Tuesday, August 3, 2010

Scots Engineers Prove Space Pioneer's 25-Year-Old Theory

Okay, so what happened to Newtonian Physics?  It appears though that they are simply applying drag to shift the orbit somewhat.  This broadens the channel of application.

Of course we are now getting fussy enough to need to work closely with natural variations in the earth’s Gravity.

It is not well understood that that very minor variation is sufficient for any satellite to get lost.  That is why close monitoring is needed.

The question is how far can we push this?  What is possible? Can we hang and orbit at 45 degrees and actually keep it there?  Not likely, but perhaps we are been Newtonian idiots and are way too trusting.  After all it would not be the first time we found ourselves trapped by our theory.

One reason I am even thinking this, is that I know that our present model of gravity is a first estimate at best and is useless for detail at times.  I have to thank a butterfly for that insight. So my hint for the day is to go think about a butterfly.

Scots Engineers Prove Space Pioneer's 25-Year-Old Theory

by Staff Writers

Glasgow, UK (SPX) Jul 27, 2010

When American space pioneer, Dr Robert L Forward, proposed in 1984 a way of greatly improving satellite telecommunications using a new family of orbits, some claimed it was impossible.

But now engineers at the University of Strathclyde's Advanced Space Concepts Laboratory have proved that Forward was right.

The late Dr Forward - a renowned physicist who worked in the United States and from his second home in Scotland - believed it was possible to use 'displaced orbits' to deploy more satellites to the north or south of the Earth's equator, helping to meet the growing demand for communications.

He proposed that the orbit of a geostationary satellite could be pushed above - or below - the usual geostationary ring around the Earth, which follows the line of the equator, by using a large solar sail propelled by the pressure of sunlight. However, critics later claimed that such 'displaced orbits' were impossible due to the unusual dynamics of the problem.

Now graduate student Shahid Baig and Professor Colin McInnes, Director of the Advanced Space Concepts Laboratory, have shown that Forward was in fact correct, in a new paper published in the Journal of Guidance, Control and Dynamics.

Professor McInnes said:"Satellites generally follow Keplerian Orbits, named after Johannes Kepler - the scientist who helped us understand orbital motion 400 years ago. Once it's launched, an unpowered satellite will 'glide' along a natural Keplerian orbit.

"However, we have devised families of closed, non-Keplerian orbits, which do not obey the usual laws of orbital motion. Families of these orbits circle the Earth every 24 hours, but are displaced north or south of the Earth's equator. The pressure from sunlight reflecting off a solar sail can push the satellite above or below geostationary orbit, while also displacing the centre of the orbit behind the Earth slightly, away from the Sun."

Although the displacement distance above or below the equator is small - of the order of 10 to 50 km - work on hybrid solar sails, which use both light pressure and thrust from a conventional electric propulsion system, is underway and aims to improve the displacement distance.

Professor McInnes added: "Other work is investigating 'polar stationary orbits', termed 'pole-sitters' by Forward, which use continuous low thrust to allow a spacecraft to remain on the Earth's polar axis, high above the Arctic or Antarctic. These orbits could be used to provide new vantage points to view the Earth's polar regions for climate monitoring."

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