Astronaut Bone Loss In Space (Page 2 of 2) in pdf

Astronaut Bone Loss In Space Page 2

Answer Key

Problem 1 – From the graph above, what is the average rate of bone loss between

age 40 and age 70 for A) Men and B)Women? Answer: A) rate = (change in mass) /

(change in time) =

(1100 – 1500) / (100 – 40) =

- 6.7 grams/year.

B) rate = (500 –

1200)/(100 – 40) =

- 11.7

grams/year.

Note: Because the signs are negative, the rate is a mass loss. As a percentage, for

men the rate is

100% x (6.7/1500) = 0.4% per year. For women it is 100% x

(11.7/1200) = 1.0% per year…more than twice as fast as for men.

Problem 2 – Suppose a 40 year old male astronaut spent 6 months aboard the

International Space Station. If he started out with 1500 grams of bone calcium, how

much calcium would remain in his bones when he returned to Earth? Answer: The

astronaut will lose

0.019 x 6 months x 1500 grams =

171 grams lost

Problem 3 - Suppose a 40 year old female astronaut spent 6 months aboard the

International Space Station. If she started out with 1200 grams of bone calcium, how

much calcium would remain in her bones when she returned to Earth? Answer: The

astronaut will lose

0.019 x 6 months x 1200 grams =

137 grams lost

Problem 4 – From the graph, how old would both astronauts be in order to have the

same amount of calcium as they did after returning to Earth? Answer: For the male

astronaut, his final bone mass is 1500 grams – 171 grams = 1329 grams. From the

graph below, this bone mass is reached when a typical male reaches the age of

about 67

years. For the female astronaut, her final bone mass is 1200 grams – 137

grams = 1063 grams. From the graph below, this bone mass is reached when a typical

male reaches the age of

about 55

years.

Space Math

Astronaut Bone Loss In Space Page 2