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Russia to send spacecraft into vicinity of the Sun In 2012, the Russian space agency gave the go head to the full-scale development of an ambitious spacecraft dedicated to studies of the Sun from a close distance. The first Russian or Soviet mission into the vicinity of the Sun faces many unprecedented technical challenges including the development of innovative electric engines and protecting the spacecraft from the searing 600-degree heat and radiation of our home star. Dubbed Inter-Gelio-Zond or IGZ, the daring space probe would follow in the footsteps of the US-German Helios mission and NASA's Ulysses spacecraft. It was also developed in parallel with the US Solar Probe and the European Solar Orbiter projects.
The trajectory proposed for the Inter-Gelio-Zond mission would take the spacecraft on a complicated spiral into the vicinity of the Sun with the help of the gravitational fields of the Earth and Venus. (Red lines indicate powered flight of the probe under the thrust of its electric engines. Dotted lines show the orbits of Earth, Venus and Mercury.) Credit: Roskosmos Mission to the Sun Russian space scientists have been considering the Inter-Gelio-Zond project since 1997, however the idea remained in embryonic stage until around 2008. At that time, the Russian space agency, Roskosmos, finally committed to finance the project as an addition to the Federal space program covering the period from 2005 to 2015. The agency gave NPO Lavochkin around a year and a half from January 2009 to May 2010 to develop a Technical Proposal for the mission. According to the plans at the time, the 8,120-kilogram spacecraft would be launched by a Soyuz-2 rocket in 2014, carrying more than 300 kilograms of scientific gear. Scientists hoped that Inter-Gelio-Zond would approach the Sun to a distance equal to 30 or 40 of its radii. (434), however by 2010, the closest point was moved back to 60-70 solar radii (still slightly closer to the Sun than the orbit of Mercury). According to estimates, the probe would need nearly two years to cruise through space to approach the Sun within 47 of its radii, while 3.7 years would be required to come as close as 34 radii. Since the Earth circles the Sun roughly along its Equator, ground observations severely limit the view of polar regions of our home star. As a result, tilting the probe's orbital plane relative to the plane of the Ecliptic (the plane of the Earth's orbit around the Sun) would provide a unique vantage point for scientists. Russian engineers devised a five-year-long mission scenario that would place Inter-Gelio-Zond into an orbit inclined 30 degrees toward the Ecliptic. According to Russian sources, the probe's final orbit would also be synchronized with the rotation of the Sun. (602) A series of maneuvers in the gravitational field of Venus and Earth would be conducted in order to "slingshot" the probe onto a Sun-bound spiral. Even with the help of planetary gravity, Inter-Gelio-Zond would still need electric engines thrusting for prolonged periods of time in order to reach its destination. According to one early concept, four solar panels with a total area of 60 square meters were designed to feed power-hungry electric engines. Upon the probe's approach to the Sun, the solar panels would swing back to hide in a shade of its thermal shield made out of tungsten, molybdenum and their alloys. Following another re-thinking of the mission, a special electrically propelled space tug from the Dvina-TM program was integrated into the design. To resolve the contradiction between the need for huge solar panels and strict limits on the size of hardware protected by the heat shield, it was decided to discard large sections of solar panels after the delivery of the spacecraft into the vicinity of the Sun. Jettisoning the panels would also dramatically reduce the severe pressure of the solar wind onto the probe. Scientific instruments onboard Inter-Gelio-Zond would look at the Sun through special filtered windows in the heat shield, sending as much as 1 gigabyte of data back to Earth. (604) To stay in touch with mission control at distances as far as 250 million kilometers, Inter-Gelio-Zond would have to use an X-band communications system, which was to be tested for the first time in the Phobos-Grunt mission. However that probe's failure to leave the Earth orbit forced a delay of the trials of X-band communications until 2014, when the Spektr-RG space observatory was to be launched into the Lagrange point behind the Earth relative to the Sun. Roskosmos also hoped to enlist ESA and NASA to provide their deep-space ground antennas for the benefit of the