QB50 Project and the Development of CubeSat Technology in China

ZHOU Jun, LIU Yingying, LIU Guanghui, BAI Bo, PANG Weijian, ZHU Peijie, YU Xiaozhou

National United Engineering Laboratory of Microsatellite Technology and Application,Northwestern Polytechnical University, Xi’an 710072

Abstract: The CubeSat refers to the low-cost nano satellite produced by international standards. The QB50 project is “an International Network of 50 double CubeSats for multi-point, in-situ, long-duration measurements in the lower thermosphere and re-entry research”. There are 23 countries and region participated in the QB50 Project. 38 CubeSats were developed and launched. Among them, four CubeSats developed by Chinese universities were sent to orbit (Three were deployed from the International Space Station, and one was launched by the Polar Satellite Launch Vehicle, PLSV). They are Aoxiang-1 (Northwestern Polytechnical University, the Asia coordinator), LilacSat-1 (Harbin Institute of Technology), NJUST-2 (Nanjing University of Science and Technology) and NUDTsat (National University of Defense Technology). Through the development of the QB50 Project, Chinese researchers and students got in touch with the concept of CubeSat and gained experience of international scientific cooperation. A lot of students took part in the assembly, integration, and test of spacecraft, which is helpful to the training of space talents. Now, many universities and institutes have the capabilities to develop CubeSats and the subsystems independently.

Key words: CubeSat, QB50 project, international scientific cooperation

1 BRIEF INTRODUCTION OF THE DEVELOPMENT OF CUBESAT TECHNOLOGY

Satellites weighing less than 1000 kg are collectively known as microsatellites, which can be classified into small satellite (100- 1000 kg), microsatellite (10 - 100kg) and nano satellite (1 - 10 kg).

In recent years, microsatellite and nano satellite have gradually become an important development direction in the international space field. Compared with traditional large satellites,they have many advantages, such as small size, light weight,short development cycle (3 - 6 months), low R & D cost (only millions of CNY) and flexible launch mode (which can be piggyback payload and launched at low cost).

CubeSat is a kind of low-cost satellite produced to international standards. In 2014, practical CubeSat technology was selected in the ten scientific and technological progress inSciencemagazine. The standard CubeSat uses U as the basic volume unit. The volume of 1U is 10 cm × 10 cm × 10 cm,and the mass is less than 1.33 kg. Up until now, the biggest CubeSat launched is the 12U “Star of Aoxiang” developed by Northwestern Polytechnical University. The standardized design method is used in the development of the CubeSat, and Commercial Off-The-Shelf (COTS) components are widely used, so the development cycle is greatly shortened, and the development cost is dramatically reduced. There are now more than 800 CubeSats that have been launched around the world, with more than 2000 expected to be launched in the next five years.The application of CubeSat technology will become an important role in land and resources census, urban planning, environmental monitoring, disaster early warning, agriculture, forestry and water conservancy and other fields[1-3].

2 BRIEF INTRODUCTION OF QB50 PROJECT

2.1 Project Background

The full name of the QB50 project is “An International Network of 50 double CubeSats for multi-point, in-situ, long-duration measurements in the lower thermosphere and for re-entry research”. The QB50 project is an international cooperation project as part of a large science program led by the European Union (EU), which was approved under the 7th Framework Programme (FP7) and became a flagship project of FP7 in 2011.It was originally planned as a constellation of 50 CubeSats. Finally, the project launched 2 precursor CubeSats and 36 scientific exploration CubeSats. The main objectives of the project are to carry out multi-point detection inthe lower thermosphere, atmosphere, at the altitude of 200 — 380 km, to verify new space technology, and to obtain extensive space engineering education[4,5].

The lower thermosphere is the least understood region of the atmosphere for human beings at present. The atmosphere of this layer is mainly composed of rarefied neutral gases. Due to the special altitude of the lower thermosphere, the existing atmospheric detection means (sounding balloon, ground lidar,sounding rocket, Earth observation satellite, etc.) is unable to conduct comprehensive detection. To obtain the temperature,wind speed, ion density and other spatially and temporally varying parameters in the region, it is of great significance to strengthening the detection of the atmosphere in the lower thermosphere using a network of CubeSats, which is of great significance in the following aspects:

1) To find out the coupling mechanism of the upper and lower atmosphere and the internal cause of the global atmospheric change;

2) Increase the lifespan of Low Earth Orbit (LEO) application satellites and manned spacecraft, increase the safe return coefficient of manned spacecraft;

3) Improve the reliability of navigation and communication systems;

4) The detection of the atmosphere in the lower thermosphere is also of great significance for military research.

