Micro- and mini-satellites of ISRO—technology and applications

With rich experience of the successful Indian remote sensing satellite series, Indian Space Research Organization (ISRO) has started theme-based satellites like Resourcesat and Oceansat. Further taking the advantage of the improved technologies in areas of miniaturization, the micro- and mini-satellite series have been started, which will provide opportunity for the payloads of stand-alone missions, for applications, study or research. These include payloads for Earth imaging, atmospheric monitoring, ocean monitoring, scientific applications, and stellar observation. The micro-satellites are of 100 kg class, planned with a payload of about 30 kg and 20 W power and mini-satellites of 450 kg class for payloads of 200 kg and power of 200 W. The first satellite in the micro-satellite series is an Earth imaging payload followed by the second satellite with scientific payloads with the participation of students. Further the scientific proposals for micro-satellites are under evaluation. Similarly the first two missions of mini-satellites are defined with first one carrying ocean and environment monitoring payloads followed by the Earth imaging satellite with multi-spectral camera with 700 km swath. The current paper touches upon the technology involved in realization of the micro- and mini-satellites and the scope of applications of the series.     

A series of small scientific satellite with flexible standard bus

Japan Aerospace Exploration Agency has a plan to develop the small satellite standard bus for various scientific missions and disaster monitoring missions. The satellite bus is a class of 250–400 kg mass with three-axis control capability of 0.02 accuracy. The science missions include X-ray astronomy missions, planetary telescope missions, and magnetosphere atmosphere missions. In order to adapt the wide range of mission requirements, the satellite bus has to be provided with flexibility. The concepts of modularization, reusability, and product line are applied to the standard bus system. This paper describes the characteristics of the small satellite standard bus which will be firstly launched in 2011.     

Principal Investigators and mission leadership

Principal Investigators of small and medium sized space and earth science missions face many challenges during formulation, design, development, integration and test, launch, and operations; these challenges may be more easily met by team leaders with prior mission experience. This paper reports the results of the first known demographic study of NASA's Principal-Investigator-led missions and makes recommendations for preparing additional space scientists to lead. The addition of a Deputy Principal Investigator to proposal teams could reduce the burden on the Principal Investigator and provide an opportunity for additional scientists to gain mission leadership experience useful on future missions. The pool of mission-knowledgeable scientists could further be expanded to include scientists earlier in their careers via carefully managed Participating Scientist Programs. Adding Deputy Principal Investigators and Participating Scientist Programs to missions as a matter of course would reinforce effective management practices, open the field of proposers, and provide concrete ways to mentor the next generation of Principal Investigators.     

Multiobjective optimization applied to structural sizing of low cost university-class microsatellite projects

In recent years, there has been continuing interest in the participation of university research groups in space technology studies by means of their own microsatellites. The involvement in such projects has some inherent challenges, such as limited budget and facilities. Also, due to the fact that the main objective of these projects is for educational purposes, usually there are uncertainties regarding their in orbit mission and scientific payloads at the early phases of the project. On the other hand, there are predetermined limitations for their mass and volume budgets owing to the fact that most of them are launched as an auxiliary payload in which the launch cost is reduced considerably. The satellite structure subsystem is the one which is most affected by the launcher constraints. This can affect different aspects, including dimensions, strength and frequency requirements. In this paper, the main focus is on developing a structural design sizing tool containing not only the primary structures properties as variables but also the system level variables such as payload mass budget and satellite total mass and dimensions. This approach enables the design team to obtain better insight into the design in an extended design envelope. The structural design sizing tool is based on analytical structural design formulas and appropriate assumptions including both static and dynamic models of the satellite. Finally, a Genetic Algorithm (GA) multiobjective optimization is applied to the design space. The result is a Pareto-optimal based on two objectives, minimum satellite total mass and maximum payload mass budget, which gives a useful insight to the design team at the early phases of the design.     

即插即用模块化卫星体系结构研究

即插即用模块化卫星是模块化即插即用技术与卫星平台技术相结合的新型卫星系统,是实现空间快速响应的重要途径。文章介绍了即插即用模块化卫星的概念;分析了即插即用技术在航天任务中的应用;概括了即插即用模块化卫星的体系结构,主要包括功能模块、即插即用标准接口、卫星平台总线和系统软件。在传统卫星分系统划分的基础上进行功能分解,提出了即插即用模块化卫星功能模块的划分方案。文章的研究结果可为中国发展即插即用模块化卫星技术提供理论参考。     

Examining the effects of anti-space weaponization arguments in the media: Some experimental findings from Canada

