NASA's Apollo astronauts, the only humans to have travelled beyond Earth's protective magnetosphere, die disproportionately of heart and blood vessel diseases, researchers said Thursday, blaming radiation.
This raises health concerns for all humans with dreams of travelling to the Moon, Mars or beyond, as space agencies and private companies vie to expand humankind's extraterrestrial footprint.
"We know very little about the effects of deep space radiation on human health, particularly on the cardiovascular system," said Michael Delp of the Florida State University.
"This gives us the first glimpse into its adverse effects on humans."
Of seven Apollo astronauts to have died to date, three (43 percent) succumbed to cardiovascular disease -- a group of ailments that includes heart attacks, brain aneurysms and strokes.
This was "four to five times higher" than for trained astronauts who never left Earth (nine percent), and those like the International Space Station crews who stayed closer to home in low-Earth orbit (11 percent).
The findings were published in the journal Scientific Reports.
"These data suggest that human travel into deep space may be more hazardous to cardiovascular health than previously estimated," the researchers wrote.
NASA's Apollo programme sent 11 manned flights into space between 1968 and 1972.
Of the 24 men who flew beyond Earth orbit into deep space, eight have died to date. The eighth, Edgar Mitchell, passed away this year, after the data had been analysed, and was not included in the study.
Beyond the magnetosphere, a magnetic "bubble" which shields Earth and its occupants, the Apollo astronauts were exposed to unprecedented levels of particle radiation, said the study.
The ISS, by comparison, orbits Earth within the magnetosphere.
- Mars colonies -
Energetic particles from galactic radiation can be dangerous to humans as they pass right through the skin and can damage cells or DNA, according to NASA.
The agency has plans for a manned trip to Mars in the 2030s, and has stated that radiation shielding "will be a crucial technology" for the voyage as well as for exploring the surface.
The study was the first to include non-flight astronauts as a comparison group in examining the long-term health of space travellers.
Comparing astronauts to the general population can yield confusing outcomes, as they are generally better educated and fitter, and have lifelong access to medical care -- all ingredients for better health.
In comparing different types of astronaut, the researchers were able to exclude any possible impact of zero-gravity on cardiovascular disease, as all three groups (Earth-bound, low-orbit and deep space) were exposed to it.
The researchers also found no difference between the three groups in terms of cancer or accidents as the cause of death.
To test a possible cause for lunar astronauts' higher incidence of cardiovascular disease, the team exposed mice to comparable radiation levels in the lab.
"After six months -- the equivalent of 20 human years -- the mice demonstrated an impairment of arteries that is known to lead to the development of atherosclerotic cardiovascular disease in humans," said a Florida State University statement.
"What the mouse data show is that deep space radiation is harmful to vascular health," added Delp.
US billionaire Elon Musk and Dutch company Mars One have mooted placing human colonies on the Red Planet.
AFP
Thu Jul 28 2016
(FILES) This undated NASA image obtained on Feb 5, 2016 shows Astronaut Edgar D. Mitchell, Apollo 14 lunar module pilot standing by the deployed US flag on the lunar surface during the early moments of the mission's first spacewalk. - AFP PHOTO/NASA
Who is Prabowo Subianto, incoming president of Indonesia?
A wealthy ex-general with ties to Indonesia's popular outgoing president and its dictatorial past, looks set to be its next leader.
Iran's supreme leader says Hamas leader's death will not halt 'Axis of Resistance'
The "Axis of Resistance", built up with years of Iranian support, includes Hamas, the Lebanese Hezbollah group, the Houthi movement in Yemen, and various Shi'ite groups in Iraq and Syria.
Putin says Russia willing to seek compromises between Iran and Israel
Russia is ready to help seek compromises between arch-foes Israel and Iran, President Vladimir Putin said on Friday, saying these would be difficult but possible.
What proposals will Russia push at the BRICS summit?
The proposal is also to establish a BRICS reinsurance company to allow uninterrupted shipment of goods and key commodities between members.
Indonesia's free meals plan in the spotlight as Prabowo readies for office
Prabowo calls the programme one of the main drivers of economic growth, eventually set to add an estimated 2.5 million jobs.
Astro AWANI's revamped English news website, AWANI International, launches on Oct 21
Astro AWANI's revamped English platform delivers in-depth global news and expert analysis to keep you informed on key developments.
Israeli strikes kill 33 people in Jabalia refugee camp in Gaza, medics say
Residents of Jabalia said Israeli tanks had reached the heart of the camp after pushing through suburbs and residential districts.
Liam Payne's ex-partner calls for media restraint after 'painful' death
Cheryl Tweedy used her statement to urge the media to remember they had a seven-year-old son, Bear, who could read the reports.
Analysts: Indonesia's strong MoF leadership team to boost investor confidence
Sri Mulyani Indrawati as head of Indonesia's Ministry of Finance is expected to instil confidence among investors.
Biden offers both a carrot and a stick to Israel as his term nears an end
Israel has frequently resisted US advice and has caused political difficulties for the Biden administration.
Putin says BRICS will generate most of global economic growth
Russian President Vladimir Putin will host a summit of the group in the city of Kazan on Oct. 22-24.
ISIS Malaysia's perspective of Budget 2025
An excellent rakyat-centric budget under the overarching principle of a caring and humane economy.
Budget 2025: Record increase in STR, SARA aid initiatives
The government will provide a significant boost to the Sumbangan Tunai Rahmah (STR) and Sumbangan Asas Rahmah (SARA) initiatives next year.
Budget 2025: EPF contributions to be made mandatory for foreign workers – PM Anwar
The government plans to make it compulsory for all non-citizen workers to contribute to the Employees Provident Fund (EPF).
What policies to expect from Indonesia's new President Prabowo
Prabowo will be open to foreign investment, his aide has said, such as by offering investors management of airports and sea ports.
Budget 2025: Govt allocates RM470 mil to empower women's participation in PMKS
The Women's Leadership Apprenticeship Program will be intensified as an effort to produce more female corporate personalities.
Israel sends more troops into north Gaza, deepens raid
Residents of Jabalia in northern Gaza said Israeli tanks had reached the heart of the camp, using heavy air and ground fire.
Indonesia ramps up security ahead of Prabowo's inauguration
Prabowo Subianto will be sworn in as Indonesia's president on Sunday with Vice President-elect, Gibran Rakabuming Raka, also taking office.
Immediate allocation of RM150 mil for local authorities, DID to tackle flash floods
Datuk Seri Anwar Ibrahim said this allocation is intended to address the recent flash floods that hit the capital and several major towns.
Budget 2025: Sabah, Sarawak to continue receiving among highest allocations - PM
Sabah and Sarawak continues to be prioritised under Budget 2025, with allocations of RM6.7 billion and RM5.9 billion respectively.