Wednesday, November 25, 2015

All round green light

Spotted on Lake Geneva, an all round green light, as well as a white light, a port light and (not visible in this long exposure) a starboard light. Not how I remember the regs but maybe its a local thing.

Saturday, November 21, 2015

Lake Geneva mooring

I got the feeling its owner was checking it out prior to winter coming, with flurries of snow on the top of the hills.

Friday, November 20, 2015

Tuesday, November 17, 2015

Another red boat in Greenland

A bit of a sad sight, beached and with what looked like fire damage.

And yes, I am raiding my photo backlog at the moment.

Saturday, November 14, 2015

Thursday, November 05, 2015

Sailing in SPAAACE - marks and lines

So how could you have start / finish lines and marks in space where this no up nor down and nothing is fixed?

A couple of ideas spring to mind, but its worth noting that space sailing is likely to be more like America's Cup racing with its virtual course borders, using electronic aids galore. In this case you could (for example) define locations with respect to an Earth Centred Inertial (ECI) coordinate frame.

Other ideas could be to use stations or satellites as marks, together with additional geometric constraints.

One such would be to define a sphere around a point or satellite. For example a race could have start to be the volume within 10 km of the International Space Station (ISS). This is simple to define but could end up with all solar sails clumped at the same, advantageous sector, most likely the point of the sphere furthest from the Earth.

Marks could be define also as sphere - for example, the figure above shows the various Earth-Sun Lagrange points, and you could imagine a race between them, such as:
- Start within 10 km of the ISS
- Pass within 100 km of L4
- Pass within 100 km of L3
- Pass within 100 km of L5
- Finish within 10 km of the ISS

This would allow solar sail craft to slightly cut the corners as they could be within 100 km while not actually going round the mark.

Alternatively the mark could be defined using a combination of distance from point or satellite plus at least as far from the central object (e.g. the Sun in these cases) as the point or satellite. More advanced ones could define solid angles using the line from the relevant central gravitational body to the mark point or satellite.

Therefore it is doable, there are ways to define such as race.

So let your imaginations go, look up at the sky, and imagine the windjammers of the future, tacking their way around the solar system.

Just keep an eye out for solar storms and those pesky space pirates!

Wednesday, November 04, 2015

Sailing in SPAAACE.... the RULES

The last post included a video that described how to sail in space using solar sails. But if you had two such craft then you could race... but what would the rules look like?

Back in 1992 the International Astronautical Federation proposed a Lunar Cup with a set of rules but I couldn't find them on-line but wondered.... what would they look like? How could port give way to starboard when in space neither concepts make sense?

An alternative could be to use the direction of motion of planets as in:

R1: Solar sail craft which has a thrust vector that when projected into the plane of the ecliptic has component clockwise must give way to those for which it is anti-clockwise (see graphic here)

But what about if they are in the same direction, what is the equivalent of windward / leeward? This is simpler as the solar sail thrust comes from photons from the sun, so that is the equivalent of windward, hence:

R2: Solar sail craft closer to the sun must give way to spacecraft further away

But what if they are on the same "tack" and same distance from the sun. The old rule remains a good one:

R3: Overtaking solar sail craft must give way to those being overtaken

There'd have to be the usual rules for safety of life, keeping watch etc. but also additional ones to handle eclipses, where a spacecraft is behind a planet so has no ability to maneuver, but similar rules to sailing could be used.

But how about marks? How could you define a course in 3D when everything is in motion?

Stay tuned for more...

Monday, November 02, 2015

Sailing..... in SPAAAAACE !

Two space music videos for you. The one above from the Planetary Society includes Carl Sagan talking about sailing.... in SPAAACE!

How cool would that be, tacking and gybing across the vastness of the cosmos.

Also from Public Service Broadcasting a video and song about Valentina: