  We present the design of a compact absolute optical frequency reference for
space applications based on hyperfine transitions in molecular iodine with a
targeted fractional frequency instability of better than $3\cdot 10^{-14}$. It
is based on a micro-integrated extended cavity diode laser with integrated
optical amplifier, fiber pigtailed second harmonic generation wave-guide
modules, and a quasi-monolithic spectroscopy setup with operating electronics.
The instrument described here is scheduled for launch end of 2017 aboard the
TEXUS 54 sounding rocket as an important qualification step towards space
application of iodine frequency references and related technologies. The
payload will operate autonomously and its optical frequency will be compared to
an optical frequency comb during its space flight.
