AJShepard -
Recall that Einstein stated that nothing can surpass the speed of light because your mass, at the speed of light, becomes infinite.
Next, remember how small we are. Jupiter has 318 times the mass of the Earth. While the Earth's magnetic field is believed to be generated by its internal dynamo—the churning of electrically conductive fluids in the core. But Jupiter is thought to be made of helium and hydrogen, which are not very conductive. This has led to theories that suggest the great pressure exerted inside the planet resulted in the formation of
liquid metallic hydrogen, which, as its name implies, conducts much like a metal.
In the superionic crystalline phase, as seemingly in evidence on Uranus and Neptune, water loses its molecular identity (H2O): negative oxygen ions (O2-) crystallize into an extensive lattice, and protons in the form of positive hydrogen ions (H+) form a liquid that floats around freely within the oxygen lattice.
"The situation can be compared to a metal conductor such as copper, with the big difference that
positive ions form the crystal lattice in the metal, and electrons bearing a negative charge are free to wander around the lattice," said Maurice de Koning, a professor at the State University of Campinas's Gleb Wataghin Physics Institute (IFGW-UNICAMP) in São Paulo state, Brazil.
De Koning led the study that resulted in an article published in
Proceedings of the National Academy of Sciences (
PNAS) and featured on the cover of its November 8, 2022 issue.
Superionic ice forms at extremely high temperatures in the range of 5,000 Kelvin (4,700 °C) and pressure of around 340 gigapascals, or over 3.3 million times Earth's standard atmospheric pressure, he explained. It is therefore impossible for stable superionic ice to exist on our planet. It can exist on Neptune and Uranus, however. In fact, scientists are confident that large amounts of ice XVIII lurk deep in their mantles, thanks to the pressure resulting from these giants' huge gravitational fields, as confirmed by seismographic readings.
"The electricity conducted by the protons through the oxygen lattice relates closely to the question of why the axis of the magnetic field doesn't coincide with the rotation axis in these planets. They're significantly misaligned, in fact," De Koning said.
Measurements made by the space probe Voyager 2, which flew by these distant planets on its journey to the edge of the Solar System and beyond, show that the axes of Neptune's and Uranus's magnetic fields form angles of 47 degrees and 59 degrees with their respective rotation axes.
To fully grasp the actions of the planets' strongest magnetic fields. you must then realise how far apart they are and that their magnetic fields, like gravity, adhere to the inverse square law, where doubling the distance from the sources reduces its strength by a factor of four, or 1/4.
The distance between the Earth and Mercury is 0.61 AU. That’s around 91,691,000 kilometers, or 56,974,146 miles.
Likewise, the distance between Earth to Venus and Mars is 0.28 AU and 0.52 AU respectively. 0.28 AU is approximately 41,400,000 km or 25,724,767 miles and 0.52 AU is around 78,340,000 km or 48,678,219 miles. In addition, the distance to Jupiter from Earth is about 4.2 AU which is approximately 628,730,000 kilometers and 390,674,710 miles.
Furthermore, the distance from Saturn to Earth is 8.52 AU which is about 1,275,000,000 kilometers or about 792,248,270 miles. Similarly, Earth’s distance to Uranus is 18.21 AU. That is about 2,723,950,000 km or 1,692,662,530 miles. Finally, the distance between Earth and Neptune is 29.09 AU. That’s around 4,351,400,000 kilometers or 2,703,959,960 miles.
As a result, you can visualise the decrease of each planet's magnetic field over these vast distances. Then examine the average distance between any two stars in our Milky Way galaxy. the average distance between any two stars in our galaxy. That number turns out to be about 5 light years, which is very close to the 4 light year distance between our Sun and Alpha Centauri, our closest stellar neighbour. Again, stellar magnetic fields are ruled by the inverse square law, too. Five light years equates to some 5,878,600,000,000 miles - almost 6 trillion miles.
Therefore, planning to propel yourself from star to star, utilising each star's inherent magnetic field, where star's lie an average of some 6 trillion miles apart, may not be a very effective means of galactic propulsion. If the speed garnered from each star or planet via its own magnetic field is sufficient when flown close enough to harness it, there are other problems - radiation and heat.
Jupiter is surrounded by an enormous magnetic field called the magnetosphere, which has a million times the volume of Earth's magnetosphere. Charged particles are trapped in the magnetosphere and form intense radiation belts. These belts are similar to the Earth's Van Allen belts, but are many millions of times more intense.
Jupiter has the most complex and energetic radiation belts in our Solar System and one of the most challenging space environments to measure and characterize in-depth. Their hazardous environment is also a reason why so many spacecraft avoid flying directly through their most intense regions, thus explaining how Jupiter’s radiation belts have kept many of their secrets so well hidden, despite having been studied for decades. In this paper we argue why these secrets are worth unveiling. Jupiter’s radiation belts and the vast magnetosphere that encloses them present us with an unprecedented physical laboratory. Voyages through the uninviting environment of Jupiter’s radiation belts presents us with many challenges in mission design, science planning, instrumentation, and technology.
