The earth and Mars orbit the sun at different speeds, as explained by Kepler’s Third Law. This means that the distance between Earth and Mars varies drastically. At its closest, mars is 33.9 million miles away, however the closest it has been for 50,000 years was in 2003, at 34.8 million miles.This happens when Mars and Earth are ‘at opposition’ and is the prime time for a space launch to mars, because it will only take about 200 days. But at its farthest, when Mars is on the opposite side of the sun, it would take far longer, and to be honest no one in their right minds would launch a spacecraft then- it would be so slow!

On average, a flight to Mars takes about 300 days. (Although it is very much dependant on the size and fuel used). Oh, and getting to Mars requires LOTS of maths: obviously, mars is always moving, so you can’t just fire it in a straight line. You have to figure out where the trajectory of your spacecraft, and the orbit of Mars will intersect- called a Hohmann transfer.

Diagram of the Hohmann Transfer.
Hohmann transfer. Basically you have to calculate where the planet will be once your craft reaches it.

Currently it is:

192.6 million miles

309 million kilometres

2.072 AU

Screenshot of the website distance to mars. Shows a cartoon image of the earth, with Low earth and GPS orbits marked. Writing says: 'if the Earth was 100 pixels..."
This is an amazing website that really highlights the distance between the Earth, Moon and Mars.
Click the image above

The spacecraft would be the astronaut’s home and workplace for at least 8 months. Each way! To compare, most astronaut’s only spend 6 months on the ISS, although Scott Kelly spent a year in space, and cosmonaut Valeri Polyakov spent a record-breaking 438 days in space (14 months) back in 1994/5. Like the ISS, there would have to be space for research, as well as taking care of astronaut’s’ physical and mental health. Sitting in a tiny Orion capsule for months on end would drive you crazy!

Scott Kelly taking a selfie in front of the cupola window on the ISS, which shows a group of islands surrounded by shallow seas and deeper seas further out. Lots of shades of blue!
A selfie of Scott Kelly from the ISS- isn’t Earth beautiful?!
image via

Living in close capacity for months on end could result in tension between the astronaut’s. So far, this hasn’t been a major issue, as they are carefully selected for mental capabilities, as well as physical, and the relatively short delay between mission control and Low Earth Orbit means that astronaut’s are able to communicate with their families or communities easily. On their way to mars, this time delay increases significantly, which will be very annoying, and possibly dangerous- just watch the film the Martian to understand the significance! When Mars is at its closest, there is about a 3 minute delay. At its farthest it can be up to 24 minutes. Which makes conversations rather difficult!

It is especially important for astronauts to exercise every day, due to the weightlessness they constantly experience, which leads to muscle atrophy- muscle weakening (as less effort is needed to produce the same amount of force, so their muscles are under less stress). This not only affects skeletal muscle, but the heart as well. On the Space Station, they have a very cool resistance machine, called ARED for exercises like deadlifts, heel raises, squats, as well as a ‘bike’ (CEVIS) and treadmill (COLBERT). Using these, Astronauts on the ISS have train for 2.5 hours a day, 6 days a week, but still lose over 20% of their skeletal muscle. To combat this, NASA is currently using the ISS to research diets, medication and other enhanced exercise programs so missions to mars become more practical, because this effect would be felt even more on longer missions, and if the mission also includes a period on the surface of mars, the astronauts need to be able to function unassisted straight away!

Although most of the equipment can be neatly folded away, it still takes up space, and so does all the other supplies they need.

One of my favourite ideas for interplanetary spacecraft is and inflatable habitat! The Orion Spacecraft has less that 9m3 of habitable space. That’s not much room at all, given that there is 85m3 per person of habitable space on the ISS, and a 2105 article from the Johnson Space Centre recommended 25m3 /person as the Minimum Acceptable Habitable Volume. I’m not sure what they will do for the proposed mission to Mars in the 2030s , but they have 10 years to think about it! Currently, the only inflatable habitat currently in space is the Bigelow Expandable Activity Module, which is currently being used for storage! It was deployed by Tim Peake in 2015, and underwent testing in 2016. At the end of 2017, NASA announced that its monitors had picked up a few micrometeorite impacts, but the protective walls are still very much intact and the pressure and radiation dosage is comparable to the rest of the station.

4 consecutive images showing the Bigelow Inflatable Module inflating after it was attached to the ISS
Photo series showing the Bigelow inflatable module inflating
Image via Wikipedia

Although, no longer science fiction, testing is slow, and an inflatable spaceship seems a long way off..

A Risky Business

As well as muscle atrophy, astronauts receive a far higher radiation dose than on Earth, meaning they are at risk of getting cancer and other complications due to DNA mutations. For a round trip to mars, the radiation dose would be around 200x the average annual dose on earth. This exponentially increases the risk, so even more measures would have to be taken, such as even thicker walls and testing.

You also have the threats of micrometeorites and depressurisation to contend with, as demonstrated by the incident last year, when a tiny hole was found on the ISS. Although the cause is disputed, and the actual danger was small, it represents a real threat to the astronauts that would be amplified on longer missions, where the spacecraft would be moving much faster, and there is possibly even more unseen ‘space junk’ also travelling at insane speeds, so collisions would be even more dangerous.

Close up of the hole against the white background of the inside walls of the ISS
The tiny hole that lead to part depressurisation of the station (nothing major, but still pretty scary!!)

Elon Musk’s goal is to reduce the price of getting to mars to about the same as buying a house! Personally, I think this is slightly wishful thinking, considering that after 60 odd years of space travel, it costs between $2000 and $20,000 per kilo depending on the rocket used and total payload mass! That means that most spaceflights, especially those entering or passing Low Earth Orbit, cost millions and billions of dollars! Currently, it is estimated to cost at least $500 billion!

Despite all the risks and obstacles, I am certain that setting foot on the moon or mars and establishing a base is achievable, and will be worth it. Why? Well after the famous JFK 1962 ‘We choose to go to the Moon’ speech, NASA’s budget soared. This had, and has, far reaching effects, as NASA’s research is more than just space, like the osteoporosis research, so a larger budget for spaceflight will benefit the whole world, in ways currently unknown!

Would you like to go to Space? To the Moon or Mars? Do you think that the benefits outweigh the risks?


If you can’t trust an atom… trust in science!

☆it’s like magic, but it’s true whether you believe in it or not!☆

See you next time!


Background: Rocket Launch timelapse against dark purple sky over flat water and a city. 
Wording: Stay Curious! And remember... Never Trust An Atom!

Radiation dosage calculated from:


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