Bernardo
from Mexico City
Has Endeavour already been upgraded to a MEDS cockpit? |
| Well,
buenos dias, Bernardo. No, Endeavour has not been upgraded to
the MEDS cockpit, or what we call the glass cockpit. At this
point, only Atlantis and Columbia have received those upgrades.
|
chris
from kansas city
Are there any new plans for a lighter yet faster and more fuel
efficient engine? Where are these plans - in the development
stage or are they even farther along? |
| Chris,
rocket scientists are always trying to find new efficiencies
in rocket engines and part of that comes from decreasing the
weight of the engines. Right now, through Space Launch Initiative,
for example, we're trying to find ways to develop engines that
reduce the weight and increase efficiency. But you do have to
remember that a lot of it is the weight of the vehicle and hopefully
through the development of new composite materials, ceramics
and other things, we'll be able to drive down the weight of
the engines, drive down the weight of the vehicles and achieve
those efficiencies. |
Kit
from Ramona, CA
I've heard that rocket engines are more efficient in a thin
atmosphere than at sea level and most efficient in a vacuum.
So why are launches generally made from sea level rather than
from a high point in the mountains? Wouldn't a launch from the
mountains save fuel since the rocket engines would be more efficient
and because the ship is already at a higher potential energy
location in relation to the Earth? |
| Well,
Kit, that's a very good question. Yes, there would be efficiencies
launching at higher elevations. But as the song says, there
ain't no mountain high enough, or big enough or safe enough
for us to have a launch facility like the Kennedy Space Center
at a higher elevation, so we'll keep launching from sea level.
Another important factor, of course, is latitude as much as
altitude. And that's why launches near the equator are much
more efficient in achieving certain orbits. |
David
from Casper, WY
I understand that the Shuttle Main Engines can be gimbaled to
aid in steering the Shuttle. How far off their standard direction
can they be moved (degrees)? |
| The
Space Shuttle Main Engines can actually be gimbaled plus or
minus about 12-and-a-half degress. |
Gabe
from Inverness, CA
How does the power of the STS main engines compare with that
of the Saturn V launch vehicle? |
| Well,
each Shuttle main engine has about 418,000 pounds of thrust,
and there are three on the vehicle, so that's about 1.2 million.
The entire vehicle, taking into account the solid rocket boosters,
is about 7 million pounds of thrust at launch. The Saturn V
vehicle in the Apollo program, with five F1 engines, each one
generating 1.5 million pounds of thrust, was about seven and
a half million pounds at launch. So, close, but not quite.
|
Callum
from Aberdeen
How many engines does STS-111 have? |
| Well,
space shuttle main engines, the SSMEs, there are three of those
on each of the orbiters, including Endeavour for STS-111. But
then you add the solid rocket boosters and of course the various
orbit maneuver engines that round out the propulsion picture
on the Shuttle. |
James
from Atlanta, GA
During launch, the three SSME's are supplied with fuel (liquid
hydrogen) and oxidizer (LOZ), but since these fuels are not
hypergolic in nature, what actually ignites the mixture? |
| Hypergolic
fuels of course are fuels that ignite when they come in contact
with each other. In a liquid oxygen-liquid hydrogen engine,
such as the space shuttle main engine, they are actually ignited
by a spark igniter. They are located in the augmented spark
igniter chamber, and they actually ignite the fuel. |
JULIO from PALM BAY
How long is the life of the main engines on the shuttle? |
| We
are making some changes. I believe you're talking about changing
the engines out from the orbiters. The engines are supposed
to have a theoretical life of about 50 missions. Probably the
most that any engine has had to date is 17 or 18 flights, but
it's difficult to measure that because you're changing out various
components, the different elements of the engine, over time
and from mission to mission. But we feel that one of the unique
qualities of the space shuttle main engine is the long life
by being a reusable engine. |
Dc
from Charleston
The last main engine upgrade was touted as improving safety
and efficiency. Are there any radical changes visible on the
horizon? |
| We've
been doing upgrades and looking for more safety and efficiency
in the engines ever since they were first created a generation
ago. And so we're constantly looking for new upgrades, and probably
the next major upgrade is the development of an advanced health
management system, which would increase safety. So we figure
that we will continue to do upgrades to make the engines safer
for the flight crews, as well as more reliable and more efficient. |
DARREL
from FT PAYNE
How much horsepower do the shuttle's main engines produce at
the time of lift off? |
| The
three space shuttle main engines generate the maximum equivalent
of about 37 million horsepower. The fuel pump alone delivers
as much as 71,000 horsepower, the oxygen pump delivers about
23,000. Just as a basis of comparison, the fuel pump alone is
probably the equivalent horsepower of 28 locomotives. And with
the horsepower of the oxygen pump, that's probably the equivalent
of 11 more locomotives. |
Shane
from Goldsboro
What process does the engine go through in preparation for the
next launch once the orbiter has landed from a previous mission? |
| The
engines are removed from the orbiter and taken to the SSME processing
facility here at Kennedy Space Center, thoroughly inspected
by our team of Rocketdyne engineers and technicians, and given
whatever kinds of parts changes need to be made. All of it is
under the principle that safety is the most important thing.
And we want to make sure that each engine, upon return, is safe
for that next flight. |
