时间:2018-12-07 作者:英语课 分类:60秒科学


英语课

诸多线索综合起来为我们描绘出一幅画面:那是火星遥远的过去,那时的火星还有着一层厚厚的大气层,令这颗星球温热暖和,从而使水能够在火星表面流淌。但如今,地表的水消失不见,而大气层变得如此之薄,任何水分都会蒸发掉。


Arriving in 2014, the Mars Atmosphere and Volatile 1 Evolution Mission (MAVEN) will see if the solar wind and radiation are behind the loss of the Martian atmosphere. Cynthia Graber reports


The clues are adding up to give a picture of a distant Martian past, when the planet had a thick atmosphere that was warm enough for water to stream on the surface. But now the water’s gone, and the atmosphere is so thin that any water would boil away.


In fact, the vestigial atmosphere is still slowly dissipating into space. Why? Well, researchers believe that solar wind and radiation is behind the theft, and they’re planning a mission to find out, called MAVEN: Mars Atmosphere and Volatile Evolution Mission


The solar wind is a stream of electrically-charged particles. It continuously flows from the sun out into space. We on Earth have protection in the form of a magnetic shield. But that shield is dead on Mars, gone for billions of years.


Instead, the solar wind and the sun’s UV radiation give an electric charge to atoms and particles in Mars outer atmosphere. Then electric fields generated by the solar wind sweep away the charged particles. So the atmosphere becomes even thinner.


Maven is scheduled to reach the red planet in 2014. Which will allow researchers to measure how much water and atmosphere are gone with the solar wind.


—Cynthia Graber

 



1 volatile
adj.反复无常的,挥发性的,稍纵即逝的,脾气火爆的;n.挥发性物质
  • With the markets being so volatile,investments are at great risk.由于市场那么变化不定,投资冒着很大的风险。
  • His character was weak and volatile.他这个人意志薄弱,喜怒无常。
学英语单词
AAGC
Aeschynomene americana
Allium schoenoprasum L.
amalgam plugger
application-development language
artificial stocking
bandage gauze
bat ribbon
binary synchronous device data block
bind-days
boysen berry
Brissaud's dwarf
chemical anticarcinogenic drug
chemoconvulsant
cherryville
Chrysomelidae
concolor
counter sample
cupids
dichloramine
disodic alkaliine
drill-sharpening machine
Echogynography
ecotonal
electrochemistry at liquid-liquid interface
electronic sign
Entale
extraneous term
fenoxazoline
fine ream
foamed polystyrene chaplet
garage shop
genus epipactiss
genus Sagina
gleewoman
haroutounian
heteropolyanion
homotopy type invariant
hot-finished material
Idb-1016
idea champions
incomplete compaction
injurious weed
isolar
jet cutting car
junta
ketchuppy
leptosols
load bearing characteristic
magnetization curve
medicinal perfume
methyl-1-testosterone
Midgard, Midgarth
mikester
military characteristics
monkey bread
moon trefoils
motor timer
mulesing
multiple-reclosing breaker
nuclear-level density
off-set seismic operation
optical fiber source
oral traditions
overfarm
overparameterize
oximctry
parachute troops
partial cracking
piston ring groove cleaner
Ponte di Legno
portal-type frame
pre-established harmony
quicktongued
ranque
rascally
salvage and salvage charge
sharpness of vision
Ship's Sinking
sovann
spiroplasma
Spy Wednesday
stamate
teleprocessor
Theilman
thiocolchicine
thread fasteners
tibetan high
Tiedemann's nerve
to pop the question
Transdanubia
trial by media
unstainable
vapor compression refrigerating machine
vertimeter
VWAP
Waddingworth
West Midland
wet snow
wet-chemical technique
white walnuts
wood pattern