# Tag Info

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It's the same reason SpaceX often does things differently: Krypton is a lot cheaper. The satellites are designed to control costs. For example, each will maneuver with Hall-effect thrusters—ion thrusters in which propellant is accelerated by an electric field. The conventional fuel for such a thruster is xenon, which offers high performance. The Starlink ...

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As with any hypothetical design, one is limited to consider if it's making some "unreasonable" assumptions. First, one may compare the claimed performance to existing technology. Nuclear rockets were abandoned early, but the completed prototypes give some lower bound for what's possible (NERVA, RD-0410). Thrust: 2000 kN (NERVA 247 kN, RD-0410 35 ...

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The problem is with the low energy density of cosmic rays in the universe. Individual cosmic rays are indeed very energetic, but there just aren't enough of them to be a significant power source for interplanetary or interstellar vehicles. The Wikipedia article about cosmic rays (https://en.wikipedia.org/wiki/Cosmic_ray) quotes the energy density of cosmic ...

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This answer has the two-impulse Hohmann transfer $\Delta V$. It is: $$\sqrt{2x\over x+1}+\sqrt{1\over x}-\sqrt{2\over x\left(x+1\right)}-1$$ where $x$ is the ratio of the higher orbit radius to the lower orbit radius, assuming (without loss of generality) that the lower orbit radius is $1$ and $\mu$ is $1$. This answer notes that in the limit of very low ...

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No Even if overall design makes a helicopter lifted first stage sensible you still need good energy density (power per KG of energy storage). Super capacitors have a special properties that make them useful but energy density by weight is not one of them. Going off the linked (and plausibly out of date) table they would need to be ten times better to equal ...

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(Top edit: The Question asserts "Xenon and krypton are popular despite their heavy mass" and asks about exploring H or He ion propellants for improved Isp. This answer shows that lighter is not better for ion thrusters, because Isp is not the proper measure of a power-limited situation. Hence, although lighter atoms have been explored for other reasons, ...

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The one thing which could conceivably fit your question and have a positive reply is an electromagnetic catapult. This would be an evacuated tube, typically hundreds of kilometers long, in which magnetic fields were used to accelerate a payload (which could be a rocket) to escape velocity (or a bit faster to allow for the energy lost to air resistance after ...

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I'll expand on @OrganicMarble's answer, it seems to me that the link there to the page on Richard Nakka's Experimental Rocketry Web Site titled Determining Total Impulse and Specific Impulse from Static Test Data is really helpful. Suppose you have built a rocket engine and you would like to see how good it is, but you don't have an extra rocket and launch ...

