This week we are joined by Alberto Caballero who has a designed a crewed interstellar spacecraft. We chat about Musk's week, Some cool Fusion news, but not cold Fusion news.
“What do you love about the future? If the future does not include being out there among the stars and being a multi-planet species, I find that incredibly depressing.”
Elon Musk
In this paper it is presented the concept and design of a new type of spacecraft that could be used to make the first manned interstellar travel. Solar one would integrate three near-term technologies, namely: the US Navy CFR fusion reactor, a larger version of NASA Sunjammer light sail, and an array of DE-STAR laser systems. A system of Fresnel lenses and flexible mirrors to propel the sail with sunlight is suggested as an alternative to this array. With a mile-long light sail, Solar One could reach an average of 22% the speed of light, arriving to the closest potentially habitable exoplanet in less than 19 years with the help of a Bussard scoop. Key challenges are reducing the weight of continuous-wave lasers and compact fusion reactors as well as achieving cryo-sleep and artificial gravity.
We are literally at the midpoint of the summer here in the northern hemisphere!!
Today marks the 61st anniversary of Explorer 6 Launch, which took the first photo of earth from orbit, about 17,000 mi (27,000 km) above Mexico on August 14, 1959. The satellite was later used as target practice for anti sat missiles. The air-launched missile, similar to Virgin Orbit, called Bold Orion, was the first-ever interception of a satellite, and it passed within about 4 miles of Explorer 6, close enough to destroy it with a nuke on board.
But the world was frowning and the US stopped working on it.
Massive thank you to Gill Norman from the BIS who leaves her job at the BIS this month. What a legend.
Monumental week for SpaceX
August the 2nd saw the return of Bob and Chunky "We are entering a new era of spaceflight," said NASA Administrator Jim Bridenstine
Elon Musk also talked about a new era and how it gets us one step closer to mars,
Then only a couple of days later we had the 150m Hop of Starship SN5.
It was incredible a single raptor engine carrying a huge stainless steel 30m tall structure, built literally outside from rolls of stainless steel. This really is a tiny step towards Mars, but I suspect will go down in history as being the moment that rockets became something new.
Nasa paper, loads of people
Normally to get fusion going you need a massive bank of lasers or a massive tokamak with complicated magnetic fields etc.
This method, however, seems to be exceedingly lightweight, all you need is some metal, some hydrogen and an electron gun!
Fusion; getting elements to combine to make a single heavier element, but not as heavy as the original pair, and release that mass change as energy, just exactly how the sun works. E=MC^2.
Fact In 1920, Arthur Eddington suggested hydrogen-helium fusion could be the primary source of stellar energy!
Now, of course, the potentially great thing about this type of fusion might be that it’s light enough to go into space, and the radiation it gives off might be easily dealt with.
How does it work.
This is not cold fusion, it’s low energy fusion. But it still gets hot.
The lattice part comes from the crystal structure of the metal, in this case urbium (pictured) or titanium, and what you do is confine a special type of hydrogen, Deuteron, (one proton one neutron) and by confining I mean it’s literally trapped in the metal, and packed into the crystal lattice like it’s in a tiny metal jail, You pack it in so it’s almost like solid hydrogen, in the metal. As the deuterium gas gets loaded into the lattice the lattice breaks apart and the metal becomes a kind of powder. But even though the deuterons are really close together, they are still not close enough to fuse, and they really don’t want to, they are both positively charged.
So how do you push them closer, the normal way is to use massive machinery. Remember the Aesop fable about the sun and the wind?
When the deuterons can be forced close enough for long enough the Strong nuclear force suddenly takes over by “tunnelling” - a quantum effect, where the probability that the nucleus is the other side of this repulsion barrier means that is sometimes is the other side and bang you have overcome what is known as the Coulomb barrier. The Coulomb barrier is smallest for isotopes of hydrogen, as their nuclei contain only a single positive charge. A diproton is not stable, so neutrons must also be involved, ideally in such a way that a helium nucleus, with its extremely tight binding, is one of the products.
Using deuterium–deuterium fuel, the resulting energy barrier is still very high but the total energy liberated is 1even higher, so you have released energy by turning hydrogen into different isotopes and sometimes helium
So here is the clever bit, the electron beam is shone onto tungsten, this releases x-Rays (high energy photons) The high energy photons are beamed into the powdery titanium/hydrogen lattice and some hit a deuteron and knocks the neutron away from its partner proton, this fast-moving neutron then goes whizzing around and hits another deuteron and knocks another pair apart. Because everything is so confined they are all getting bashed by one another and getting pretty violent in the lattice, the photons stirring up all the trouble. But another advantage of the lattice is that the negatively charged electrons in the lattice itself seem to shield the positively-charged deuterons, so they can get closer than normal, then suddenly the strong force get a chance to kick in and hey presto some fusion.
When two deuterons fuse, they create either a proton and tritium (a hydrogen atom with two neutrons), or helium-3 and a neutron. In the latter case, that extra neutron can start the process over again, allowing two more deuterons to fuse. Occasionally in what is know as Oppenheimer-Phillips stripping reactions, deuterons collide with the lattice and fuse with the titanium atoms, and this also creates useful energy.
Basically this seems like a really neat way of getting nuclear fusion going, it might turn out not only to be useful for spacecraft, as a powersource for laptops even? Or scaled up and powering the local grids etc.
The problem with nuclear energy even Fusion on of the by-products is high-energy neutrons that go round smashing up machinery and worse DNA, making things radioactive, and they are really hard to stop because they have no charge of course. This technology seems to be able to do aneutronic reactions and gives off helium nuclei that quickly turn into useful and harmless helium.
Other promising reactors, which are in the next interview, are the Lockheed Martin Compact Fusion Reactor.project at Lockheed Martin’s Skunk Work, A 200 MW Pth reactor, 18 m long by 7 m in diameter, produces about a 2000 ton reactor, similar in size to an A5W nuclear submarine fission reactor.The blanket component that lines the reactor vessel has two functions: it captures the neutrons and transfers their energy to a coolant, and forces the neutrons to collide with lithium atoms, transforming them into tritium to fuel the reactor. The blanket must be an estimated 80–150 cm thick and weigh 300–1000 tons
Not to be confused with fission realtors like the KRUSTY which work on keeping Uranium confines and reflecting back the neutrons, heating a core, that then heats liquid sodium to power the thermal reactor. These things only weigh about 1500kg and produce 1Kw energy.