Student nanosatellite IGOSat
Université Paris Diderot develops a student project of nano-satellite creation, within the Labex UnivEarthS. It is a project of the program JANUS CNES – French Space Agency – to coaching students satellites in France.
Initiated in 2013, this small satellite (30 cm x 10 cm x 10 cm), designed entirely by students, should be launched in 2019.
IGOsat horizon is primarily an educational project and progresses through successive generations of student work. Since the beginning of development, more than 150 students participated in the design, testing or simulations of the mission. It also has the support and expertise of researchers and professors from the University Paris Diderot and associated laboratories: APC, IPGP and AIM.
The GPS Payload
The Radio-occultation payload is using the same measurement technique used already by various space missions, such as GPS/MET, CHAMP and FORMOSAT-3/COSMIC (Schreiner et al., 2007) mission (http://www.cosmic.ucar.edu). The FORMOSAT-3/COSMIC has been the first mission providing atmospheric profiling using a constellation of 6 microsatellites of 60 kg each. The Radio-occultation payload carried onboard IGOSat aim to prove that this science case can be investigated at a nano-satellite scale.
Measuring the TEC from space is in complementarity to ground-based observations, producing data over the oceans and different observational geometry. Among the science objectives of this payload, there is also the possibility to measure ionospheric scintillation indices for observing small-scale irregularities in the ionosphere. The response of the ionosphere to changes in solar activity and to magnetic storms will be studied and gravity waves propagation in the ionosphere will be investigated through the induced small variations of TEC. Those waves are generated in the ionosphere by various physical processes, including tropospheric convection and tsunamis (fig. 1).
Fig. 1. Vertical profile of a gravity wave detected using radio-occultation data from FORMOSAT/COSMIC3.
The final scientific products of this payload will be Vertical profiles of ionospheric electron density. They will be obtained using an inversion algorithm (“onion peeling”) based on the hypothesis of spherical symmetry of the ionosphere
GPS Payload Principal Investigator : Pierdavide Coïsson
The scintillator payload
The Scintillator payload principles are based upon the XGRE instrument onboard the TARANIS CNES microsatellite (https://taranis.cnes.fr/en/TARANIS/index.htm). The XGRE detection unit is made of a sandwich composed of a crystal superposed by two plastic scintillators, read with a photo-multiplier; it is designed to detect electrons and gamma rays coming from Transient Luminous Events. The Scintillator payload carried in IGOSat is using a Silicon Photomultiplier (requiring a voltage between 15 to 75 times lower than typical photo-multipliers) with CeBr3 crystal scintillator, that has never been flown in space before.
Flux map of 1 MeV electrons at 650 km simulation
with OMERE from the DEMETER mission.
Some observations of the electrons spectra around the Earth have already been performed in the past, mostly in the 60’s and 70’s, leading to the electrons space distribution model AE8 from NASA. The DEMETER mission from CNES (Sauvaud et al., 2006) updated the observational data between 2004 and 2006 in the energy range from 70 to 2500 keV, at an altitude around 710km. The DEMETER results demonstrated an evolution of the spectrum at low energy when local magnetic conditions (such as storms) where met, that will be interesting to follow at higher energy with IGOSat. On the other hand, the AMS-02 experiment (Battiston, 2008) carried onboard the ISS measured high energetic electrons (above 200 MeV). IGOSat will complete these data by observing spectra between 1 and 20 MeV.
There are few measurements of gamma rays in the magnetic belts for now, mostly because of the difficulty to do measurements above 1 MeV, as the flux to observe is commonly lower than the radioactivity induced by the interaction between the cosmic rays and the satellite itself. This noise is globally proportional to the mass of the satellite, and a nano-satellite should be therefore able to tackle this challenge, and the data may enable to separate the components between the internal radioactive noise, the Earth albedo and the belts emission. The CORONAS-1 (Bucik et al, 1999) mission measured spectrums between 0.12 – 0.32 MeV and 3.0 – 8.3 MeV, and a lot of instruments observed the gamma rays from the atmosphere below 1 MeV (such as Beppo-SAX, SWIFT, INTEGRAL) (Ajello et al., 2008). IGOSat will complete the data by observing the spectra between 20 keV and 2 MeV.
Scintillator Payload Principal Investigator : Philippe Laurent
Since the beginning of development, more than 200 students participated in the design, testing or simulations of the mission. It also has the support and expertise of researchers and professors from the University Paris Diderot and associated laboratories: APC, IPGP and AIM.
POSITION NAME SURNAME LABORATORY NAME GRADE, EMPLOYER WP leader Hubert Halloin APC Ass. Prof, Univ. Paris Diderot WP member Hana Benhizia APC/IPGP Research Engineer WP member Pierdavide Coisson IPGP Ass. Prof, Univ. Paris Diderot WP member Philippe Laurent APC CEA Agent WP member Hien Phan APC PhD Student, Univ Paris Diderot WP member Philippe Lognonné IPGP Professor, Univ. Paris Diderot WP member Antoine Petiteau APC Ass. Prof. Univ. Paris Diderot WP member Alain Givaudan APC Research Engineer, CNRS WP member Bernard Courty APC Research Engineer, CNRS WP member Pierre Prat APC Research Engineer, CNRS WP member More than 200 students since Sept 2012 – L2 to predoc students, from Paris Universities and beyond
IGOsat is primarily an educational project, meaning that its development is thought to give the best ‘return’ towards the involved students. In that kind of projects, it is often said that 90% of the success is to develop, based on students’ works, a flight-ready satellite. A successful launch and data acquisition account for another other 5%. The last 5% consist of the scientific return of the mission.
