1. Diane Guo
Mission to Mars
Grade 10 Science
Mission To Mars
Building a Space Shuttle
Figure 1: Labeled diagram of space shuttle
There are several reasons I chose this design, from the shape, mass and functions. Figure 1 is
the spaces shuttle I have designed. I designed my space shuttle in a cone shape, because cone
shape will reduce the resistance force on the space shuttle. There are two wheels under the
space shuttle, they are used for the landing of the space shuttle. There is a rudder at the end of
the space shuttle, it is used as a speed brake when it breaks through the atmosphere and tries
to land.The space shuttle will be made with titanium on the outside layer of the space shuttle.
Titanium is widely used for military uses and aeronautical uses. Titanium is hard enough for a
space shuttle, it is a material that is hard to bend or deform. When going through the
atmosphere, titanium can help protecting the space shuttle. 1The speed brake will increase
drag once it starts to work, the top and bottom half split open to increase air resistance,
therefore decrease the speed of the space shuttle. Aslo, to reduce speed, I will use a parachute
when its is at around 10 kilometers above the earth, which is around the troposphere,
1 http://en.allexperts.com/q/Metals-2415/stongest-metal-1.htm
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2. Diane Guo
Mission to Mars
Grade 10 Science
because then the space shuttle will have enough time to decelerate. Usually an empty space
shuttle would weight around 74,843 kg, but with solid rocket boosters and all the fuels it
weights around 4 million pounds (2 million kg), and has a velocity around 17,500 miles per
hour (27,359km per hour). The momentum of the space shuttle will be p= mv, which is
2,000,000 x 8 =16,000,000 kg m/s.
The space shuttle is very heavy, so at the same time there will be a lot of weight force reacting
on it. I will use Newton’s 2nd law F=ma to calculate the weight force. Fw=mg= 2,000,000 x
9.81=1.962x10^7 (N)
Although the space shuttle weight a lot, however there are ways to overcome the weight force.
I will have two solid rocket boosters, and 3 engines to help bring up the space shuttle. The two
solid rocket boosters are used to provide most of the force that is needed to bring the space
shuttle off the launch pad. The 2 solid rocket boosters provide about 70% of the force, while
the engines provide the rest 30%. 2
Usually, when a person cough, it produces a g force of 3.5 g; a rollar coaster has a g force of
6.7g.3 An astronaut in orbit experience 0 g, because there is no gravity in space, it is called
weightlessness. Weightlessness occurs when there is no force of support or acceleration on
your body.
2 http://science.howstuffworks.com/space-shuttle.htm
3 http://www.wisegeek.com/what-is-g-force.htm
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3. Diane Guo
Mission to Mars
Grade 10 Science
Launching your Rocket
Figure 2: Labeled diagram of the rocket Figure 3: Launching of a rocket
As shown in Figure 3, first the computers
takes over control of the rocket and the space shuttle, then the shuttle’s engine ignite one by
one. The solid rocket boosters will ignite and lifts the entire space shuttle off the pad. At
around 1 minute time, the engines are at their best position to work. At around two minutes,
the solid rocket boosters separate from the orbiter, parachutes that are attached to them will
deploy, falling into the ocean nearby. At around 8.5 minutes the fuels inside the external tank
will be burn out. The External Tank separates from the space shuttle, burns off itself, and the
three engines push the space shuttle into orbit.4 The fuel I will be using for the engine is
monomethyl hydrazine. Because when the two substances combined together, they light up
and start to burn automatically, it is because there is no oxygen mixed with the two
substances. Most importantly, when they burn, no sparks will be produces, that way the safety
of the astronauts will be better. If there is sparks when the fuel is burned, there will be
chances that the sparks will lead to serious explosion with the fuel. Oxidizer will also be
needed, it will be kept separately with the fuel in two different tanks. Helium will help to push
the fuels through pipes that connect to the engine. The reason why helium is been used is
4 http://science.howstuffworks.com/space-shuttle.htm
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4. Diane Guo
Mission to Mars
Grade 10 Science
because it is a natural gas that would not burn, this increases the safety of the astronauts.
Each solid rocket booster carries more than 1 million pounds (45,359 kg) of solid propellant,
and the external tank carries more than 500,000 gallons of fuel. They together suport the
space shuttle and the engine to its orbit.
This diagram helps to explain
Newton’s third law, “For every
action there is an equal and
opposite reaction.” The space
shuttle has a weight force of
2,000,000 Newtons, and thrusters
to help the space shuttle to lift off.
The resultant force is the force that
is reacted back to te rocket and
therefore it will rise up to the sky.
Figure 5: parallel forces
acting on a plane to keep it straight.
Figure 4: Free body diagram of the space shuttle
Overcoming Problems during the journey
Because Earth is third from the sun and mars is the forth, the Earth revolves faster than Mars
around the sun, so the distance between Earth and Mars is varied from 54.6 million km up to
225 million km.5 The average distance between Earth and Mars is about 225 million km. IF we
assume the speed of the space shuttle is 28,000 km per hour (672,000 km per day), then it
will take 333 days just to reach mars! Therefore, I will launch the rocket when the Earth is
closest to Mars, which is around 55 million km far. If the distance is only 55 million km, the
time it takes to reach mars will be reduced to 82 days. So the whole journey of mission to
mars will take approximately 164 days, about 5 and half month.
