  The High Energy cosmic-Radiation Detection (HERD) facility is one of several
space astronomy payloads of the cosmic lighthouse program onboard China's Space
Station, which is planned for operation starting around 2020 for about 10
years. The main scientific objectives of HERD are indirect dark matter search,
precise cosmic ray spectrum and composition measurements up to the knee energy,
and high energy gamma-ray monitoring and survey. HERD is composed of a 3-D
cubic calorimeter (CALO) surrounded by microstrip silicon trackers (STKs) from
five sides except the bottom. CALO is made of about 10$^4$ cubes of LYSO
crystals, corresponding to about 55 radiation lengths and 3 nuclear interaction
lengths, respectively. The top STK microstrips of seven X-Y layers are
sandwiched with tungsten converters to make precise directional measurements of
incoming electrons and gamma-rays. In the baseline design, each of the four
side SKTs is made of only three layers microstrips. All STKs will also be used
for measuring the charge and incoming directions of cosmic rays, as well as
identifying back scattered tracks. With this design, HERD can achieve the
following performance: energy resolution of 1\% for electrons and gamma-rays
beyond 100 GeV, 20\% for protons from 100 GeV to 1 PeV; electron/proton
separation power better than $10^{-5}$; effective geometrical factors of $>$3
${\rm m}^{2}{\rm sr}$ for electron and diffuse gamma-rays, $>$2 $ {\rm
m}^{2}{\rm sr}$ for cosmic ray nuclei. R\&D is under way for reading out the
LYSO signals with optical fiber coupled to image intensified CCD and the
prototype of one layer of CALO.
