Though ancient cultures often saw comets as harbingers of doom, the cosmic "dirty snowballs" are now viewed as important objects that could help scientists learn more about the early evolution of the solar system.
In November 2014, the European Space Agency's Philae probe was dropped from the Rosetta spacecraft, becoming the first human-made spacecraft to soft-land on the surface of a comet. Sending a probe to a comet is one thing. But if astronauts were to land on a comet, what would they experience while living there?
In recent decades, NASA and other space agencies have launched several missions to study comets, so anyone visiting a comet would have at least some knowledge about the cosmic bodies. [Living On Halley's Comet Explained(Infographic)]
For instance, in 1986, Europe's Giotto spacecraft flew into the coma the large, diffuse cloud of gas and dust around a comet's core, or nucleus of Halley's Comet to capture the first images of a comet's nucleus. In 2004, NASA's Stardust spacecraft collected dust samples from the coma of the Comet Wild 2. And in 2005, the Deep Impact collider smashed into the Comet Temple 1 to study the guts of the comet's nucleus.
Photographs from comet missions have revealed that comet nuclei are quite small, ranging from less than a mile to tens of miles across. Some of them also have irregular shapes, sometimes resembling the end of a dumbbell.
"The reason they are so irregular is because their gravity is so low," said Althea Moorhead, a researcher with the Meteoroid Environments Office at NASA's Marshall Space Flight Center. "I think it would be strange to live on a comet for that reason."
On Earth and other spherical bodies, gravity is directed straight down. But if you were on a dumbbell-shaped comet, gravity might pull you down and to the side, depending on where you were standing, Moorhead told Space.com.
However, that gravitational tug wouldn't be overwhelmingly strong. The gravity of Halley's Comet, for example, is about equal to the gravity of Mount Everest if you were to remove the mountain from Earth and deposit it in space if you were to drop an object from chest level, it would take about two minutes to hit the ground.
"Its gravity is so low that if you can jump 8 inches [20 centimeters] on Earth, you could jump off Halley's Comet," Moorhead said, adding that you'd want to be very careful with your physical activities.
Comets, particularly the irregularly shaped ones, could offer up interesting features to explore, such as impact craters or cavities formed from the sublimation of material. But you'd likely get bored rather quickly. "For something like Halley's Comet, the total surface area is the same as the island of Lanai [in Hawaii]," Moorhead said. Lanai is about 140.5 square miles (364 square kilometers).
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What It Would Be Like to Live On a Comet
