CanSat
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CanSat ( English for canned satellite ) is a radiosonde that is brought into the air either by rocket or by weather balloon , but only reaches low heights and therefore does not enter a satellite orbit. The construction and launch of a CanSat demonstrates the entire process of a real space mission to students . Due to their low costs, more and more schools and pupils can also take part in CanSat competitions outside of school.
For CanSat competitions, it is necessary that the payloads fit into a beverage can with a diameter of 66 mm and a height of 115 mm and a weight of less than 350 g. Antenna technology z. B. for Automatic Packet Reporting System (APRS) can be mounted outside. However, the diameter must not increase until the CanSat is released. The landing and recovery system used varies with the altitude, which can vary depending on the competition. CanSats are usually fitted with a parachute to limit damage during the landing phase so that the CanSats can be reused.
background
In 1998, about 50 students from 12 universities and faculties in the United States and Japan met at a symposium in Hawaii. It was the first “University Space Systems Symposium” that was initiated under the “CanSat Leader Training Program”. Here Bob Twiggs , professor emeritus at Stanford University , co-author of the Cubesat standard and radio amateur , suggested the idea from which the nanosatellite standard later developed. The idea of bringing a payload in the volume of a beverage can into the atmosphere was formulated. Its volume should be around 350 ml and the mass should be up to around 500 g. This led to the ARLISS project, which began in 1999, in which mainly American and Japanese universities participated. The first launch took place on September 11 of the same year and has been annually since then. The standard is accepted and open worldwide. The original idea, which continues to spread, was to launch up to three payloads of 350 ml each or a CanSat with a larger volume. The rockets can carry up to 1.8 kg and reach a height of 4000 m. This enables transport flights for around 400 euros. More and more starts are being promoted through public or sponsored competitions.
In 2000, the objectives of CanSat projects were very different: B. the calculation of the time of opening of the parachute system using barometer data or the use of a differential GPS system. The conditions for this project became more complex in 2001 when the return criterion was added. In the landing phase, a CanSat should be aimed at a target. This mission was very successful and in 2002 students at the Space Robotics Lab at Tōhoku University achieved a target approach of 45 m and in 2006 of 6 m.
CanSat components
Main parts
Some components can be found in every CanSat:
battery
The network-independent supply of energy is essential for the operation of all systems. Lithium-polymer batteries (LiPo) are most commonly used due to their performance and power-to-weight ratio . The LiPo batteries have a voltage of 3.5 to 3.8 V and are often used for cell phones, cameras or notebooks.
Microcontroller
The microcontroller processes the signals from the external sensors, such as the altimeter or accelerometer, and controls the transmitter. Most microcontrollers have an internal memory for the flight data determined.
Other instruments
Aside from the above, more can be added as part of the terms of the competition.
barometer
It consists of a pressure measuring cell that is connected to the microcontroller and sends a signal with a voltage value corresponding to the measured air pressure. The microcontroller uses the normal atmospheric pressure differences to calculate the altitude.
thermometer
The operation is similar to that of the barometer, but the voltage signal for the microprocessor depends on the measured temperature. The microprocessor processes this signal by assigning a temperature value.
GPS receiver
The Global Positioning System is the US satellite navigation system. The receiver uses this data to triangulate its position with at least four satellites each in order to achieve greater accuracy. This information is sent to the microcontroller through a serial port.
The GPS receiver should be at a point in the CanSat from which the GPS satellites are as possible in the line of sight.
camera
A mini camera can be integrated in the CanSat housing to film or take photos during the flight. Since a CanSat usually cannot receive, the microcontroller should trigger the signals to operate the camera.
Accelerometer
This sensor consists of one or more accelerometers that are on different axes to each other. Accelerometers can be used to collect data or to determine position (through integration). The best accelerometers for determining location are called an inertial navigation system (INS). These are used on some CanSat models. The accuracy of the accelerometer depends on the calibration of the sensor. Proponents of this sensor appreciate the fact that GPS is not needed and thus immunity to magnetic interference can be achieved. This enables a free choice of the placement within the CanSat housing.
