166
Faculty Sections / Re: ওজন কমাতে শর্করা একেবারেই বাদ?
« on: July 14, 2015, 03:42:24 PM »
useful 
News:
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167
Faculty Sections / Re: তৈরি করুন "পারফেক্ট" মিষ্টি দই!
« on: July 14, 2015, 03:40:21 PM »
very good
168
Faculty Sections / Re: প্রেরণা্মূলক উক্তিগুলো
« on: July 14, 2015, 03:39:40 PM »
Good to understand
169
Science and Information / Space Junk is a Problem. Is a Laser Cannon the Solution?
« on: June 25, 2015, 01:12:03 PM »
There’s a general rule in media reporting called Betteridge’s Law: Whenever a headline poses a question–especially a sensational one–the answer is “no.” I’m going to break the law this time. An orbiting laser cannon is not only an intriguing technology but, yes, it’s one of the most promising ways to clean up the ever-thickening cloud of dangerous debris surrounding the Earth.
And just to be clear, space junk is a danger. There are about 25,000 human-made objects larger than your fist flying around in orbit, and about half a million pieces bigger than a dime. If you include millimeter-scale shrapnel, the number of rogue bits reaches deep into the millions. Typical speeds in low-Earth orbit are about 30,000 kilometers per hour (18,000 miles per hour), ten times the velocity of a rifle bullet. You see the problem: A little impact can pack a big wallop.
So far, there have not been any space-junk catastrophes remotely resembling the sensationalized events in the movie Gravity, but the reality is still disconcerting. In 2009, a $50 million Iridium communications satellite was destroyed by a collision with a defunct Russian satellite. Three years later, the Fermi space observatory had a near miss with another Soviet-era satellite. NASA had to clad the International Space Station in shielding to protect it from repeated small impacts, and the agency sometimes moves the whole station to dodge larger pieces of junk. Orbiting debris adds cost and risk to the space business.
The proposed space-station laser cannon (left) would work in conjunction with a telescope called EUSO to track and destroy space debris.
And just to be clear, space junk is a danger. There are about 25,000 human-made objects larger than your fist flying around in orbit, and about half a million pieces bigger than a dime. If you include millimeter-scale shrapnel, the number of rogue bits reaches deep into the millions. Typical speeds in low-Earth orbit are about 30,000 kilometers per hour (18,000 miles per hour), ten times the velocity of a rifle bullet. You see the problem: A little impact can pack a big wallop.
So far, there have not been any space-junk catastrophes remotely resembling the sensationalized events in the movie Gravity, but the reality is still disconcerting. In 2009, a $50 million Iridium communications satellite was destroyed by a collision with a defunct Russian satellite. Three years later, the Fermi space observatory had a near miss with another Soviet-era satellite. NASA had to clad the International Space Station in shielding to protect it from repeated small impacts, and the agency sometimes moves the whole station to dodge larger pieces of junk. Orbiting debris adds cost and risk to the space business.
The proposed space-station laser cannon (left) would work in conjunction with a telescope called EUSO to track and destroy space debris.
170
Faculty Sections / Re: স্বাস্থ্য রক্ষায় ও গৃহস্থালীর কাজে বেকিং সোডার অজানা কিছু ব্যবহার
« on: June 14, 2015, 02:32:43 PM »
very useful. thanks
171
Faculty Sections / Re: নিমের পাতার ব্যবহার
« on: June 14, 2015, 02:18:03 PM »
thanks for sharing
172
Be a Business man/woman / Re: 4 Tips For Overcoming Obstacles
« on: June 09, 2015, 03:20:22 PM »
useful