NASA's Reusable Space Plane
<p>After 30 years of service, NASA's fleet of three space
shuttles is standing down for good.</p>
<p>The final shuttle mission planned, the <a
href="http://www.space.com/12046-nasa-space-shuttle-final-flight-atlantis-sts135.html">STS-135
launch of Atlantis</a>, launched in July 2011. After that, the orbiters will
be headed to museums to live out their lives on public display. </p>
<p>As we say goodbye to the iconic reusable space planes,
here are eight surprising shuttle facts to keep in mind:</p>
Top Speed
<p>While in orbit, the space shuttle travels around Earth at
a speed of about 17,500 miles (28,000 kilometers) per hour. At this speed, the
crew can see a sunrise or sunset every 45 minutes. [<a
href="http://www.space.com/12104-10-amazing-space-shuttle-photos.html">Top 10
Space Shuttle Photos</a>]</p>
Well Traveled
<p>The combined mileage of all five orbiters is 513.7 million
miles (826.7 million km), or 1.3 times the distance between Earth and Jupiter. Each
orbiter, except for Challenger, traveled farther than the distance between
Earth and the sun.</p>
Presidential Attention
<p>Only one president has been on hand to witness a space
shuttle launch. President Bill Clinton, along with his wife Hillary Clinton, watched
Mercury astronaut John Glenn's return to space on the STS-95 flight on Oct. 29,
1998 from the Kennedy Space Center in Florida.</p>
<p>President Obama had planned to watch the shuttle Endeavour
lift off on its final mission STS-134, on April 29, 2011, but that launch was
delayed. The <a
href="http://www.space.com/11530-obama-visits-nasa-space-center-shuttle-launch.html">President
and his family did visit the spaceport</a> anyway.</p>
Space Science
<p>The space shuttle isn't just a mode of transport: It's a
laboratory, too. There have been 22 Spacelab missions, or missions where
science, astronomy, and physics have been studied inside a special module
carried on the space shuttle. </p>
<p>Spacelab, a reusable laboratory built for use on space
shuttle flights, allowed scientists to perform experiments in <a
href="http://en.wikipedia.org/wiki/Microgravity">microgravity</a>.
Starting in 1983's Challenger missions, animals became a prime component of
space science. On the STS-7 mission, the social activities of ant colonies in
zero gravity were examined, and during STS-8, six rats were flown in the Animal
Enclosure module to study animal behavior in space.</p>
Taking the Heat
<p><The space
shuttle's Thermal Protection System, or heat shield, contains more than 30,000
tiles that are constructed essentially of sand. </p>
<p>All of the
tiles are thoroughly inspected before liftoff – they are a crucial tool that
allows the space shuttle to endure the intense heat endured when the shuttle
re-enters Earth's atmosphere to land. After the tiles are heated to peak
temperature, the tiles can cool fast enough to be held in your hand only a
minute later.</p>
Packing on the Pounds
<p>The heaviest space shuttle orbiter, Columbia, weighed
178,000 pounds (80,700 kg), roughly the weight of 13 African Elephants. </p>
<p>Columbia, the <a
href="http://www.space.com/11345-photos-nasa-space-shuttle-1st-flight-sts1.html">first
space shuttle to fly</a>, weighed the most because NASA was still searching for
lighter materials to use, and integrated some of these into the later orbiters.
</p>
Official Monikers
<p>The space shuttle program is officially known as the Space
Transportation System (STS), and so each shuttle mission is designated with the
prefix "STS." </p>
<p>Initially, the missions were given sequential numbers
indicating their order of launch, from STS-1 through STS-9. However, because the
then-NASA administrator James Beggs suffered from triskaidekaphobia (the fear of the number 13) and wanted
to avoid associations with the unlucky Apollo 13 mission, the agency drew up a
new numbering system for space
shuttle missions, according to NASA history accounts by several astronauts at
time.</p>
p>What would have been STS-11 was named STS-41B, STS-12
became STS-41C, and STS-13 was STS-41D. The first number was the last digit in
the fiscal year (1984), the second number indicated the launch site (1 for
Kennedy Space Center, and 6 for Vandenberg Air Force Base), and the letter
indicated the sequence (A was the first launch of the year, and so on). </p>
<p>After the 1986 Challenger disaster, when that shuttle and
its STS-51L mission crew were lost, the agency resumed the sequential numbering
system, starting with STS-26. </p>
Tweeting from Space
<p>On May 11, 2009, astronaut Michael J. Massimino, a
crewmember of the space shuttle Atlantis’ STS-125 mission, became the first
person to use the microblogging site <a
href="http://www.space.com/6695-twitter-message-space.html">Twitter in space</a>.
</p>
<p>Writing as @Astro_Mike, he tweeted "From orbit:
Launch was awesome!! I am feeling great, working hard, & enjoying the
magnificent views, the adventure of a lifetime has begun!"</p>
<p>Since then, many astronauts from NASA and other space
agencies have posted Twitter messages from space. One, NASA spaceflyer Doug
Wheelock, won a Twitter Shorty Award earlier this year for the posts and photos
he shared from space using the website during his months-long stay aboard the
International Space Station.</p>
<p>For NASA's final space shuttle mission, all four of
Atlantis' crewmembers have Twitter alias. They are: commander Chris Ferguson (@<a
href="http://www.twitter.com/Astro_Ferg">Astro_Ferg</a>), pilot Doug Hurley (@<a
href="http://www.twitter.com/Astro_Doug">Astro_Doug</a>), mission specialist
Sandy Magnus (@<a href="http://www.twitter.com/Astro_Sandy">Astro_Sandy</a>)
and mission specialist Rex Walheim (@<a href="http://www.twitter.com/Astro_Rex">Astro_Rex</a>).</p>
<p>Atlantis's final mission is STS-135 and will fly a 12-day
mission to deliver vital supplies and spare parts to the International Space
Station. NASA is retiring all three of its shuttles after 30 years to make way
for a new program aimed at sending astronauts on deep space missions to an
asteroid and other targets.</p>
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