Mars-Bound Astronauts Could Face Higher Risk of Cancer

[Buster's Uncle]

Mars-Bound Astronauts Could Face Higher Risk of Cancer
By Miriam Kramer | SPACE.com – 23 hrs ago..

The Curiosity rover, with RAD mounted to its top deck, was folded inside the MSL spacecraft on its trip to Mars, sitting immediately beneath the descent module and above the heat shield.

 
Astronauts who travel to Mars one day could be exposed to dangerous levels of radiation during their trip, even if shielding techniques are used, a new study shows.

When the Mars Science Laboratory launched on Nov. 26, 2011, it began a 350-million-mile (560 million kilometers) trip to the surface of the Red Planet. During its voyage, a group of researchers, including Southwest Research Institute scientist Cary Zeitlin, monitored exactly how much radiation a piece of science hardware on the Mars rover Curiosity was exposed to over the 253-day journey from Earth to Mars.

"In space, it's between a 100 and 1,000 times higher dose rate [of radiation] than on Earth," Zeitlin told SPACE.com. "It's highly uncertain what the health risk is from these exposures." [Could Radiation Harm Astronauts Traveling to Mars? (Video)]

Zeitlin, whose study is detailed in the journal Science this week, collected the data with his team by turning on the Radiation Assessment Detector (RAD) instrument while Curiosity was in flight. The instrument was active from 10 days after launch until about three weeks before landing.


Shielding from cosmic rays

By monitoring the variety and strength of each of the energetic particles entering the Mars Science Laboratory's hull, Zeitlin and his team were able to accurately track which particles of radiation got through and which were blocked by the ship's shielding.

If they were to travel to Mars, astronauts would be exposed to two forms of cosmic radiation that don't pose a serious risk on Earth. One of those sources of radiation — galactic cosmic rays — are difficult to shield against and regularly fly through space-faring vessels. On the other hand, the second source of radiation — solar energetic particles — can be at least partially blocked by robust shielding used to protect spaceflyers.

"The rover itself during the trip was surrounded by the equipment used for the entry, descent and landing," Zeitlin said. "RAD was very unevenly shielded. About half was lightly shielded. The heat shield below didn't really provide very much in the way of shielding. But above, there was quite a bit, and on a human inhabited vehicle, you would want it much more uniform."


Worth the risk?

The research could have implications for future NASA missions to Mars. If space agency scientists expect that radiation exposure over the course of a mission will increase an astronaut's risk of developing fatal cancer over his or her lifetime by at least 3 percent, NASA deems the mission too dangerous, Zeitlin said.

Certain people are at higher risk of developing these kinds of radiation-induced cancers: Young women are most at risk, while older men are in less danger. Even with the margin of error built into Curiosity's new results, however, the dose rate of the radiation that any astronaut would receive during the initial and return flights would probably put them over the 3 percent limit, Zeitlin said.

Zeitlin and his colleagues estimate that astronauts would be exposed to about 0.66 Sievert (Sv) — the unit scientists use for measuring radiation — of galactic cosmic ray radiation during the round-trip to Mars, not including their time spent on the surface of the Red Planet. About 1 Sv of radiation exposure is usually associated with about a 5 percent bump in fatal-cancer risk later in life.

The dose rate of radiation that the planetary explorers would be exposed to on the surface of Mars would be lower than the amount of cosmic radiation in space. However, it could still be significant, Zeitlin said.

Although this level of radiation might not make astronauts immediately ill, it still could impair their ability to conduct research from Mars. "There is some concern that there could be damage to cognitive ability that would manifest itself in the short run," Zeitlin said.


Future of space travel

Astronauts aboard the International Space Station are exposed to both galactic cosmic rays and solar energetic particles during their six months in orbit, but an astronaut flying to Mars would get a higher dose over a longer period of time.

