Kaguya (space probe)

Kaguya
Kaguya
NSSDC ID	2007-039A
Mission goal	Earth moon
Client	JAXA
Launcher	H-2A
construction
Takeoff mass	1,720 kg (+ 795 kg fuel)
Instruments
13
Course of the mission
Start date	September 14, 2007
launch pad	Tanegashima Space Center
End date	June 10, 2009
Sep 14 2007 begin Oct 3, 2007 Reaching the lunar orbit Oct 9, 2007 Deployment of the Okina relay satellite Oct 12, 2007 Deployment of the VRAD satellite Ouna Feb 12, 2009 Impact of the Okina relay satellite June 10, 2009 Impact on the moon

Kaguya ( Japanese か ぐ や ) was a lunar orbiter of the Japanese space agency JAXA , which was in use from 2007 to 2009. The launch of Kaguya took place on September 14, 2007 from Tanegashima Space Center on board an H-IIA rocket.

Project name and mission goals

Under the project name SELENE ( Sel enological and En gineering E xplorer, while Greek name of the moon and Greek moon goddess ), the mission to the moon princess in Japanese legend The Tale of the Bamboo Cutter named. The operators described the space probe as "The largest lunar mission since the Apollo program", that is, the largest lunar mission since the Apollo program .

The primary goals of the mission were to study the mineralogical composition of the moon , topography , geology , gravity and plasma in the moon and sun - earth systems . In addition, the probe should test new technologies that will be crucial for future lunar missions.

technology

The mission consisted of three satellites: a large orbiter , which had to carry most of the scientific payload, a VLBI radio satellite (VRAD) and a relay satellite for communication between the earth and the main orbiter during the phases of flight behind the moon with no direct signal path to earth.

Orbiter

The cuboid main orbiter is approximately 2.1 m × 2.1 m × 4.2 m in size and divided into two parts: the 2.8 m long upper mission module with most of the scientific instruments and the detachable 1.2 m long lower drive module. A single solar panel is located on the side of the space probe, the 1.3 m high gain antenna is attached to another side of the probe, at a 90 ° angle to the solar panel. A 12 m long magnetometer boom protrudes from the front of the probe; another four 15 m long radar antennas are attached to the corners of the mission module.
The total empty weight of the probe was 1720 kg, plus 795 kg of fuel.

The energy supply from the solar panel, which consists of 22 m² GaAs / Ge solar cells , can generate up to 3486  W of power. The solar cells dine four NiH ₂ - storage batteries with a capacity of 35 per  Ah , a voltage of 50  V supply. Communication takes place via the high gain antenna in the S and X band with data rates over the X band of up to 10  Mbit / s to a 60 m large parabolic antenna and over the S band (2263.6 MHz) of up to 2  Kbit / s s to a 40 m large parabolic antenna. Four omnidirectional S-band antennas are used to transmit commands to the probe at a speed of 1 Kbit / s. The storage capacity of the on-board storage system is 10  GB .

The main engine of the probe is located in the drive module and delivers a thrust of 500  N through combustion of NTO and hydrazine . The Mission Module carries 13 scientific instruments:

• a multi-band camera
• a terrain camera
• a TV camera
• a spectral profiler
• an X-ray spectrometer
• a gamma ray spectrometer
• a radar
• a laser - altimeter
• a magnetometer
• a plasma imager
• a charged particle spectrometer
• a plasma analyzer
• and two pieces of equipment for radio experiments.

Two plates were attached to the outer shell of the probe, on which the names and messages of over 410,000 people had been engraved.

Subsatellites

The two engineless subsatellites of Kaguya are very similar in structure. Each has an octagonal cylindrical shape and measures 1.0 m × 1.0 m × 0.65 m with a mass of 50 kg. Both satellites have a dipole antenna and are rotationally stabilized at ten revolutions per minute. The solar cells on each side deliver 70 W of power, each feeding a 26 V NiMH battery with a capacity of 13 Ah.

VRAD satellite (Ouna)

The satellite has one X-band and three S-band radio sources. In conjunction with the relay satellite, it enables earth-based differential VLBI measurements ( Very Long Baseline Interferometry ). The satellite was launched on October 12, 2007 in a polar orbit between 100 km and 800 km and should be able to orbit in the orbit for over a year.

