Estimad@s Clientes y/o amantes del LEAN:
Reconozco que este tema me ha apasionado, por lo que le voy
a dedicar un segundo post, relacionado solamente con dos de los apasionantes retos
técnicos a los que se enfrentará el Equipo de Breakthrough Starshot:
-El láser que impulsará las naves
hasta alcanzar un 20% de la velocidad de la luz
-Las velas solares
El contenido de este escrito está sacado de la revista
Investigación y Ciencia, en su número de Mayo 2017
Un láser de 100 Gigavatios
La forma de alcanzar una fracción considerable de la
velocidad de la luz es empleando un láser 100 Gigavatios, potencia nada usual
El Departamento de Defensa de EEUU ha fabricado láseres más
potentes, pero solo se activaron durante billonésimas de segundo
Sin embargo, el láser de Starshot tendrá que actuar sobre
cada vela durante varios minutos
Para alcanzar semejante potencia durante tanto tiempo, una
batería de pequeños láseres de fibra óptica combinaría los rayos en un único haz
coherente
El Departamento de Defensa también ha construido baterías de
láseres en fase, pero con 21 láseres agrupados en una red de no más de 20 cm de
lado. Eso permite alcanzar unas docenas de kilovatios
Starshot tendría que incorporar 100 millones de estos
láseres con potencias de kilovatios y disponerlos en una red cuadrada de 1 km
de lado
Velas que soporten aceleraciones de hasta 60.000 g
Los Starchips estarían propulsados por la luz que incidiese
y se reflejase en sus velas
Cuanta más luz se refleje, mayor será el impulso y más
rápido avanzará la vela
Para alcanzar el 20% de la velocidad de la luz, la vela
debería reflejar el 99,999% de la luz incidente
Las velas deberían ser enormemente ligeras, con un espesor
de pocos átomos
En el ensayo más parecido efectuado hasta ahora, se empleó
un haz de microondas para acelerar hasta 13 g una vela fabricada con una lámina
de carbono
Sin embargo, la vela de Starshot tendrá que soportar
aceleraciones de hasta 60.000 g
Y al igual que el StartChip, también tendrá que resistir el
polvo interestelar: Hoy por hoy, no existe un material que sea a la vez ligero,
fuerte, reflectante, resistente al calor y que no cueste millones de dólares
¿Cuán lejos queda eso de la tecnología
actual?..........apasionante ….¿no?
(Mi escrito anterior)
La revista Investigación y Ciencia del mes de Mayo recoge en
portada que una serie de científicos de prestigio, entre los que se encuentra
Stephen Hawking ( el famoso astrofísico británico en silla de ruedas ) está
trabajando en serio para explorar los problemas técnicos a los que se
enfrentaría el reto de mandar una misión a Alfa Centauri, el sistema solar más
cercano al Sol
El plan está financiado por un multimillonario, Yuri Milner
El Proyecto se llama “Breakthrough Starshot”, y pretende
usar láseres para acelerar una flota de microchips al 20% de la velocidad de la
luz
Los retos técnicos son inmensos, pero como dice Philip
Lubin, físico de la Universidad de Californiaaa en Santa Bárbara, que escribió
el artículo base del inicio de los trabajos, titulado “Hoja de ruta para un
viaje interestelar”: Puedo explicarle por qué es difícil y por qué es caro,
pero no por qué es imposible
Básicamente, se trataría de usar láseres para acelerar una
flota de microchips al 20% de la velocidad de la luz; las naves tardarían 20
años en llegar. Una vez allí, captarían imágenes y tomarían datos que tardarían
4,3 años en llegar ( los años luz a los que se encuentra Alfa Centauri de la
Tierra )
En líneas más abajo, adjunto los links más interesantes que
he visto por ahí
Breakthrough
starshot
Challenges
Sub-gram
scale 1W diode lasers are currently widely available at very low costs. The
manufacturing trend has seen power double for the same mass every two years. It
is anticipated this trend will continue for these devices for some time. More...
