Travelling to Mars? Pick the right flight time.

     NASA sent men to the Moon nine times, with astronauts landing and walking on the lunar surface six times. As of this writing, 49 spacecraft have been launched towards Mars by the U. S and other countries. Twenty-five of those, over half, were total or partial failures. Of the others, some simply passed by, snapping pictures along the way. Some went into orbit, and several sent a lander down to the surface to further study the planet in closer detail. No humans have made the trip to Mars, but NASA and some private space launch companies have plans to do so.

Traveling to Mars is hard. Any one of hundreds of systems could fail. One particularly grave risk exists for humans flying to Mars, even if all the systems work perfectly. Space is full of deadly cosmic radiation. An astronaut flying in an unprotected or poorly protected spacecraft is unlikely to survive the trip.

                                                                        Mars, credit NASA

An international team of space scientists conducted a study to answer two questions: Would cosmic radiation pose too grave a threat to human life on a round trip to Mars? And, could the decision of when to launch such a mission help protect astronauts?

The study concluded that spacecraft ferrying humans to Mars can carry sufficient shielding to protect the astronauts from lower levels of radiation. But for maximum survivability, the timing of the launch is critical.

The cosmic radiation of concern comes from two sources. Our sun emits cosmic rays in the form of the solar wind, radiation that shielding can protect astronauts from. More lethal is the radiation from galaxies, supernovas, and all the other inhabitants of space beyond our solar system. While these outside cosmic rays are deadlier, they can generally be deflected by the sun’s magnetic field. That protective envelope is strongest during solar maximum when the sun has more and larger sunspots.

                                                        Cosmic ray sources, credit NASA

The study suggests that such a roundtrip flight to Mars in a well-shielded craft must take no longer than four years, limiting the exposure to cosmic rays, and must occur during solar maximum when the sun’s activity can help protect the astronauts. The scientists involved in the study conclude, “We estimate that a potential mission to Mars should not exceed approximately 4 years, limiting exposure to cosmic radiation. This study shows that while space radiation imposes strict limitations and presents technological difficulties for the human mission to Mars, such a mission is still viable.”

It’s not too late to sign up for a trip to the Red Planet.

 

 

Each month, I write an astronomy-related column piece for the Oklahoman newspaper. On the following day, I post that same column to my blog page.

This is reprinted by permission from the Oklahoman and www.Oklahoman.com.