William Shatner oldest astronaut at 90 – Here's how space tourism could affect older people

Blue Origin's New Shepard Launch on Oct. 13, 2021, see this video still. William Shatner is seen floating in front of his window with the Earth visible in background.
This article was first published by The Conversation. Space.com's Expert voices: Op-Ed and Insights was contributed by the publication.

Nick Caplan, Northumbria University's Newcastle Professor of Aerospace Medicine and Rehabilitation

Christopher Newman, Professor Space Law and Policy at Northumbria University in Newcastle

Space is the ultimate frontier. After boldly venturing where no 90-year old has gone before, William Shatner discovered the truth. Shatner flew for 10 minutes suborbitally on Blue Origin's New Shepard, 55 years after Captain James T Kirk first appeared on our screens in "Star Trek".

Shatner is now the oldest person to travel to space. This breaks the record held by Wally Funk (82 years old), who flew on the New Shepard's inaugural crewed spaceflight in July. Funk was among the Mercury 13 women who were qualified for spaceflight in 1960s, but never flew.

Spaceflight is now being offered to older adults by commercial spaceflight companies. It's time to think about the possible physical effects that space flight could have on them.

Video: William Shatner looks out from space at Earth in awe

Photo: Space launch by William Shatner with Blue Origin

The human body adapts quickly after just a few days spent in space. Because they aren't being used to move or stand up to gravity, the bones of astronauts begin to lose their density.

These changes don't pose a problem in microgravity but can increase the risk of injury (back pain, bone fracture) when you return to Earth. These adaptations are similar to those that affect people on Earth but occur much faster than age-related changes. Astronauts spend a lot of time in space exercising to reduce them.

A 90-year old person might be traveling in space with deconditioned muscles and bones. Their body may adapt further to gravity, which could pose additional risks. Although we can speculate, it is not possible to predict how their bodies will react to being separated from gravity.

Even if Shatner spends only a few moments in microgravity, he won't have to worry too much. Their health is most at risk from the physical and mental stresses they experience during launch, reentry into Earth's atmosphere, landing, and recovery.

William Shatner, actor in "Star Trek", poses for a photograph with Blue Origin NS-18 crewmates. This was taken during his record-setting launch to suborbital space at 90 years old on October 13, 2021. Blue Origin. Image credit.

Shatner, along with his three passengers, would feel vibrations during launch due to thrust generated by New Shepard’s BE-3 engine. This engine is more than 1,000,000 horsepower or more than 2,000x as powerful than the 480 horsepower of the Tesla Model 3.

They would experience acceleration, or g-forces of 3g. This is a difficult concept to explain. It feels like you have three people about the same size as yourself sitting on your chest pushing you into your chair. During re-entry into atmosphere, the g force reaches 6g.

High g-forces have great effects on the human body. High g-forces can cause blood to be pulled from the head, which can lead to brain starvation. This can cause visual changes such as tunnel vision, loss or complete loss (greyout) and, in some cases, a loss of consciousness due to g-force-induced g-forces. These can happen at 3g.

However, simulations of sub-orbital flight paths using a centrifuge with people aged 20 to 78 showed that older people could tolerate the higher g-forces during atmospheric re-entry.

Spaceflights commercially are making it possible for more people to fly to space. Blue Origin, image credit

New Shepard's engines are turned off towards the end, allowing it slow down and begin falling back to Earth. The high G-forces suddenly disappear, and passengers feel weightless. This rapid entry into microgravity can often lead to space sickness in trained astronauts.

Because there is no gravity, the vestibular system (our position sensors) can get confused. They don't know if you are moving or if your direction is up or down. Space sickness may be more common in older, less-trained astronauts who might already have vestibular impairments.

Blue Origin and Virgin Galactic, the spaceflight companies created by Richard Branson and Jeff Bezos, offer only a glimpse of space. They will nevertheless make important contributions to our understanding the health effects spaceflight has on increasingly diverse populations.

This article was republished by The Conversation under Creative Commons. You can read the original article.

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