Cubesats operating in deep space face challenges Earth-orbiting cubesats do not. 15 deep space cubesat 'prototypes' will be launched over the next two years including the two MarCO cubesats, the 2018 demonstration of dual communication system at Mars, and the 13 diverse cubesats being deployed from the SLS EM1 mission within the next two years. Three of the EM1 cubesat missions, including the first deep space cubesat 'cluster', will be lunar orbiters with remote sensing instruments for lunar surface/regolith measurements. These include: Lunar Ice Cube, with its 1-4 micron broadband IR spectrometer, BIRCHES, to determine volatile distribution as a function of time of day; Lunar Flashlight, to confirm the presence of surface ice at the lunar poles, utilizing an active source (laser), and looking for absorption features in the returning signal; and LunaH-Map to characterize ice at or below the surface at the poles with a compact neutron spectrometer. In addition, the BIRCHES instrument on Lunar Ice Cube will provide the first demonstration of a microcryocooler (AIM/IRIS) in deep space. Although not originally required to do so, all will be delivering science data to the Planetary Data System, the first formal archiving effort for cubesats. 4 of the 20 recently NASA-sponsored (PSDS3) study groups for deep space cubesat/smallsat mission concepts were lunar mission concepts, most involving 12U cubesats. NASA SIMPLEX 2/SALMON 3 AO will create ongoing opportunities for low-cost missions as 'rides' on government space program or private sector vehicles as these become available.
Lunar Ice Cube, a science requirements-driven deep space exploration 6U cubesat mission was select-ed for a NASA HEOMD NextSTEP slot on the EM1 launch. We are developing a compact broadband IR instrument for a high priority science application: un-derstanding volatile origin, distribution, and ongoing processes in the inner solar system. JPL’s Lunar Flash-light, and Arizona State University’s LunaH-Map, both also EM1 lunar orbiters, will provide complimentary observations to be used in understanding volatile dynamics on the Moon.
Coronal mass ejections (CMEs) and corotating interaction regions (CIRs) as well as their source regions are important
because of their space weather consequences. The current understanding of CMEs primarily comes from the Solar and
Heliospheric Observatory (SOHO) and the Solar Terrestrial Relations Observatory (STEREO) missions, but these
missions lacked some key measurements: STEREO did not have a magnetograph; SOHO did not have in-situ
magnetometer. SOHO and other imagers such as the Solar Mass Ejection Imager (SMEI) located on the Sun-Earth line
are also not well-suited to measure Earth-directed CMEs. The Earth-Affecting Solar Causes Observatory (EASCO) is a
proposed mission to be located at the Sun-Earth L5 that overcomes these deficiencies. The mission concept was recently
studied at the Mission Design Laboratory (MDL), NASA Goddard Space Flight Center, to see how the mission can be
implemented. The study found that the scientific payload (seven remote-sensing and three in-situ instruments) can be
readily accommodated and can be launched using an intermediate size vehicle; a hybrid propulsion system consisting of
a Xenon ion thruster and hydrazine has been found to be adequate to place the payload at L5. Following a 2-year transfer
time, a 4-year operation is considered around the next solar maximum in 2025.
The Solar Imaging Radio Array (SIRA) is a mission to perform aperture synthesis imaging of low frequency solar, magnetospheric, and astrophysical radio bursts. The primary science targets are coronal mass ejections (CMEs), which drive shock waves that may produce radio emission. A space-based interferometer is required, because the frequencies of observation (<15 MHz) are cutoff by the ionosphere. SIRA will require a 12 to 16 microsatellite constellation to establish a sufficient number of baselines with separations on the order of kilometers. The microsats will be located quasi-randomly on a spherical shell, initially of diameter 10 km or less. The baseline microsat, as presented here, is 3-axis stabilized with a body-mounted, earth-directed high gain antenna and an articulated solar array; this design was developed by the Integrated Mission Design Center (IMDC) at NASA Goddard Space Flight Center (GSFC). A retrograde orbit at a distance of ~500,000 km from Earth was selected as the preferred orbit because the 8 Mbps downlink requirement is easy to meet, while keeping the constellation sufficiently distant from terrestrial radio interference. Also, the retrograde orbit permits imaging of terrestrial magnetospheric radio sources from varied perspectives. The SIRA mission serves as a pathfinder for space-based satellite constellations and for spacecraft interferometry at shorter wavelengths. It will be proposed to the NASA MIDEX proposal opportunity in mid-2005.