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Thrust isn't the bottle neck. Rather thrust to mass. In other words, acceleration. A 10 kilowatt Hall thruster exerts about half a newton. Half a newton is about a tenth of a pound or a little more than an ounce. If the power source, Hall Thruster and payload have a total mass of 500 kilograms, an ounce of force doesn't give much acceleration. About $1 ... 8 This video explains it. In short, it all boils down to golden middle between energy requirements, thrust and specific impulse. Ionizing lighter noble gases requires much higher potential - much more energy input, larger solar batteries, higher cooling requirements, circuitry and structure toughened against higher voltages and energies. While specific ... 7 the VASIMR test planned by Ad Astra has been cancelled: On December 8, 2008, Ad Astra signed an agreement with NASA to arrange the placement and testing of a flight version of the VASIMR, the VF-200, on the International Space Station (ISS),[24] but the plan was scrapped in 2015. The reason: But a series of agreements with NASA, dating back to June 2005, ... 6 tldr; No, our current technology is far too weak. Electrostatic Thrusters The term 'electric power' when it comes to engines can mean a few things, but the closest we currently have in spaceflight to a pure 'electric engine' are Electrostatic thrusters. These essentially use electricity to power electromagnets that accelerate charged particles backwards at ... 6 There is no theoretical reason to think it would work. Its inventor based it on his fundamental misunderstandings of relativity and basic Newtonian mechanics. (Amusingly, Shawyer's analysis assumes Earth's surface is at absolute rest...he appears to be a geocentrist [1].) Alternative theoretical explanations are at the level of handwaving attempts to explain ... 5 Short answer : No. We do not have storage capacity of energy in either electric or chemical form that would allow to convert back the chemical energy into electric energy if required, and allow us to propell a rocket into space.. Current achievements & Future work : But what does it mean to use electric power to propell a rocket? The general accepted ... 5 For inexpensive, especially per ton of payload launched to high velocity you could consider the nuclear shotgun or project orion. There are a few environmental and regulatory issues, and the shotgun is probably not suitable for delicate payloads like humans. 5 In principle, ion thrusters can be scaled to very large thrusts, but their thrust per watt of input power is inherently low. This means that the power supply for any electrical thruster is going to be very heavy, so the thrust-to-weight ratio is always going to be low. This holds for solar, radiothermal, and even nuclear reactor supplies; it's possible that ... 5 Specific heat, also known as heat capacity, in J/kg K (Joules per kilogram per Kelvin). Water, of all liquids, has the highest specific heat; ammonia and hydrazine have much lower specific heats. Also, most metals don't react with gaseous hydrazine, it being an oxygen slurper. The chapter "Conclusions and Recommendations", p. 24 sqq of this document, ... 5 It is certainly possible to mount electronic components to survive 100G, see HARP which had instrumented rounds firing at thousands of G. The fundamental step is to mount everything in epoxy with the aim to have everything be roughly the same density with no air gaps or denser sections to keep forces in direction of motion, not attempting to displace things ... 5 Ion thrusters are usually specified with two numbers: thrust and electrical power. As an example, let's take the NSTAR engine of DS1. According to Wikipedia it produced 92 mN thrust at a power of 2.3 kW. Now we can apply Newtons well-known formula to determine the acceleration $$F = m \cdot a \quad \rightarrow a = \frac{F}{m}$$ as well as the velocity change ... 5 The amount of propellant required to achieve a certain delta-V is dependent on the ratio between the starting and ending mass of the spacecraft, according to the Tsiolkovsky rocket equation; a given thruster and fuel supply will get you more delta-V on a smaller spacecraft and less delta-V on a larger one. That is, 0.058 km/s per kg is not an inherent ... 5 With current technology: 4.3AU. From wikipedia, it appears that the most powerful flight-proven RTG had a power density of 5.4W/kg. From NASA, current (as of 2017) solar technology has a power density of 100W/kg. The power output of a solar cell drops off with the square of the distance from the sun. So, let's assume we have 1 kW at 1 AU. The mass of this ... 5 So the basic fact is that the delta-V from LEO to LLO (low lunar orbit) using a high-thrust system is about 4 km/s and using a low thrust system it's about 8. source So, using something like a vacuum raptor engine ($I_{sp}$382s) you need a mass ratio of about 2:1. That is, for every ton you want to deliver to LLO you need 2 tons of methalox in LEO. Using ... 4 No. Electric power has a very low thrust. It would require an enormous amount of energy to lift, far beyond even the most concentrated engine today. The closest is the Electron Rocket, which uses batteries to run the turbopumps vs exhaust from the rocket that most systems today use. But that still isn't really electric, only one portion of the rocket is ... 4 No. If there were an alternative that is both inexpensive and more efficient than chemical fuels, it would be used already. There is one promising candidate: several companies are working on rocket engines that burn methane with LOX, with potentially better performance than the usual RP-1/LOX. The big challenge in ion thrusters is scaling them up and ... 4 Beam Powered Propulsion - firing a laser up the rear end of a vehicle to heat some reaction mass - is a proposed method for both launch to space and in space. It would be electrically powered. Variants of beam powered propulsion include giving added push to solar sails and electric thrusters using power beamed to the spacecraft (to PV panels) rather than ... 4 Cold gas thrusters are about the most energy-efficient propulsion system actually used. They can give quite high amounts of thrust (as Mythbusters demonstrated on a couple episodes with things like scuba tanks), and the propellant can literally just be compressed air (nitrogen or helium are more likely), but they are hopelessly low performance for a primary ... 4 If by "pressure in the thrust beam" you mean the force on the vehicle from the beam, that's just called thrust. (The pressure of the plasma itself is minuscule, and not really of interest.) Then the three things you're talking about are related simply:$T=g_n I_{sp}{dm\over dt}$, where$g_n\$ is the standard gravitational acceleration at the surface of the ...

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To add to Mark Adler's right-on-the-money (as usual!) answer: although ionization method doesn't explicitly enter into the classical performance equations, this paper discusses the non-unity efficiencies involved in propellant ionization and their effects on electric propulsion system performance. The effects aren't huge: the paper quotes up to 6% loss of ...

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The first flown Ion Engine from the United States was the Deep Space One testbed mission, which was one of the Better-Faster-Cheaper missions of the late 1990s. However, the technology was around for quite a bit longer than that. The basic design, the Hall Effect thruster, was studied by both the US and the USSR in the 1960s, and the first public mention ...

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