To Mars in three days?
At the end of February, many media outlets reported that NASA had come up with a way to fly to Mars and other planets at light speeds. It was about the work of the professor of physics at the University of California at Santa Barbara, Philip Lubin (Philip Lubin). The meaning of the messages was that NASA, in the person of the aforementioned professor, was going to launch probes to the planets of the solar system and beyond using laser light from the Earth. They promised delivery of a 100-pound vehicle to Mars in three days and other fantastic opportunities. Apparently, due to the apparent yellowness of the headlines, no one dared to publish similar news here and on similar resources. I was wondering what is still behind the loud headlines and that’s what I found out.
In fact, the news was not so fresh, some media published it back in the summer of 2015. Now the impetus for this topic has given the publication of a video clip popularly explaining the proposed technology by the NASA 360 podcast (and the subsequent repost by the Space.com site).
This video does not contain any scientific and technical details, but consists almost entirely of various fragments of the Shuttle launches and other space videos. It is only said about the technology itself that it is supposed to use photon propulsion, i.e. pulse energy of photons. In fact, the idea of a photon engine is not new at all, however, researchers suggest a completely new approach - the transmission of momentum is accomplished by “illuminating” a moving object with a laser beam from the Earth or from the orbital platform. Thus, it is proposed to get rid of the necessary fuel reserves on board the object itself, and it is argued that such an approach will achieve near-light speeds.
Philip Lubin is a project manager for NASA's DEEP-IN (Directed Energy Propulsion for Interstellar Exploration) project. In April 2015, he published a scientific paper entitled “A Roadmap to Interstellar Flight” , in which he proposed a technology for transmitting photon momentum to a spacecraft using an array of lasers installed on Earth, and also provided calculations confirming the theoretical possibility this technology. In August 2015, NASA allocated $ 100,000 for further studies of this group.
Further, I will try to briefly outline the main points outlined in this work.
The introduction to the work says that over the past 60 years of the space age, mankind has made great strides in the development of space technology, with the exception of only the high-speed characteristics of spacecraft. For example, Voyager-1 managed to leave the solar system only after 37 years of flight, having a speed of 17 km / s, i.e. 0.006% of light. This is clearly not enough to fly even to the nearest stars.
For remote transmission of energy, it is proposed to use the photon driver (photon driver) - an array of lasers, kilowatt class, with exactly the same phases, working as a single light source. Such an approach will make it possible to abandon the development of a single superpowerful laser, as well as giant optical systems (since each laser in the array has its own optical system). A similar array is described in other studies by a research group called the DE-STAR (Directed Energy System for Targeting of Asteroids and ExploRation). It is proposed to supply the array with the energy of the corresponding set of solar panels.
It is proposed to build DE-STAR arrays of different sizes, in a logarithmic progression from their number. Those. DE-STAR 1 will have a side of 10 meters, DE-STAR 2 - 100 meters and so on. For example, the characteristics of an array of the maximum size DE-STAR-4 and a power of 50-70 Gigawatts, which, being in low Earth orbit, will allow to disperse a femtosatellite (made in the form of a single crystal, weighing about 1 gram) with a sail with a side of 1 meter, made from a thin film, to a speed of about 26% of the light in about 10 minutes. Such a device will reach Mars in 30 minutes, overtake Voyager-1 in less than 3 days and reach Alpha Centauri in about 15 years. As other examples, it is said that such an array could accelerate an object weighing 100 kg to about 2% of the speed of light, and an object weighing 10,000 kg to 1,000 km / s.
Considering that it takes very little time to accelerate a femtosatellite, after which an array of lasers is practically unnecessary, theoretically, you can launch hundreds of such devices daily and run about 40,000 units a year, which will allow one for each square degree of the sky ( it is estimated that the total mass of all femtosatellites will be about 80 kg).