Measurements in the radiation belts of Uranus and Neptune, sampled only once by the Voyager 2 spacecraft, should definitely be part of any future attempt to explore the two planets. Saturn’s radiation belts were surveyed in depth thanks to the 13-year Cassini mission at the Kronian system. In comparison, Jupiter’s radiation belts, while visited by numerous missions and monitored for decades through their synchrotron emission, still hold onto many of their secrets. No single mission, payload, or observation campaign was ever designed to capture and/or cope with their full scale, complexity, dynamics, and energetics, as argued in the two follow-up subsections.
View attachment 2543
Jupiter’s magnetospheric region hosting the inner radiation belts (center). The moons Io, Europa, Ganymede, and Callisto are drawn, while the Io plasma torus and associated plasma disc are shown in red (Image Credit: John Spencer). Information on the inner electron and ion radiation belts are shown on each side. Color radiation belt maps are from models in, used with permission from Quentin Nénon. They cover the distances inward of Europa.
The above gives you an idea of the size, intensity and make up of Jupiter's radiation belts. Recall that Earth, too, has an area of high levels of radiation constrained by its magnetic field - the Van Allen Belt.
So, one must be mindful of the deadly radiation contained or constrained within planetary or stellar magnetic lines of force.
To wrap this first part up, let's recall that an infinite mass requires an infinite energy to move it.
Two, the distances involved between stars and planets effectively rule out having their magnetic lines of force being used to propel an interstellar vehicle with any notable success. Additionally, such use would vary immensely over time and directly proportional to the distances between the selected magnetospheres.
Thirdly, the magnetic lines of force, or the magnetosphere, harbor dangerous levels of radiation necessitating layers of shielding, adding mass to the conveyance.
To travel the distances you have in mind, one must examine other more exotic propulsive systems.
The underlying issue is that our closest star system is 4.25 light-years away from the sun. To reach this destination promptly without running out of fuel and victuals, space propulsion must be rethought because current reactive chemical technology is inadequate for long-distance spaceflight. There are three promising propulsion schemes for efficient short-term interstellar flight currently in development: ion thrusters, fusion-driven rockets, and the laser-pushed light sail.
For long-distance spaceflight, the Tsiolkovskjy rocket equation, which governs the motion of all rockets, becomes a major concern.
v = ve In m0mf
This equation relates the velocity gain of vehicle, v, to the exhaust velocity, ve, of the reaction mass and the ratio of the initial mass of the rocket, m0, to its final mass, mf. The plot of this equation below, listed as Figure 2, shows that as the desired momentum change v increases, the required amount of fuel increases exponentially.
The trading of velocity gain for lower fuel consumption results in longer flight durations. This dilemma between fuel consumption and flight time puts interstellar travel in a problematic situation. The propulsion solutions presented below seek to overcome this obstacle by either pushing the practical limits of the rocket equation or simply circumventing it.
An ion thruster is a form of electric propulsion that relies on injecting charged particles into an electric field to accelerate them. The resulting force propels the spacecraft using Newton’s third law. This is still a rocket concept, but instead of ejecting high-temperature combustion products, ions are discharged. This has a significant impact on the fuel consumption of this propulsion system, making it more efficient than combustion engines (2). The anatomy of the ion engine is illustrated in Figure 3.
Electrostatic Ion Thruster Diagram (Source: NASA)
The fusion-driven rocket scheme attempts to exploit the tremendous amount of nuclear energy released by atomic synthesis to either directly expel hot plasma or heat and accelerate a propellant. The physics of fusion is governed by Einstein’s mass-energy equivalence equation.
E = mc²
When two atoms collide and fuse, the resulting reaction produces a new atom and the mass difference mbetween the reactants and the products are converted to energy, E, as shown in Figure 4. This equation states that the conversion factor between mass and energy is the square of the speed of light c, which is about 300 000 km/s. The large value for c is the reason behind the enormous amount of energy that is released from these collisions (3).
Unlike electric and nuclear propulsion, the laser-pushed light sail is a propellantless scheme that relies on the principle of direct momentum transfer. The energy source is a stationary laser that sends a large light beam from Earth to a thin sheet of material moving in space called a light sail, which carries the probe (4). Although the momentum equation (3) from classical physics suggests that massless objects like photons can’t carry momentum, the laws of quantum mechanics and special relativity allow any particle that carries energy to have momentum, regardless of whether they have mass or not, as demonstrated in the general form of the relativistic equation (4). In the quantum world, all wave-like particles have energy since they have a non-zero frequency as shown by Plank’s equation.
p = mv
p = E2 – (mc2)2(c2)
E = hf
Hence, as illustrated below, the momentum carried by the photons can be transferred to the sail throughout the interstellar journey. This simple solution allows for high-velocity missions without the limitation of the rocket equation.
Schematic Schematic of the Laser Propulsion Concept
As far as warp drives, the bending of space, the utilisation of wormholes and black holes for travel, and putting colonists and crew to sleep for 50 or a hundred years, all remain in the realm of science fiction at the present while presenting a host of technical and biological problems to overcome.
See:
https://www.calculateme.com/astronomy/light-years/to-miles/5
See:
https://public.nrao.edu/ask/what-is-the-average-distance-between-stars-in-our-galaxy/
See:
https://www.thenakedscientists.com/forum/index.php?topic=30636.0
See:
https://link.springer.com/article/10.1007/s10686-021-09801-0
See:
https://phys.org/news/2023-01-superionic-ice-contributes-magnetic-anomalies.html
See:
https://stemfellowship.org/rethinking-space-propulsion-for-interstellar-travel/
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