1. Explain why “floating” space debris is a misconception. Floating debris is a misconception because instead of the debris floating in space, it is actually within the earth’s gravitational orbit causing it to travel at dangerous speeds of 17,725 miles per hour. The debris resistance to the earth’s gravitational pull creates the orbital motion, posing the risk of collision if traveling within the same orbit.
b. Using a motion equation from your physics text (cite chapter and page), demonstrate that an object falling vertically in earth’s atmosphere descends 16 vertical feet in the first second. x – x0 = v0t + ½ at2 (Chp 2, page 23)
16 ft = (0 seconds)(1 second) + 1/2 (32 feet/sec2)(1 sec)2
16 ft = 0 + ½ (32 ft/sec2)(1 sec)2
16 ft = (16 ft/sec2)(1 sec)2
16 ft = 16 ft
c. Using Dr. Crassidis’ orbital debris speed estimates, the kinetic energy present in a 150 gram piece of space debris is equivalent to that of a Toyota Prius at what speed (mph)?
KE = 1/2mv2
KE of 150g object = KE of Prius ½ (150g)(7923.76m/s)2 = ½ (1393436g)(x)2
(150g)(7923.76m/s)2 = (1393436g)(x)2
(150g)(62786040.77) = (1393436g)(x)2
(6758.76)= (x)2 x= 82.2117 m/s or 183.429 mph
The Prius would have to be traveling at 82.2117 m/s or 183.429 mph
17,725 mph 1 hour 1 minute 1609.34 1 x 60 mins x 60 secs x 1 miles = 7923.76 m/s
2. Technical Challenges: describe the 4 major problems associated with tracking space debris (bullet point paragraph format)
One major technical problem that was discussed was tracking the excessive amounts of debris in space. An estimated amount of 22,000 items are tracked by the US alone, at sizes larger than 10 cm in diameter. In total there are about 150,672,00 pieces of space debris in total. These pieces range from sixes of .1cm to 10cm and larger. This makes it difficult to track such a vast amount of debris, creating a inadequacy with the readings from current sensors.
The second technical problem referred to in lecture is Data Association, which is a major problem given the consistency of debris in space. New sensors have the capability of tracking more debris but it also is makes it more difficult to distinguish between previously tracked debris and newly discovered debris. This is because the debris are all shown through a radar field that displays each individual object as a radar blip, then fades from view making it difficult to establish radar readings from one another.
A third technical problem that is dealt with is the modeling of disturbances. This is when an object is thrown out of its predicted orbit. The drag of the object through air molecules is one of the disturbances that can perturb the orbit. Currently, there are no accurate models for estimating air density of low Earth objects. Having this information available still wouldn’t allow for us to know the shape of these objects. Different shapes cause a difference in drag of the object, which influences the path of the object. What also alters the path of debris is Solar Radiation pressure because of its exposure to electromagnetic radiation.
A fourth technical problem that happens when trying to track space debris is non-gaussian errors. These marginal errors occur with all technology especially when dealing with observations from great distances. Radar reading will not signal each object of debris simultaneously, causing a slight percent of error. This is a problem because the calculated location of each object does not always correspond with the actual location, posing a greater chance of failure when performing high-risk situations such as collisions.
3. Engineering Approach: describe the 4 major approaches for mitigating space collisions outlined by Dr. Crassidis, citing relevant examples.
Shielding protects satellites from small objects and debris. The Whipple Shields are designed