However, the satellite must be designed for a valuable science return, keeping in mind the intrinsic constraints of a students, nanosatellite’s project. IGOsat embarks two innovative scientific payloads onboard a 3U CubeSat platform.
Since the beginning of the project, more than 230 students have now worked, in one way or another, for the IGOsat project. It is used at the EIDD (Ecole d’Ingénieur Denis Diderot, M1 & M2), STEP and OSAE masters as applications subjects for teaching projects. During the internship periods, the IGOsat project welcomed students from French Universities and Engineering Schools (Universities Paris 6, 7 and 11; ISAE/SUPAERO; University Toulouse III…) but also from other countries (University of Science And Technology in Hanoï ; National Institute of Technology in Rourkela, India ; etc.).
Moreover, since November 2015, a Vietnamese student (Hien T. Phan) is working full time for the IGOsat project, more specifically on the detailed design of the scintillator payload and the preparation of the science data analysis of the mission (PhD supervisors : Philippe Laurent and Hubert Halloin). The Vietnamese government funds Hien’s grant, with a additional contribution from the LabEx.
We present hereafter the technical status of the main (sub)systems of the satellite. This work was presented at the Critical Design Review (CDR) in September 2017. The project has therefore entered Phase D, i.e. the Assembly, Integration, Tests and Qualification of the engineering and flight models.
We list here a few items of the results presented by the student during the CDR. They represent a good overview of the work performed during the last year:
- System studies for the IGOsat mission: System engineering is crucial for the IGOsat project (as it is for any space mission). Based on previous works performed by students during Phase B, various budgets (power, communication, mass, …) and mission profile are maintained to take into account the latest technical developments of the subsystems.
- Detailed mechanical design and vibration studies : The mechanical design of the satellite has been updated in 2017 to take into account changes in the satellite configuration (A deployable solar panel, new size for the scintillator payload and solar panels, implementation of the required kill switches for launch operations, etc.). This work was done by a bachelor student from the USTH in Hanoï.
- Design and test bench of the scintillator payload: One of the IGOsat payload is a scintillator detecting electrons and gamma-rays, read by a SiPM matrix. Since November 2015, Hien Phan (PhD student funded by the Vietnamese government) is working on the detailed design of this payload.
- Design and test beds for the GPS payload: The second IGOsat payload is dedicated to the measurements of the Total Electronic Content of the ionosphere, thanks to a dual frequency GPS antenna (and associated receptor).
- Design and realization of the Power Management System: The PMS turned out to be much more difficult to design than expected… Serious flaws were identified in the first version of the card and a complete re-design of the power management system (from solar panels to batteries and power distribution) had to be done and the corresponding electronics card produced.
- Attitude Control and Restitution System: Until 2015, IGOsat design assumed a pointing attitude with the length along the velocity axis. However, detailed study of the control system showed that this orientation was difficult to maintain and not optimal for the communication capabilities. It was then decided to revise the attitude of the satellite with a Nadir attitude, i.e. the long axis towards the center of the Earth. A magnetometer and gyrometer will also be used in IGOsat. They have been selected, partially tested, and modeled for use in the attitude restitution algorithm.
- Telecommunication systems: The development the telecommunication system was addressed this year from both sides: the space and ground segments… Thanks to the work of a master student, we have now a fully operational ground station.
- On-board computer and data management: During spring and summer 2016, a major effort has been put on the development of the on-board computer. The chosen design is derived from QB50 satellites developed at the Ecole Polytechnique and Ecole des Mines de Paris.
These items represent only the most significant works performed by the students during the last year. Every training period, project and, of course, review led to an extensive documentation (reports, user manuals, drawings, etc) that will be used by future students. The studies becoming more and more technical as the project definition goes into the details, more scientists and research engineers from the APC and IPGP are involved in the supervision of the students.
Natacha Combier and Hubert Halloin,
IGOSAT : IONOSPHERIC AND GAMMA RAY OBSERVATION SATELLITE, THE NANOSATELLITE OF THE UNIVERSITE PARIS DIDEROT,
Proceedings of the Small Satellites and Services Symposium, 26-30 May 2014, http://congrexprojects.com/2014-events/4S2014/proceedings
Marco Agnan, Hubert Halloin, Pierdavide Coisson, Philippe Laurent, Thanh-Hien Phan,
IGOSAT (Ionospheric and Gamma-ray Observations Satellite): Feedbacks from an educational CubeSat with scientific returns through technology demonstration
Proceedings of the Nanosat Symposium, 18-19 October 2016, (link still not available).
Hien Phan et al.,
IGOSat – A 3U CubeSat for Measuring the Radiative Content in Low Earth Orbit and Ionosphere
Nuclear Instruments and Methods in Physics Reasearch A, to be submitted
Apart from participating to various conferences, the IGOSat team, together with the communication team of the LabEx and the support from the Space Campus, organized the Second Workshop dedicated to students’ CubeSats. This workshop was held on July 6th and 7th 2017 at IPGP. It gathered students, engineers and scientists working on the different French CubeSat project (plus OPS-sat from ESA and different private companies). The first goal of this workshop (and its originality compared to other nanosat workshops) was to be focused on the students’ needs: what information is relevant and where to get it ?
The morning sessions were dedicated to short presentations of the projects and dedicated available tools for designing CubeSat missions. Afternoon sessions were organized as open discussions on different themes, in order to address the questions of the students (and others…) participating to nanosats’ projects. It is foreseen to organize a third workshop in the summer 2018. One improvement (suggested by the participants) would be to invite even more private companies to gather the return of experience, the required and available technologies and stimulate possible partnerships.
The presentations, movies of the workshop and photos can be found on the IGOSat website: http://www.igosat.fr.