Awning (space travel)

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The sun sail , also known as light sail , photon sail or solar sail , is a concept in which the radiation pressure of sunlight is used to drive space probes (English solar-sail propulsion , SSP). The German engineer Hermann Oberth (1923) and the Russian space pioneer Konstantin Ziolkowski (1924) had similar ideas in the 1920s . The term “solar sailing” was first coined by Richard Garwin (1958).

The acceleration possible through a solar sail is very low compared to other drives. Therefore, concepts for the use of solar sails envisage mission periods of many years. The technological challenge is to unfold and maneuver foils in space that are very light and very large. While NASA temporarily stopped development, Japan successfully tested the IKAROS in 2010 .

concept

With the solar sail, the radiation pressure of the sun is to be used as a drive source . With the solar constant of 1.367 kW / m² (radiant power density of the sun at a distance of the earth), the result is a radiation pressure of 9.1 μN / m² - with complete, perpendicular reflection, which, however, does not make sense on interplanetary orbits. The inclined feathering position is typical, in which a tangential force component occurs with which the orbital energy can be increased or decreased. The force acting on one square meter of sail area in the area of ​​the earth's orbit is then about 4 µN.

So very large areas and long times are required to accelerate even small masses significantly. That means the sail has to be very thin. With a mass coverage of 10 g / m², including the payload, the acceleration would be 0.4 mm / s² and a speed increase of 10 km / s would take almost a year.

The intensity of the sunlight depends on the inverse square of the distance. Close passages of the sun could take advantage of this to achieve greater acceleration values.

Practical trials

Znamya -2 (1993)

The first test of an unfolding mechanism for foil sails and their position control took place in 1993 from the Russian space station Mir . The experiment served the plan to illuminate northern Russian cities with much larger reflectors. To do this, Progress -M 15 remotely docked and was set in rotation at a distance of 230 m to stabilize the position. The 40 kg reflector was stretched out to a diameter of 20 m on an electrically driven axle by centrifugal force. However, the edges of the eight foil segments connected at the circumference did not unfold completely. In the early dawn the reflex could be seen from southern France to eastern Europe.

DLR demonstrator (1999)

In 1999, the ESA / DLR project "Solar Sail" demonstrated the unfolding of a 20 m × 20 m solar sail on the ground. The sail consisted of four CFRP jibs that spanned a Kapton sail when it was extended. The tubes of the boom consisted of two rolled-up half-shells, which were given their original shape when they were unrolled. NASA's JPL contributed a sail segment to the demonstrator.

Artist's impression of the Planetary Society's Cosmos-1 model

Cosmos 1 (2001)

In 2001, a suborbital test by Cosmos Studios and the Planetary Society failed because the third stage of the Wolna rocket used did not separate. Cosmos 1 should have unfolded eight 5 µm thick segments made of aluminum-coated Mylar using inflatable tubes. In 2005, failure of the first stage prevented orbital deployment at an altitude of 800 km. The experiment should demonstrate an increase in orbits due to the solar sail.

Space Agency ISAS (2004)

In August 2004, the Japanese space agency ISAS successfully tested the deployment of two solar sails in a suborbital flight with the sounding rocket S-310 . The deployment mechanism is based on the use of centrifugal force in a rotational movement. This movement was initiated on the sounding rocket after reaching the 200 km limit, so that the 10 m solar sail could unfold.

One of the two 20-meter solar sails whose deployment was tested by NASA in 2005.

NASA Glenn Research Center (2005)

In 2005, the world's largest simulator for space conditions, the Plum Brook's Space Power Facility, tested the deployment of two competing solar sail designs.

IKAROS (2010)

The force effect on a solar sail in space was measured for the first time with the Japanese interplanetary space probe IKAROS, which was launched on May 20, 2010. During six months the change in speed caused by light pressure was 100 m / s.

NanoSail-D2 (2011)

On January 20, 2011, the 4 kg and 33 × 10 × 10 cm³ nanosatellite NanoSail-D2 opened an approximately 10 m² sail in a 640 km high orbit. The NASA experiment was used to test a technology to make space debris burn up faster in the atmosphere through air friction. Since the sail was not aligned head-on to the flow, as calculated in advance, but flat, the deorbiting took 240 days instead of the planned 70 to 120 days - NanoSail-D2 burned up in the atmosphere on September 17, 2011.

Sunjammer (2014)

The Sunjammer should unfold a 38 m × 38 m large awning and show the maneuverability and navigability of the sail. The start date was initially given at the end of 2014 and was later postponed to January 2015. The project was finally discontinued in October 2014 before the start.

