Sunday, October 24, 2010

Kaguya HDTV: Imaging Earth and Moon

HDTV image near Andersson (50◦S, 262◦E) from an altitude of 11 km, by the WIDE camera on board SELENE-1 (Kaguya), April 16, 2009. The controlled impact of the spacecraft occurred Moon at 18:25 (UT), June 10, 2009. View the full-size image, HERE [JAXA/NHK/SELENE].

Yamazaki & Mitsuhashi,
NHK (Japan Broadcasting Corporation)
October 12, 2010

High-Definition Television (HDTV) system has a resolution that is twice that of conventional television in terms of both vertical and horizontal resolution and a wider picture aspect ratio of 16:9. Research and development into HDTV was started in the 1970s by NHK (Japan Broadcasting Corporation) (Fujio et al. 1980, 1982). The HDTV system, characterized by its higher resolution and wider picture aspect ratio, appeals strongly to viewers thanks to the “presence” of its images, and has been adopted in many Japanese households. HDTV was firstly carried into space in 1998 onboard the Space Shuttle. Imaging of the Earth from a spacecraft in an Earth-revolving orbit was conducted manually by an astronaut.

In order to load the system into a manned spacecraft, the system was examined and improved with respect to toxic substances, fire prevention, and electromagnetic radiation in the communication frequency band (Yamazaki 2001). NASA’s (National Aeronautics and Space Agency) evaluation was that a three-CCD type HDTV had a color representation closer to natural color than that of film or a single-CCD camera, and thus was most suitable for observations of the Earth (Robinson et al. 2000). However, a HDTV system had not been sent into deep space onboard an unmanned spacecraft.

Another "normalized" take on the Kaguya HDTV now-iconic “Earth-set” behind Malapert Massif, Shackleton and the lunar south pole, obtained by the TELE camera November 7, 2007. Full-sized, full-width view, HERE [JAXA/NHK/SELENE].

The first still image of the Earth viewed from space was taken by the weather satellite TIROS-1 on April 1, 1960. The image of an “Earth-rise” from the lunar horizon was acquired by an Apollo 8 astronaut with a 70 mm film camera on December 22, 1968. The first movies of the Earth, the Moon and the lunar landing module were shot by Apollo 11 astronauts using a video camera on July 16, 1969. No other videos of the Earth and the Moon were acquired from lunar orbit from the completion of the Apollo mission until 2006, though still images of Moon were acquired by Clementine UV/VIS camera (Nozette et al. 1994) and SMART-1’s AMIE multicolor micro camera (Josset et al. 2006).

The lunar-orbiting explorer Kaguya/SELENE (Selenological and Engineering Explorer) was developed by JAXA (Japan Aerospace Exploration Agency) to conduct scientific observations of the lunar surface and the environment around the Moon using 15 mission instruments while in a lunar-revolving orbit. The HDTV system was selected in 2001 as the last mission instrument to be carried onboard the Kaguya. The primary objective of adopting an HDTV system was the acquisition of high-resolution movies of the Earth and the Moon, in particular the Earth-set and the Earth-rise from the Moon, for public outreach purposes.

Following the launch of the spacecraft atop an HII-A rocket on September 14, 2007, from the Tanegashima Space Center in Japan, Kaguya’ s HDTV system acquired clear moving images of the lunar surface and the Earth until the end of the mission on June 11, 2009 (e.g., Honda et al. 2008a; Mitsuhashi et al. 2008). The total amount of images obtained by the HDTV system was 6.3 TB. Although the primary objectives of using the HDTV system were public outreach and to record images for educational purposes, the HDTV images are currently expected to also be useful in lunar surface studies because of the characteristics afforded by the HDTV system, such as oblique views and sequential data acquisition (Honda et al. 2008b, 2009).

A perspective view of the lunar surface acquired by HDTV is helpful in acquiring a general view of lunar features on a 100-km scale. In addition, HDTV movies are adequate for the observation of an opposition surge on the lunar surface, as well as the transient phenomena such as glow over the lunar horizon after sunset or before sunrise, and the Earth’s “diamond ring” shown in Sect. 8.

This paper describes the specifications of the HDTV system and onboard data processing, as well as the data obtained during the mission period.

View the Springer description and abstract, HERE.
Read the full technical report text (pdf), HERE.

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