The QB50 project was led by international research institutes, which include the Von Karman Institute for Fluid Dynamics(VKI), Innovative Solutions In Space (ISIS), QinetiQ Space NV,Surrey Space Centre (SSC) - University of Surrey, Mullard Space Science Laboratory (MSSL)-University College London (UCL),Switzerland Space Center EPFL, Delft University of Technology(TU Delft), Leibniz-Instituts für Atmosphärenphysik, Stanford University, Northwestern Polytechnical Universiy (NPU) and others.The initiators are shown in Table 1[6,7]. VKI is the QB50 project chief coordinator. NPU served as Asia coordinator.

Table 1 QB50 Project original initiating organizations

More than 40 universities, research institutes, and companies from 23 countries and region participated in the QB50 Project.38 CubeSats were developed and launched. So far, these Cube-Sats had begun measuring the atmosphere in the lower thermosphere and sending the data to the ground stations.

2.2 Project Programmes

Two precursor CubeSats of the 38 CubeSats of the QB50 project were used to carry out pilot tests for the project on January 28, 2013. The feasibility of the project and the payloads used were verified. Ten CubeSats carried Ion/Neutral Mass Spectrometer (INMS) for the measurement of ions and neutral particles. Fourteen of them carried a Flux-φ-Probe-Experiment(FIPEX) to measure the distribution of oxygen atoms and oxygen molecules in the lower thermosphere, and ten carried the Multi-Needle Langmuir probe (mNLP) to measure the electron temperature and density of the plasma. Two of them carried de-orbiting devices for In-Orbit Demonstration (IOD) of drag sail de-orbiting technology. Table 2 shows the basic information of the QB50 project CubeSats[7].

Table 2 Information of the QB50 project CubeSats

Satellite name Size QB50 sensor Country Lead institute 20 LINK 2U INMS South Korea KAIST 21 SNUSAT 1 2U FIPEX South Korea Seoul National University 22 SNUSAT 1b 2U FIPEX South Korea Seoul National University 23 qbee50-LTU-OC 2U FIPEX Sweeden Open Cosmos Ltd. &Lulea University of Technology 24 BEEAGLESAT 2U mNLP Turkey Istanbul Technical University 25 HAVELSAT 2U mNLP Turkey HAVELSAN 26 Phoenix 2U INMS Chinese Taipei NCKU 27 PolyITAN-2-SAU 2U FIPEX Ukraine National Technical University of Ukraine 28 QBUS 1, Challenger 2U INMS USA University of Colorado 29 QBUS 2, Atlantis 2U FIPEX USA University of Michigan 30 QBUS 4, Columbia 2U FIPEX USA University of Michigan 31 Pegasus 2U mNLP Austria FHWN 32 NUDTSat 2U INMS China National University of Defense Technology 33 VZLUsat 1 2U FIPEX Czech Republic VZLU 34 DragSail-CubeSat 3U IOD Germany FH Aachen, University of Applied Sciences 35 UCLSat 2U INMS UK UCL 36 Inflate Sail 3U IOD UK University of Surrey 37 URSA MAIOR 3U mNLP Italy Sapienza University of Rome 38 LituanicaSAT 2 3U FIPEX Lituania Vilnius University

2.3 Timeline of Project Progress

On November 17, 2009, the first QB50 Project Workshop was held in Sint-Genesius-Rode, Brussels, Belgium, which played a key role in establishing the project application and preliminary research for QB50 Project. In 2010, initiating institutes such as VKI, ISIS, SSC, MSSL, EPFL, TU Delft, Leibniz-Institutsfür Atmosphärenphysik, Stanford University, NPU, etc.,had formally submitted the project proposals to FP7 of the EU.On November 28, 2011, the EU signed the document to approve the implementation of the project.

The initially selected launcher for QB50 was the Russian Shtil 2.1 in Figure 1. However, the launcher provider withdrew from the project for many complicated reasons. Since then, the QB50 consortium board had compared a variety of launchers, including candidates from EU, the USA, China,Japan, Ukraine and India. Considering the political, economic,launch orbit and other factors, the QB50 consortium board announced that it had chosen Cyclone4 of Alcantara Cyclone Space (Ukrainian-Brazilian joint venture) on January 27,2014. On June 19, 2014, two QB50 precursor CubeSats,qb50p1 and qb50p2, were sent into orbit by the Dnepr launcher. In January 2016, the Cyclone 4 launch strategy was canceled due to financial and technical problems.

