Australian news, and some related international items

Perils to austronauts’ health – high radiation and low gravity

High Radiation, Low Gravitation: The Perils of a Trip to Mars, Sunscreen and calcium supplements aren’t enough to protect Mars-bound space travelers from radiation and a lack of gravity in outer space.   July 23, 2021 – 17:00Yuen Yiu, Staff Writer   (Inside Science) — Back in May, SpaceX launched its Starship SN15 prototype to about the cruising altitude of a commercial airliner before landing it safely. The company claims future versions of the rocket will be able to take 100 passengers at a time to the moon, and even Mars.  

But while it’s one thing to send a rocket to Mars, it’s another to send people there alive. And it’s yet another thing to make sure the people can be as healthy as they were when they left Earth. 

Besides packing enough fuel and air and water and food for the seven-month-long journey to Mars (and more for a return trip if you want a return ticket), there are other luxuries we enjoy here on Earth that the spaceship will have to provide if we want to stay healthy during the long flight. 

Nasty sunburns and zero gravity

Earth’s atmosphere and magnetic field protect us from harmful space radiation, but passengers bound for Mars will lose that protection. So, their spaceship would need to provide some kind of radiation shielding.

Depending on where radiation comes from, it may be made of different particles and have different energies, which would require different means of shielding and pose different levels of danger to our radiation-prone DNA. For example, radiations from energetic particles ejected from the sun behave very differently than cosmic rays from outside our galaxy. 

So, how many times more radiation would a Mars-bound astronaut experience compared to what they would experience on Earth? 

Enough to be of concern, according to Athanasios Petridis, a physicist from Drake University in Des Moines. According to calculations by his team, high-end estimates for radiation exposure during a round trip to Mars are in the range of several Sieverts (Sv). For reference, the U.S. Nuclear Regulatory Commission has set 0.05 Sv/year as the dose limit for workers who are exposed to radiation at their jobs.

Solar weather also plays a role in the amount of radiation you would get in space. For instance, the 11-year solar cycle affects the amount of radiation the sun emits. However, due to the complicated interplay between sun-generated radiation and cosmic rays from outer space, it may not be worth it to time the launch around these cycles. 

“There are enough competing factors in radiation exposure that trying to plan around the solar cycle is like trying to time the stock market, which usually results in losing,” said Kerry Lee, a radiation analyst from NASA in Houston, Texas.

The lack of gravity can also wreak havoc on the human body given enough time. Astronauts aboard space stations have been shown to lose 1 to 1.5 % of the mineral density in their weight-bearing bones every month. They also tend to lose muscle mass, even when exercising as much as they do on Earth. ………..

July 24, 2021 - Posted by | Uncategorized

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