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Analysis of asteroid impact probabilty

(i) Based on the characteristics of its orbit, what type of Solar System object is 2008 TC3? Explain how you have arrived at your answer.
(ii) Measurements of 2008 TC3â??s orbit in October 2008 led to an initial estimate that it had a 0.3% probability of impacting the Earth in 10 yearsâ?? time. By January 2009, improved measurements had led to an increase in the estimated probability of impact to 8%. Further observations in March 2009 led to a revised probability of 0.7%.
Using the copy of Figure 3, which you should submit as part of your assignment, show how the Torino Scale number of 2008 TC3 has changed as measurements of its orbit improved (label each point). Note that Figure 3 has a log scale.

(iii) Recent mathematical modelling has shown that as the orbit determination improves, the calculated collision probability can temporarily go down (but not to zero) as well as up, for an asteroid that will eventually impact the Earth.
Observations made in June 2009 now confirm a definite impact (i.e. it is certain to occur with 100 % probability; in this eventuality the probability of impact cannot now decrease). How would you recommend that scientists and decision makers communicate the risk and uncertainty to the public at each of the four time points (Oct. 2008, Jan. 2009, Mar. 2009 and June 2009) when the impact assessments were made?
(iv) It is decided to launch a spacecraft to mitigate the threat from 2008 TC3. These options are given on Table 2. Give possible disadvantages for each option by completing this Table and submitting it as part of your assignment. You may find that some disadvantages are appropriate to several mitigation techniques, but do try to give unique answers as far as possible.


Solution Preview

Based on calculations in the previous question [orbit.doc] the furthest departure of the object 2008TC3 is 1.689 AU. The mean distance of Mars from the Sun is 1.524 AU [1][2] and that of Jupiter 5.203 AU [2]. Therefore we can infer that the object 2008TC3 spends a great deal of its time between the orbits of Mars and Jupiter. Such orbits are typical of the Asteroid belt objects so implying that 2008TC3 is a member of this group and is indeed an Asteroid.

We can say that the orbit of 2008TC3 has been calculated to have the following probabilities of impact

Oct 2008: 0.3% probability. Thus looking at the Torino classification map this puts a marker between the 0.1% probability marker and the 1% marker. As the probability scale is logarithmic we have to use Log(3) which ~4.8 so can say that draw a line half way along to the right of the 0.1% marker in the vertical direction and along this line lies the Torino mark for 2008TC3. Next we need to look at the average KE of 2008TC3 which was determined from the calculation in [orbit.doc] to be 8.8 x 10^16 J so we construct a horizontal line from the E = 8.8 X 10^16 J vertical axis. The point we mark to classify 2008TC3 on the Torino scale is thus ...

Solution Summary

Analysis of asteroid 2008 TC3 and its changing values on the Torino scale to determine its threat of Earth impact