Further, the work provides calculations of the necessary energy for accelerating objects to near-light speeds, as well as calculations of the necessary sizes of sails to collect the transmitted energy. It is also proposed to use part of the energy received for the spacecraft’s own needs, which on the one hand will reduce the efficiency of energy transfer, and on the other hand, it will significantly facilitate the apparatus itself. In addition, the design and calculations necessary for the construction of an array of lasers are given.
A serious problem can be the braking of the device that arrived at the place. For this purpose, it is proposed to use the energy of photons emitted by a star, stellar wind, as well as magnetic binding to the plasma of a stellar system. It is indicated that it will take many years of experimentation to learn how to use these opportunities, but span missions are now available.
Another practical aspect of using laser arrays can be long-distance communication with devices. For example, the calculation is again given for the DE-STAR-4 array with a wavelength of 1.06 μm and a power of 50 Gigawatts. It is said that at a distance of 1 light year the diameter of the light spot will be 2 * 10 6 meters (2,000 km), which for a probe weighing 100 kg and a receiving antenna with a diameter of 30 meters will allow you to receive data at a speed of 2 * 10 18bit / s (assuming that the device needs to receive 40 photons to encode the 1st bit). At the same time, having a 10 W laser transmitter on board, the device will be able to transmit information in a similar way at a speed of 1 * 10 9 bit / s (i.e. 1 Gbit / s). Similarly, it is calculated that being close to Proxima Centauri, this data transmission system will provide a speed of about 70 Mbit / s. Those. humanity will have the opportunity to watch in real time a video broadcast from a neighboring star system.
As additional opportunities for using the laser array, military and protective purposes are offered, for example, protection against asteroids, as well as signal transmission to extraterrestrial civilizations.
At the end of the article, some calculations for future spacecraft sent using a laser array with a capacity of 70 Gigawatts are given:
Thus, the article says that the proposed technology, despite its fantastic nature, is quite possible in the foreseeable future and is clearly more real than wormholes, teleportation and anti-matter engines. Of course, it will take some time until the technologies develop enough to create spacecraft weighing units of grams and the laser arrays necessary for acceleration. To agree with this or not - everyone can decide for themselves. It is important for me that NASA also saw a healthy grain in this work and is funding further developments. The next steps may be first ground testing of the technology for transferring momentum, and then testing in orbit of the earth laser arrays of different powers.
As expected, the proposed theory has opponents. In addition to the technical impossibility of launching such a spacecraft at the present time, other theoretical and practical difficulties are also mentioned. For example, they say that the laser sail is very hot during the operation of the laser system, or that if the sail (and it should reflect 99.99% of the energy received) reflects 70 Gigawatts of energy back into the laser array, then the latter will not be greeted. They also mention Newton’s 3rd law, according to which a colossal counteraction force will act on the space platform on which the array of lasers will be installed (although the platform itself, according to the calculations of the same critics, will have an exorbitant mass of about 300,000 tons).
In any case, time will tell who was right and who was not.
I apologize for the use of the term “femto satellite” for the devices mentioned in the article, since the original uses the term “wafer scale spacecraft”, which is not translated by any term I know.
List of links:
In fact, the news was not so fresh, some media published it back in the summer of 2015. Now the impetus for this topic has given the publication of a video clip popularly explaining the proposed technology by the NASA 360 podcast (and the subsequent repost by the Space.com site).
This video does not contain any scientific and technical details, but consists almost entirely of various fragments of the Shuttle launches and other space videos. It is only said about the technology itself that it is supposed to use photon propulsion, i.e. pulse energy of photons. In fact, the idea of a photon engine is not new at all, however, researchers suggest a completely new approach - the transmission of momentum is accomplished by “illuminating” a moving object with a laser beam from the Earth or from the orbital platform. Thus, it is proposed to get rid of the necessary fuel reserves on board the object itself, and it is argued that such an approach will achieve near-light speeds.
