摘要: The concept of solar thermal propulsion (STP) has been around for many years. One approach, shown in Figure 1, uses an off-axis parabolic concentrator mirror like a large magnifying glass to focus the sun's energy and heat-working... 展开 The concept of solar thermal propulsion (STP) has been around for many years. One approach, shown in Figure 1, uses an off-axis parabolic concentrator mirror like a large magnifying glass to focus the sun's energy and heat-working fluid such as hydrogen to very high temperatures (3,000 K). The hydrogen is then expelled through a nozzle to produce thrust. This innovative concept is predicted to have twice the specific impulse of currently used chemical upper stage propulsion systems, and can therefore place twice the payload mass into geosynchronous orbit. Alternatively, smaller and cheaper launch vehicles can be used for the same payload size. The main drawback is the low thrust level of 0.1 to 10 lb, thus requiring trip times of 30-60 days. However, many payloads can tolerate longer trip times. 收起