Relay Satellite (Okina)

The relay satellite also has one X-band and three S-band radio sources and is used to relay the signal between the orbiter and Earth, which is necessary for measurements of the gravitational field on the back of the moon. The satellite was launched on October 9, 2007 in an orbit with a periapsis of 100 km and an apoapsis of 2400 km and should function for one year; in fact, it did not hit the back of the moon until February 12, 2009 at 7:46 p.m. (JST).

mission

Launch of the launcher with the Kaguya lunar probe (Photo: Narita Masahiro)

The start of the Kaguya mission, originally planned for late 2005 , was postponed to August 2006 due to the false launch of the sixth H-2A rocket at the end of 2003. The start was later postponed further into 2007. A date planned for August 16, 2007 had to be postponed to September 13 due to incorrectly installed capacitors in the subsatellites. Bad weather forced JAXA to postpone the start for another 24 hours.

On September 14, 2007, at 1:31 UTC, Kaguya was brought by an H-2A rocket from the Tanegashima Space Center into a 270 km high parking orbit around the earth with an inclination of 30.4 °. After that, the probe was sent on a journey to the moon.

On September 29th, a sequence of images of the earth in high resolution image quality was recorded for the first time. The photos show the earth from a distance of 110,000 km.

After two course corrections, Kaguya reached the moon on October 3, 2007 and entered a polar lunar orbit between 101 km and 11,471 km altitude at 21:20 UTC; Kaguya needed 16:42 hours for one cycle.

On October 9, at 0:36 UTC, Kaguya launched the Rstar relay satellite into a lunar orbit between approximately 100 km and 2,400 km above the lunar surface. The VRAD satellite followed three days later and its orbit is lower.

As planned, the orbiter entered its polar target orbit on October 19, 2007 with a two-hour orbital period. After the lowering of the apoapsis, the orbit was between 80 km and 123 km above the surface of the moon. This orbit was to be maintained for a year, for which orbit corrections were planned approximately every two months. Two days later, Kaguya was put into operational mode and the system check started.

During the test phase of the Ikegami HDTV camera , the Orbiter recorded two films of several minutes in high resolution on October 31st. It was the first HDTV to be made of the surface of the moon.

The test phase of all on-board systems ended after two months, and Kaguya began its scientific operation on December 21, 2007. According to JAXA, the X-ray and charged particle spectrometers (CPS) were not yet working at full capacity. The former consists of four individual cameras that can be interconnected to achieve a higher resolution. During the check, there was too much noise in simultaneous operation .

Kaguya hit the lunar surface on June 10, 2009 at 20:25 CEST at 80.4 ° E, 65.5 ° S near the crater Gill at a planned 6,000 km / h . The flash of light caused by the impact could be observed by terrestrial telescopes such as the Anglo-Australian Telescope in Australia and the Mount Abu Observatory in India.

Scientific results

The mission provided more precise three-dimensional topographical images of the moon's surface and a measurement of the gravitational field also on the far side of the moon. For example, the depth of the Pythagoras crater could be determined more precisely at up to 4,800 m and the Schrödinger crater was photographed in detail for the first time.

Kaguya also provided the first images of the interior of Shackleton Crater at the South Pole: however, the hoped-for evidence of water ice was not found there.

A map of the lunar surface showing the distribution of uranium , thorium and potassium could be created based on the measurements of the gamma ray spectrometer (GRS) from December 14, 2007 to February 17, 2008 and from July 7 to October 31, 2008.

During the first evaluations of the measurement data in 2009, a 65-meter-wide opening in the floor was discovered in the area of ​​the Marius Hills in Oceanus Procellarum , which indicated the presence of a larger cave. The GRAIL mission of NASA (2012) provided more concrete evidence of lunar caves, which were confirmed in the further evaluation of the Kaguya data. The opening of the moon, discovered in 2009, could therefore be part of a 50-kilometer-long and 100-meter-wide lava tunnel .