Sub-gram-scale
2 megapixel cameras are currently widely available at very low costs. The trend
has been a doubling of pixels for the same mass every two years. More...
Sub-gram
scale microprocessors are currently widely available at very low costs. The
trend has been a doubling of processor count for the same mass every two years.
It is anticipated that these devices will continue this trend for some
time. More...
Comments: 21. Last comment by Robert Clark – Jun 06, 2017
02:56.
Battery
design is one of the most challenging aspects of the mission. Currently under
consideration for the energy source onboard are plutonium-238, which is in
common use, or Americium-241. 150mg has been allocated for the mass of the
battery. This includes the mass of the radioisotope and the
ultra-capacitor. More...
The power
available needs to be balanced with the tasks that need to be completed on the
nanocrafts. The radioisotope power sources establish the power budget in the
most conservative design. More...
Comments: 9. Last comment by Breakthrough Initiatives – Mar
21, 2017 18:46.
A
protective coating is required for the dust collisions and the erosions caused
by atomic particles in the interstellar medium. More...
Comments: 26. Last comment by Breakthrough Initiatives – Jan
05, 2017 02:18.
To inform
the study, a beamer in the 100 GW class was considered. If, for example, 10-5 of
the energy is absorbed by a 4mx4m sail, it will be heated by about 60kW per m2,
which is roughly 60 times more than sunlight illumination on Earth. This will
heat the material but not melt it. More...
Comments:
57. Last comment by Breakthrough Initiatives – Apr 04, 2017 22:41.
Building a
skeleton structure that will be able to hold the sail in shape during launch,
be resilient to the interaction with the interstellar medium and potentially be
able to modify the shape of the sail, is a major challenge given the gram-scale
mass constraint. More...
Beam shape
and lightsail structure should be optimized for stability during the launch
phase. In this period, on the order of 10 minutes, an illumination energy of
order 1TJ is delivered to the sail. More...
Comments: 28. Last comment by Breakthrough Initiatives – Mar
21, 2017 18:48.
The
estimated cost of the laser array is based on extrapolation from the past two
decades, and the prospects of mass production to reduce the associated
cost. More...
In order to
test the feasibility of the system, the case of a meter-scale sail was
examined. For example, to focus the light beam on a 4mX4m sail across an
acceleration distance of 2x106 km requires a focusing angle of
2 nano-radians (0.4 milliarcseconds), which is the diffraction limit for a
kilometer-scale light beamer operating at a wavelength of 1 micron. More...
The
atmosphere introduces two effects: absorption (or ‘reduction of transmission
from unity’), and loss of beam quality (or ‘blurring of the beam spot’). The
transmission of the atmosphere at a wavelength of 1 micron is extremely good,
exceeding 90% at high altitude ground-based sites. More...
Comments: 35. Last comment by moh kranis – Apr 29, 2017
09:55.
Power
generation and storage at the launch site is challenge. Developing a site with
adequate infrastructure to generate the energy at a high altitude site is
difficult. More...
Comments: 42. Last comment by Robert Clark – Jun 06, 2017
03:22.
The light
beamer must focus a spot smaller than the sail onto the sail, as it orbits
60,000km above the Earth’s surface. More...
Comments: 12. Last comment by khokolateKke@gmail.com – Jun 06, 2017
23:54.
There are a
number of effects that make this task difficult. These include beam
instabilities, laser mode issues, differential forces on the sail, differential
heating of the sail, and instabilities in the atmosphere induced by the energy
of the beam. More...
Comments: 21. Last comment by Nathan Bemis – Apr 22, 2017
17:54.
In order to
bring a nanocraft to within 1AU of a planet in a system like Alpha Centauri,
accurate locations of all the bodies near the path of flight would be
required. More...
Comments: 6. Last comment by Breakthrough Initiatives – Nov
05, 2016 03:32.
