Posts Tagged ‘Interstellar Ramjets’

Crowdfunded Solar Sail Spacecraft Makes Successful Flight

August 6, 2019

Bit of science news now. Last Friday’s I for 2nd August 2019 reported that a satellite developed by the Planetary Society and funded through internet fundraising had successfully climbed to a higher orbit using a solar sail. This propels spacecraft using only the pressure of light, just like an ordinary sail uses the force given by the window to propel a ship on Earth, or drive a windmill.

The article on this by Joey Roulette on page 23 ran

A small crowdfunded satellite promoted by a TV host in the United States has been propelled into a higher orbit using only the force of sunlight.

The Lightsail 2 spacecraft, which is about the size of a loaf of bread, was launched into orbit in June. 

It then unfurled a tin foil-like solar sail designed to steer and push the spacecraft, using the momentum of tiny particles of light called photons emanating from the Sun – into a higher orbit. The satellite was developed by the California-based research and education group, the Planetary Society, who chief executive is the television personality popularly known as Bill Nye the Science Guy.

The technology could potentially lead to an inexhaustible source of space propulsion as a substitute for finite supplies of rocket fuels that most spacecraft rely on for in-flight manoeuvres.

“We are thrilled to declare mission success for Lightsail 2,” said its programme manager Bruce Betts.

Flight by light, or “sailing on sunbeams”, as Mr Nye called it, could best be used for missions carrying cargo in space.

The technology could also reduce the need for expensive, cumbersome rocket propellants.

“We strongly feel taht missions like Lightsail 2 will democratise space, enable more people send spacecraft to remarkable destinations in the solar system”, Mr Nye said.

This is very optimistic. The momentum given to a spacecraft by the Sun’s light is very small. But, like ion propulsion, it’s constant and so enormous speeds can be built up over time. It may be through solar sail craft that we may one day send probes to some of the extrasolar planets now being discovered by astronomers.

In the 1990s, American scientists designed a solar sail spacecraft, Star Wisp, which would take a 50 kg instrument package to Alpha Centauri. The star’s four light years away. The ship would, however, reach a speed of 1/3 that of light, meaning that, at a very rough calculation, it would reach its destination in 12 years. The journey time for a conventional spacecraft propelled by liquid oxygen and hydrogen is tens of thousands of years.

Although the idea has been around since the 1970s, NASA attempt to launch a solar sail propelled satellite a few years ago failed. If we are ever to reach the stars, it will be through spacecraft and other highly advanced unconventional spacecraft, like interstellar ramjets. So I therefore applaud Nye and the Planetary Society on their great success.