火星殖民
Colonization of Mars

context: zh_tw: 人類目前對太空輻射知之甚少。2003 年，NASA 林頓・約翰遜太空中心開始在布魯克黑文國家實驗室的太空輻射實驗室（Space Radiation Laboratory）運用粒子加速器模擬太空輻射。有關人員在實驗室研究了太空輻射對受到遮蔽技術保護的生物的影響。最初，實驗人員發現較低的慢性太空輻射並不如預料中危險，輻射甚至對生物產生了放射激效（Radiation Hormesis）這種正面效果。
en: Much remains to be learned about space radiation. In 2003, NASA's Lyndon B. Johnson Space Center opened a facility, the NASA Space Radiation Laboratory, at Brookhaven National Laboratory, that employs particle accelerators to simulate space radiation. The facility studies its effects on living organisms, as well as experimenting with shielding techniques. Initially, there was some evidence that this kind of low level, chronic radiation is not quite as dangerous as once thought; and that radiation hormesis occurs. However, results from a 2006 study indicated that protons from cosmic radiation may cause twice as much serious damage to DNA as previously estimated, exposing astronauts to greater risk of cancer and other diseases. As a result of the higher radiation in the Martian environment, the summary report of the Review of U.S. Human Space Flight Plans Committee released in 2009 reported that "Mars is not an easy place to visit with existing technology and without a substantial investment of resources." NASA is exploring a variety of alternative techniques and technologies such as deflector shields of plasma to protect astronauts and spacecraft from radiation.In September 2017, NASA reported radiation levels on the surface of the planet Mars were temporarily doubled, and were associated with an aurora 25-times brighter than any observed earlier, due to a massive, and unexpected, solar storm in the middle of the month.
qas: question: zh_tw: 初步證據表明了什麼？
en: What did the initial evidence suggest?
answers: zh_tw: text: 最初，實驗人員發現較低的慢性太空輻射並不如預料中危險，輻射甚至對生物產生了放射激效（Radiation
en: text: this kind of low level, chronic radiation is not quite as dangerous as once thought; and that radiation hormesis occurs

context: zh_tw: 火星與地球之間的單向通訊延遲時間，最短 3 分鐘，最長 22 分鐘。而火星 - 地球實時通訊，則是不切實際的，因為兩地之間存在嚴重的時滯問題。NASA 發現，火星與地球在上合（Superior Conjunction）期間可能會斷絕，為期兩星期。不過，實際通訊情況取決於多個因素，如通訊系統的鏈路餘量和最低資料傳輸速率。現實中，大部分火星的通訊斷絕時間長達一個月。在 L4、L5 點放置衛星，就應該可以解決這一問題。衛星的造價並不是問題，因為，衛星造價對整個殖民計劃的開銷來說，微不足道。不過，體積和功率的問題，導致這一設想不切實際。而且，上述地區的固有穩定性雖然有利於衛星保持位置，但是，卻會招來塵埃和小行星，令到衛星安全受到威脅。儘管這一地區潛在危險，STEREO 的探測衛星仍然能夠毫髮無損地透過這一地區。斯特拉斯克萊德大學的進階太空概念實驗室與 ESA 提出瞭解決問題的方法：在高非開普勒軌道放置一種新式衛星。新式衛星採用小推力推進器，如離子發動機和太陽帆。推進器的作用是修改衛星的固有軌道。即使太陽在地球和火星之間，衛星也能透過離開軌道平面，“懸浮” 在火星之上的方式維持兩地通訊。衛星因為靠近火星地表，所以沒有 L4、L5 點衛星的問題。而且，衛星仍能維持地球和火星之間的通訊。
en: The one-way communication delay due to the speed of light ranges from about 3 minutes at closest approach (approximated by perihelion of Mars minus aphelion of Earth) to 22 minutes at the largest possible superior conjunction (approximated by aphelion of Mars plus aphelion of Earth). Real-time communication, such as telephone conversations or Internet Relay Chat, between Earth and Mars would be highly impractical due to the long time lags involved. NASA has found that direct communication can be blocked for about two weeks every synodic period, around the time of superior conjunction when the Sun is directly between Mars and Earth, although the actual duration of the communications blackout varies from mission to mission depending on various factors—such as the amount of link margin designed into the communications system, and the minimum data rate that is acceptable from a mission standpoint. In reality most missions at Mars have had communications blackout periods of the order of a month.A satellite at the L4 or L5 Earth–Sun Lagrangian point could serve as a relay during this period to solve the problem; even a constellation of communications satellites would be a minor expense in the context of a full colonization program. However, the size and power of the equipment needed for these distances make the L4 and L5 locations unrealistic for relay stations, and the inherent stability of these regions, although beneficial in terms of station-keeping, also attracts dust and asteroids, which could pose a risk. Despite that concern, the STEREO probes passed through the L4 and L5 regions without damage in late 2009.
qas: question: zh_tw: 從太陽第四顆行星到地球的通訊延遲時間，最短是多少？
en: What is the shortest amount of time a communication is delayed from the fourth planet from the sun to Earth?
answers: zh_tw: text: 3 分鐘
en: text: 3 minutes