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STS-111 International Space Station Q & A
Before
the KSC Direct! webcast of the STS-111 launch, space enthusiasts from
all over the world submitted questions for our Space Station expert, Nick
Cummings. The questions were answered during the show. In case you missed
the webcast, or would like to review each of the questions and answers,
we have provided the STS-111 ISS Q&A in its entirety below.
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Krunal
from Bensalem, PA:
Do you believe in that the design of the ISS will cause a problem
in case of a meteor shower? Why? |
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That's a really good question. The space environment
is a very harsh environment: there's radiation and micrometeorite
strikes, and other things in the environment that cause it
to be very hazardous. So, one of the things that we've designed
the space station for is to protect the astronauts against
micrometeorite striking the outer shell of the space station.
Now, in doing so, the basic design philosophy of the pressurized
modules has been to develop an inner shell, which contains
the pressurized interior of the space station, and then a
layer of insulation around that inner shell, and then an outer
armor plating, if you will, to the exterior. And what that
does is protects against small pieces of debris that strike
the station and can cause leaks. Now, for larger pieces of
debris: they actually track them and have to actually move
the space station out of the way of the larger pieces that
could cause serious damage to the station.
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Luis
from San Juan:
What kind of contingency plan does the ISS have in case of an
emergency? How long do life support systems on board last for
the stranded astronauts? Is there such a thing as an emergency
launch to the ISS using the current Space Shuttles? |
| Well,
there are several redundant systems on the space station, which
really enable the astronauts to survive for long periods of
time without a space shuttle or a Russian re-supply ship coming
to bring additional supplies. Now, in the event of an outright
emergency, where the lives of the astronauts were threatened,
they would have to evacuate the space station using the Soyuz
module, but the life support systems themselves are designed
to last for months at a time without a re-supply ship. |
Mark
from Whitehaven, UK:
What would you say to date has been the greatest benefit to
mankind from the space station, and what is its predicted benefits? |
| Well,
I think it's all a matter of judgment, but to me the greatest
benefit of the space station is the international cooperation
to date that we've had with over 16 different countries contributing
to the International Space Station; countries that were at one
time, enemies of each other, have now come together to do something
that will benefit mankind. I think down the road the space station
will bring great leaps in science, in medical fields, in the
materials manufacturing fields, and it will also teach us a
lot about long duration human space flight so that we can expand
our civilization beyond Earth. |
David
from Oakdale, CA:
Why is the center truss section called S-Zero?
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| That's
actually a really good question, because the trusses are named
for whether they're on the starboard side or the port side;
so you have S-Zero, S-One, P-One, S-Three, P-Three, P-Four,
S-Four, P-Five, S-Five. Well, S-Zero being in the middle, I
guess they couldn't decide whether to call it S-Zero or P-Zero,
and maybe they flipped a coin or whatever else and decided to
call it S-Zero, but it's actually in the center, it's not on
the starboard side or the port side, so it could have just as
easily been named P-Zero. |
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Chary
from the Philippines:
Does the International Space Station have any hardware or
machines that were specifically invented for it and cannot
be found anywhere else? What are they?
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| Well,
the International Space Station has lots of unique hardware
elements that were designed specifically for the International
Space Station. They also use off-the-shelf technology when possible;
one instance of that is the cameras that they use on the space
station for the interior of the space station are actually just
off-the-shelf camcorders. But, some, there's certainly a great
amount of technology that was developed specifically for the
International Space Station to function specifically in the
space environment. I think one of the best examples of that
is the Canadian robotic arm. The Canadian robotic arm was developed
specifically for the International Space Station and fills the
task of actually constructing the International Space Station,
and it doesn't even function in the Earth environment in the
one-G conditions that we have here on Earth. |
Sandeep
from Kuala Lumpur:
When will the International Space Station be completed? |
| Well
also that's a very interesting question. The core complete milestone
that we are reaching for right now is due in the mid-2004 timeframe.
Now, after we finish building what's essentially the core of
the International Space Station then we have a lot of additional
options to add elements developed by international partners,
and other additional features that we might want to add. The
fact that the space station was designed the way it was allows
us to once we get to the core complete milestone to expand it
to provide lots of additional capabilities. |
Bernardo
from Mexico City:
Which ISS docking port is being used by the Soyuz TM-34 spacecraft?
Also, where in the Station will Endeavour and Leonardo dock? |
| Well,
the Soyuz module is nominally docked to the end of the Russian
service module. Now, there are additional docking ports on the
Russian functional cargo block, I'm sorry, on the bottom of
the service module, where the Soyuz modules can be docked. And
when they bring a second one up onto orbit in order to switch
out the first one when they have to replace them, they actually
have to move one of the Soyuz modules from the end of the service
module to the bottom of the service module, and the second service
module goes on to the end. The Space Shuttle, on the other hand,
docks to the American side of the space station, to the Destiny
laboratory. And the MPLM, Leonardo, in this case, is docked
to Node-1, which was also built by an American company, Boeing.
