Module 2: DISCOVERING THERE
Activity 1: SCIENCE
Submission: Please print this assignment, clearly show all work, scan the completed assignment and
submit one document (.pdf) to the Dropbox. When submitting your assignment to Dropbox, please
follow the file naming procedure:
first initial.last name_module2science
Example: m.hernandez_module2science
Context:
On Feb. 15, 2013, a small asteroid entered Earth’s atmosphere over Chelyabinsk, Russia, and
startled onlookers with its fiery appearance and shockingly loud noise. NASA estimates the asteroid
was approximately 15 meters in diameter with a mass of approximately 10,000 metric tons and
traveled approximately 20 kilometers per second. Infrasound stations nearby and as far away as
Antarctica and nearly halfway around the world detected the low-frequency sound waves
generated by the meteor. The infrasound data indicates that the event, from atmospheric entry to
the meteor’s airborne disintegration, took 28.5 seconds. The entry angle to horizontal was about
18° and the terminal part of the fireball was at about 25 km altitude.
1.
What is the straight-line distance the meteor traveled through Earth’s atmosphere?
D=tv d=20*28.5= 570 km
2.
Compute the volume of the asteroid, assuming it was nearly spherical.
V of a sphere= 4/3πr3.
3.
4/3π7.53 𝑉 ≈ 1,767.15 m3
A) Compute the density of the asteroid. P=m/v p=1e7/1,767= 5,659.31 kg/m3 or 5.65931
g/cm
B) What does this tell you about the physical composition of the asteroid? Is it primarily
ice? Rock? Iron?
NASA High School Aerospace Scholars
This lesson was adapted from JPL Education, JPL educator Dr. Ota Lutz with input from JPL scientist Paul Chodas
The most likely candidate for the composition of the meteor is some sort of rock because the
density of iron is 7.8 g/cm3, and ice has a density of .98 g/cm3. Consequently, rocks can have
varying densities because there are many types of rocks.
4.
How much kinetic energy was released by the event? Give answer in Joules and kilotons.
K= ½mv2
5.
½ 10,000,000m(20)2= 2e9 j or 4.78 kilotons of tnt.
At what altitude did atmospheric entry occur? What layer of the atmosphere is this?
567.1 km above sea level. This layer is known as the thermos/exosphere.
570 cos(18) + 25 = 567.1 𝑘𝑚