Atmospheric signal delay affecting GPS measurements made by space vehicles during launch, orbit and reentry

In this thesis, I present neutral atmosphere, ionosphere and total delays experienced by GPS signals traveling to space vehicles during launch, orbit and reentry. I calculate these delays for receivers at 0 km to 1700 km altitude by ray-tracing through the Global Reference Atmosphere Model (1999) and the International Reference Ionosphere (2001). These delays are potentially much larger than those experienced by signals traveling to GPS receivers near the surface of the Earth, but are primarily experienced at negative elevation angles, and are therefore most relevant for space vehicles with limited visibility of GPS satellites and during launch and reentry. I compare these signal delays to the delays predicted by three onboard delay models: the Altshuler and NATO neutral atmosphere delay models, and the Klobuchar ionosphere delay model. I find that these models are inadequate when the space vehicle is in orbit. The NATO model will suffice during the final period of reentry, where it predicts the neutral atmosphere delay to within 1 m of the ray-traced value, but it will not suffice when a satellite is rising or setting. I propose a method to extend the NATO model for receivers at higher altitudes. The Klobuchar model will suffice for most satellites during reentry, but will potentially predict ionosphere delays with errors up to 30 m, and will not suffice when a satellite is rising or setting.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2005

Author dc:creator

• Thessin, Rachel Neville

Advisor dc:contributor.advisor

• Anthony J. Bogner and Thomas A. Herring.

• Aeronautics and Astronautics.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/33211

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/33211