Status report for the development of the Antarctic penetrator: No.2. 1990-year program

• Main Authors: Kazuo Shibuya, Katsutada Kaminuma, Masahiko Hayakawa, Akio Fujimura, Shigeki Tsukamoto, Hitoshi Mizutani, Isao Yamada, Junji Koyama, Minoru Kasahara, Kiyoshi Ito, Toshihiko Kanazawa
• Format: Article in Journal/Newspaper
• Language: English; Japanese
• Published: National Institute of Polar Research 1992
• Subjects: Geography (General); G1-922; Antarctic; The Antarctic; Antarc*; Antarctica
• Online Access: https://doi.org/10.15094/00008773; https://doaj.org/article/e774728d6387454aa38f24e6db64b3eb

GPS differential positioning test on the Antarctic penetrator was made at the Aoyama Pasture, Ishikari-Tobetsu-machi, Hokkaido. The reference GPS receiving site was chosen in Hakodate, 200km southwest of the Aoyama Pasture, taking the planned operation on the SΦr Rondane Mountains 400km profile in Antarctica into consideration. Three dummy penetrators were dropped twice by changing the release height in the range 160-1000m above the ground. Six impact positions of the deployed penetrators were determined by a relative carrier phase measurement to an accuracy of 0.1m, and the position results were compared with the post-processed GPS differential positions. When 10-20s duration GPS position data could be acquired at an interval of 1s before and after the release instance (1s accuracy to UTC) of the penetrator, the estimated impact position by tracing the falling trajectory was found to be within 30m offset from the actual impact location determined by the relative carrier phase measurement. When the GPS hovering data could be acquired for at least 1 minute duration just above the impact crater, the calculated impact location via the hovering-helicopter GPS position data was found to be within 10m offset from the actual impact location. The height accuracy of GPS differential positioning was ±10m (PDOP=5-20), which is considered to degrade to ±20m when the coordinates of the reference GPS receiving site were determined by the time-average of point-positioning results. As for attitude of the dropped penetrator, the declination from vertical was found to be within ±5°, when the penetrator was dropped from the slowly-moving (below 20km/h) helicopter 200m above the ground.