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Raymond
from Fresno, CA:
Is it possible to give the times and locations of when the ISS
passes over Central California? |
| Well,
it's actually possible to find out when the space station will
be passing over your head no matter where you live, and there's
a website, it's http://spaceflight.nasa.gov, and if you go that
website, you can follow links and actually no matter what city
you are in the country, you can find out when the space station
will be traveling overhead. |
Mike
from Mt. Dora:
With respect to the space station, why can't we just shoot the
trash off towards the sun instead of bringing it back to Earth? |
| Well,
that's actually a question that I used to wonder about when
I was growing up, why didn't we just put all the trash into
the sun to save our garbage problems here on Earth. Unfortunately,
it would take a lot of rocket power to get anything to the Sun,
and so it's sort of a limiting factor to be able to launch something
out the sphere of influence of the Earth. Now, the trash on
the International Space Station, not all of it is brought back
to Earth. Some of it is placed in the Russian Progress modules,
which are sent on a trajectory into the Earth's atmosphere that
burns it back up. So it's not all brought back to Earth, just
some of it in the MPLM modules. |
Ryan
Voll from Red Deer:
After the completion of the ISS, how much will it contribute
to the flight of humans to Mars, and return trips to the Moon? |
| Well,
this kind of goes with the earlier question, about what the
benefits of the International Space Station are. If we're going
to go to Mars, or spend long periods of time on the Moon, we
have to learn what the effects of long term space flight is
going to be on our astronauts. We don't have a lot of information
about what the space environment does to our astronauts, beyond,
say six months. There are astronauts, particularly from Russia,
who have spend more time than that in space, but very few, so
we don't have a large amount of data, and it'd be very risky
to send astronauts to Mars, to spend say, a year and a half
outside of the Earth environment, or more, without knowing exactly
what the effects of the long term exposure to space would be.
So, the International Space Station in addition to us just developing
the technology to live in space for large amounts of time, it
gives us the information that we need about how long astronauts
can safely stay in space. |
Daniel
from Zenon Park:
Is it possible to use a flywheel mechanism to produce power
for the space station? Have there been any experiments using
this technology to produce power in space? |
| Well,
it's actually not possible to use flywheels to generate power
in the classical sense, but you can use flywheels to store power.
So, you would have to use some other source to generate the
power, but then to store it you could spin up flywheels and
then use the kinetic energy from the flywheels to actually store
energy. But because the power requirements of the space station
are so large, it's a lot more practical for us to use batteries
to store power on the station. So, the answer to the question
is no, we don't use flywheels to store power. |
Taylor
from Colorado Springs:
How many different civilian contracting companies, on average,
participate in the building of one of our space station modules? |
| Well,
most of the American space station modules were developed and
built by the prime contractor for the space station, which is
Boeing. Now, Boeing has dozens, if not hundreds of subcontractors
that it uses to build everything from the smallest screw used
on the space station to a complex computer, or a solar array.
So, there's one prime contractor, but dozens, if not hundreds
of subcontractors. |
Butch
from Rochester Hills:
When the space station needs to make an orbital adjustment,
do the occupants of the space station feel the movement of the
adjustment? |
| Well,
the reason why I think that's such a good question is because
it really highlights one of the most fundamental laws of physics
we have, and there are basically three laws of physics that
Isaac Newton postulated hundreds of years ago, and one of those
laws it that force equals mass times acceleration.. Now, the
key thing about these laws is that no matter where you are in
the universe, they are true. So whether you're on Earth or whether
you're in space, these laws are true. Now, this particular law,
force equals mass plus acceleration, when you press the gas
pedal in your car, your car accelerates, you go from say, 55
miles an hour to 60 miles an hour. That acceleration is what
causes you to feel that force. Now, in space, when they fire
the thrusters on the space station, the space station also accelerates.
But the acceleration is generally very, very small. So sometimes
the astronauts might not notice the space station is accelerating.
But that also brings in another interesting point, in what they
might see, since the astronauts are floating free with respect
to the space station, that when the space station fires it thrusters,
the space station would move, and the astronauts, not touching
one of the surfaces, would not move, so they would see the space
station actually moving around them. |
Joey
from Australia:
During a 24 hour period, how many times does the ISS orbit the
Earth? |
| Well,
the space station orbits Earth about every 90 minutes, so that
means in a 24 hour day, the space station orbits approximately
16 times. |
Matt
from Columbia:
In operating, marinating, and troubleshooting problems on the
ISS, how involved does the ISS crew get versus the control center
team? |
| Well,
that's a very good question. NASA has an entire army of people
supporting the operations of the International Space Station.
Of course, the astronauts are often the first line of defense,
and especially in emergency situations, they have to make quick,
critical decisions that will allow everybody to be safe. Now,
the mission control people are a huge part of supporting that
and laying out those plans for the emergency situations. But,
in the event that something goes wrong on the station, NASA
has the ability to go back to the people who actually designed
the hardware and ask them what they think about the problem,
and if it's something they might have seen before in ground
testing. So it's a collaborative effort across all of the different
countries that make up the hardware that we use on the International
Space Station. |
Diana
from Hilton Head:
On certain days we are able to visualize the space station as
it seems to streak across the sky. How fast is the ISS traveling? |
| Well,
in order for the space station to stay in orbit, it has to travel
at 7 kilometers per second, which the equivalent in miles per
hour, is around 15,500 miles per hour. So that's pretty fast!
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