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
8-level vestigial sideband
a brass farthing
ace boon coons
active-centre
additional cannon pinion
Aegean Islands
alae vomeris
Alexander's crown
ampex
Amstelmeer
arats
Auranti cortex siccatus
automatic multi-screwdriver
backtrackings
bipolar front end
birth ratio
browzing
calibration liquid
Calochortus albus
Cau, Song
cdot
claim entitlement
Clarensac
classified as
colometrogram
containment cooling system
contract transportation
convolution operation
cooling method
CPRO
data handling equipment
diarylmaleimide
e in altissimo
energy-sapping
enforcement notice
entropy balance equation
Erb paralysis
exemplary role
fabry perot cavity
ferrimagnetisms
fishery processing ship
foreign capital in flow
furnace foundation
furnculosis
gauze sponge
godelier
grafite
grasps the nettle
hold in pledge
huntington-heberleim sink and float
hydraulic machine
hylion
infusoriform embryo
iodobromite
ketonic ester
logic(al) value
magnetic card filing cabinet
manufacturer's wire
masais
mauremys reevesii
memory time
migratory thrombophlebitis
misstating
nail smith chisel
noise pollution
NOT AND
optical depolarization
order Salientia
p.c.b.s
parabolic flight
permitio
perpendicular electric constant
persuadability
phlegmasia
pstis
pulse attenuator
Red Cross and Red Crescent
rheology of elastomers
saddle-bows
safe handling of cargo
screw driver for cruciate slot
seminists
smooth-surface
space-based observation
spherical iron particle
superfamily sphecoideas
theory of genasthenia
time-to-pulse height converter
to the advantage of
toric smoothing machine
touchinesses
translation tool
tread bracing layer
unryu-gata
vertical velocity gradient
waist packs
waitressed
walt whitmen
wholesomest
work loose
zinc dithiofuroate
Zitazonium