Inter-Gelio-Zond mission. The Moscow-based Lebedev Physics Institute started working on four instruments for Inter-Gelio-Zond, which would be controlled by a single computer. The resolution of these instruments would be five times higher than that onboard of the Koronas-Foton spacecraft, Russia's previous short-lived solar observatory in the Earth orbit. According to Inter-Gelio-Zond project scientists, for the first time, humans would get a chance to see the magnificent corona of the Sun with a resolution of just 300 kilometers and witness ejections from the polar regions of the Sun in unprecedented detail and from a unique vantage point. Development In March 2009, Roskosmos announced a tender for the initial stage of Inter-Gelio-Zond's development, allocating 25 million rubles until 2010. (The total budget for the mission was estimated at 4,200 million rubles.) As expected, NPO Lavochkin, the prime developer of the nation's planetary probes, was awarded the contract. In May 2009, NPO Lavochkin subcontracted the IZMIRAN research institute to develop some scientific payloads for the mission. A number of other leading Russian and foreign scientific centers were also expected to contribute their instruments. By 2011, as the scientific team and its extensive array of instruments had been selected in the course of the preliminary design, the project faced a familiar problem of mass deficit. The amount of scientific payload was now quoted at 120 kilograms. The preliminary design for the project was expected to be completed before the end of 2011. Work in 2012 As of 2012, Inter-Gelio-Zond was still expected to use electric engines, a protective heat shield covered with carbon-based insulation and solar panels with an active cooling mechanism in order to function in the vicinity of the Sun. However, challenges in the development of an electric propulsion system and radiation-hardened avionics pushed the launch date for the mission from the middle to the end of the decade. By August 2012, a presentation published by NPO Lavochkin quoted a launch date for Inter-Gelio-Zond in 2019. In October 2012, NPO Lavochkin's team defended the preliminary design of the Inter-Gelio-Zond project at the meeting of a division of the Scientific and Technical Council, NTS, of the Russian space agency, Roskosmos. The council recommended the development of two similar spacecraft in order to increase the chances of success for the mission and to widen its scope, even though the available budget funded only a single probe. In any case, by November, Inter-Gelio-Zond project was cleared to proceed to a full-scale development. According to industry sources, the overcrowding of the spacecraft with science instruments could help with the decision to split the mission into two vehicles, which would allow to unload some of experiments to a backup probe. At the same time, the dual mission lifting off in two different launch windows could increase scientific return by making the same measurements from two different points or even providing stereo imagery. In another major upgrade for the project, the much larger Proton rocket rather than Soyuz-2 was promised to be used to launch the mission. PEP project According to advance Russian planning, the Inter-Gelio-Zond project could pave the way to a pair of probes known as the Polar Ecliptic Patrol, PEP. They would be launched into elliptical orbits with a diameter of 0.5 astronomical units extending far above the Ecliptic for the round-o-clock monitoring of the Sun and of the solar wind. As all Russian planetary missions got pushed back during 2013 and 2014 by an average of three years, the Inter-Gelio-Zond project was not an exception. By 2014, its launch was rescheduled from 2019 to around 2022. (709) In 2013, another reorganization of the Solar System department within the Russian Academy of Science formed the Solar Physics section, which was put responsible for the Polar Ecliptic Patrol, PEP, project. The preliminary study (known in Russian as NIR) for the Polar Ecliptic Patrol was now expected to be completed by 2014 and folded into the Inter-Gelio-Zond, IGZ, project. Clearly, with the IGZ postponed well into the 2020s and featuring two spacecraft, there was no point to pursue a parallel project. At the same time, the studies of the Polar Ecliptic Patrol within the Solar Physics section would be succeeded by a new initiative looking into the possibility of building an exotic solar-sailing spacecraft.
Evolution of the Inter-Gelio-Zond project:
Science instruments proposed for the Inter-Gelio-Zond mission:
Expected budget for the Inter-Gelio-Zond project (as of July 2008):
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