Speed kills: Highly relativistic spaceflight would be fatal for passengers and instruments

作     者：William A. Edelstein Arthur D. Edelstein 

作者机构：Johns Hopkins School of Medicine Baltimore USA University of California San Francisco San Francisco USA 

出 版 物：《Natural Science》 (自然科学期刊（英文）)

年 卷 期：2012年第4卷第10期

页      面：749-754页

学科分类：1002[医学-临床医学] 100214[医学-肿瘤学] 10[医学] 

主　　题：Interstellar Travel Spaceflight Relativistic Spaceflight Space Travel Radiation 

摘      要：Highly relativistic speeds are desirable for interstellar travel. Relativistic time dilation would reduce the subjective duration of the trip for the travelers, so that they can cover galaxy-scale distances in a reasonable amount of personal time. Unfortunately, as spaceship velocities approach the speed of light, interstellar hydrogen H, although only present at a density of approximately 1.8 atoms/cm3, turns into intense radiation that would quickly kill passengers and destroy electronic instrumentation. In addition, the energy loss of ionizing radiation passing through the ship’s hull represents an increasing heat load that necessitates large expenditures of energy to cool the ship. Stopping or diverting this flux, either with material or electromagnetic shields, is a daunting problem. Going slow to avoid severe H irradiation sets an upper speed limit of v ~ 0.5 c. This velocity only gives a time dilation factor of about 15%, which would not substantially assist galaxy-scale voyages. Diffuse interstellar H atoms are the ultimate cosmic space mines and represent a formidable obstacle to interstellar travel.