"Scientists need to validate theories and models with actual measurements, which RAD is now providing. These measurements will be used to better understand how radiation travels through deep space and how it is affected and changed by the spacecraft structure itself," Donald Hassler, a program director at the Southwest Research Institute and principal investigator of the RAD investigation, said in a statement. "The spacecraft protects somewhat against lower-energy particles, but others can propagate through the structure unchanged or break down into secondary particles."

The new findings will allow scientists to use hard data in computer models set up to investigate just how much radiation astronauts could encounter on their journey to another planet. This kind of research could be particularly important for NASA in the coming years, as officials from the space agency gear up to possibly send humans to Mars by the 2030s.

Scientists from the Christian Albrechts University of Kiel in Germany, the German Aerospace Center and NASA also contributed to the new study.

http://news.yahoo.com/mars-bound-astronauts-could-face-higher-risk-cancer-180740401.html

In other space science news, the Sun rose in the East this morning, achieving a new record for consistency.

[Buster's Uncle]

Astronauts face radiation threat on long Mars trip
By ALICIA CHANG | Associated Press – 21 hrs ago..

This artist rendering shows the Orion space capsule that NASA wants to use for a deep space mission. Astronauts traveling to and from Mars would be bombarded with as much cosmic radiation as they’d get from a full-body CT scan about once a week for a year, researchers reported Thursday, June 30, 2013. NASA aims to send a crew to orbit the red planet by the mid-2030s. (AP Photo/NASA)

 
LOS ANGELES (AP) — Astronauts traveling to and from Mars would be bombarded with as much radiation as they'd get from a full-body CT scan about once a week for a year, researchers reported Thursday.

That dose would, in some cases, exceed NASA's standards and is enough to raise an astronaut's cancer risk by 3 percent.

As plans for deep space exploration ramp up, radiation is a big concern — from high-energy galactic cosmic rays spewed by distant supernova explosions to sporadic bursts of charged particles hurled by the sun. Earth's magnetic field helps to deflect much of that harmful radiation.

NASA aims to send a crew to orbit the red planet by the mid-2030s. Private outfits like Inspiration Mars — backed by NASA engineer-turned-space tourist Dennis Tito — are seeking volunteers for a Mars flight.

There have been previous efforts to gauge the radiation risk for future Mars travelers, but the best estimate is coming from NASA's Curiosity mission. Tucked inside the rover when it launched in 2011 was a radiation sensor that took readings during the 8 1/2-month cruise to Mars.

From those figures, scientists calculated a spacefarer's radiation exposure for a quicker six-month voyage in a similarly shielded spacecraft. Roundtrip: about 662 millisieverts. That's a sizable chunk of an astronaut's career cap of 1,000 millisieverts which many international space agencies use to limit the accumulated radiation dosage in space.

NASA's threshold depends on age and gender. The career dose limit for 30-to-60-year-old male astronauts who never smoked ranges from 800 to 1,200 millisieverts. For female astronauts, the limit ranges from 600 to 1,000 millisieverts.

The radiation exposure from a Mars journey is similar to getting a full-body CT scan every five or six days, said lead researcher Cary Zeitlin of the Southwest Research Institute in Boulder, Colo.

The estimate is just for zipping there and back; it doesn't include time spent on the Martian surface, which would add to an astronaut's exposure. How much more would depend on length of stay and available shelter.

"You'd like the radiation exposure to be lower, but it is what it is," said Dr. Norm Thagard, the first American to fly on the Russian space station Mir, who had no role in the research. "Given the importance of such a mission, the mission should be done."

The analysis appears in Friday's issue of the journal Science. The amount of radiation likely won't change unless there's a rocket engine developed that can speed up the interplanetary ride, researchers said.

"You want to get there as quickly as possible" to reduce radiation exposure, said Don Hassler, scientist in charge of the radiation instrument aboard Curiosity.

Radiation on a Mars trek would be higher than what crew members cocooned inside the International Space Station typically face — about 200 millisieverts per year. By contrast, people on Earth are typically exposed to about 3 millisieverts a year.