Philip Lubin is a project manager for NASA's DEEP-IN (Directed Energy Propulsion for Interstellar Exploration) project. In April 2015, he published a scientific paper entitled “A Roadmap to Interstellar Flight” , in which he proposed a technology for transmitting photon momentum to a spacecraft using an array of lasers installed on Earth, and also provided calculations confirming the theoretical possibility this technology. In August 2015, NASA allocated $ 100,000 for further studies of this group.
Further, I will try to briefly outline the main points outlined in this work.
The introduction to the work says that over the past 60 years of the space age, mankind has made great strides in the development of space technology, with the exception of only the high-speed characteristics of spacecraft. For example, Voyager-1 managed to leave the solar system only after 37 years of flight, having a speed of 17 km / s, i.e. 0.006% of light. This is clearly not enough to fly even to the nearest stars.
For remote transmission of energy, it is proposed to use the photon driver (photon driver) - an array of lasers, kilowatt class, with exactly the same phases, working as a single light source. Such an approach will make it possible to abandon the development of a single superpowerful laser, as well as giant optical systems (since each laser in the array has its own optical system). A similar array is described in other studies by a research group called the DE-STAR (Directed Energy System for Targeting of Asteroids and ExploRation). It is proposed to supply the array with the energy of the corresponding set of solar panels.
It is proposed to build DE-STAR arrays of different sizes, in a logarithmic progression from their number. Those. DE-STAR 1 will have a side of 10 meters, DE-STAR 2 - 100 meters and so on. For example, the characteristics of an array of the maximum size DE-STAR-4 and a power of 50-70 Gigawatts, which, being in low Earth orbit, will allow to disperse a femtosatellite (made in the form of a single crystal, weighing about 1 gram) with a sail with a side of 1 meter, made from a thin film, to a speed of about 26% of the light in about 10 minutes. Such a device will reach Mars in 30 minutes, overtake Voyager-1 in less than 3 days and reach Alpha Centauri in about 15 years. As other examples, it is said that such an array could accelerate an object weighing 100 kg to about 2% of the speed of light, and an object weighing 10,000 kg to 1,000 km / s.
Considering that it takes very little time to accelerate a femtosatellite, after which an array of lasers is practically unnecessary, theoretically, you can launch hundreds of such devices daily and run about 40,000 units a year, which will allow one for each square degree of the sky ( it is estimated that the total mass of all femtosatellites will be about 80 kg).
Further, the work provides calculations of the necessary energy for accelerating objects to near-light speeds, as well as calculations of the necessary sizes of sails to collect the transmitted energy. It is also proposed to use part of the energy received for the spacecraft’s own needs, which on the one hand will reduce the efficiency of energy transfer, and on the other hand, it will significantly facilitate the apparatus itself. In addition, the design and calculations necessary for the construction of an array of lasers are given.
A serious problem can be the braking of the device that arrived at the place. For this purpose, it is proposed to use the energy of photons emitted by a star, stellar wind, as well as magnetic binding to the plasma of a stellar system. It is indicated that it will take many years of experimentation to learn how to use these opportunities, but span missions are now available.
Another practical aspect of using laser arrays can be long-distance communication with devices. For example, the calculation is again given for the DE-STAR-4 array with a wavelength of 1.06 μm and a power of 50 Gigawatts. It is said that at a distance of 1 light year the diameter of the light spot will be 2 * 10 6 meters (2,000 km), which for a probe weighing 100 kg and a receiving antenna with a diameter of 30 meters will allow you to receive data at a speed of 2 * 10 18bit / s (assuming that the device needs to receive 40 photons to encode the 1st bit). At the same time, having a 10 W laser transmitter on board, the device will be able to transmit information in a similar way at a speed of 1 * 10 9 bit / s (i.e. 1 Gbit / s). Similarly, it is calculated that being close to Proxima Centauri, this data transmission system will provide a speed of about 70 Mbit / s. Those. humanity will have the opportunity to watch in real time a video broadcast from a neighboring star system.
As additional opportunities for using the laser array, military and protective purposes are offered, for example, protection against asteroids, as well as signal transmission to extraterrestrial civilizations.
