Japanese space agency JAXA decided to launch their Super Low Altitude Test Satellite already in fiscal year 2017. This spacecraft was designed specially to conduct tests of flight on extremely low orbit – even beyond altitude of 180 km.
According to JAXA launch of the H-IIA rocket with SLATS vehicle under the fairing is possible in fiscal year 2017. It means that launch will be performed before end of March 2018 (fiscal year 2017 started in 1st April 2017). Probably SLATS will be piggyback payload during another mission of JAXA satellite: GCOM-C (Global Change Observation Mission – Carbon cycle).
SLATS satellite is technology demonstrator designed to test technologies necessary to perform flights on very low Earth orbit on altitude of 180 – 250 km with last phase of the mission covering flight even below 180 km point. Planned mission duration is 18 months, satellite will be launched and delivered to 628 km orbit. Next it will gradually reduce speed with chemical propulsion and after reaching altitude of 300 km where atmosphere is dense enough, it will rotate solar panels vertically and perform aerobraking. After reaching altitude of 250 km SLATS will initialize Xenon ion engines to control altitude more precisely. Propulsion will generate thrust at 17 mN using 12 kg of propellant and electric power from onboard batteries charged by solar arrays. Next it will perform air density measurements and verify how presence of atomic oxygen (AO) can affect on construction of satellites. Also flying on extremely low orbit will show how materials, electronics, computers are reacting for this conditions and how this affects on degradation process. These two measurements will be performed using two main sensors of SLATS. Atomic oxygen will be measured by Atomic Oxygen Fluence Sensor, based on 8 Thermoelectric Quartz Crystal Microbalances placed inside and outside satellite and containing polyimide film which reacts with Atomic Oxygen with changing its mass. Measuring this changes will show level of AO on current altitude. Degradation process of the material samples will be recorded by Material Degradation Monitor device. It is basically instrument based on construction with containers with samples of materials and cameras showing how they are react for changing conditions and level of Atomic Oxygen. Satellite will also perform Earth observations with utilization of optical sensor (OPS) to check change of spatial resolution with decreasing altitude.
Satellite was designed and built under cooperation between JAXA and Mitsubishi Electric Corporation (MELCO). It weighs 400 kg and its dimensions are 2.5 m x 5.2 m x 0.9 m with fully extended solar arrays. Satellite is powered by solar panels providing up to 700 w of power and onboard batteries. It is equipped with Xenon Ion Propulsion and ordinary chemical thrusters fueled with 34 kg of N2H4 and providing 4 x 1 N of thrust.