At 23:11 Beijing time April 18, 2017,the first 28 CubeSats of the QB50 project in Figure 2 were sent to the International Space Station (ISS) successfully by the Atlas-V Launcher/Cygnus cargo spacecraft from the Cape Canaveral Air Force Station in Florida.One month later, the CubeSats were successively deployed from ISS. On June 23,2017, the other 8 CubeSats were successfully launched into orbit by the Indian Polar Satellite launch vehicle (PLSV) -XL.

Figure 1 Shtil 2.1 for QB50 and the installation scheme of the CubeSat system[8]

Figure 2 CubeSats loaded with satellite deployer awaiting delivery to Atlas-V[8]

3 DEVELOPMENT OF CUBESAT TECHNOLOGY IN CHINA

3.1 China’s Participation in QB50 Project

In 1999, Professor Jordi Puig-Suari of the California Polytechnic State University and Professor Bob Twiggs of Stanford University put forward the reference design of the CubeSat. In June 2003, the world’s first CubeSats were launched. However,before the QB50 project, there was no team in China conducting research into CubeSats. In fact, the initial research of Cube-Sats in China just came from the traction of the QB50 project.Since then the NPU, Harbin Institute of Technology (HIT),Nanjing University of Science and Technology (NJUST) and National University of Defense Technology (NUDT) have become involved in the QB50 project, and successfully launched their CubeSats as shown in Table 3[8]. Figure 3 is the photo of Aoxiang-1 (left one) deployed from the International Space Station.

The technical specifications of CubeSats developed by Chi- nese universities are shown in Table 4.

Table 1 CubeSats developed by Chinese universities and their main information

Figure 3 Aoxiang-1 (left one) deployed from the International Space Station

The objectives of the development of the Chinese QB50 CubeSats are as follows:

1) A series of scientific experiments and technical demonstrations were carried out, including the detection of the lower thermosphere, an experiment of a high precision attitude control system and anew orbit determination mission.

2) Expand international cooperation and exchanges.The QB50 project is the largest space project in the world. In the process of QB50 development, domestic research teams have the opportunity to communicate and cooperate with foreign first-class satellite development teams,which improves the research capability of domestic CubeSats and realizes the first deployment of domestic CubeSats from ISS and expands the influence of China in the area ofinternational cooperation in space.

Table 4 The technical specifications of the Chinese QB50 CubeSats

3) Education and training. The QB50 project plays an important role in education and training. In recent years,hundreds of people, including young teachers and students, have participated in the development of QB50 CubeSats and gained first-hand experience in microsatellite research, enabling training at a number of the universities for their CubeSat development teams.

As the only Asia initiator and the Asia coordinator, the NPU Aoxiang team is led by Professor ZHOU Jun and has good cooperation with the EU QB50 Consortium board in the past six years to conduct a great deal of work.

1) In the early stage of the project, NPU was responsible for the activities of universities and research institutes in Asia, participated in the different phase of the review of national applications for the CubeSat programs, coordinated the development progress of CubeSats in Chinese universities etc.

2) As the satellite is a sensitive high-tech system, many countries have strict control over the import and export of satellites, involving a large number of complicated procedures between China, Europe, the USA and other countries. To ensure the smooth export of the satellite, under the leadership of the China National Space Administration, NPU cooperated with China Great Wall Industry Corporation (CGWIC) and jointly completed the QB50 satellite (developed by universities in China)along with completing launch licenses and satellite export licensing procedures.

3) NPU, also coordinated with the State Radio Regulator of China, Amateur Radio Management Committee of the Radio Association of China, International Telecommunications Union (ITU) and International Amateur Radio Union (IARU) regarding the application and coordination of satellite communication frequency bands in China.

4) NPU cooperated with VKI, ISIS and other launcher companies for satellite integration testing, which involved the cooperation and coordination with relevant agencies in China, EU, the USA and other countries.

Finally, the QB50 CubeSats developed by NPU, HIT,NUDT and NJUST were exported to Europe in time for integration testing and transported to the USA for launch.

3.2 QB50 Project and the NPU Aoxiang Microsatellite Team

The NPU Aoxiang microsatellite team had worked six years on the QB50 Project, accumulating abundant experience in the area of international scientific cooperation, and constructing an international cooperation exchange platform for domestic and foreign universities. NPU has carried out extensive satellite cooperation with the universities and research institutes in Belgium, Netherlands, the USA, Germany, Britain, Canada, France,Switzerland, etc..

1) In 2013, NPU successfully hosted the QB50 Asia Workshop, which was highly valued by international satellite community, including the International Astronautical Federation (IAF), and had a wide social impact.

