Vanguard is the third mission that is being conducted within the Technology Demonstrator Platform (TDP) series of rocket and balloon experiments at Technische Universität Müchen (TUM). The first two missions were conducted during the 7th cycle of the REXUS/BEXUS program in 2013/2014 (see here and here for details about those missions). This third mission is part of the 9th cycle and is slated to be launched into the stratosphere aboard the BEXUS 22 research balloon in October 2016.
We are a group of students from E18 SDS, the MOVE-II nanosatellite team, and WARR. Vanguard combines a physics experiment, which was developed during the TDP-1 AFIS-P mission, with a new set of data handling and communication electronics designed for the MOVE-II satellite.
In the Vanguard experiment we aim to develop the necessary systems of a space-based experiment in such a compact way that it is possible to conduct complex scientific measurements on a small platform such as scientific research balloons, sounding rockets or nanosatellites.
Research under microgravity conditions is essential for many fields in materials science, physics, and biology. Sounding rockets and nanosatellites are relatively low-cost platforms for experiments that can work within the constraints of these systems---such as short times of microgravity and limitations in size, power consumption, and data transfer rate, respectively. For atmospheric sciences, sounding rockets and stratospheric research balloons offer other unique capabilities with regard to reachable altitude and mission duration.
Experiments conducted on any of these platforms require compact low-power command and data handling systems, as well as compact yet sufficiently powerful communication systems, if remote control or a direct downlink of science data are required. In order to reduce the development effort for new experiments, we aim to develop and test a light-weight low-power data handling system that can be easily adapted to a range of mission requirements.
To verify the operational capabilities of the system in flight, our experiment incorporates a new particle telescope as the main science payload. The detector can measure the energy- and angle-dependent flux of charged particles in the stratosphere. The interaction of cosmic rays with molecules of the atmosphere and the subsequent creation of secondary particles results in an environment that is relatively unknown so far at altitudes between 15 to 25 kilometers.
Earth’s atmosphere shields us against cosmic radiation from the sun and from sources outside of our solar system. Without this shielding the radiation level on Earth would be too high for living organisms and we could not live on this planet. Cosmic ray particles that hit Earth will interact with molecules in the upper layers of the atmosphere and are absorbed before they can reach ground. If the energy of the impinging particle is very high (bigger than several gigaelectronvolt) new particles can be created in the interactions in the atmosphere.
These new-created particles have lower energies than the original particle and also different directions of motion. The intensity and composition of these particles changes with atmospheric depth, since these particles then again are absorbed. At around 15-20 km altitude the flux of these so-called secondary particles is largest. This region is called Pfotzer maximum. The composition, energy spectrum and angular distribution of the particles is not fully understood yet. Nevertheless, these measurements are needed to improve our understanding of the interactions of cosmic rays with our atmosphere, in order to make more precise measurements with ground-based air shower telescopes that use characteristics from the shower of secondary particles to reconstruct information about the primary particle that has hit Earth.
Today, advances in many fields of scientific research cannot be achieved without conducting experiments in space or near-space environments. For small to medium-sized experiments, stratospheric research balloons, sounding rockets, and nanosatellites are relatively low-cost options to reach the desired grades and durations of microgravity, or the altitudes required for atmospheric research. However, besides size and mass limitations, experiments are constrained by their maximum power consumption and data transfer rate. In addition, scientists often need to develop experiment-specific command and data handling systems and communication solutions in order to control the data acquisition and transfer the results to a ground station. Besides the increased risks associated with the development of new systems, this approach also requires significantly more development effort and a larger mission budget, compared to solutions using mostly commercial off-the-shelf systems.
The CubeSat program MOVE-II at TUM aims to develop an adaptable CubeSat bus, capable of supporting complex experiment payloads. Two of its main components are a new command and data handling system (CDH) and a new UHF/VHF/S-band communication (COM) system.
For space missions, a fault-tolerant on-board computer providing dependable computing resources and data storage in high radiation environments is required. Using radiation-hardened components or implementing extensive redundancy concepts are not generally preferable solutions for small experiments such as MOVE-II due to budget and size limitations, as well as (potentially) increasing system complexity and power consumption. A certain level of fault tolerance and system dependability can be achieved by choosing an appropriate system architecture based on COTS components and a robust software implementation.
Dependability requires consistent and reliable storage of program code and supplementary data, a fact that makes storage integrity a central requirement.
After the selection end of December 2015 we started to design our experiment. The preliminary design review (PDR) took place at our future launch site at Esrange Space Center near Kiruna in northern Sweden in mid of February. The finalization of our design was reviewed during the critical design review (CDR) at the European Space Research and Technology Centre in Noordwijk (Netherlands) mid of May. After finishing the design we started with the construction and implementation of our experiment.
The REXUS/BEXUS program offered by the German Aerospace Center (DLR) in cooperation with the Swedish National Space Board (SNSB) and the European Space Agency (ESA) provides student teams with an opportunity to fly an experiment on a stratospheric balloon at heights of 25 - 30 km. The basic idea behind BEXUS is to provide an experimental space platform for students in the field of aerospace technology.
The REXUS/BEXUS programme is realized under a bilateral Agency Agreement between the German Aerospace Center (DLR) and the Swedish National Space Board (SNSB). The Swedish share of the payload
has been made available to students from other European countries through a collaboration with the European Space Agency (ESA).
EuroLaunch, a cooperation between the Esrange Space Center of SSC and the Mobile Rocket Base (MORABA) of DLR, is responsible for the campaign management and operations of the launch vehicles. Experts from DLR, SSC, ZARM and ESA provide technical support to the student teams throughout the project.
The BEXUS balloons are launched from SSC, Esrange Space Center in northern Sweden.