While very young unmanned aircraft industry looks at ways to improve small unmanned aircraft systems (UAS) for specific tasks such facility security, infrastructure inspection, or precision agriculture, a New Mexico-based aerospace founder is thinking bigger and longer-term ones. Titan Aerospace, a one-year-old aircraft designer, last week unveiled its Solara 50 and Solara 60 unmanned aircraft. These are two large solar-powered>> high-altitude vehicles the company plans to send up into space for weeks,months>> and eventually years at a time without ever having to land. Titan doesn't refer to these concept aircraft as "drones  " or "unmanned aircraft system," but instead calls them "atmospheric satellites" for their ability to remain in the sky for extended periods of time just as orbital   satellites do. The company hopes to provide a platform of less than $2 million that governments, private industry, and research institutions can put high into the atmosphere for extended periods of time for a little part of the cost of a space satellite. The idea is that an atmospheric satellite can conduct most of the same operations as an orbital one: atmospheric observation and weather monitoring, communications relay, oceanographic research, and earth imaging. Other operations are impractical for space satellites, such as border security, maritime traffic monitoring and anti-piracy   operations, disaster response, or agricultural observation. And with continuous flight time of up to five years, Solara's aircraft would have endurance   on par with (......) many small satellites, making them a more attractive choice for a range of these applications. "If you have to go up to the orbital satellite and rent that service>> that's a lot of money," says Dustin Sanders, Titan's chief electrical engineer. "And launching a satellite, that can cost billions of dollars. We're trying to do a single-million-dollar-per-aircraft platform. And the operation cost is almost nothing--you're paying a little money and make sure the aircraft doesn't do anything stupid. " We know from the passage that the atmospheric satellite can continue to stay in the sky for   _
five years six years seven years eight years
Question: While very young unmanned aircraft industry looks at ways to improve small unmanned aircraft systems (UAS) for specific tasks such facility security, infrastructure inspection, or precision agriculture, a New Mexico-based aerospace founder is thinking bigger and longer-term ones. Titan Aerospace, a one-year-old aircraft designer, last week unveiled its Solara 50 and Solara 60 unmanned aircraft. These are two large solar-powered>> high-altitude vehicles the company plans to send up into space for weeks,months>> and eventually years at a time without ever having to land. Titan doesn't refer to these concept aircraft as "drones  " or "unmanned aircraft system," but instead calls them "atmospheric satellites" for their ability to remain in the sky for extended periods of time just as orbital   satellites do. The company hopes to provide a platform of less than $2 million that governments, private industry, and research institutions can put high into the atmosphere for extended periods of time for a little part of the cost of a space satellite. The idea is that an atmospheric satellite can conduct most of the same operations as an orbital one: atmospheric observation and weather monitoring, communications relay, oceanographic research, and earth imaging. Other operations are impractical for space satellites, such as border security, maritime traffic monitoring and anti-piracy   operations, disaster response, or agricultural observation. And with continuous flight time of up to five years, Solara's aircraft would have endurance   on par with (......) many small satellites, making them a more attractive choice for a range of these applications. "If you have to go up to the orbital satellite and rent that service>> that's a lot of money," says Dustin Sanders, Titan's chief electrical engineer. "And launching a satellite, that can cost billions of dollars. We're trying to do a single-million-dollar-per-aircraft platform. And the operation cost is almost nothing--you're paying a little money and make sure the aircraft doesn't do anything stupid. " We know from the passage that the atmospheric satellite can continue to stay in the sky for   _
A. five years
B. six years
C. seven years
D. eight years
Answer: