A small micrometeroid massing 6.0 grams hits the space station at a velocity of 22,000 m/s.
a) What’s its kinetic energy?
Kinetic Energy (KE) = 0.5× mv2 where m = mass (Kg), v = velocity (m/s)
Kinetic Energy (KE) = 0.5× (0.006 Kg) (22000 m/s)2 =
1.452×106 J (Kgm2/s2)
b) A bullet if fired from a .45 pistol, what is its KE?
According to Xiao, bullet from .45 pistol weighs 14.5grams and moves at velocity 380 m/s, hence;
Kinetic Energy (KE) = 0.5× (0.0145 Kg) (380 m/s)2 =
1.0469×103 J (Kgm2/s2)
c) Which one would do more damage, and by what percent or factor?
The small micrometeroid would do more damage due to its high kinetic energy.
Percent of more damage = =
Percent of more damage = 1387 %
Question 2
a) If the Sun’s power at Earth’s orbit is , what is it at Mercury’s orbit?
According to Twickens, Mercury is 0.387 astronomical unit (AU), Earth is 1 AU and Uranus is 19.2 AU from the Sun.
Insolation (W) is power divided by area.
Area Radiated AEarth = 4휋RE2 = 4(3.14) (1.5×1011m)2 = 2.83×1023
m2
WEarth = P/AEarth , hence P = WEarth × AEarth = 1370 w/m2
× (2.83×1023m2) = 3.9×1026w
Area radiated for Mercury is;
Area Radiated AMercury = 4휋RM2 = 4(3.14) [(0.387AU) (1.5×1011m)]2
= 4.23×1022 m2
Sun’s Power at Mercury (WMercury) = P/AMercury = (3.9×1026w) / (4.23×1022 m2)
Sun’s Power at Mercury (WMercury) = 9220 w/m2
b) What is it at Uranus orbit?
Area radiated for Uranus is;
Area Radiated AUranus = 4휋RU2 = 4(3.14) [(19.2AU) (1.5×1011m)]2 = 1.04×1026 m2
Sun’s Power at Uranus (WUranus) = P/AUranus
= (3.9×1026w) / (1.04×1026 m2)
Sun’s Power at Uranus (WUranus) = 3.75 w/m2
Question 3
Why do we use rockets with multiple stages?
Engel states that the multiple stages use in rockets launching, is to make the rocket more efficient by reducing its weight through getting rid of out of work parts for example empty fuel tank and so forth.
Question 4
Where is the Ionosphere, and what causes it?
Ionosphere is a part of the Earth’s atmosphere with charged particles which have effect on radio waves. The charged particles are caused by ultra-violet rays from the Sun colliding with neutral atoms leaving electrons and ions free, resulting in ionization of that part of the Earth’s atmosphere.
Question 5
a) What are the Van Allen radiation belts?
Van Allen belts are layers of charged particles held around the earth’s atmosphere by the earth’s magnetic field. The layers are separated into two zones, the outer belt and inner belt.
b) What are the altitudes of the two belts?
They are contained in the magnetosphere where the charged atoms are strongly affected by the magnetic fields of Earth and Sun.
c) What particles are in each belt? Hint: one belt has two particles, the other only one.
The inner belt contains protons and electrons while the outer belt contains only electrons.
Question 6
Compared to Earth’s Gravity on the surface 9.8 , what is the gravity at the limit of the sphere of influence (SOI). The radius of the SOI is 9.25×105 Kilometers.
Gravity of SOI (g) = G×M/r2 where G is the gravitational constant, M is mass, r is radius
G = 6.67×10-11newton-meter2/Kg2, Assuming mass of Earth, M = 5.98×1024 Kg
r = 9.25×105 Km
Gravity of SOI (g) = 6.67×10-11newton-meter2/Kg2 ×5.98×1024
Kg/(9.25×105×103m)2
Gravity of SOI (g) = 4.67×10-4m/s2
Question 7
How much delta V is required to de-orbit the ISS? Assume it’s in a circular orbit at 415 Km and we want to lower that orbit into the atmosphere at 75 Km. Use Eq. 9-85.
ΔVdeorbit
=
Radius of Earth = 6,378.14 km, GM of Earth = 3.99×1014
m3/s2
Ra = (6,378.14 Km + 415 Km) × 1,000 = 6,793,140 m
Rb = (6,378.14 Km + 75 Km) × 1,000 = 6,453,140 m
Va = =
Va = 7500 m/s
ΔVdeorbit
= =
ΔVdeorbit = 49 m/s
Question 8
I have a satellite in a circular orbit at 450 Km. Suddenly the Air Force notices that an object is in the same circular orbit at 125,000 Km. They ask me to move my satellite up to that object.
Calculate the Hohman transfer from 450 Km to 125,000 Km.
R1 = 450 Km, R2 = 125,000 Km
Hohman transfer = (R1+R2)/2 = (450 Km + 125000 Km) / 2 = 62,725 Km
a) Give the circular speed at 450 Km
Radius of Earth = 6,378.14 km, GM of Earth = 3.99×1014
m3/s2
Ra = (6,378.14 Km + 450 Km) × 1,000 = 6,828,140 m
Rb = (6,378.14 Km + 125000 Km) × 1,000 = 1.314×108 m
Va = =
Va = = 1.05×104 m/s
b) Give the delta V to get it to 125,000 Km
ΔV = where V is initial satellite velocity and Re is radius of Earth
ΔV =
ΔV = 4400 m/s
c) Give the circular speed at 125,000 Km
Vb = =
Vb = = 3000 m/s
d) Give the delta V to circularize the orbit (no plane change needed)
V = = = 1743 m/s
Question 9
a) What are Hypergolic propellants?
Hypergolic propellants are materials which at room temperature, do not need external ignition forces to initiate combustion.
b) Name two advantages of hypergolic over compressed gas systems.
i) Hypergolic propellants are easier to store long term than compressed gas systems.
ii) Hypergolic propellants systems are reliable and can be launched within a short period of time than compressed gas systems.
c) Name a disadvantage of hypergolic over Hydrogen-Oxygen rockets.
Hypergolic propellants cannot be powered off, regulated down and powered back on.
Question 10
a) What is the mathematical and verbal definition of Specific Impulse?(Example F = ma, Force equals mass times acceleration).
Specific Impulse equals engines thrust (force) divided by weight of fuel burned in one second, that is, Specific Impulse =
b) Why is it important?
It is an indication of the engine’s efficiency, the higher the value, the more efficient the engine.
c) If I have one rocket at an Isp of 15 and another at 20, which is better? Assuming both are of the same thrust and are being used for the same job?
The one with Isp of 20 is better as it is more efficient as it uses less fuel since thrust is the same.
Question 11
Why do you use a star pattern on a solid rocket motor?
A star pattern adds more burn area which allows greater start-up pressure and also increase volumetric efficiency.
Question 12
a) What is a hybrid rocket motor?
A hybrid rocket motor is one which uses two different propellants, that is, one propellant is solid and the other is either gas or liquid.
b) Name a typical fuel and oxidizer.
Fuel – Hydrazine and its derivatives.
Oxidizer – Liquid oxygen.
Question 13
In your opinion, what has been the most important advance in space technology/engineering?
The discovery of other planets apart from the Earth.
Question 14
A beam of light at 0.5 micrometers has more energy than an x ray.
X-ray have a wavelength of 1×10-10m, according to quantum theory, energy of a photon is inversely proportional to its wavelength hence X-rays have more energy. Answer is false to the above statement.
Question 15
Sea launch takes their rocket to the equator and launches it there. Why does sea launch do this
a) Technically and
At the equator, anything on the surface of the earth, is in motion at 1670 Km/hr. thus increasing the amount of thrust.
b) Any other reason?
Assists the rocket to stay in orbit by gaining enough momentum from the push on the equator.
Question 16
a) Can a spacecraft in LEO around the earth detect an outdoor distilling operation using a 6 µm infrared detector?
According to Nguyen, for infrared detectors above 4 µm, the Earth becomes a dominant infrared radiation source hence spacecraft in LEO can detect the outdoor distilling operation.
b) They are heating corn mash to evaporate alcohol and are in full view of your satellite, why or why not, be brief.
Alcohol is a fuel and once exposed to any oxidation in the atmosphere, it will initiate combustion and hence cause damage to the satellite.
Question 17
What is the total radiance emittance (Wb) of the surface of the Sun? Assuming the surface of the Sun has a temperature of 5,500oC.
Total radiance emittance (Wb) = σ Where σ = 5.67×10-8 W/m2.K4 is Stefan-Boltzmann constant and T is absolute temperature in K.
Total radiance emittance (Wb) = (5.67×10-8 W/m2.K4) (5773K)4
Total radiance emittance (Wb) = 6.3×107 W/m2
Question 18
How long is the wavelength of 1640 AM radio station, that is, 1640 kHz?
