  The great success of the Rossi X-Ray Timing Explorer (RXTE) has given us a
new probe to study strong gravitational fields and to measure the physical
properties of black holes and neutron stars. Here, we describe a
"next-generation" x-ray timing mission, the Relativistic Astrophysics Explorer
(RAE), designed to fit within the envelope of a "medium-sized" mission. The
main instruments will be a narrow-field x-ray detector array with an area of at
least ten times that of RXTE, and a wide-field x-ray monitor with good
sensitivity and few arcminute position resolution. We describe the design of
the instruments and the science which will be possible with a factor of ten
increase in collecting area.
