An explosion occurs when the timescale for the energy release by some process is much shorter than the timescale on which a system can adjust to damp the energy release process. In the present day Sun, nuclear fusion is a very slow process: on average it takes many billion years for a proton to fuse with another. This timescale is quite temperature dependent, so you might have thought the centre of the Sun might heat up quickly, leading to a runaway "explosion". However, an increase in temperature leads to an increase in pressure that would expand the Sun, reducing the core density and temperature and decreasing the rate of nuclear fusion again. The timescale for the Sun to react in this way is just millions of years, so this acts like a thermostat that keeps the reactions under control.
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Though initially designed for refueling, NASA plans to expand the capabilities of Restore-L to include other maintenance activities that will extend the life of an orbiting spacecraft. “Restore-L effectively breaks the paradigm of one-and-done spacecraft,” says Satellite Servicing Capabilities Office (SSCO) Associate Director Frank Cepollina in a prepared statement. Once deployed, the robot could act as a gas station in space, providing satellites with much-needed propellant. On the maintenance side, the robot one day may be able to manufacture and assemble components in space and use them to service a satellite. It also may be used to reduce space accidents by removing space junk from orbit.
The earliest of civilizations were based around river valleys. This allowed them to irrigate fresh water to their crops allowing for better farming and therefore, bigger and better civilizations.
Middle class P.................
