It generates the electric field which energizes the tail, and even compresses it so it squirts materials back towards Earth to cause substorms that disrupt satellite communications, interfere with terrestrial power lines, and push the auroras towards lower latitudes. Actually, they are called hydrogen ions, but since most hydrogen is made of one proton circled by one electron, a hydrogen ion is just a free proton. And protons don't carry ID cards to tell whether they came from the Sun or the Earth. Other satellites at present do not carry instruments that can neutralize the plasma sheath as TIDE does. Flights with suborbital rockets can only make limited contributions to solving the question.
TIDE works on a global scale and long-term trends.
Rockets also sample the source region for the polar fountain, while TIDE looks at the destinations and what happens to the particles. Because each orbit measures a single arc over the polar region, Chappell would like to make a series of low-energy measurements, with the plasma source on, to get full coverage of the entire polar region under a range of seasonal conditions and different levels of solar activities. AGU Fall 1997 Meeting , Moscone Center, San Francisco, Calif., Dec. 8-12. Thursday, Dec. 11, room MC 310. Barbara L. Giles, Charles R. Chappell, D. C. Delcourt, T. E. Moore, M. O. Chandler, P. D. Craven.