LightSail (2015)

A technology demonstrator for Lightsail 2, which was launched into space when the Boeing X-37 took off on May 20, 2015 and which burned up in the atmosphere a few days later after its sail was unfolded.

LightSail 2 (2019)

LightSail 2 is a 5 kg experimental 3U cubesat from the Planetary Society . Together with various payloads from the US Department of Defense and NASA, it was brought into low-earth orbit on June 25, 2019 by SpaceX with a Falcon Heavy . LightSail 2 is not designed to leave Earth orbit. The satellite has a 32-square-meter square awning that was deployed on July 23, 2019. Within a week, the apogee of the orbit was raised by about two kilometers due to solar sail propulsion. According to the Planetary Society, it was the first successful demonstration of a pure solar sail drive in earth orbit.

SIASAIL-1 (2019)

The Institute for Automation of the Chinese Academy of Sciences in Shenyang (中国科学院 沈 阳 自动化 研究所) had launched on August 31, 2019 with a Kuaizhou-1A solid propellant rocket from the Jiuquan Cosmodrome Xiaoxiang-1 07 (潇湘 一号 07 卫星) of SpaceTY GmbH from Changsha (长沙 天 仪 空间 科技 研究院 有限公司) installed an apparatus that was smaller than a billiard ball and in which a folded solar sail with the mast mechanism was located. In a first step, the device called SIASAIL-1 (天 帆 一号, Pinyin Tiānfān Yīhào , German: "Himmelssegel 1") was extended from the housing of the satellite and rotated by 90 °. Thereafter, four masts were extended from the corners of the apparatus, which stretched the 0.6 m² square sail (see below), a process that was completed and verified on December 25th. In the further course it will be tested to what extent the small sail can lift the 8 kg satellite out of orbit.

In the previous satellite Xiaoxiang-1 03, which was launched on January 21, 2019, a similar large, two-part sail was not intended as a propulsion system, but as a method to allow the small satellite to re-enter the earth's atmosphere after it had completed its task Reduce the amount of space debris in low orbits. Observations carried out between November 2019 and May 2020 showed that with the solar sail the time to re-entry was shortened from 16 to 6 years, in years with high solar activity to 1 year.

Near-Earth Asteroid Scout (approx. 2021)

The NEA-Scout is a 6U-Cubesat spacecraft from NASA, which is to be launched on the Artemis 1 lunar mission and to fly past the 1991 VG asteroid . The sun sail complements a conventional cold gas drive .

System components

The “sun sails” drive concept requires wafer-thin foils, which are ten to a hundred times lighter than paper , including the reflective coating and spanning framework, and at the same time tear-resistant enough to be unfolded from a compact package to make a football field several times the size.

design

A NASA paper distinguishes the following three types:

  1. three-axis stabilized square sails
  2. spin-stabilized rotor blade sails (Eng .: Heliogyro)
  3. Spin-stabilized circular sails
Sail-design-types.gif

In addition to these, there are also solutions, some of which result from combinations of the above three types. So has IKAROS z. B. a square sail, but the deployment mechanism is based on centrifugal force, which meant that the satellite needed a spin stabilization. Accordingly, a distinction must be made between the deployment mechanisms (utilization of centrifugal force, mechanical extension, ...), the different types of satellite stabilization and the sail geometry ( square , circular , rotor blade-like, ...).

material

MSFC manager Les Johnson is holding a carbon fleece that could make sun sails more tear-resistant in the future.

A sun sail usually consists of a carrier layer, usually PET / Mylar , Kapton or Kevlar , and is metallized differently on the two sides in order to obtain the appropriate emission and reflection values. A thin chrome layer is used to achieve a high emission value on the side facing away from the sun, to dissipate the absorbed energy, and a thin aluminum layer is supposed to generate a high reflectivity.

