Let's be practical
Sending tourists around the Moon still seems impossibly ambitious, so let's focus on "sub-orbital" flights. These will take participants to the edge of space, around 100km above Earth, so they can experience "weightlessness" (microgravity) and the breath-taking view of our precious blue planet below.
Apart from lots of spare cash, what do we need to be a space tourist?
The first essential component is a spaceship that can withstand high G-forces (gravitational forces) and the sub-space environment, and launch, fly and land safely. It must protect us from environmental hazards outside — extreme high altitude and low barometric (atmospheric) pressure, extreme cold and a virtual absence of oxygen.
A lot of training
We will need highly trained and experienced pilots, and to be suitably trained and attired ourselves.
In his book Endurance, Nasa astronaut Scott Kelly mentions that he had been training since 1999 in one way or another for his 2015-16 year-long mission to the International Space Station. We would expect our space pilots also to have been through a long apprenticeship.
What about ourselves? Like any fledgling exploration enterprise, commercial imperatives are well ahead of governmental regulation, so it is likely to be left up to operators as to what training is required.
However, we can expect this to include informed consent and emergency response training, and physiological familiarisation training. This might include time in a centrifuge to simulate high G-forces, an altitude chamber to simulate low atmospheric pressure and low oxygen levels, and perhaps "parabolic" flights to provide an experience of weightlessness (like the infamous Nasa "Vomit Comet" — a zero gravity plane).
So who's in?
This brings us to the tricky question of who should be a space tourist?
Only the fittest, healthiest people can become astronauts. However, the bar is likely to be a lot lower for space tourists, and each commercial provider will, for now, set its own standards. Passengers may need to visit a specialist doctor for a "space medical" and an assessment of their response to training.
People with pre-existing medical conditions will not necessarily be excluded. That said, they will need to demonstrate an ability to manage the psychological and extreme physiological stresses of a sub-orbital journey, such as high G-forces and relative hypoxia (low oxygen) at altitude, and to handle themselves safely in an emergency.
In addition to providing a pressurised cabin with supplemental oxygen, risk mitigation strategies may include passengers wearing body-hugging pressure suits for protection against the effects of sudden depressurisation and hypoxia.
Even if you get past these hurdles, there is no way of predicting who will develop space motion sickness (nausea and/or vomiting) when exposed to microgravity. This occurs due to the disorientation of the vestibular (balance) system in the inner ear when it loses its familiar inputs. This risk should not be a deal-breaker (the same as for astronauts), but would need to be well managed as it could otherwise be hazardous for everyone in the cabin.
With any type of human exploration, there are risks as we push boundaries, and there are inevitably mishaps and fatalities as a result. Space tourism will most likely not be immune, which means I will not be rushing into booking a ticket (even if I could afford it).
• Rowena Christiansen is a medical education tutor, doctor and researcher, University of Melbourne As children, surely most of us had dreams of becoming an astronaut.
- The Conversation
