---
title: "In 2014, the European Space Agency placed a satellite in orbit around comet 67P/Churyumov-Gerasimenko and then landed a probe on the surface. The actual orbit was elliptical, but well approximate it as a 50 km diameter circular orbit with a period of 11 days."
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url: "https://nerd-notes.com/ubq/23210/"
date_modified: "2025-09-23T03:29:00+00:00"
---

# In 2014, the European Space Agency placed a satellite in orbit around comet 67P/Churyumov-Gerasimenko and then landed a probe on the surface. The actual orbit was elliptical, but well approximate it as a 50 km diameter circular orbit with a period of 11 days.

In 2014, the European Space Agency placed a satellite in orbit around comet 67P/Churyumov-Gerasimenko and then landed a probe on the surface. The actual orbit was elliptical, but we can approximate it as a 50 km diameter circular orbit with a period of 11 days.

**Part a)** What was the satellite’s orbital speed around the comet? (Both the comet and the satellite are orbiting the sun at a much higher speed.) *(3 points)*

**Part b)** What is the mass of the comet? *(3 points)*

**Part c)** The lander was pushed from the satellite, toward the comet, at a speed of 70 cm/s, and it then fell-taking about 7 hours -to the surface. What was its landing speed? The comet’s shape is irregular, but on average it has a diameter of 3.6 km. Assume the lander experienced constant acceleration form the time it left the satellite. *(3 points)*


*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/23210/*