Electronic compass
Sometimes it is necessary to use a compass to determine the direction of flight of the CanSat, for example to make a controlled landing. In this case, the compass sensor is a very small sensor that, like a traditional compass, measures the angle between heading and north. This angle is transmitted to the microprocessor via a potential difference . The microcontroller interprets the incoming signals and acts accordingly. If the intention is to land the CanSat on a target without using a GPS receiver, this sensor plays a crucial role.
Types of CanSat
There are essentially two types of CanSat models, as well as an open class:
CanSat for learning telemetry
Their primary goal is the acquisition and transmission of data from the flight in real time, called telemetry , which are processed by a ground station. CanSats in this category do not have a control system as the aim is not to land at a certain point, but to collect data during the flight or the case, which is usually not controlled. Of the instruments mentioned in the previous sections, the most commonly used are: barometer, thermometer, GPS and camera.
Comeback (recurring) CanSat
With this type of CanSat the main task is to make it land in a controlled manner as close as possible to a target marked by GPS coordinates. These devices can be navigated by GPS and / or INS. This position is forwarded to the microcontroller, which calculates the position of the target with the analysis of this data. From this, the angle that it has to take to reach the destination is calculated and the corresponding instructions are sent to the position control and navigation electronics (= control system). This process is repeated continuously to make corrections. Such a returning CanSat also collects data from the flight. However, since the number of sensors that the CanSat can transport is smaller, the data obtained are more scarce than with the previous type. A Comeback CanSat always has a control system to maneuver it towards a specific target.
A distinction is made between comeback CanSat with a parachute or paraglider and / or a rotor and wing.
CanSat with parachutes or paragliders
These CanSat models are u. a. Equipped with a simple attitude control mechanism to generate a change in the longitudinal axis during flight. The CanSat then turns in one direction or the other. This type of control is not very effective in terms of the accuracy of the location, as the landing phase is slow and the large surface area of the parachutes can make control difficult.
CanSat with wings or rotors
Mechanically more complex, but less susceptible to weather conditions than CanSats with parachutes or gliders. This type of CanSat is very difficult to control due to the higher rate of fall and requires an electronic position control system on board the payload, which corrects the tilt and rotation of the rotating CanSat several times per second. Shortly before landing, the parachute or paraglider is usually opened so that the payload survives the landing.
Open class
Any flying robot that has not been classified in one of the previous two categories of the CanSat standards can be presented in this category. Most of the CanSats in this category are robots for testing new systems or new designs that have not yet been tested. (Technology demonstrations).
Educational goals
The low cost of implementation, short lead time and simplicity of design compared to space projects make CanSat a popular educational project. Since space research is interdisciplinary, the application of space technology in school lessons offers a wide range of attractive topics.
A CanSat project is a learning process known as problem based learning. An approach in which students are presented with open problems through successive challenges. Starting with the CanSat design, through component integration, correct operation, programming, calibration and testing of the components as well as checking to the preparations for the start and the subsequent data analysis, the young scientists are required to work together in a team by distributing the tasks. CanSat projects have a lot to do with researching and developing one's own skills.
Competitions
The European Space Agency (ESA) annually initiates CanSat competitions for high school students. The aim of the competition is to get young people interested in natural sciences and technology in general and space travel in particular.
In addition to international and European competitions, there are national competitions. The idea of ESA is that a national CanSat competition takes place in each ESA member country and that the winners of the national competitions then take part in the international and European competition. In October 2014, during WorldSpaceWeek 2014 , the first CanSat competition took place in Germany. This is to be continued annually with ten student teams starting each year. More information can be found on the CanSat Germany website .
Web links
Individual evidence
- ↑ APRS
- ↑ Mission: Planetary Atmospheric Entry Vehicle ( Memento of the original from October 28, 2011 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ CanSat Leader Training Program
- ^ Robert J. Twiggs: International CanSat Workshop. (PDF; 696 kB) February 2007, accessed on April 3, 2013 (English).
- ^ R. Walker et al .: ESA Hands-on Space Education Project Activities for University Students: Attracting and Training the Next Generation of Space Engineers. (PDF; 1.5 MB) 2010, accessed on April 3, 2013 (English).
- ↑ www.cansat.eu
- ↑ www.worldspaceweek.org ( Memento of the original from October 12, 2012 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ www.cansat.de