The most
challenging element in terms of cooling the laser array system would be the
small optical instruments in front of the primary mirror. This would be
addressed with conventional cooling systems and possibly by cooling the beam
director assemblies (lens assemblies). More...
Comments: 8. Last comment by Breakthrough Initiatives – Feb
28, 2017 11:05.
The
radiative flux on an object such as a bird, airplane, or spacecraft moving
through the beam would be about the same as the output energy flux at the beamer,
or 100 kw/m2 – about two orders of magnitude above sunlight on
Earth. More...
Comments: 6. Last comment by Peter Jaquiery – Apr 20, 2017
03:30.
Comments: 3. Last comment by Peter Jaquiery – Apr 20, 2017
03:28.
Breakthrough
Starshot has no intention of colliding any nanocraft with any object in space.
Even though an accidental collision between a nanocraft and another object is a
remote possibility happens, the resulting effects must still to be
examined. More...
Comments: 13. Last comment by Breakthrough Initiatives – Nov
05, 2016 04:31.
Based on
estimates of the density of dust in the local interstellar medium, over the
course of a journey to Alpha Centauri each square centimeter of the frontal
cross-sectional area of the StarChip and lightsail would encounter about 1,000
impacts from dust particles of size 0.1 micron and larger. However, there is
only a 10% probability of a collision with a 1 micron particle, and a
negligible probability of impact with much larger particles. More...
Comments: 30. Last comment by Stuart Heinrich – Apr 10, 2017
16:14.
Since the
trajectory to Alpha Centauri would take the nanocrafts away from the ecliptic
plane of the solar system, there would be much less impact from solar system
dust than from interstellar dust. Little is currently known about the dust
content in the Alpha Centauri star system. More...
Comments: 6. Last comment by Breakthrough Initiatives – Dec
06, 2016 18:31.
The mean
free path and Larmor radius of interstellar plasma particles is far greater
than the size of the nanocraft, meaning that they would impact the nanocraft
walls independently rather than forming a bow shock. More...
Comments: 12. Last comment by Breakthrough Initiatives – Aug
01, 2016 14:55.
The voyage
from earth to our nearest neighbor, at up to 20% of the speed of light, takes
about 20 years. Maintaining the functioning of a sophisticated nanocraft
through the rigors of deep space over this time is a challenging task. More...
Comments: 2. Last comment by Breakthrough Initiatives – Aug
01, 2016 14:58.
During an
encounter with an exoplanet, the nanocraft’s camera would need to rotate in
order to image the target. More...
Comments:
14. Last comment by Robert Clark – Jun 06, 2017 12:53.
Finding the
Earth should be reasonably straightforward, given its proximity to the Sun,
which would be bright from the vantage of Alpha Centauri. The on-board star
tracker would also be useful, as would locking onto the Starshot laser
system. More...
Comments: 28. Last comment by Simon Dawson – Apr 13, 2017
02:12.
Images of
the target planet could be transmitted by a 1Watt laser onboard the nanocraft,
in a ‘burst mode’ which uses the energy storage unit to rapidly draw power for
the power-intensive laser communications mode. Upon approach to the target, the
sail would be used to focus the laser communication signal. More...
Comments: 35. Last comment by Breakthrough Initiatives – Mar
21, 2017 19:02.
Recent
advances by groups at MIL Lincoln Labs and the Jet Propulsion Laboratory have
demonstrated that it is possible to detect single photons emitted by lasers
from very large distances. More...
Comments: 18. Last comment by Breakthrough Initiatives – Mar
21, 2017 19:03.
Clearance
for launches will be required from all the appropriate government and
international organizations. More...
Comments:
18. Last comment by Breakthrough Initiatives – Feb 02, 2017 19:02.
Videoclip
de animación
Que disfrutéis cada hora del fin de semana
Un cordial saludo
Alvaro Ballesteros
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