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#1 2017-12-18 09:32:46

From: UK
Registered: 2008-03-24
Posts: 7,208

To Mars in 3 Days?

Has this proposal for a laser driven sail craft that could get to Mars in 3 days been discussed before?

Reducing transit time would be a real game changer for Mars's development.

Let's Go to Mars...Google on: Fast Track to Mars


#2 2017-12-18 09:44:32

Registered: 2016-11-26
Posts: 2,419

Re: To Mars in 3 Days?

Robert Zubrin discusses laser powered light sails in his book "Entering Space," and concludes the overall power requirement is enormous. If the spacecraft using light sail is accelerated to that speed, the amount of energy require to slow for planetary capture is then huge. This is another TANSTAFL idea.


#3 2017-12-18 13:01:43

From: South Bend, IN
Registered: 2002-01-15
Posts: 1,701

Re: To Mars in 3 Days?

I doubt we have the capacity to generate that much laser light, and if we could, any mistake would fry the vehicle.


#4 2017-12-18 15:46:07

From: The Fortunate Isles
Registered: 2007-08-27
Posts: 3,859

Re: To Mars in 3 Days?

Is this the doped sail idea, where thrust would be generated by ablation? That has a far higher thrust than a pure light sail.

Deceleration is a pain, though. I don't think we'll be going any quicker than a 3 month travel time to Mars until we have orbital infrastructure at both sides. Microwave beamed power, perhaps. In space you can have big rectannas.

Use what is abundant and build to last


#5 2017-12-18 18:54:53

From: New Hampshire
Registered: 2004-07-22
Posts: 29,310

Re: To Mars in 3 Days?

In theory, the closest the planets could come together would be when Mars is at its closest point to the Sun (perihelion) and Earth is at its farthest point (aphelion).

In that case, the planets would be 33.9 million miles (54.6 million kilometers or 0.3646 AU) from each other. But that has never happened in recorded history. The closest known approach was about 34.64 million miles (55.76 million km or 0.37273 AU) in August 2003.

When both planets are at aphelion and  are on opposite sides of the Sun, they can be 250 million miles (401 million km or 2.689 AU ) apart.
The average distance is approximately 225 million km ( or 1.50403 AU).

The Earth has a shorter orbital period than Mars, it passes in between Mars and the Sun approximately every 780 days, or 2 years and 50 days.

Here is an image of the positions of  Mars , Earth  and the Sun in August 2003


The next time Mars will come closer than August 2003 will be on August 28, 2287, when Mars will be 0.37225 AU distant. The least distance between Mars and the Earth during this millennium will be 0.37200 AU on September 8, 2729.

That all said 1 day of speeding up, 1 day of coasting, and finally 1 day to slow down to orbital capture....if each leg is equal distance then we are at the closest of round numbers 36 miilion or just 12 million miles or 500,000 mph.. On January 19, 2006, New Horizons was launched from Cape Canaveral Air Force Station by the Atlas-V rocket directly into an Earth-and-solar escape trajectory with a speed of about 16.26 kilometers per second (58,536 km/h; 36,373 mph).


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