Rosetta was a European Space Agency mission that followed Comet 67P/Churyumov-Gerasimenko and studied it up close as it moved around the Sun. Its small lander, Philae, became the first spacecraft to make a controlled landing on a comet nucleus in 2014. The mission matters because comets preserve ancient material from the early solar system.
By measuring gas, dust, ice, and surface features, Rosetta helped scientists study how planets and small bodies formed.
Key Facts
- Rosetta arrived at Comet 67P in August 2014 after a journey of about 10 years.
- Philae landed on 67P on 12 November 2014, but bounced because its anchoring harpoons did not fire.
- Comet 67P has a very weak gravity, so escape speed is only about 1 m/s near the surface.
- Orbital speed around a body is approximated by v = sqrt(GM/r).
- Solar radiation decreases with distance according to intensity proportional to 1/r^2.
- Comet activity increases near the Sun as ice sublimates, changing solid ice directly into gas.
Vocabulary
- Comet nucleus
- The solid central body of a comet, made of ice, dust, rock, and organic-rich material.
- Orbiter
- A spacecraft that travels around another body in a planned path to collect data over time.
- Lander
- A spacecraft designed to touch down on the surface of a planet, moon, asteroid, or comet.
- Sublimation
- The process in which a solid changes directly into a gas without becoming liquid first.
- Gravity assist
- A maneuver that uses a planet's motion and gravity to change a spacecraft's speed or direction.
Common Mistakes to Avoid
- Treating a comet like a solid asteroid with strong gravity is wrong because comet 67P has extremely weak gravity and a fragile surface environment.
- Assuming Philae failed completely is wrong because it returned valuable science data even after bouncing and coming to rest in a shaded location.
- Using Earth landing ideas without adjustment is wrong because parachutes do not work in space and a comet has almost no atmosphere.
- Thinking comet tails are always behind the comet's path is wrong because dust and gas tails are shaped mainly by sunlight and the solar wind.
Practice Questions
- 1 Rosetta traveled for about 10 years before reaching comet 67P. If it covered a total path length of 6.4 billion km, what was its average speed in km/s? Use 1 year = 365 days.
- 2 If sunlight at 1 AU has an intensity of 1360 W/m^2, what is the intensity at 3 AU using the inverse square rule?
- 3 Explain why landing on a comet requires anchoring systems even though the lander has very little weight there.