HERMES: HEmera Returning MESsenger

Stratospheric long-duration balloons (LDBs) are a cheap and easy way to access the near space, allowing geophysical and cosmological observations.

A common issue for LDBs  is the high bit rate data transferring. Just few hours after launch balloons are nor reachable with direct radio link, and satellite links are, simply, too expensive.  For this reason the satellite link is used only for house keeping and remote control, and scientific  data are recorded on board.   This makes  mandatory to recover the payload to get the observation’s results, a difficult task operating in polar areas, impossible  during the polar winter.

The aim of the project is to provide an autonomous glider capable of physically carrying data and samples from the stratospheric platform to a recovery point on the ground. The glider itself  can also transport instruments and can make measurements during the flight. We estimate that an electrical motorglider released in the stratosphere can fly for several hundreds kilometres.

The glider  is installed on the balloon payload through a remotely controlled release system (which provides its own direct radio link  and satellite communications), and connected to the main computer to receive data and geographic coordinates of the recovery point. The glider trajectory can be monitored with Iridium SBD, and remotely controlled using Iridium too.

The glider is a carbon fiber reinforced foam structure, a compact and robust design, self-stable, which has been shown to steer correctly in the lower stratosphere.

Several test have been conducted with motorized and non motorized gliders,   showing  that the presence of the engine helps the aircraft to get into flight attitude, at around 20 km of altitude, compared to 10 km achieved in non-motorized flights.