This study examines how political activists are framing the space weaponization debate in Canada and whether their arguments can influence public attitudes and perceptions about the issue. Eighty university students from two undergraduate courses were recruited as participants in a quasi-experiment. One class (n = 38) was exposed to the documentary Masters of Space, an episode of the Canadian Broadcasting Corporation's program The Nature of Things, and another class (n = 42) served as the control group. Pre-test and post-test questionnaires were used to measure the effects of viewing anti-weaponization arguments in the media, while also controlling for the influence of prior beliefs and background characteristics of participants. Results suggest that visually depicting the use of satellite technology in society can convince viewers that satellites are important to their way of life, but not necessarily to the defense of North America. Framing missile defense as a ‘space weapon in disguise’ also seemed to raise opposition to Canada's participation in continental missile defense. The findings, meanwhile, indicate that viewers respond strongly to the issue of space debris and that mobilizing support for joint military space projects may best be achieved by emphasizing the usefulness of these projects for locating and tracking such debris. In the end, media exposure seemed to help legitimize anti-weaponization arguments based more on rational self-interests than on idealistic beliefs. These findings can have implications for the way space policies are communicated to the public.     

Cost-driven design of small satellite remote sensing systems*

Earth remote sensing (alongside communications) is one of the key application of Earth-orbiting satellites. Civilian satellites in the LANDSAT and SPOT series provide Earth images which have been used for a vast spectrum of applications in agriculture, meteorology, hydrology, urban planning and geology, to name but a few. In the defence sector, satellite remote sensing systems are a critical tool in strategic and tactical planning – for the countries which can afford them. To date, remote sensing satellites have fallen into one of these two categories: military missions driven by the requirement for very high resolution and orbital agility; and multipurpose civil satellites using general purpose sensors to serve a diverse community of end users. For military-style missions, the drive to high resolution sets the requirements for optics, attitude control and downlink data bandwidth. For civil missions, the requirement to satisfy multiple, diverse user applications forces compromises on spectral band and orbit selection. Although there are exceptions, many small satellite remote sensing missions carry on in this tradition, concentrating on ultra high resolution products for multiple user communities. This results in satellites costing on the order of US $100 M, not optimised for any particular application. This paper explores an alternative path to satellite remote sensing, aiming simultaneously to reduce cost and to optimise imaging products for specific applications. By decreasing the cost of the remote sensing satellite system to a critical point, it becomes appropriate to optimise the sensor's spectral and temporal characteristics to fit the requirements of a small, specialised user base. The critical engineering trade-off faced in a cost driven mission is how to reduce mission cost while still delivering a useful product to the selected user. At the Surrey Space Centre, we have pursued an engineering path using two dimensional CCD array sensors, commercial off-the-shelf lenses and gravity-gradient stabilised microsatellites. In spite of the inherent limitations of such systems, recent successes with the Thai Microsatellite Company's Thai-Phutt satellite show that a system costing in the region of US $3 million, can approach the spectral and spatial characteristics of LANDSAT. Surrey's UoSAT-12 minisatellite (to be launched April, 1999) will further develop this cost-driven approach to provide 10 m panchromatic resolution and 30 m multi-spectral resolution. This paper describes the Thai-Phutt and UoSAT-12 imaging systems, explaining the engineering methods and trade-offs. Although Surrey is presently the only centre presently pursuing such implementations, our paper shows that they deserve wider consideration.     

Piloted operations at a near-Earth object (NEO)

In late 2006, NASA's Constellation Program sponsored a study to examine the feasibility of sending a piloted Orion spacecraft to a near-Earth object. NEOs are asteroids or comets that have perihelion distances less than or equal to 1.3 astronomical units, and can have orbits that cross that of the Earth. Therefore, the most suitable targets for the Orion Crew Exploration Vehicle (CEV) are those NEOs in heliocentric orbits similar to Earth's (i.e. low inclination and low eccentricity). One of the significant advantages of this type of mission is that it strengthens and validates the foundational infrastructure of the United States Space Exploration Policy and is highly complementary to NASA's planned lunar sortie and outpost missions circa 2020. A human expedition to a NEO would not only underline the broad utility of the Orion CEV and Ares launch systems, but would also be the first human expedition to an interplanetary body beyond the Earth–Moon system. These deep space operations will present unique challenges not present in lunar missions for the onboard crew, spacecraft systems, and mission control team. Executing several piloted NEO missions will enable NASA to gain crucial deep space operational experience, which will be necessary prerequisites for the eventual human missions to Mars.Our NEO team will present and discuss the following:

• •new mission trajectories and concepts;
• •operational command and control considerations;
• •expected science, operational, resource utilization, and impact mitigation returns; and
• •continued exploration momentum and future Mars exploration benefits.