Curiosity flew to Mars during a period of low to moderate solar activity. A manned mission that launches during a solar flare or storm would encounter more radiation.

NASA engineers are testing propulsion systems and researching ways to reduce radiation exposure on a Mars flight. Among the possibilities: Have astronauts wear a deployable shield resembling a heavy winter coat or have them hunker down in a storm shelter aboard the spacecraft during periods of high solar activity.

"Before we can send astronauts there, we need to understand the environments and hazards that they would face" said Chris Moore, deputy director of advanced exploration systems at NASA headquarters.

Now, cancer-related risk estimates are "no more than a rough guesstimate," David Brenner, an expert on radiation-induced cancer at Columbia University, said in an email.

Thagard, the former NASA astronaut, said he was exposed to 120 millisieverts during his 115 days in low-Earth orbit aboard Mir. Despite the potential health risks, Thagard said there likely won't be a shortage of astronauts willing to hop on a Mars flight.

Since landing near the Martian equator last summer, Curiosity has continued to track radiation as it rolls across the dusty surface toward its eventual mountain destination. The rover has turned up the best evidence yet of an ancient watery Mars. A separate study published in Science detailed the existence of more than 500 rounded pebbles near its crater landing site — the result of being shaped by long-ago flowing water.

http://news.yahoo.com/astronauts-face-radiation-threat-long-mars-trip-180457783.html

[Buster's Uncle]

Trip to Mars would likely exceed radiation limits for astronauts
By Irene Klotz | Reuters – 18 hrs ago..


CAPE CANAVERAL, Florida (Reuters) - Radiation levels measured by NASA's Mars Curiosity rover show astronauts likely would exceed current U.S. exposure limits during a roundtrip mission to Mars, scientists said on Thursday.

The rover landed on Mars in August to search for habitats that could have supported past microbial life.

Results taken during Curiosity's eight-month cruise to Mars indicate that astronauts would receive a radiation dose of about 660 millisieverts during a 360-day roundtrip flight, the fastest travel possible with today's chemical rockets. That dosage does not include any time spent on the planet's surface. A millisievert is a measurement of radiation exposure.

NASA limits astronauts' increased cancer risk to 3 percent, which translates to a cumulative radiation dose of between about 800 millisieverts and 1,200 millisieverts, depending on a person's age, gender and other factors.

"Even for the shortest of (Mars) missions, we are perilously close to the radiation career and health limits that we've established for our astronauts," NASA's chief medical officer Richard Williams told a National Academy of Sciences' medical committee on Thursday.

An astronaut living for six months on the International Space Station, which flies about 250 miles above Earth, receives a dosage of about 100 millisieverts.

An abdominal X-ray scan generates about 10 millisieverts.

At NASA's request, the Institute of Medicine panel is looking into ethics and health standards for long-duration spaceflights.

"We're looking at that 3 percent standard and its applicability for exploration-type missions," added NASA's Edward Semones, spaceflight radiation health officer at the Johnson Space Center in Houston, during a conference call later with reporters.

"The snapshot today is that we would exceed our limit," Semones said.

NASA also is looking into alternative propulsion technologies to speed up the trip to Mars and different types of spacecraft shielding.

Information from Curiosity about how much and what type of radiation astronauts can expect on the Martian surface is due to be released later this year.

The research was published in this week's edition of the journal Science.

http://news.yahoo.com/trip-mars-likely-exceed-radiation-limits-astronauts-000023588.html

[Lord Avalon]

OK, but what are the chances of gaining superpowers? 

[Buster's Uncle]

Much higher that you will end up looking like the Thing than Mr. Fantastic, for sure.

...

Manned Mars Missions Will Need Superfast New Propulsion Systems to Beat Radiation Threat
By Mike Wall | SPACE.com – 6 hrs ago..

