KSat Stuttgart e.V.

Rexus/Bexus Programm

REXUS/BEXUS is an internaional student program in cooperation with the german aerospace center (DLR) with the swedish national spaceboard (SNSB). This program is designed as a competition and allows students to realize their own ideas and test their own experiments in conditions comparable to space. This includes the influence of space radiation or the behavior in micro gravity environment.
There are two options available for experiments: First the nearly six meter long rocket (REXUS) that is able to reach an altitude up to 100 km and secondly a stratospheric ballon (BEXUS), that is able to reach 35 km in free flight.

 

During the whole project duration the german student teams will be supervised by the DLR spaceflight managment Bonn. They get to know the complete flow of a spaceproject, from the idea to the final publications of results.

MIRKA2-RX (Microreturncapsule2-REXUS) is our first REXUS experiment and we achieved a great success. The REXUS rocket, that is able to reach the "edge" of the atmosphere,  gave us the unique opportunity to test our micro re-entry capsule 2 (MIRKA2) during realistic conditions and to qualify it for the application for the CAPE project.

 

 

Objectives of the MIRKA2-RX Mission:

Primary:

  1. Qualify the Low Orbit Technical Unit Separator (LOTUS) capsule sepration system in micro gravity environment.
  2. Qualify the capsule electrions in spaceflight conditions.

  3. Qualify the Iridium communication link.

Secondary:

  1. Record the aerodynamic behaviour of the capsule during the return to earth.

  2. Recover the capsule after landing.

 

The setup of MIRKA2-RX is devided in two autonomous systems, the capsule and the experiment module.

The Capsule:

The shape of the capsule is derived from the ReEntry Breakup Recorder (REBR) developed by NASA and is the smallest re-entry capsule to date. It contains several sensors to measure occurring temperatures, attitude and pressure during return to earth. Furthermore, a GPS-receiver for position data and an Iridium transceiver is used to transmit data to the ground station.

 

A special feature is the implemented beacon, which is placed in the upper segment of the capsule. It is used to enable a convenient recovery of the capsule after impact and is not planned in the later MIRKA2 capsule of the CAPE mission.

 

The experiment module:

The experiment is housed within the rocket module, only the ground segment is not part of the rocket. The experiment is segmented in several subsystems.

 

The separation mechanism LOTUS was developed to ensure that the capsule is safely and deactivated transferred to the ejection point. This separation mechanism fits within one CubeSat Unit (10x10x10 cm3) to be compliant for CubeSat applications. The capsule is secured to a carriage, which is locked in position by using a wire. When the separation is triggered the wire is cutter by using a pyrocutter, which is commonly used device of parachutists.

 

The electronic box is located behind the separation mechanism. It inhabits the board computer of the experiment (bottom panel), the pyrocutter control board (middle panel) and the mirror system of the capsule electronics (top panel). The mentioned mirror system serves as a redundant data source for comparison and verification purposes of the used electronics in the capsule.

 

Furthermore, two cameras are located in the experiment module to observe the ejection from different angles. This can be used later on for a separation analysis.

 

 

Mission Sequence

After the integration of the capsule into the experiment module and the mating of all modules with the rocket motor, the REXUS 19 rocket was launched on 18.03.2016 at 6:10 MEZ in Kiruna. The detailed mission phases:

 

This video shows the animated mission:

 

Results

Every primary mission objective was fulfilled and even the recovery of the capsule was possible! A detailed analysis is currently going on.

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