Does mass matter to measure mass?

Q: The two spacecraft of the Gravity Recovery and Interior Laboratory mission were identical, according to NASA. They had to have the same mass to do their job of accurately measuring variations in lunar gravity. True or false, and why?

Send a response of up to 250 words that someone in any field could understand to by noon Eastern Oct. 13 for a chance to have it published in the next issue.


We asked you why the clouds in Jupiter’s Great Red Spot rotate counterclockwise.

WINNER: Jupiter’s Great Red Spot rotates counterclockwise on its southern hemisphere because it is a high-pressure anticyclonic megastorm. To understand the mechanics of the Great Red Spot’s seemingly nature-defying cyclone, we first need to understand how a normal low-pressure cyclone works. A normal low-pressure cyclone on Earth starts when water evaporates, generally in a hot tropic ocean, and condenses into clouds in which a low-pressure column of air forms due to rising hot air. The higher-pressure air from outside then rushes into the low-pressure column. In an anticyclone, the opposite happens as there is high-pressure cold air that rushes outward to the lower-pressure surrounding air. If the center of the cyclone is located below the equator of Earth, since the angular velocity of the air and Earth at the equator is larger than that below it, the air will be sucked in and spiral inward in a clockwise rotation to conserve angular momentum; this is the Coriolis effect in action. In an anticyclone, since the air is rushing outward, the angular velocity is slower due to the flow starting below the equator and bending in a counterclockwise direction toward the faster-moving equator to conserve angular momentum. Just like lesser-known high-pressure anticyclones on Earth, the Great Red Spot on Jupiter functions in the same way on a much larger scale.

Frank Lucci

San Antonio, Texas

AIAA high school member at the Basis San Antonio Shavano charter school.

Does mass matter to measure mass?