  Due to ionosphere absorption and the interference by natural and artificial
radio emissions, ground observation of the sky at the decameter or longer is
very difficult. This unexplored part of electromagnetic spectrum has the
potential of great discoveries, notably in the study of cosmic dark ages and
dawn, but also in heliophysics and space weather, planets, cosmic ray and
neutrinos, pulsar and interstellar medium, extragalactic radio sources, and
even SETI. At a forum organized by the International Space Science
Institute-Beijing (ISSI-BJ), we discussed the prospect of opening up this
window for astronomical observations by using a constellation of small or
micro-satellites. We discussed the past experiments and the current ones such
as the low frequency payload on Chang'e-4 mission lander, relay satellite and
the Longjiang satellite, and also the future DSL mission, which is a linear
array on lunar orbit which can make synthesized map of the whole sky as well as
measure the global spectrum. We also discuss the synergy with other
experiments, including ground global experiments such as EDGES, SARAS, SCI-HI
and High-z, PRIZM/Albatros, ground imaging facillities such as LOFAR and MWA,
and space experiments such as SUNRISE, DARE/DAPPER and PRATUSH. We also
discussed some technical aspects of the DSL concept.