 
To keep astronauts safe and healthy during long on future missions to Mars, superfast new propulsion technologies will likely be necessary, experts say.

Crewmembers flying to Mars and back using traditional chemical thrusters would be exposed to the high radiation levels of deep space for 12 to 17 months. That's simply too long to keep astronauts' radiation doses from fast-moving particles known as galactic cosmic rays within currently acceptable limits, researchers said.

At the same time, they added, improved shielding is needed to help protect deep-space explorers from charged particles blasted out by the sun. (Traditional shielding does little good against cosmic rays.)

"We need to get there faster to reduce the impact of the galactic cosmic rays, but we need to have shielding, local shielding, on board to eliminate the effects of solar particle events," Eddie Semones, spaceflight radiation health officer at NASA's Johnson Space Center in Houston, told reporters Thursday (May 30). "So it's hand in hand."


Acceptable radiation doses

NASA astronauts are not allowed to accumulate a career radiation dose that would increase their lifetime risk of developing fatal cancer by more than 3 percent. For perspective, a career dose of 1 Sievert (or 1,000 millisieverts) is associated with a 5 percent increased risk.

While scientists have long suspected that a manned Mars mission would brush dangerously close to upper dose limits, data gathered by NASA's Mars rover Curiosity rover during its eight-month cruise to the Red Planet last year have enabled them to put some hard numbers on the problem.

The interior of Curiosity's spacecraft, which blasted off in November 2011, received about 1.8 millisieverts of galactic cosmic ray radiation per day, researchers announced today. (Solar particles contributed an additional small amount, raising the total dose by perhaps 3 percent.)

That's bad news for a traditionally powered manned Mars mission.

"Given this data, and our models that confirm it, we currently would exceed our acceptable limits of 3 percent excess fatal cancer," Semones said.

Radiation levels on the Martian surface are expected to be considerably lower than those in deep space. Preliminary results from Curiosity announced late last year suggest that astronauts walking around on the Red Planet would receive about 0.7 millisieverts per day — roughly the same dose experienced by crewmembers of the International Space Station.


Reducing the risk

Surrounding crewmembers with water would help lower their radiation dose during the trek to Mars, because hydrogen is the best known shield against cosmic rays, said Chris Moore, deputy director of advanced exploration systems at NASA Headquarters in Washington, D.C.

But Moore agreed with Semones that advanced propulsion systems are also needed. He specifically mentioned nuclear thermal rockets as a promising option, saying they could potentially cut the total travel time to 180 days.

Such a system is far from ready for action, however.

"It's a long-range technology-development activity, and it will probably be many years before that is ready," Moore said. "But it is part of our mission architecture for sending humans to Mars, is to use nuclear rockets."

NASA is currently working toward getting astronauts to the vicinity of Mars by the mid-2030s, as directed by President Barack Obama. The space agency may still launch a manned mission around that time, even if superfast new propulsion systems aren't yet ready to go, officials said.

"We're looking at that standard, that 3 percent standard, and its applicability for exploration-type missions," Semones said. "Those discussions are going forward now on how to handle that, and what steps we can take to protect the crew."

http://news.yahoo.com/manned-mars-missions-superfast-propulsion-systems-beat-radiation-135244300.html

Run a current through the hull sufficient to produce a strong magnetic field.  I doubt that the power requirements would make this feasible, mind you, and for all I know the long term exposure to the magnetic field might be worse for you, but it could work, maybe.

[Lord Avalon]

Much higher that you will end up looking like the Thing than Mr. Fantastic, for sure.

It's clobberin' time! 


You know, the ability to project a force field bubble would perhaps be the most useful of their powers in space or on Mars.

[Buster's Uncle]

Sue's actually got the best powerset, yes.  There's no end to the neat stuff you could do with forcefields and power over visibility - and it's a wonder Reed never figured out how to extend that to power over electromagnetic frequencies outside the visible range, to make radiation-proof shields...