1. Preface: Byron D. Tapley

   • Byron D. Tapley

   EditorialNotes 17 August 2012 Pages: 268 - 271

2. Gravity model determination from the GRACE mission

   • Byron D. Tapley

   OriginalPaper 17 August 2012 Pages: 273 - 285

3. Trajectory options for DUNE, a Near-Earth Dust telescope

   • Jeffrey S. Parker
   • George H. Born

   OriginalPaper 17 August 2012 Pages: 287 - 309

4. Fast design of repeat ground track orbits in high-fidelity geopotentials

   • Martin Lara
   • Ryan P. Russell

   OriginalPaper 17 August 2012 Pages: 311 - 324

5. Subcycle analysis for ICESat’s repeat groundtrack orbits and application to phasing maneuvers

   • Nadège Pie
   • Bob E. Schutz

   OriginalPaper 17 August 2012 Pages: 325 - 340

6. Navigation and control of the TanDEM-X formation

   • Oliver Montenbruck
   • Ralph Kahle
   • Jean-Sebastien Ardaens

   OriginalPaper 17 August 2012 Pages: 341 - 357

7. The nature of the quaternion

   • Malcolm D. Shuster

   OriginalPaper 17 August 2012 Pages: 359 - 373

8. Estimation of total electron content (TEC) using spaceborne GPS measurements

   • Key-Rok Choi
   • E. Glenn Lightsey

   OriginalPaper 17 August 2012 Pages: 375 - 399

9. A high order method for estimation of dynamic systems

   • Manoranjan Majji
   • John L. Junkins
   • James D. Turner

   OriginalPaper 17 August 2012 Pages: 401 - 440