literature

Web links

Individual evidence

  1. Hermann Oberth: The rocket to the planetary spaces. Michaels-Verlag, 1984, ISBN 3-89539-700-8 .
  2. a b c d C. Garner u. a .: A Summary of Solar Sail Technology Developments and Proposed Demonstration Missions. (PDF; 1 MB) NASA / JPL / DLR , 1999, accessed on November 11, 2011 (English).
  3. ^ Les Johnson et al .: Status of solar sail technology within NASA , Advances in Space Research, 2010, doi : 10.1016 / j.asr.2010.12.011 .
  4. ^ RA Mewaldt, PC Liewer: An Interstellar Probe Mission to the Boundaries of the Heliosphere and Nearby Interstellar Space. (PDF; 2.2 MB) 1999, archived from the original on July 21, 2011 ; accessed on June 5, 2011 .
  5. ^ David SF Portree: Mir Hardware Heritage, Part 2 - Almaz, Salut, and Mir. (PDF; 956 kB) In: NASA Reference Publication 1357. NASA , 1995, p. 138 , accessed on December 7, 2011 (English).
  6. Gunnar Tibert, Mattias Gärdsback: Space Web - Final Report / Znamya (p 5/6). (PDF; 6.5 MB) ESA , accessed on November 11, 2011 (English).
  7. M. Leipold et al. a .: Solar Sails for Space Exploration - The Development and Demonstration of Critical Technologies in Partnership. (PDF; 624 kB) ESA , June 1999, accessed on November 12, 2011 (English).
  8. a b L. Herbeck u. a .: Solar Sail Hardware Developments. (PDF; 522 kB) ESA / DLR , Kayser-Threde , 2002, accessed on November 12, 2011 (English).
  9. ^ E. Reichl, S. Schiessl (vfr.de): Space 2006 - With chronicle of the space year 2005
  10. ^ D. Coulter: A Brief History of Solar Sails. (PDF) NASA , July 31, 2008, accessed November 12, 2011 .
  11. O. Mori et al. a .: Dynamic and Static Deployment Motions of Spin Type Solar Sail. (PDF; 291 kB) ISAS / JAXA , 2004, accessed on November 12, 2011 (English).
  12. ^ Glenn Research Center: Sailing on Sunbeams: Solar Power to Advance Interplanetary Travel , May 13, 2005.
  13. Yuichi Tsuda: Solar Sail Navigation Technology of IKAROS . JAXA . 2011. Retrieved March 18, 2012.
  14. NASA's Nanosail-D 'Sails' Home - Mission Complete , November 29, 2011.
  15. Solar Sail Demonstrator ('Sunjammer')
  16. ^ Dan Leone: NASA Nixes Sunjammer Mission, Cites Integration, Schedule Risk . In: spacenews.com , October 17, 2014. 
  17. Werner Pluta: Lightsail: Sailing before the solar wind. Golem.de , July 9, 2015, accessed on July 13, 2015 .
  18. A satellite sets sail to be gently pushed by the sunlight . Neue Zürcher Zeitung from June 25, 2019
  19. The Planetary Society lightsail-factsheet-2019
  20. Lightsail 2 has launched
  21. Planetary Society: DEPLOYMENT COMPLETE! July 23, 2019, accessed on July 23, 2019 .
  22. Jason Davis: LightSail 2 Spacecraft Successfully Demonstrates Flight by Light. Planetary Society, accessed July 31, 2019 .
  23. 沈 阳 自动化 所在 轨 进行 太阳 帆 关键 技术 试验 取得 成功. In: sia.cn. December 25, 2019, Retrieved December 29, 2019 (Chinese).
  24. ^ Company. In: en.spacety.com. Retrieved December 29, 2019 .
  25. ^ Wu Yong: Solar sail in earth orbit is big breakthrough for China. In: chinadaily.com.cn. December 27, 2019, accessed December 29, 2019 .
  26. 我 首次 完成 太阳 帆 在 轨 关键 技术 试验. In: cnsa.gov.cn. December 27, 2019, accessed December 29, 2019 (Chinese).
  27. ^ Gunter Dirk Krebs: Xiaoxiang 1-07 (TY 1-07). Retrieved December 29, 2019 .
  28. 不凡 的 大 国: 又 得 突破 , 我国 新 技术 成功 完成 试验 , 外 媒 媒 : 中国 正在 引领 世界 发展. In: mbd.baidu.com. January 13, 2020, accessed January 13, 2020 (Chinese).
  29. 潇湘 一号 03 星 完成 我国 首 个 在 轨 展开 离 轨 帆 实验 , 将 离 离 轨 时间 缩短 至 1 年. In: spaceflightfans.cn. May 18, 2020, accessed May 18, 2020 (Chinese). This is a different concept from the international test satellite DeorbitSail-1 from 2015, in which no solar sail was used, but a brake sail that interacts with the atmosphere.
  30. NEA Scout. NASA, accessed July 3, 2019 .
  31. Gunter Dirk Krebs: NEA Scout. Retrieved July 3, 2019 .
  32. NASA facts - Solar Sail Propulsion. (PDF; 148 kB) NASA , April 2005, accessed on November 19, 2011 (English).