9 we have a go for main engine start
five four three two one zero booster
ignition and liftoff of Columbia a new
decade of spaceflight begins six five
four three two one ignition and liftoff
of discovery and the Ulysses spacecraft
bound for the polar regions of the Sun
that Space Shuttle Orbiter is rocketing
into space but what is space how do we
get there how do we stay there how do we
get back to earth again well before we
answer these questions let's look at
some history of man Rockets this man
Robert H Goddard is considered to be the
father of modern rocketry he began
testing Rockets as a young man and in
1926 he launched the world's first
liquid-fuel rocket he was also the first
to propose using both solid and liquid
propellants on the same rocket
why is that an important idea because
that's how he boosts the Space Shuttle
into orbit today it was in 1956 when a
team of scientists engineers led by
Bernhard von Braun launched the Jupiter
C rocket this was the first time that we
launched anything that went high enough
to get into space two years later
another Jupiter C traveled in space but
this time had left a satellite up there
to orbit the earth then in 1961 only
months after the Soviet Union sent their
first astronaut into space NASA launched
the first American into space on board
the Freedom say things were moving
pretty fast first we had the mercury
program
then Gemini and then just eight years
after the first human would went into
space a Saturn 5 rocket launched the
Apollo spacecraft carrying the first
astronauts to the moon
today astronauts fly into space in a
different vehicle the Space Shuttle
Orbiter to give us enough energy to get
into orbit we use special engines and
propellants let's look at the shuttle a
little differently this is what we call
the stack sitting on the launch pad here
in Florida let's look at it the way an
engineer might look at it
the solid rocket boosters or SRBs burn a
solid fuel the external tank where ET
carries liquid oxygen and liquid
hydrogen for the shuttles main engines
this combination of solid and liquid
propellants are very powerful we're
launch we start the liquid main engines
burst then the solid rocket boosters
ignite and lift the whole stack off the
pad downrange twenty two nautical miles
the solid rocket boosters push the
shuttle for about two minutes and up
through the thickest part of the
atmosphere then we separate from the
Boosters the shuttles main engines
continue to burn for another seven
minutes
pushing the orbiter fast enough to get
into space okay
and here's the result we're in space but
we're in space are we in other words how
far above the earth have we come let's
use this picture to help explain here is
the surface of the earth here would be
the Earth's highest mountain Mount
Everest which is about 6 miles high and
right here would be where commercial
airplanes fly about 6 to 7 miles above
sea level the astronauts that went to
the moon went 240 thousand miles above
the earth and if we can put that on this
picture to scale it would be 5000 feet
this way well where does that leave us
here in the Space Shuttle well right now
in the Space Shuttle we are about right
here 160 miles above the earth for
example though the Space Shuttle can
even go higher sts-31 that deployed the
Hubble Space Telescope went all the way
out to here 300 miles above the earth
so what's it like up here well let's do
a weather report from space well Tom I'm
gonna have a little problem with that
because there is no weather in space in
order to have whether you have to have
an atmosphere up here in the Space
Shuttle we're well above the Earth's
atmosphere so I can't give you a port on
their weather but I can tell you what
the conditions are going to be like
outside today we can expect a scorching
high of about 300 degrees Fahrenheit
outside today in the Sun that's about
150 degrees celcius down to a real
freezing low of 150 degrees below zero
which is a minus 100 degrees Celsius in
the shade we can expect the relative
humidity to be zero and our barometric
pressure is also going to be zero now
some of our viewers out there may be
wondering why are these extreme
conditions outside when we're only a
hundred and sixty miles up above the
Earth's surface and the living
conditions down there are so nice well
the reason is is down on the surface of
the earth we have an atmosphere the
atmosphere performed as a protective
blanket for us when we live down on the
surface of the earth here for example is
a picture of what the earth looks like
from a satellite 23,000 miles above the
earth you can see that much of the
surface of the earth is covered by
clouds these clouds are the part of the
atmosphere that you can see the visible
part of the atmosphere the clouds were
made up of water molecules those water
molecules are what account for the
relative humidity of our atmosphere the
total weight of the atmosphere above a
point on the surface of the earth is
what it makes up for the barometric
pressure now we don't have to worry
about our climate here in the Space
Shuttle when we're up here in space
because we have an air-conditioner but
we call our environmental control system
on board this environmental control
system will maintain our temperature a
nice comfortable 77 degrees Fahrenheit
which is about 25 degrees Celsius
relative humidity will stay at about a
constant 50% enter barometric pressure
will be about 29.92 inches of mercury
back to you Tom
thanks Bruce as you can see the
environment in space is very harsh so
here in the orbiter we have to make the
environment duplicate the environment
that is down on the Earth's surface
and even though we're over 150 miles up