At the end of the article, some calculations for future spacecraft sent using a laser array with a capacity of 70 Gigawatts are given:
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
|---|---|---|---|---|---|---|---|---|
| 1 g | 0.85 m | 186 s | 4.01 * 10 9 m | 4.31 * 10 7 m / s | 0.14 | 6.10 * 10 7 m / s | 0.20 | 2.37 * 10 4 g |
| 10 g | 2.7 m | 1050 s | 1.27 * 10 10 m | 2.43 * 10 7 m / s | 0.081 | 3.43 * 10 7 m / s | 0.11 | 2.37 * 10 3 g |
| 100 g | 8.5 m | 5880 s | 4.01 * 10 10 m | 1.36 * 10 7 m / s | 0.046 | 1.93 * 10 7 m / s | 0.064 | 237 g |
| 1 kg | 27 m | 3.32 * 10 4 s | 1.27 * 10 11 m | 7.67 * 10 6 m / s | 0.026 | 1.08 * 10 7 m / s | 0.036 | 23.7 g |
| 10 kg | 85 m | 1.86 * 10 5 s | 4.01 * 10 11 m | 4.31 * 10 6 m / s | 0.014 | 6.10 * 10 6 m / s | 0.020 | 2.37 g |
| 100 kg | 270 m | 1.06 * 10 6 s | 1.27 * 10 12 m | 2.43 * 10 6 m / s | 0.0081 | 3.46 * 10 6 m / s | 0.011 | 0.237 g |
| 1000 kg | 850 m | 5.88 * 10 6 s | 4.01 * 10 12 m | 1.36 * 10 6 m / s | 0.0046 | 1.93 * 10 6 m / s | 0.0064 | 0.0237 g |
| 10 000 kg | 2.7 km | 3.32 * 10 7 s | 1.27 * 10 13 m | 7.67 * 10 5 m / s | 0.0026 | 1.08 * 10 6 m / s | 0.0036 | 2.37 * 10 -3 g |
| 100 000 kg | 8.5 km | 1.86 * 10 8 s | 4.01 * 10 13 m | 4.31 * 10 5 m / s | 0.0014 | 6.10 * 10 5 m / s | 0.0020 | 2.37 * 10 -4 g |
- Apparatus weight
- Sail size
- The time during which the device moves away at a distance at which the spot of the laser beam completely illuminates the sail
- The distance from the light source at which the spot of the laser beam completely illuminates the sail
- Speed at this point
- Fraction of the speed of light
- Maximum speed in continuous lighting
- Percentage of the speed of light in constant light
- Acceleration at the moment when the spot of the laser beam completely illuminates the sail
Thus, the article says that the proposed technology, despite its fantastic nature, is quite possible in the foreseeable future and is clearly more real than wormholes, teleportation and anti-matter engines. Of course, it will take some time until the technologies develop enough to create spacecraft weighing units of grams and the laser arrays necessary for acceleration. To agree with this or not - everyone can decide for themselves. It is important for me that NASA also saw a healthy grain in this work and is funding further developments. The next steps may be first ground testing of the technology for transferring momentum, and then testing in orbit of the earth laser arrays of different powers.
As expected, the proposed theory has opponents. In addition to the technical impossibility of launching such a spacecraft at the present time, other theoretical and practical difficulties are also mentioned. For example, they say that the laser sail is very hot during the operation of the laser system, or that if the sail (and it should reflect 99.99% of the energy received) reflects 70 Gigawatts of energy back into the laser array, then the latter will not be greeted. They also mention Newton’s 3rd law, according to which a colossal counteraction force will act on the space platform on which the array of lasers will be installed (although the platform itself, according to the calculations of the same critics, will have an exorbitant mass of about 300,000 tons).
In any case, time will tell who was right and who was not.
I apologize for the use of the term “femto satellite” for the devices mentioned in the article, since the original uses the term “wafer scale spacecraft”, which is not translated by any term I know.
List of links: