  The history of the Milky Way is encoded in the spatial distributions,
kinematics, and chemical enrichment patterns of its resolved stellar
populations. SEGUE-2 and APOGEE, two of the four surveys that comprise SDSS-III
(the Sloan Digital Sky Survey III), will map these distributions and enrichment
patterns at optical and infrared wavelengths, respectively. Using the existing
SDSS spectrographs, SEGUE-2 will obtain spectra of 140,000 stars in selected
high-latitude fields to a magnitude limit r ~ 19.5, more than doubling the
sample of distant halo stars observed in the SDSS-II survey SEGUE (the Sloan
Extension for Galactic Understanding and Exploration). With spectral resolution
R ~ 2000 and typical S/N per pixel of 20-25, SEGUE and SEGUE-2 measure radial
velocities with typical precision of 5-10 km/s and metallicities ([Fe/H]) with
a typical external error of 0.25 dex. APOGEE (the Apache Point Observatory
Galactic Evolution Experiment) will use a new, 300-fiber H-band spectrograph
(1.5-1.7 micron) to obtain high-resolution (R ~ 24,000), high signal-to-noise
ratio (S/N ~ 100 per pixel) spectra of 100,000 red giant stars to a magnitude
limit H ~ 12.5. Infrared spectroscopy penetrates the dust that obscures the
inner Galaxy from our view, allowing APOGEE to carry out the first large,
homogeneous spectroscopic survey of all Galactic stellar populations. APOGEE
spectra will allow radial velocity measurements with < 0.5 km/s precision and
abundance determinations (with ~ 0.1 dex precision) of 15 chemical elements for
each program star, which can be used to reconstruct the history of star
formation that produced these elements. (abridged)