in space here the pressure inside the
space shuttle is almost the same as it
is at sea level see it's fool this
altimeter into reading almost zero well
now we know where space is and what
space is how do we stay here
once we've arrived well 300 years ago an
English scientist Sir Isaac Newton
figured out a way to do this
he began by showing a very high mountain
the imaginary mountain was so high that
its peak poked above all the atmosphere
he put a cannon on top of the mountain
and fired cannonballs will use baseballs
okay here's our imaginary mountain let's
pretend that we can climb to the top of
this mountain with a sack of baseballs
now if we throw one of these baseballs
straight out from the top of the
mountain when it goes straight out like
a ball straight down like B or fall on a
curved path while C is correct the
baseball would fall on a curved path
even on this tall mountain it still
feels gravity this is because the ball
has two motions acting on it at the same
time it's trying to go straight out and
it's also falling toward the earth the
result is the baseball travels on a
curved path and lands right here
now let's throw another ball only this
time much faster
see it goes farther than the first if we
throw another ball even faster than the
last one that goes farther still so the
faster we throw the balls the farther
around the earth they go
now we'll take our last ball and throw
it as hard as we can just like the other
balls it falls in a curved path but this
one is moving so fast that it circles
the earth we'll have to duck to missile
it won't be safe to stand up for a while
because unless something gets in the way
the ball will continue to fall around
the earth on a curved path we call this
an orbit of course the Space Shuttle
doesn't launch when the mountain but we
still need a lot of speed to get into an
orbit around the Earth
so how fast do we need to be going to
get into orbit well it's a space shuttle
at a speedometer like the one in your
car it would have to get all the way to
17,500 miles per hour to make it into
space
so how fast is that well it took the
early pioneers months to cross the
United States by wagon
it took the first transcontinental
trains a week to cross by rail
it would take about three days of
driving round the clock to get across by
car and it takes about five hours for
the average airline that's like
coast-to-coast but on board the shuttle
we cross the country in ten minutes
that's about five miles a second you see
the Space Shuttle goes around the earth
16 times every earth day that means we
see a sunrise and a sunset once every 90
minutes this could be a problem up here
on the orbiter if I woke up when it was
light and went to bed when it was dark
I'd be getting up and going to sleep
every 45 minutes so instead we just plan
out our days like we would on earth
another thing you should know is we just
don't float around on the orbiter
because there is no gravity we still
feel Earth's gravity so why are we
floating
because we're falling let's say this
string is gravity and let's say this
Apple is like a spaceship orbiting the
Earth you see its gravity in our speed
that keeps us in orbit without gravity
we would fly off into space and never
come back
here's another example when I dropped
this Apple on earth it falls when I drop
an apple here on the Space Shuttle it
falls - it just doesn't look like it's
falling
and that's because we're all falling
together the Apple me and the orbiter
we're not falling towards the earth
we're falling around it
let's imagine that we can send Bruce
down to the nearest elevator on earth
the elevator is going to the top of a
very tall building
suddenly when he reaches the top the
cable breaks in the elevator car with
Bruce in it begins to fall what will
happen inside the elevator well since
he's falling and the elevator is falling
the same rate he starts to float his
body isn't pushing on the inside of the
elevator anymore
he has no weight he's weightless if he
had an apple with him it would float too
just like the one in the orbiter because
Bruce the Apple and the elevator would
all be falling together it would be a
fun ride until he hit the bottom and
that's why things float around up here
even really big things because we're all
falling on a curved path around the
earth
well now our work in space is done and
it's time to go home so how do we do it
well first we have to slow down let's go
back to our imaginary Mountain here's
our baseball orbiting the earth it's
going around every 90 minutes - we know
the other baseball's weren't able to get
into orbit because we didn't throw them
fast enough now to bring the baseball
back for more of it
all we have to do is slow it down just a
bit watch what this looks like
those were maneuvering engines firing we
use them to slow down
here's what it looks like from outside
the orbiter when they fire they slow us
down just enough to make a safe descent
just like the baseball we've got to slow
down to get out of little bit we glide
back to earth under computer control
until our altitude is about fifty
thousand feet then the commander and
pilot take over and land our space
shuttle just like an airplane
space is great but a safe touchdown sure
feels good after traveling two million
miles in five days it's nice to be back
home again so now we know that it takes
a lot of power to push the orbiter
through the atmosphere and into
low-earth orbit in space we have to go
very fast to stay in space and we have
to slow down just enough to allow
Earth's gravity to pull us out of orbit
when we want to return that's how we get
into space how we stay there and how we
get back
he might have 10987 thick we go for main
engine start