With the goal of in-situ radiation dosimetry, SSPACE (Small-spacecraft Systems and PAyload CEntre), IIST Thiruvananthapuram, India, is developing a constellation of 3U CubeSats with AHAN as the first in this series expected to be launched by 3rd quarter of 2023. The CubeSat is about 2kg in mass with a nominal power consumption of about 3 Watts. The CubeSat houses a Geiger-Muller Counter for radiation dosimetry, which serves as the payload. The satellite is developed with all in-house subsystems which will also serve the purpose of flight validation of the subsystems.