     

Developments in space activities in Poland

Poland has a long-standing tradition in space activities. Polish institutions have participated as co-investigators in almost all European Space Agency (ESA) science projects, as well as on many other missions. However, the first Polish satellite (PW-SAT) was only launched in 2012. Poland was one of the first Eastern European countries to conclude a Cooperation Agreement with ESA in the peaceful use of outer space; it was signed in 1994 and followed by a second in January 2002. Negotiations on Polish membership in the ESA were started in autumn of 2011, and ended in April 2012. Following ratification of the agreement, Poland officially became the 20th Member State of ESA on 19 November 2012. This article examines how Poland is setting its way as a space nation. It describes recent developments in the Polish space programme, including the road to Poland's full membership in the European Space Agency.     

The origin of the smaller, faster, cheaper approach in NASA’s solar system exploration program

The current emphasis on smaller, faster, cheaper (SFC) spacecraft in NASA’s solar system exploration program is the product of a number of interacting – even interdependent – factors. The SFC concept as applied to NASA’s solar system exploration program can be viewed as the vector sum of (1) the space science community’s desire for more frequent planetary missions to plug the data gaps, educate the next generation of scientists, provide missions to targets of opportunity, and enable programmatic flexibility in times of budgetary crisis; (2) the poor publicity garnered by NASA in the early 1990s and the resultant atmosphere of public criticism (creating an opportunity for reform); (3) The Strategic Defense Initiative Organization’s and the National Space Council community’s desire to advance the Space Exploration Initiative and their perception that the NASA culture at the time represented a barrier to the effective pursuit of space exploration; (4) the effective leadership of NASA Administrator Daniel Goldin; and (5) the diminishing budget profile for space sciences in the early 1990s. This paper provides a summary of the origin of the smaller, faster, cheaper approach in the planetary program. A more through understanding of the history behind this policy will enable analysts to assess more accurately the relative successes and failures of NASA’s new approach to solar system exploration.     

A low-cost femtosatellite to enable distributed space missions

A new class of distributed space missions is emerging which requires hundreds to thousands of satellites for real-time, distributed, multi-point sensing to accomplish long-awaited remote sensing and science objectives. These missions, stymied by the lack of a low-cost mass-producible solution, can become reality by merging the concepts of distributed satellite systems and terrestrial wireless sensor networks. However, unlike terrestrial sensor nodes, space-based nodes must survive unique environmental hazards while undergoing complex orbital dynamics. A novel sub-kilogram very small satellite design is needed to meet these requirements. Sub-kilogram satellite concepts are developing elsewhere, such as traditional picosatellites and microengineered aerospace systems. Although viable technical solutions, these technologies currently come at a high cost due to their reliance on high-density technology or custom manufacturing processes. While evaluating these technologies, two untapped technology areas became evident that uniquely encompass low cost and mass producibility by leveraging existing commercial production techniques: satellite-on-a-chip (SpaceChip) and satellite-on-a-printed circuit board (PCBSat). This paper focuses on the design, build, and test results of a prototype PCBSat with a prototype unit cost less than $300. The paper concludes with mission applications and future direction.     

The ESA approach to low-cost planetary missions

While ESA has never adopted the mantra of “cheaper, faster, better” there has been considerable pressure to reduce mission costs in recent years. To this end, ESA has implemented a number of changes to its procurement procedures which are now being implemented in missions such as SMART-1, Mars Express and which will be applied to future missions such as the Mercury Cornerstone. This paper outlines the approach taken to each and describes the missions.     

Development of a scheduling algorithm and GUI for autonomous satellite missions

In this paper, a scheduling optimization algorithm is developed and verified for autonomous satellite mission operations. As satellite control and operational techniques continue to develop, satellite missions become more complicated and the overall quantity of tasks within the missions also increases. These changes require more specific consideration and a huge amount of computational resources, for scheduling the satellite missions. In addition, there is a certain level of repetition in satellite mission scheduling activities, and hence it is highly recommended that the operation manager carefully considers and builds some appropriate strategy for performing the operations autonomously. A good strategy to adopt is to develop scheduling optimization algorithms, because it is difficult for humans to consider the many mission parameters and constraints simultaneously. In this paper, a new genetic algorithm is applied to simulations of an actual satellite mission scheduling problem, and an appropriate GUI design is considered for an autonomous satellite mission operation. It is expected that the scheduling optimization algorithm and the GUI can improve the overall efficiency in practical satellite mission operations.     