Gravitational force is the reason that causes the Earth and Mars orbit around the sun, it is
something that everything on Earth has. Newton’s law of universal gravitation stated that
5 http://www.space.com/14729-spacekids-distance-earth-mars.html
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5. Diane Guo
Mission to Mars
Grade 10 Science
every point mass in the universe attracts every other point mass with a force that is directly
proportional to the product of their masses and inversely proportional to the square of the
distance between them.
The space shuttle is a completely different environment from the earth, therefore the
astronauts will be facing a lot of problems during their mission to mars. First of all, the air in
the space shuttle must be similar to Earth, so that the astronauts can breathe properly. In
order to do that the orbiter will be carrying liquid oxygen and liquid nitrogen along with the
space shuttle. Another major problem is water. Water will be made from liquid oxygen and
hydrogen in the fuel cells, where it turns the fuels into water. 6 The food that the astronauts
eat are in several forms: dehydrated, low moisture, heat-stabilized, irradiated and fresh. 7
Inside the space shuttle there will be a cabin for food supplies and refreshment equipments.
Because the space shuttle is leaving Earth for 162 days, so I won’t bring many fresh food,
because they will not last very long, and will take up the limited space in the food cabin. I will
be sending 2 astronauts into the space, if we assume 1 astronaut eat 100 g for each dish, and 4
different dishes are provided for each meal. 3 x 400 = 1200g (per day) 1200 x 162= 194,400 g
≈ 194kg . 194 x 2= 388 kg The space shuttle will bring approximately 400 kg of food into
space for 2 people to eat during the 162 days. The excrete that will be create, will just simply
go out to space. The astronauts will wear a bag inside their space suit, the bag will have a tube
that is connected to a machine that will eliminate all the waste into the space. One every
important thing for the astronauts to do is to exercise. It is because they are trapped in a small
area for a very long time with out moving a lot, their muscle will get weaker than they were on
Earth. Therefore, I will have fitness equipments on the space shuttle, so that the astronauts
can exercise as much as they can to reduce the weaken of their muscle. If any outside part of
the space shuttle breaks, the astronaut will go out and fix it with a safety tether. It will hold
the astronaut onto the space shuttle. They will also use cloth tethers when the astronauts
need to use both their hands to fix the space shuttle. If te tether breaks, the astronaut can use
the air bag at the back of their space suit to get back to the space shuttle.
Landing on Mars
6 http://science.howstuffworks.com/space-shuttle.htm
7 Ibid
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6. Diane Guo
Mission to Mars
Grade 10 Science
Figure 6: Labeled diagram
of Mars lander
After 81 days of flying, the space shuttle will reach the surface of Mars. Figure 6 is a diagram
that shows the Mars lander coming out from the space shuttle. The Mars lander is also a cone
shape, because it has to fit into the head of the space shuttle. When the space shuttle is getting
close to Mars, the gear on the space shuttle will open and the Mars lander will come out. The
red region in the diagram is where the fuels will be, the fuel is for getting out of the space
shuttle and getting back. While the lander stays on Mars, the space shuttle will stay put near
by Mars, so that when the time is up, the lander can easily get back to it. Because the space
shuttle is moving at a great speed, it has to decelerate before landing on Mars. It will start to
decelerate around 5000 km away from Mars, so by the time it is near to Mars it can be
stopped easily. The gravity on Mars is 38% of Earth8, so the space shuttle will weigh around
77,000 x 0.38 = 29,260 kg on mars. (The space shuttle’s weight changed from 2,000,000 kg to
77,000 kg because the rockets and the external tank were dropped off before going into
space) The momentum of the space shuttle will therefore just be 29,260 kgm/s because it
won’t be moving on Mars.
8 http://www.universetoday.com/22603/mars-compared-to-earth/
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7. Diane Guo
Mission to Mars
Grade 10 Science
Re-launching your Shuttle to return to Earth
To get back from Mars to Earth, the space shuttle will first communicate with the ground. The
way is to send a digital signal from the space shuttle back to Earth. The advantage of using
digital signals is that numbers, letters, sounds, images can also be send back to Earth. 9 Also,
digital signals does not cause errors to the information, and the information can be copied as
many times as you want. When the space shuttle is about 225 km away from Earth, the speed
will be 3000 km/h.10 When it is 40 km away from the runway, the speed will decrease to 1000
km/h.11 When the space shuttle is 610 meters above the Earth,12 the astronaut will release the
parachute and the speed brake, they will help the space shuttle slow down by creating air
resistance.
Source
9 http://www.diffen.com/difference/Analog_vs_Digital
10 http://wiki.answers.com/Q/How_does_a_space_shuttle_come_back_to_earth
11 Ibid
12 Ibid
7