2) NPU initiated and held the “2U” CubeSat Structure Design Competition in 2011, the Shaanxi “Aoxiang Cup” CubeSat Design Competition in 2012, and the China Graduate Future Flight Vehicle Innovation Competition in 2015. Thousands of Chinese students participated in the competitions. The series of events caused a far-reaching impact on international students.In 2018, NPU will hold the China Microsatellite Symposium (www.microsatsymp.com) and International CubeSat Mission Contest (www.cubesatcontest.com),which will be held in Xi’an from November 18 to 20,2018. The above activities have received recognition from International CubeSat research teams.

During the research of QB50 Project, NPU has developed a series of CubeSat subsystems. An on-board computer,magnetic torquer, reaction wheel, power supply system and other key components used in “Aoxiang-1” which were all independently developed in China. In the process of the QB50 Project, NPU has also made considerable progress in the field of microsatellites. On April 24, 2016, the first university satellite ground station in Shaanxi province was constructed and commissioned into use for NPU. On June 25, 2016, The world’s first 12U CubeSat “Star of Aoxiang” was successfully launched from Wenchang, Hainan. On January 9, 2017, the “Xingyun experiment-1”, a 2U CubeSat jointly developed by NPU and China Aerospace Science and Industry Corporation (CASIC),was successfully launched at the Jiuquan Satellite Launch Center.On April 18, 2017, at the Cape Canaveral Air Force Station in Florida, USA, NPU successfully launched the 2U CubeSat,“Aoxiang-1”.

Figure 4 Aoxiang-1 was delivered to the launch provider in the Netherlands

Through the development of QB50 Project, NPU has established capabilities such as the overall design of CubeSats,the development and production of subsystems, the assembly and integration of CubeSats, satellite test, environmental test,Telemetry Tracking and Command (TT&C) and so on. Regarding CubeSat technology, NPU has formed a modular, standardized and serialized development procedure, which includes the thermal vacuum, vibration, impact spectrum, constant overload,high and low temperature and the other related experiment capability. With the adaptability to different load requirements and mission requirements, the developed CubeSats and there subsystems have high reliability. The research team has successfully developed 2U, 3U, 6U, 12U CubeSats, and standard subsystems such as the on-board computer, magnetic torquer, reaction wheel, electrical power system, structure, electromagnetic ejection deployers, and so on. The specifications of general design, assembly integration and test have been formulated. The“Aoxiang” series of satellite subsystems have been successively used in more than 10 microsatellite missions such as those for China Aerospace Science and Technology Corporation, Tsinghua University and the Spacety.

In April 2018, the Shaanxi Provincial Development and Reform Commission and NPU jointly released the “Shaanxi-1”satellite constellation plan. The project will be completed in three phases, one of which will consist of 72 international standard CubeSats in LEO. After the constellation is built, it could realize high frequency and revisit remote sensing for the Shaanxi Province and the “Belt and Road” entire region. The object of the mission isto provide general survey of land and resources,urban planning, environmental monitoring, disaster warning,agriculture, forestry and water to provide immediate, detailed,intuitive image information.

3.3 Development Trend of International CubeSat Technology

With the development of CubeSat technology, the developers of CubeSats are no longer satisfied with the application of CubeSats in LEO. At present, the hotspot of CubeSat technology is deep space exploration and constellation networking.Through carrying the different innovative payloads, deep space exploration CubeSats could obtain the information about the composition of space objects such as the moon and asteroids,as well as obtain the characteristics, distribution, and state of all kinds of resources, which have high research value. The first deep space CubeSats have been launched by NASA in May 2018. They are the 6U Cube Marco-1 and Marco-2. Their main mission is to support InSight Mars Lander’s landing on the Martian surface as the communication relay. Also, the United States plans to launch a series of deep space exploration Cube-Sats, including Biosentinel, NEA Scout, and Lunar Flashlight in 2019.

The CubeSat constellation has a broad application prospect in the field of communication and remote sensing. Several CubeSats have been distributed in single orbit or multi-orbit planes to form constellations against specific requirements,which can improve the coverage of the ground and shorten the revisit period. At a lower cost to achieve or even exceed the functions of large satellites and reduce system damage, the Planet in the USA has built a constellation for remote sensing applications and Spire also has built another constellation for meteorological research and application.

Although the development of CubeSat technology in China started later than foreign research institutions, more and more Chinese researchers joined the research and development of CubeSat technology taking advantage of the low cost, short development period and easy access to space. With the accumulation of the CubeSat technologies and rapid pace of industrialization, Chinese research teams will be able to carry out more innovative missions and the Chinese CubeSats can enter into the international market.