Astronauts traveling to and from Mars would be bombarded with as much radiation as they would get from a full-body CT scan about once a week for a year, researchers reported.
That dose would, in some cases, exceed NASA’s standards and is enough to raise an astronaut’s cancer risk by three 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.
Photo: Reuters
照片:路透
NASA aims to send a crew to orbit the red planet by the mid-2030s. Private outfits like Inspiration Mars 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 eight-and-a-half-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 — round-trip approximately 662 millisieverts.
The estimate is just for zipping there and back. It does not include time spent on the Martian surface, which would add to an astronaut’s exposure.
(AP)
往返火星的太空人面臨的輻射量,多達持續一年每週一次接受全身斷層掃描的劑量,研究人員報告指出。
這種劑量,在某些情況下,超過美國航空暨太空總署(NASA)的標準,並足以將太空人罹癌的風險提高百分之三。
當太空探險計畫大增,輻射是一大關切——從遙遠的超新星爆炸噴發的高能銀河宇宙射線,到太陽投射的帶電粒子零星爆裂。地球磁場有助於偏移大量的有害輻射。
NASA企圖在二0三0年代中期前將一組太空人送上這顆紅色星球的軌道。諸如「靈感火星」等民間企業也招募志願者前往火星。
此前就有針對未來火星旅人所做的輻射風險測量,但最佳推估來自NASA的「好奇號」任務。當這部探測車於二0一一年發射時,其內部便裝有輻射感應器,在前往火星的八點五個月航程中擷取輻射數據。
藉由那些數據,科學家計算太空人在較快的六個月航程中,在類似防護的太空船內暴露在輻射下的劑量。來回一趟︰約六百六十二毫西弗。
這個推估只是航行到那裡和返航的劑量,並未包括待在火星表面的時間,這段時間將增加太空人的輻射暴露量。
(美聯社/翻譯: 魏國金)
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