University of Applied Science Heidelberg Cubesat project.
In Cooperation with the European Radio Astronomy Club.
Author: Peter Wright
With Building and Using a Cubesat project a multitude of complicated problems have to be solved, for University Students at the beginning of their careers everything is new land, this means that building such a project is a very valuable tool to help such young people to become good engineers! Working in a team to solve very complicated engineering problems with the goal at the end of the day to launch a Flight tested Satellite is about the best start in life any engineer could have.
It is our intention to use the here proposed Cubesat Project to train a whole group of young engineers at one time so giving, so even if the launch vehicle fails the investment will have been Justified, we obviously hope that the experiment will be a success!
It is also our intention to have parallel to the University grade work also associated work being done at the same time for things like downlink capability, here it is possible to get Young children and young adults to manage the problems of tracking and telemetry via Amateur Radio, this will be the excuse to give them the opportunity to gain an Amateur Radio Licence, a very useful thing to do as a young person as such experience is useful a life long in associated fields. Obviously also this is also intended to get young School students interacting with University at an early stage which will hopefully motivate them to go on to study Engineering.
The projects I would like to suggest here fall into 2 categories: on flight verification of new technology to so gain Heritage of new developed parts, and Radio Astronomy at frequencies not normally observable due to natural blocking from our Ionosphere.
The on flight Verification experiments we would like to fly are from 2 new developments of firstly Solar Cells with much higher effectivity as the ones standard today, the second area is that of new Lithium Polymer Battery not yet Qualified for Space use. This is for us an enormous stroke of luck as it allows hopefully our experiment to fly for much longer than 3 months.
The second area here is that of an experiment to do some real Science. I am the president of the European Radio Astronomy Club www.eracnet.org we are about 350 People in about 19 countries who are all doing professionally or in our spare time Radio Astronomy. From the Earth we have 2 windows that are open to the cosmos the optical window and the Radio Window, and it is this that is most interesting, main objects of interests are Solar Radio Bursts and Radio Radiation from Jupiter and its moon Io, here Radio Observations have been made for many years at frequencies high enough to be able to penetrate through the Ionosphere, and a great deal of Observations are made today still at short wave Frequencies, A notable Experiment with participants all over the world is the Radio Jove project from the Goddard Space Flight Centre. This Experiment done in conjunction with the Ohio State University as Well as the Nancey Radio Telescope in France here by us in Europe, All observations however are above the NUF of about 16 MHz, What is needed here is a Space born Satellite to cover the frequency Spectrum from DC up to this frequency to deliver into the Internet live Observational Data to improve the frequency coverage of the existing network, I may add that almost all of the people gathering data at the moment are voluntary people just doing Science. I think the addition of such a Satellite based Data Source would reward this community immensely in their present work.
The Technical set up of the Radio Astronomy Package:
The technology of a wide band Spectrum Analyser today is very simple; it basically consists of an antenna, an impedance matching circuit, wide band gain stage and a DSP FFT A/D Converter. A software algorithm to process the data and reduce it and then the Telemetry unit.
As it is very easy to downlink via a short wave frequency around 30 MHz also an interesting idea is to re-Radiate a special area of interest at a shifted frequency so allowing a selected portion of Spectrum to be down linked at a higher frequency, A network of simple ground stations may so be built with nothing other than a simple wire Dipole and a short wave Receiver. The Radio Jove Network already existing may so be upgraded.
Using the widely spread number of Ground stations run by Volunteers in the AMSAT Organisation it is possible to build up a network of Semi Automatic Ground stations all linked via the internet, the modes of operation are Master the control station in Heidelberg, Server the “Cubesat”, Relay the AMSAT Ground stations and Client a network of users who may listen only via the internet or via short wave who will be informed via the internet exactly what the Cubesat is doing, For instance what frequency band is being re-radiated on the short wave downlink channel as well as satellite related data like charging current for the batteries. Such Internet clients may also make requests to the master station to observe specific things which will then be processed into the flight plan.
Using the network of AMSAT Volunteers it is possible to get a high downlink data rate, Using an orbit known position its possible to plan the AOS (Acquisition of Signal) and LOS (loss of Signal) in relation to the Geographical position of the Ground stations it is possible so to make an exact timetable months in advance to allow the Equipment to be turned on and running for the flyovers, it is so possible to plan exactly the Downlink timetable for the Cubesat to so get maximum data transfer. To make a software Internet based downlink network of this kind has never been done and it would produce long after our Cubesat project a useful tool, It is also possible to integrate other Cubesats flying at the same time as the Heidelberg Cubesat into this network, It is common practice observed today that the more individual AMSAT Stations are involved in useful support work the happier they are and the more reliable there work becomes.
The European Radio Astronomy Club has to date no downlink capability by its members, the Cubesat project is the excuse to change this, once installed the ERAC members have then a capability to perform general ground station activities to support other cubesat projects in the future so improving performance of the cubesat program for all future and existing flights.
Stanford University have developed a standard platform as a lego type system, it is possible to use ready designed and flight tested units to serve common problems like computing and telemetry. It is our intention to use such modules where possible or at least to use them as Reference designes! Allot of problems have to be solved concerning the experiment alone with a small team so the use of flight tested units will not only solve problems it will also allow Students to concentrate on the development of new technology rather than re-inventing the wheel.
The key componant of the radio astronomy package is the Analog to digital converter A/D this is today very wide band indeed DC to 50MHz with sample rates of up to 104 MHZ using a product from Analog Devices with 16 bit depth, it is obviously possible to use a clock generator / synthesizer to change the sample rate at will so saving power where needed, a simple spectral sweep occasionally will give a method to save power if all values are low “Sleep” if a Radio Event is detected this may be used as a “Wake Up” command to do some high grade sampling of say a Jovian Event. As Jovian events are predictable this may also be done via Timetable ! By an interesting event the data may be saved until packet hand shaked by a ground station before being erased. The A/D may be multiplexed to allow digital reading of other sensors onboard like charging or discharging current, temperature or any other simple detector on board. At this early stage the Radio Telescope is the main Scientific Package to be flown but if space, form factor as well as power allows it would be wise to keep open the possibility of flying simple little things like Magnetometers or Geiger counter/ Sintelation Detectors. When looking at say Solar events this will give valuable data correlating hopefully to the Radio Astronomy Experiment. This project alone will provide a number of Students a very challenging BSc or Masters theme as well as maybe a Phd.
I think one of the most challenging and rewarding aspects of our proposed Cubesat project is the interaction with Amateur as well as profeshional Scientists to command observational Requests via the internet and distrobute the results, with the energy of the ERAC Community