BX24 – LOTUS-XD (Light power and Optical Transmission experiment of University Students – eXtra Data)
Launch Date: 20 October 2017
Wireless power transmission gives the opportunity to provide space devices especially landers and rovers in dark space regions with energy. Examples are lunar craters or the polar caps of the moon and mars which undergo polar nights. To provide this energy, the idea is to combine a power transmission and a relay satellite for communication to transmit simultaneously data and energy with one satellite to the device, located in a dark region. LOTUS_XD shall test in a BEXUS-gondola, in a near space environment, several LaserPower-Converter(LPC) laser pairs to investigate which one is the best for this purpose. Therefor different laser configurations, LPC temperatures and data rates shall be tested. The data transmission may be possible either with the LPC or an extra device. Typically a RTG is used on the device to keep the electronics at operating temperature. This leads to a heavy energy and thermal supply and last, not least the radioactive nuclear pellets must be affort- and available. Alternatively electric devices can be implemented to withstand low temperatures and to be able to freeze-to-death voluntarily. LOTUS_XD shall implement a circuit that allows such a freezed device to be controlled warmed up to operating temperature. The advantage of this system is that rovers can experience a complete shutdown for whatever reason, e.g. dust storms. Flown lunar rovers like Yutu and Lunochod used nuclear heat sources to maintain a minimum temperature of -20 °C at lunar nights. It is the aim of LOTUS_XD, to show that it is possible to freeze electronics below that temperature and heat them up again, so that nuclear sources are not required. The heating process will be maintained by wireless transmitted energy, simulating the whole system as described above in near space environment. A second arrangement shall collect any data and controll the experiment.
BX22 – LOTUS-D (Laser Optical Transmission experiment of University Students – DATA)
Technical University of Dresden, Germany
Launch Date: 5 October 2016
Because of the high data rates which can be achieved by simultaneously reducing the required power, laser communication becomes more important in aerospace engineering. Furthermore the small volume and mass of the subsystem are advantages compared to conventional radio communication systems. Due to these advantages laser communication is increasingly common for satellites. In addition to the inter satellite communication, the communication between satellites and ground stations is also important. The prevailing weather conditions have a strong impact on achievable data rates.
The LOTUS-D experiment shall establish a communication link between a small ground station and the balloon. By means of a modulated LED a predefined data sequence will be send to the balloon gondola. The light will be transmitted through a telescope, which parallelizes and points the light beam at the balloon. Therefore a pointing system which uses image recognition to direct the light beam to the balloon plays an important role. The data sequence will be received and compared with the original data sequence deposited on the balloon. Depending on different weather conditions and distances a resulting Bit Error Rate can be determined at the gondola.
BX22 – TPD-3 Vanguard (Technology Demonstrator Platform 3 “Vanguard”)
Technical University Munich, Germany
Launch Date: 5 October 2016
Research under microgravity conditions is essential for many fields in materials science, physics, and biology. Sounding rockets and nano-satellites 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.
RX19 – LiME (Link made early)
Ernst-Abbe-Hoschschule, Jena, Germany
Launch Date: 17 March 2016
In recent years, the popularity of small satellites increased much. Many cube satellites (CubeSats) are ejected into space every year. Every satellites has a need for communication with ground stations on earth. As antennas on such small spacecrafts have to be lightweight and simple, the creators often rely on simple antenna schemes, often made from measuring tape or small wires. This often rules out the possibility of using directional antennas for communication. Another problem occurs after ejection: When ejected from the deploying satellite, it is given some angular velocity. Much research has been done in the domain of CubeSat attitude control. Often, this is implemented using passive, magnetic approaches, where Earths magnetic eld is used to continually slow down the rotation and eventually making it stop, aligning the satellite in a predetermined attitude towards earth. This – in combination with the simple antennas used –
makes it hard to maintain communication links with these satellites.
To help with better communication in this rst phase of rotation, the LiME experiment proposes a dynamic scheme for communication – based on current satellite attitude. Put in simple words, the satellites can use simple directional antennas and only transmit when these are facing earth.
As attitude determination is also a well-researched topic in the CubeSat area, this scheme may help to drastically improve communication in early mission phases of CubeSats.
