Apr 29, 2016 02:52 themis.chapoul@hotmail.fr Posted on: Breakthrough Initiatives

yop,

I am not physicien, but with lasers on earth, you will lost lot of power to cross Ozone Layer and up the cost of the beam building ( i dont know the %), after you put the reparations of the beam faillure.

If i have understand, the light sail is propelled by photons.
the formula say, that on photonique sail:
P=h/Y

p= momentum kg⋅m⋅s-1
h=Planck constant
y=Wavelenght " meters"

so the power is generated by radiation.

Photons can be issues by a decrease excitation of electron during a radioactive desintegration in Gamma Ray.

Why dont you put Hight Radioactive material in constant desintegration on the satelite or part of the sail to have a minimum constant power?

I know!! it can't supply the majorities of power, but can it supply enough to reduce a little the price of all the earth Beam installation or give more power momentum to the ship?

ok, the ship is heavyer, but you have constant Gamma ray pulsation, and electronique can be protect of Gamma ray.


Have a good day,
Jerome Chapoul

May 21, 2016 20:30 Brent Hasty Posted on: Breakthrough Initiatives

Rather than using a ground based laser array for photonic acceleration, could the sails be sufficiently accelerated by flying them through the earth's (or jupiter's) gravatational lense point?

Using the earth's gravatational lense location where the solar density and impulse from our star would be amplified to an hourglass of high photon density is already available and would cost nothing to build.

May 25, 2016 17:46 Giulio Prisco Posted on: Centauri Dreams

Following up from my previous comment "I think this option [a launch site on the far side of the moon] should be considered. It's likely to more than double the overall cost of the project, but the establishment of a moonbase on the far side - which could double as an astronomical observatory and other uses - is a worthy goal in itself and could attract its own funding."

I wish to put a visionary wild idea on the table for discussion - but isn't visionary wild ideas what Starshot is about?

Recently an initiative called "The DAO" raised more than $150 million in a few weeks in the world's largest crowdfunding to date. See my news report here:
https://bitcoinmagazine.com/articles/the-dao-raises-more-than-million-in-world-s-largest-crowdfunding-to-date-1463422191

The last passages are relevant:

"[Internet entrepreneur and activist David Orban] Orban is persuaded that The DAO can be a pathfinder and a model for very ambitious crowdfunded initiatives to tackle important challenges, including a new global phase of the space program. “With The ĐAO now being implemented this is starting to make sense,” says Orban. “From the $10M order of magnitude crowdsales two years ago, to the $100M crowdsale today, we will get to $1B in a couple of years, and then to $10B in another two-three. Those are meaningful numbers to fund a Mars mission (if not a Mars colony yet). See also this author’s 2009 essay on “A Virtual World Space Agency,” which didn’t mention DAOs only because the concept wasn’t yet popular at the time."

If "from the $10M order of magnitude crowdsales two years ago, to the $100M crowdsale today, we will get to $1B in a couple of years, and then to $10B in another two-three," then the DAO model could permit raising the funds to establish a moonbase on the far side with a Starshot launch site.

The DAO fundraising model is for-profit (those who buy in the crowdsale expect to get a return, like for an IPO), but I guess the project could be profitable through merchandising, media rights, and of course leasing sites to initiatives like Starshot.

Jun 14, 2016 09:12 michael.million@sky.com Posted on: Centauri Dreams

Finance may be raised by selling discs with peoples and family names etched into the sail, there are then shot out of the solar system at great speed or could be used to land on other planets, Great way to test the system and get finance.

Jul 14, 2016 23:34 reepicheep75@hotmail.com Posted on: Breakthrough Initiatives

Rocket lasers!

This seems like a good reason to make low cost launching infrastructure and tech the next target rather than getting to the moon or Mars. Once you have that you can go to the moon, Mars, or build a space laser more easily.

Jul 23, 2016 21:15 Breakthrough Initiatives Posted on: Breakthrough Initiatives

Good questions. But there is some confusion here. Chemical lasers like the COIL on the (cancelled) ABL program were interesting for some applications, though ultimately not great for ABL. They are capable of high power but they are extremely costly to run, use expendables, have generally nasty chemicals AND most importantly are NOT phase combinable in a way that works for us. The latter point is critical to the success of the Starshot initiative. Starshot will use a large number of modest power electrically driven solid state laser amplifiers (~ 0.1-3 kw is the current idea) in a phased array arrangement. The system is called a MOPA (Master Oscillator Power Amplifier) design and is similar to a phased array radar system. It is self synchronized (phase “locked”) as there is really only ONE laser in the system (the master oscillator) and the other “lasers” are technically laser amplifiers (light amplifiers). The system does not use expendables, is completely solid state (fiber amplifiers) and most importantly can be made into a phased array. The “wall plug” efficiency of the system is currently greater than 40% and is rising. We expect above 60% by the time the final Starshot system is deployed.