Revolutionary systems and technologies for missions to the outer planets

The Advanced Deep Space System Development Program is managed by the Jet Propulsion Laboratory for NASA and is also called X2000. X2000 is organized to create advanced flight and ground systems for the exploration of the outer planets and beyond; it has been created to develop the engineering elements of flight and ground systems. Payloads will be developed by another team. Each X2000 delivery gets its requirements from a set of planned missions, or “mission customers”.The X2000 First Delivery Project supports missions to the Sun (to 4 solar radii), Europa (looking for a liquid ocean), Mars (in support of several Mars missions including a sample return), a comet (including a sample return), and Pluto followed by a trip into the Kuiper belt. This set of missions leads to some outstanding requirements:

• 1.1. Long-life (10–12 years)
• 2.2. Total Ionizing Dose of 4 Mrad (for a Europa Orbiter)
• 3.3. Average power consumption less than or equal to 150 Watts
• 4.4. Autonomous operations that result in an extreme reduction in operations costs

This paper describes the X2000 first delivery and its technologies following a brief overview of the program.     

Psychological considerations of man in space: problems & solutions

With concrete plans for long duration flight taking form a new impetus is lent to preparing man for this hostile and unnatural environment. Cramped conditions, isolation from family and loved ones, work stress, fear, and incompatibility with fellow crew, are but a few of the problems suffered by astronauts and cosmonauts during their long missions in orbit about the earth.

Although criteria for selection of crew is one aspect of attacking the problem, it has not solved it Notwithstanding good selection, team combination, and counselling before flight, problems have still occurred with unwanted consequences. Incompatibility of team members, far from being the exception, has been frequent. This has been detrímental both physiologically and psychologically for the individual as well as for the operational success and safety of the missions.

Because problems will inevitably occur in future long duration missions, especially when they are of international and multi-cultural nature, the importance of dealing with them is underlined. This paper takes a different approach towards ameliorating these problems, namely that of psychological group training before a mission.     

Women and couples in isolated extreme environments: applications for long-duration missions

Expedition teams provide a number of analogs relevant to crew selection for long-duration space missions. Three groups were studied that varied in team composition. Group 1 was a two woman international dyad that traversed the Antarctic continent in 97 days. Similarities in problem solving approach, respect for each other's opinions, and a collaborative process of decision making were evident. Group 2 was composed of four women, all from different countries, engaged in a six week trek across Greenland. The most important factors in overcoming interpersonal difficulties and contributing to the successful completion of the expedition were mutual respect and motivation to maintain positive and supportive relationships. Group 3 consisted of three married couples from different countries icelocked on a boat in the High Arctic for a 9 month period. The emotional support of and ability to confide in their partner were extremely important in alleviating interpersonal tensions, and contributed to the generally effective functioning of the group. Women add an element of emotional support and help to other team members that is not as evident in all-male groups. Selection of couples with strong bonds to each other is another paradigm for crew selection for extended missions.     

Characterization of Lithium-Polymer batteries for CubeSat applications

With the development of several key technologies, nanosatellites are emerging as important vehicles for carrying out technology demonstrations and space science research. Nanosatellites are attractive for several reasons, the most important being that they do not involve the prohibitive costs of a conventional satellite launch. One key enabling technology is in the area of battery technology. In this paper, we focus on the characterization of battery technologies suitable for nanosatellites.Several battery chemistries are examined in order to find a type suitable for typical nanosatellite missions. As a baseline mission, we examine York University's 1U CubeSat mission for its power budget and power requirements. Several types of commercially available batteries are examined for their applicability to CubeSat missions. We also describe the procedures and results from a series of environmental tests for a set of Lithium Polymer batteries from two manufacturers.     

Policy for robust space-based earth science,technology and applications

Satellite remote sensing technology has contributed to the transformation of multiple earth science domains, putting space observations at the forefront of innovation in earth science. With new satellite missions being launched every year, new types of earth science data are being incorporated into science models and decision-making systems in a broad array of organizations. Policy guidance can influence the degree to which user needs influence mission design and when, and ensure that satellite missions serve both the scientific and user communities without becoming unfocused and overly expensive. By considering the needs of the user community early on in the mission-design process, agencies can ensure that satellites meet the needs of multiple constituencies. This paper describes the mission development process in NASA and ESA and compares and contrasts the successes and challenges faced by these agencies as they try to balance science and applications within their missions.     

北斗工程IGSO/MEO/GEO发射轨道设计

随着我国航天事业的蓬勃发展，运载火箭发射要求也呈现多样化。北斗卫星导航系统是我国自行研制的全球卫星导航系统，经历三步跨越式发展，目前已经全面建成。CZ-3A系列火箭承担了北斗工程全部发射任务，该工程对火箭倾斜同步转移轨道（IGTO）、中圆转移轨道（MTO）、地球同步转移轨道（GTO）新类型轨道要求。介绍了该类轨道特点，讨论了火箭发射方案、发射轨道设计及高空风双向补偿方法。实际飞行考核充分证明了发射轨道设计的正确性，设计方法确保了北斗工程全部发射任务取得圆满成功，为北斗工程顺利实施奠定了基础。