科普类作文的开题特点【Moore原创】

原文 New Scientist/SPACE
http://www.newscientist.com/arti ... lect-asteroids.html
05 May 2012. Magazine issue 2863. For similar stories, visit the Solar System Topic Guide
个人感觉，此文的写作有些技巧，推荐仔细读出味道来

题目 Swarm of pebbles could safely deflect asteroids

FLINGING pebbles at an asteroid sounds like a fruitless task, but a new calculation shows that this could deflect an Earthbound rock.

It takes surprisingly little force to deflect an asteroid, provided it is done several years before the projected impact. Previous ideas have included landing an engine on the asteroid to push it away from a collision, and using mirrors or lasers to vaporise its surface and provide thrust to shift its course.

Alison Gibbings and Massimiliano Vasile, aerospace engineers at the University of Strathclyde, UK, have another solution. A 500-kilogram swarm of fingernail-sized spacecraft would, they calculate, deflect a fast-moving, 250-metre asteroid by nearly 35,000 kilometres - easily enough to avoid a collision, provided the swarm hits eight years, or about three orbits, before the expected Earth impact. A swarm could be launched from Earth in a single rocket. After release, pebbles could harness the thrust provided by reflected sunlight to steer themselves into a tight cloud directed at the asteroid.  

Best of all, each pebble would be too small to crack the asteroid into still-dangerous pieces, the pair reported on 17 April at the Astrobiology Science Conference in Atlanta, Georgia.

此贴仅分析两点-----------------------------------------------------------------
1 Heading 【Swarm of pebbles could safely deflect asteroids 】
swarm (rhetoric)---aggregation of persons or animals, especially when in turmoil or moving in mass
deflect----to turn aside or cause to turn aside (TECH terminology)
asteroid---key word of the text
ARTICLE USE---- do you best to eliminate the articles in the heading.

2 【FLINGING pebbles at an asteroid sounds like a fruitless task, but a new calculation shows that this could deflect an Earthbound rock.】
fling---throw (sth) violently, angrily or hurriedly
at---toward (a goal). 'at' is a 'tough' word, particularly in TECH-english
a...calculation --- article 'a' implies NewInformation and a specific event (rather than comceptual meaning)
this---repetition/reword of the theme 'FLINGING....asteroid'
earthbound(or earth-bound)---headed for the earth (Capital 'E' in the article)
ANALYSIS
This is a typical structure, particularly the use of 'this':  (a fact) +a calculation shows that this + (comment). Here, a declarative sentence starts the topic, where 'sounds like' and 'could' improve the conceptual stringency of scienific English and the choice of words 'fling' and 'fruitless' add more color to the declaration. Such combination reveals a fact that most of the IELTS reading texts are styled closer to popular science stories than those true journal papers. In the next two paragraphs, it is easy to find this feature and verify what I enphasised above.

If we can notice the features as deonstrated in this analysis when reading IELTS, then everything becomes easy.
下面添加第二段的分析
【2】It takes surprisingly little force to deflect an asteroid, provided it is done several years before the projected impact.【3】 Previous ideas have included landing an engine on the asteroid to push it away from a collision, and using mirrors or lasers to vaporise its surface and provide thrust to shift its course.
SEMANTIC COHESION: 'an asteroid'--- backward referrence, heading word, also CONTRAST TO 'little force-fling'.
TEXT DEVELOPMENT: a general/simple demonstration of the text heading.

【3】Previous ideas have included landing an engine on the asteroid to push it away from a collision, and using mirrors or lasers to vaporise its surface and provide thrust to shift its course.
a collision--- may be replaced by 'its collision'?
Thank 雅思哥 for the award. I put a comment on this question.
In general, the replacement of 'a collision'  by 'its collision'  seems possible. 【to put it away from its collision】would attract more attention to the host 'it' and enhance the active role of 'it'. In this case, if 'to something' is added behind 'collision', then the meaning is more complete. But the author wanted to leave a room for the reader's thinking (about a collision with the earth), and tried to focus more on the measure (i.e. landing...on...). This focus is indicated by the parallel structure landing-using.