A simple analogy to keep in mind is that our system is like a modern super computer in that it uses a large number of modest subsystems to form one large synthetic entity. In the case of all modern super computers we use a large number of modest processors that are data synchronized to form a large super computer. In our laser array we use a large number of modest laser amplifiers that are synchronized into a large “super laser” though we do not normally use the latter term.

As for cooling, the laser amplifiers are cooled with room temperature water flowing through a heat exchanger in each amplifier. These heat exchangers are relatively simple and similar to the liquid heat exchanger sold for personal computers. The Sharshot system is only operational for about 100-300 seconds per launch and one option is to simply use a phase change material so no heat exchanger is needed. This is an option we are exploring.

As for power some people have mentioned Petawatt (1000 Terawatt) lasers. These are only pulsed lasers with typically sub micro or nanosecond pulses and not appropriate for our needs. We must run continuously (CW) in order to keep the power on the reflector (sail) for long enough to accelerate the spacecraft to sufficient speed. It is NOT just power on the spacecraft but energy (power x time) that is important.

For technical details see section 2.9 in the paper “A Roadmap to Interstellar Flight”:
http://arxiv.org/abs/1604.01356
It will often be referred to as the “roadmap” paper.

You can find a photon propulsion calculator to design your own mission and see the trades between the various system parameters here:
http://www.deepspace.ucsb.edu/projects/starshot
This calculator implements the equations in the above “roadmap” from sections 2, 2.1 and 2.2.

The cost analysis of the laser array used for Starshot is strongly dependent on the exponential growth in performance and exponential drop in price for the solid state lasers we are using. This is discussed in section 2.9 and shown graphically in Figure 11 of the “roadmap” paper . We are on a “Moore’s Like Law” for photonics in Starshot and this is critical to enable to dramatic cost reductions we are on the way to achieving. With a “half time” (time increment to ½ the cost for the same power) of about 1.5 years we have a similar situation to the consumer electronics world where the price of flat screen TV’s , computers, smart devices etc drops for the same performance level. This will allow us to meet our cost goals.

– Prof. Philip Lubin, Breakthrough Starshot

Aug 01, 2016 08:02 michael.million@sky.com Posted on: Centauri Dreams

This laser system could also be used to supply power to moon bases where they will have solar cell arrays. There will have power for a significant amount of time over most of the moon during the 2 week long night. By integrating other projects into the basic design costs can be shared amongst the stakeholders.

Aug 24, 2016 10:25 michael.million@sky.com Posted on: Centauri Dreams

The cost of the whole system could be reduced significantly if MHD technologies are used and 'sold' under licence to other companies and governments around the world. We could significantly reduce the cost of the launch system by receiving 'not for profit' royalties and aid the world in its need for electrical energy. Sinking investment into MHD technologies may pay handsomely in the future not only for space flight but also the electrification of the world. MHD electrical generators have high efficiencies and even greater if the waste heat is used for other forms of electrical generation.

We are going to need to horizontally and vertically integrate the launch system to reduce the cost of the project significantly.

Aug 26, 2016 11:51 Adam Skrodzki Posted on: Breakthrough Initiatives

Hi,

anyone know any sources how to solve photon recycling?

I've found something in "Hypothetical Spacecraft and Interstellar Travel"

While "Launch Efficiency" for high speeds looks reasonable (like 10%) they decrease drastically
for higher massees and lower speeds (lower lasers powers) For example efficiency for 100MW
20 gram probe is as low as 0,187 %.

Have You considered implementation of photon recycling for low speeds, so costs of launch
of probes to explore our solar system would decrease drasitically what whould allow to provide service of launching such probes to the civil market and rise significant amouts of money to support further project development.

I guess it is very likely that providing such innovative service to civil market would cause its mass use and by that would allow speed up development, improve technology lower costs.


Let wide public support that project effectivly, so You can faster achieve this awersome goal!

Aug 31, 2016 09:54 michael.million@sky.com Posted on: Centauri Dreams

Another way to reduce cost may be to have satellites coated in the reflective material and use the laser/s to move then about in orbit or controlled destructive re-entry or even to bring them down to earth slowly below the melting point of the satellites materials for repairs or upgrades for re-launch. The ability to reduce the cost of repairs and upgrades to satellites is worth billions to the communication industry.