Wavelength of 1640 AM radio station = Speed of Light c (m/s) / frequency (Hz)
Wavelength of 1640 AM radio station = 3×108 m/s / 1640×103 Hz
Wavelength of 1640 AM radio station = 183 m
References
Bentley, Matthew. A. Spaceplanes: From Airport to Spaceport. Available at: <https://books.google.co.ke/books?id=rk1Sivcwyc4C"pg=PA55"lpg=PA55"dq=advan tages+of+hypergolic+propellants+over+compressed+gas+systems"source=bl"ots=TiO NC62odU"sig=uvIULmQ23k3c-UK3B- zFsrYgMNY"hl=en"sa=X"ved=0ahUKEwi6k9O5jrvZAhXO41MKHdoADskQ6AEIY DAI#v=onepage"q"f=false> [Accessed Feb. 24, 2018].
Calculate Surface Gravity. Available at: <http://nova.stanford.edu/projects/mod-x/ad- surfgrav.html> [Accessed Feb. 24, 2018].
Davis, Stephen. M. " Yilmaz, Nadir. Advances in Hypergolic Propellants: Ignition, Hydrazine, and Hydrogen Peroxide Research. 15 Sep, 2014. Available at: <https://www.hindawi.com/journals/aae/2014/729313/> [Accessed Feb. 24, 2018].
Definition of Van Allen Radiation Belts. Available at: <https://economictimes.indiatimes.com/definition/van-allen-radiation-belts> [Accessed Feb. 24, 2018].
Engel, Joshua. Why do rockets have multiple stages? Are boosters an essential part of every launch vehicle? 19 May, 2013. Available at: <https://www.quora.com/Why-do-rockets- have-multiple-stages-Are-boosters-an-essential-part-of-every-launch-vehicle> [Accessed Feb. 24, 2018].
Fundamentals of Thermal Radiation. Available at: <http://kntu.ac.ir/DorsaPax/userfiles/file/Mechanical/OstadFile/Sayyalat/Bazargan/cen58 933_ch11.pdf> [Accessed Feb. 24, 2018].
Hunt, Gordon. The 10 biggest developments in space exploration in the past year. 29 Oct, 2015. Available at: <https://www.siliconrepublic.com/innovation/the-10-biggest-developments- in-space-travel-in-the-past-year> [Accessed Feb. 24, 2018].
Kushnir, Yochanan. Solar Radiation and the Earth's Energy Balance. The Climate System 2000. Available at: <http://eesc.columbia.edu/courses/ees/climate/lectures/radiation/> [Accessed Feb. 24, 2018].
McElroy, Michael. B. Ionosphere and Magnetosphere. Available at: <https://www.britannica.com/science/ionosphere-and-magnetosphere> [Accessed Feb. 24, 2018].
Nguyen, Tam. Attitude Determination using Infrared Earth Horizon Sensors. Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, Cambridge SSC14-VIII-3. Available at <https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=3096"context=smallsat> [Accessed Feb. 24, 2018].
Rocket and Space Technology. Available at <http://www.braeunig.us/space/problem.htm> [Accessed Feb. 24, 2018].
Stein, Steven D. Benefits of the Star Grain Configuration for a Sounding Rocket. United States Air Force Academy Department of Astronautics, USAFA, CO, 80841. Available at: <http://spacegrant.colorado.edu/COSGC_Projects/symposium_archive/2007/papers/S07_ 14_Star_Grain_Configuration_for_Sounding_Rocket.pdf> [Accessed Feb. 24, 2018].
Specific Impulse. Available at: <https://www.grc.nasa.gov/www/k-12/airplane/specimp.html> [Accessed Feb. 24, 2018].
The Effects of Earth's Upper Atmosphere on Radio Signals. Available at: <https://radiojove.gsfc.nasa.gov/education/educ/radio/tran-rec/exerc/iono.htm> [Accessed Feb. 24, 2018].
Twicken, Joe " Wigand Rob. Kepler’s Law. 05 Feb, 1998. Available at: [Accessed Feb. 24, 2018].
Why is it better to launch a spaceship from near the equator? Available at: <http://www.qrg.northwestern.edu/projects/vss/docs/navigation/2-why-launch-from- equator.html> [Accessed Feb. 24, 2018].
Xiao, Haile. Which one makes a bullet dangerous, its kinetic energy or its momentum? 22 Apr, 2014. Available at: <https://www.quora.com/Which-one-makes-a-bullet-dangerous- its-kinetic-energy-or-its-momentum> [Accessed Feb. 24, 2018].
X-ray Crystallography/Foundations. Available at: <https://en.wikibooks.org/wiki/Xray_Crystallography/Foundations> [Accessed Feb. 24, 2018].