Additionally, it will be possible to realize satellite missions without any attitude control. For example to investigate the radiation hardness of COTS-electronic components. Furthermore, the dynamic communication scheme might reduce the power consumption, which is a critical point
for small satellites.
The scheme is to be designed, implemented and tested on satellite models, ejected from a REXUS rocket in the REXUS 19/20 cycle. The experiment includes analyzing the conditions such satellites face after ejection, deriving.
BX18 – ARCA (Advanced Receiver Concepts for ADS-B)
Ernst-Abbe Hochschule Jena, Germany
Launch Date: 10 October 2014
The team wants to improve an ADS-B receiver to receive signals from airplanes in high altitudes. ADS-B stands for Automatic dependent surveillance Broadcast. This signal is transmitted by big airplanes to control the airspace. The receiver may be used on a cubesat satellite later.
RX08 – TUPEX-3 (TU Berlin Pico-satellite experiment III)
TU Berlin, Germany
Launch Date: 4 March 2010
The dual objectives of TUPEX-3 were the in-flight verification of a newly developed communication system and a sun sensor for pico- and nano-satellites. Future data transfer between these satellite systems, will occur both between the ground and space segment, as well as directly between the satellites. In order to make this communication strategy possible, a novel telemetry and telecommand system using the UHF band is currently being developed at the TU Berlin. The experiment is based on three or four identical radio modules, which imitate a multi-satellite system. During flight, one module on the REXUS rocket exchanged data with the other “ground based” communication units. A connection between the “satellites” was established, and data was transferred and saved with a time stamp. In such a way the suitability of the communication system could be verified to enable an in-orbit cross-link between future satellites of the TU Berlin. The sun sensors were based on a photosensitive device and were optimized in regard to power consumption, mass and volume. A special feature of these sun sensors is that they determine the vector of the sun in the body-fixed coordinate system of the satellite, independent from other hard- and software. As a result, they can be readily integrated into different systems. During the REXUS flight, a data logger unit especially designed for the experiment stored data from several sun sensors, and reference sensors for later evaluation.
TUPEX-3 ISLE Conference Paper
RX08 – VECTOR (VErification of Concepts for Tracking and ORientation)
TU München, Germany
Launch Date: 4 March 2010
The dual purpose of the VECTOR experiment was to verify a space based data processing system and to demonstrate a high precision tracking and orientation system for space based applications. The On-Board-Data-Handling (OBDH) unit was developed for coding of high data rates, real-time Field Programmable Gate Array (FPGA) based video processing and CCSDS conformable packetizing and de-packetizing. During the test-flight, the performance and link stability of four S-Band blade antennas was evaluated and transmitted to the ground. An integrated camera was also made available to observe and transmit separation and re-entry of the REXUS vehicle, as well as the deployment of other experiments by video transmission over the S-Band link. The signals sent via the S-Band antennas onboard the REXUS sounding rocket, were automatically tracked by a space qualified S-Band receiver antenna, with a pointing mechanism on the ground, to demonstrate high accuracy and autonomy for future inter-satellite communication technologies. All received data was de-multiplexed and split into telemetry and video, and displayed in real-time by an associated data processing system.
BX08 – REM (Radio Emission Monitor)
DLR & UAS Bremen, Germany
Launch Date: 10 October 2009
The purpose of the REM experiment was to flight-test a communications payload capable of receiving L-Band signals from aircraft, thereby ascertaining the maximum range of coverage for a given antenna-receiver configuration. For the experiment, two different antenna systems were used: a Planar (beam) antenna and a Rod antenna. The Rod antenna was used to verify the Planar antennas performance, and to act as a secondary receiver in the event of orientation problems occurring with the beam system. The antennas were capable of receiving Mode-S and L-Band signals; both of which are widely used for Air Traffic Control (ATC) purposes. Both of these receiver systems interrogated in-range aircraft to determine their position; including longitude and latitude, identity and category, airborne velocity, extended squitter status and barometric altitude. To increase the reliability of the results, a ground based Mode-S receiver was also used. This ground system had been tested extensively prior to launch, receiving signals from a range of 350 km. With the greater altitude of the airborne system, the receiver range was expected to increase substantially.