NotesFAQContact Us
Search Tips
Peer reviewed Peer reviewed
Direct linkDirect link
ERIC Number: EJ1124199
Record Type: Journal
Publication Date: 2017-Jan
Pages: 3
Abstractor: As Provided
ISSN: ISSN-0031-921X
Slow Down or Speed Up? Lowering Periapsis versus Escaping from a Circular Orbit
Blanco, Philip
Physics Teacher, v55 n1 p38-40 Jan 2017
Paul Hewitt's "Figuring Physics" in the Feb. 2016 issue asked whether it would take a larger velocity change to stop a satellite in a circular orbit or to cause it to escape. An extension of this problem asks: What "minimum" velocity change is required to crash a satellite into the planet, and how does that compare with the velocity change required for escape? The solution presented here, using conservation principles taught in a mechanics course, serves as an introduction to orbital maneuvers, and can be applied to questions regarding the removal of objects orbiting Earth, other planets, and the Sun. In this article I examine the possible effects of a single coplanar impulse on a satellite in a circular orbit around an isolated spherical planet of mass M. I treat these impulses as "instantaneous" (of duration much less than the orbital period), which is a good approximation for most spacecraft.
American Association of Physics Teachers. One Physics Ellipse, College Park, MD 20740. Tel: 301-209-3300; Fax: 301-209-0845; e-mail:; Web site:
Publication Type: Journal Articles; Reports - Evaluative
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A
Grant or Contract Numbers: N/A