See also

• Chronology of the moon missions
• List of man-made objects on the moon

literature

• Motomaro Shirao, Charles A. Wood: The Kaguya lunar atlas - the moon in high resolution. Springer, New York 2011, ISBN 978-1-4419-7284-2 .
• M. Kato et al. a .: The Kaguya Mission Overview . (PDF) In: Space Science Review , 154, 2010, pp. 3-19

Web links

Commons : Kaguya (space probe)  - collection of images, videos and audio files

• Kaguya project website JAXA (English)
• Bernd Leitenberger: Selene
• SELENE - or Kaguya, the princess of the moon . Raumfahrer.net, September 13, 2007
• SMART-1 latest maps for Kaguya's lunar impact ESA Science & Technology, June 11, 2009
• The Kaguya spacecraft crashes on the moon - Astronomy Picture of the Day from June 29, 2009.

Individual evidence

1. ^ Successful Image Taking by the High Definition Television . JAXA, October 1, 2007 (English)
2. ↑ Lunar orbit injection was confirmed . JAXA, October 5, 2007 (English)
3. ^ Result of the Separation of the Relay Satellite (Rstar) . JAXA, October 9, 2007 (English)
4. ^ Result of the Separation of the VRAD Satellite (Vstar) . JAXA, October 12, 2007 (English)
5. ↑ Japan's lunar explorer enters observation orbit . ( Memento of October 27, 2007 in the Internet Archive ) Xinhua, October 19, 2007 (English)
6. ↑ World's First Image Taking of the Moon by HDTV . JAXA, November 7, 2007 (English)
7. ↑ KAGUYA (SELENE) . JAXA (English)
8. ↑ Kaguya's end as a foretaste of LCROSS .
9. ↑ About the observation result of KAGUYA flash at contract impact . kaguya.jaxa.jp, accessed April 22, 2014
10. ↑ H. Araki et al. a .: Lunar global shape and polar topography derived from Kaguya-LALT laser altimetry . In: Science , 323, 2009, pp. 897-900, PMID 19213910
11. ↑ N. Namiki et al. a .: Far side gravity field of the moon from four-way Doppler measurements of SELENE (Kaguya) . In: Science , Volume 323, 2009, pp. 900-905, PMID 19213911
12. ↑ Hiroshi Araki, Seiichi Tazawa, Hirotomo Noda and others. a .: Present Status and Preliminary Results of the Lunar Topography by KAGUYA-LALT Mission. In: Lunar and Planetary Science , Vol. 34 (2008), ISSN  0197-274X PDF
13. ↑ HDTV Wide viewing angle "Schrodinger"
14. ↑ J. Haruyama et al. a .: Lack of exposed ice inside lunar south pole Shackleton Crater . In: Science , 323, 2009, pp. 938-939, PMID 18948501
15. ↑ Noboyuki Hasebe (Waseda University, Tokyo) et al .: p. 18. (PDF) In: Journal of the Physical Society of Japan , Vol. 78, Suppl. A (English)
16. ↑ Naoyuki Yamashita (Waseda University, Tokyo) et al .: Precise Observation of Uranium, Thorium, and Potassium on the Moon by the Selene GRS . (PDF; 368 kB) Contribution to the 40th Lunar and Planetary Science Conference (English)
17. ^ Brian Handwerk: First Moon "Skylight" Found - Could House Lunar Base? , National Geographic News, Oct. 26, 2009.
18. ↑ Loic Chappaz, Rohan Sood, Henry Melosh, Kathleen Howell, David Blair, Colleen Milbury, Maria Zuber: Evidence of large empty lava tubes on the Moon using GRAIL gravity , Geophysical Research Letters, January 13, 2017.
19. ↑ Article in 'The Guardian' [1]
20. ↑ T. Kaku, J. Haruyama, W. Miyake, A. Kumamoto, K. Ishiyama, T. Nishibori, K. Yamamoto, Sarah T. Crites, T. Michikami, Y. Yokota, R. Sood, HJ Melosh, L Chappaz, KC Howell. Detection of intact lava tubes at Marius Hills on the Moon by SELENE (Kaguya) Lunar Radar Sounder. Geophysical Research Letters, 2017; DOI: 10.1002 / 2017GL074998