Sat, Oct 05, 2013 - Page 11 News List

Astronauts face radiation threat on long Mars trip
太空人火星之旅面臨輻射威脅

US astronaut Michael Hopkins, left, and Russian cosmonauts Oleg Kotov, center, and Sergey Ryazanskiy attend a training session at the Star City space center outside Moscow on Aug. 23.
美國太空人霍普金斯(左),俄羅斯太空人柯托夫(中)及萊雅詹斯基八月二十三日於莫斯科郊區參加星辰市太空中心訓練。

Photo: Reuters
照片:路透

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.

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。

TODAY’S WORDS 今日單字

1. outfit n.

公司;機構 (gong1 si1; ji1 gou4)

例: Some big outfits are working on developing similar products.

(一些大公司正致力研製這類產品。)

2. round-trip n.

來回之行 (lai2 hui2 zhi1 xing2)

例: It will cost you US$1,500 round-trip.

(來回票費用是一千五百美元。)

3. zip v.

迅速行動;以尖嘯聲行進

(xun4 su4 xing2 dong4; yi3 jian1 xiao1 sheng1 xing2 jin4)

例: We zipped through the homework and then went to a movie.

(我們迅速寫完作業,然後去看電影。)


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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