(Bloomberg) -- Billionaire Masayoshi Son’s project to have unmanned aircraft with base stations provide wide-area telecommunications connectivity is about to get cash.

Son’s telecom unit SoftBank Corp. on Friday priced 30 billion yen ($264 million) of notes whose proceeds the company said will go exclusively to its High Altitude Platform Station (HAPS) business. The bonds were sold as sustainability notes, the first from the company. 

SoftBank began exploring alternatives to terrestrial antennas after the 2011 earthquake and tsunami knocked out a broad swath of its network in Japan. The risk to vital telecommunications from natural disasters was again visible this month after a massive underwater volcanic eruption in Tonga disabled an undersea Internet cable, cutting off that nation’s international communications.

Still, SoftBank faces challenges in successfully commercializing the project where others have failed. Google parent Alphabet Inc. said last year it would wind down its high-altitude internet beaming project Loon. SoftBank announced in September it had acquired about 200 patents from Loon.  

SoftBank has said it expects full-scale commercial services from its HAPS business to begin in 2027. The company’s solar-powered unmanned aircraft, Sunglider, completed its first stratospheric test flight in New Mexico in 2020. 

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