That is because, unlike the rockets currently used to get into orbit, they are air-breathing.
Currently, the fastest air-breathing aircraft is the SR-71, which accelerates to slightly over Mach 3.
Much of the fighting in the operation is at elevations above 11, 000 feet, where thin air makes breathing more difficult.
Its disruptive technology is a novel air-breathing and rocket engine that would enable the ship to go to space in one leap.
The cumulative effect of these and other constraints imposed by START I and START II will be to degrade significantly the deterrent value of the air-breathing leg of the U.S. strategic triad.
Instead of breathing clean air, you're breathing particles that make it harder for your lungs to function and get oxygen.
The delivery device had to explode the air inside its breathing chamber at supersonic speeds to form an aerosol cloud of insulin.
He enriched the oxygen or the carbon dioxide in the air breathed by experimental subjects and found not a hint of suppression or exacerbation of yawning compared with control subjects breathing normal air.
Route 66 boasted a full luxury interior with air-conditioning, desalination equipment and even an air compressor for underwater breathing hoses.
More children are drinking polluted water and breathing polluted air.
According to the American Lung Association, 41 percent of Americans live in areas where air pollution can make breathing not just more difficult but dangerous.
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The tube, resting inches below the pregnant mom's mouth, sucks air into a special filter, giving an approximate measurement of the air that she is breathing.
The caller wondered when other African-Americans were going to realize that Obama wasn't like them, because he's an elitist living an extraordinary life and breathing rarified air.
China has five of the world's 10 most polluted cities, and on an average day in China's major cities, 75 percent of the residents are breathing unclean air.
Perhaps the most important thing to be aware of when it comes to snoring is a condition called obstructive sleep apnea, where loud snoring is paired with gasps for air or pauses in breathing for more than about 15 seconds.
The boat, called Route 66, cruised at more than 20 knots and frequently hit speeds in excess of 30 knots, or 55 kilometers an hour. (Note that America's Cup racers max out at 16 knots, and they're basically empty shells with nary a cushion to sit on.) Route 66 boasted a full luxury interior with air-conditioning, desalination equipment and even an air compressor for underwater breathing hoses.
As an early environmental activist, I worried about my baby breathing the dirty air in New York City.
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Lastly, he entered the Houses of Parliament, and stood in the silent debating chamber of the Commons, breathing the stale air.
And while a rejuvenated Bristol are breathing the rarefied air of the Premiership, Evans could be rattling round a half-empty Stoop, a fallen squire cursing the cruel realities of the modern game.
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The report says people living near incinerators may be exposed to a range of toxic chemicals, by breathing in contaminated air, eating food which has been contaminated, or by skin contact with affected soil.
Prop traders, even if they are "ring fenced" from other trading desks, still have access to information the bank has on customer positions, if only by virtue of breathing the same air as their client-facing colleagues.
To cope with air pollution in China, artist Matt Hope produced a "Breathing Bike, " that consists of a fighter pilot's breathing mask attached to a pedal-powered air filtration system.
Still, much of the pleasure of the cruise is being aboard the gulet, lounging on deck and breathing in the sea air.
This prevents air flowing through the lungs, causing breathing problems and sometimes damaging the lung tissues.
They stroll along Ojai Avenue from art gallery to art gallery, enjoying stunning views of the Topa Topa Mountains and breathing in the smog-free air.
Finally, we caught wind of an innovative breathing mask that filters CO2 from the air, converts it into energy, and stores it to power a cellphone or portable music player.
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"Birds have very intensive breathing, and such extreme levels of air pollutants have definitely affected them, " he said, explaining that it was possible for birds to basically drop dead from the skies.
Breathing particulate-laden (aka smoggy) air may be hardening your arteries faster than normal, according to research published today in PLOS Medicine.
Dr Chris Guz explained that patients often reacted as the breathing tube of the ventilator was placed in their air passage.
Nolen says air pollution can cause asthma attacks, heart attacks, strokes, lung conditions and difficulty breathing for some people.
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