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Radiation Makes Mars Mission Unlikely

1:30 PM, Sep 22, 2013   |    comments
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CAPE CANAVERAL, FL -- An American expedition to Mars is the Holy Grail of U.S. human spaceflight, but more than a half-century after the dawn of the Space Age, the reality is this: NASA is "no-go," at least for now.

To send an expedition to Mars today, NASA would have to knowingly expose astronauts to cancerous, or even lethal, levels of space radiation. It's an ethical quandary for those involved in NASA's renewed push toward deep-space exploration. And it's being explored by some of the most distinguished scholars, scientists, engineers, health professionals and ethicists in the nation.

It's "the elephant in the room," NASA Chief Astronaut Robert Behnken recently told a National Academy of Sciences committee.

"We're talking about a lot of ionizing radiation, almost a guarantee for cancer, and you are really close to the edge of the range for lethal exposure," said Kristin Shrader-Frechette, a University of Notre Dame professor and a specialist in ethical issues that arise in scientific research and technology development. "If we can't get shorter transit times in space, and we can't get better shielding, then we really can't do (a Mars) spaceflight."

The situation is prompting a wholesale reconsideration of how much space radiation astronauts can be exposed to and whether those limits should be eased to enable deep-space exploration. .

The prospect raises scores of thorny questions, including these:

• Should astronauts be allowed to volunteer for a flight when NASA knows space radiation exposure limits almost surely will be exceeded?

• Should a true understanding of the risk, and informed consent, be enough for someone to volunteer for a Mars mission?

• Should NASA's chief astronaut or chief medical officer be given authority to grant individual waivers to the limits?

• Should NASA, Congress or the White House have the authority to knowingly approve a waiver, or going even further, a one-way mission to the red planet - one that includes no plans for a return to Earth?

The jury is still out. The National Academy's Institute of Medicine took up the issue this year and is deliberating. A report is due in April 2014.

NASA's Astronaut Office has already weighed in.

"The Astronaut Office actively supports readdressing the policies for crew health standards for exploration missions ... primarily because NASA will likely exceed the current medical standards to effectively pursue exploration" beyond low Earth orbit, Behnken said.

Here's the situation:

On a 500-day round trip to Mars, astronauts would fly outside the Earth's magnetic field, which largely protects International Space Station crews and the planet from deadly forms of space radiation.

Those flying beyond Earth orbit would face consequential radiation risks, including exposure to:

• Solar energetic particles generated by solar flares or coronal mass ejections from the sun.

• Galactic cosmic rays from exploding stars, quasars and gamma ray bursts outside our solar system.

Shielding and sheltering measures can protect crews from solar energetic particles, but new breakthroughs in lightweight materials are needed to make deep-space missions possible.

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