nuclear-news

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…….

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.

Galactic cosmic rays, however, are penetrating and can cause acute radiation sickness. Exposure also can cause circulatory and neurological diseases, and can result in latent cancer effects — astronauts could get cancer and die earlier than they otherwise would.

NASA follows standards established by the National Council of Radiation Protection and Measurement. Models based partly on data collected in the aftermath of the 1945 Hiroshima atomic bombing were used to set those standards.

Astronauts are not allowed to accumulate a career radiation dose that would exceed a 3 percent increase in lifetime risk of developing a fatal cancer.

In considering an easing of the limit, the Astronaut Office says other issues also should be addressed. NASA analyses show current limits also would:

• Ostensibly discriminate against women.

• Reduce the pool of astronauts who qualify for mission assignments.

Male and female astronauts face the same level of risk — the 3 percent increase in what NASA calls “Risk of Exposure-Induced Death” for fatal cancer.

But women have a lower threshold for space radiation exposure than men, largely because the increased risk from breast, ovarian and uterine cancers…….http://www.usatoday.com/story/news/nation/2013/09/22/radiation-exposure-makes-manned-mission-to-mars-unlikely/2847577/