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ESA is working on such an engine. an ESA-led team has built and fired an electric thruster to ingest scarce air molecules from the top of the atmosphere for propellant, opening the way to satellites flying in very low orbits for years on end The molecules collected by the intake designed by QuinteScience in Poland are given electric charges so that ...


10

(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, ...


9

The number of thrusters doesn't matter (that will change how quickly you can execute your $\Delta v$, not the ultimate amount of change you can perform). Just take the efficiency figure from the engine (the linked page says $I_{sp}$ up to 5000s), and plug it in. You can then either take an existing mass fraction and solve for $\Delta v$, or plug in some ...


8

Probably not. To control the point of reentry, you need to be able to adjust from a perigee high enough to not promptly reenter (i.e. above 200km) to one low enough to promptly reenter (i.e. below 80km) in significantly less than the time it takes to complete a single orbit -- otherwise, the unpredictable effects of drag in the variable density upper ...


7

Why is the thrust to weight ratio of ion thrusters so low? Because (as the OP notes) the thrust is so low. Why is the thrust so low? Because the pressure/density of the plasm is so low. Why is the pressure/density so low? In order to give the electrons a long enough mean free path to build up tens of eV of energy before they hit their first atom. Why ...


6

Yes, according to multiple sources, including the answer to this question. The estimated drag forces on the ISS, on average, appear to be about 0.25N (although some estimates put it as high as 0.9N). So yes, in theory, a constant thrust could do it. Now, you'd have to contend with the power drain. I believe HiPEP thrusters use somewhere in the range of ...


6

Ruling out nuclear propulsion in the comments pretty much rules out electric thrusters of all flavours as well since the Juno mission is notable for pushing the limits of solar power, and only needs enough to operate sensors and radio link and is still 1/5 solar panels by dry weight (340 kg making 486 W, where electric demands for thrusters are in kW). For ...


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

Carbon-carbon (CC) grids were used on the mu10 microwave discharge ion thrusters on the 'Hayabusa' asteroid sample return mission. They are being used at this very moment on the Hayabusa2 spacecraft. I believe CC grids are planned to be used on the NEXIS engine for the NASA Jupiter mission and the Cross Enterprise Technology Development Program (CETDP). CC ...


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 ...


4

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 ...


3

According to wikipedia each Nustar engine on Dawn used 2100W, and achieved 92mN of thrust with an exhaust velocity around 30 km/s. So from the thrust and the exhaust velocity we can compute the Xenon mass flow as $0.092/30000 = 3\times 10^{-6} kg/s$. Now each kilogram of Xenon has a kinetic energy of $1/2 \times 30000^2 = 4.5\times 10^8 J/kg$ so the power ...


3

There are some examples of space reactors: 3kW@385kg: BES-5 5kW@1000kg: TOPAZ At your 24400kg weight budget that scales to 100-200kW electrical output. But these are thermionic(3% efficiency) and you may be able to do better with gas turbine (30%-50% efficiency), or not (secondary loop, turbine and generator machinery are heavy). Let's make a rough ...


3

This is going to depend very much on mission intent and time frame. If mission duration is in years and overall mass is small electric propulsion may work, and do so for lower overall mass. Especially if the mission on arrival requires large amounts of power so large solar cells are not wasted mass. If aim is to get there quickly and with a large payload (eg ...


3

Can't speak to the sea level Isp (other than agreeing with your intuition that it's bogus), but the thrust is clearly in error. NASA testing of the engine in 1993 showed < 100 mN thrust in vacuum, with associated Isp's between 1000 and 2000. source


3

Let's do a back-of-the-envelope calculation, carrying only one digit with whatever input data we can find. The satellites are about 200kg, and various commentators suggest the thrusters can provide about 100mN thrust or so. That's an acceleration of $0.5\times 10^{-3}$ m/s/s, or about 2m/s per hour. Even a small acceleration builds up quadratically, and ...


3

In this answer to What propulsion system would not pollute the surface when landing on a pristine celestial body? I ballpark estimated that the angular spread of an ion beam from an ion engine could be 1° or less based on plasma temperature. A small fraction of the ions passing nearest any acceleration grid wires might get deflected farther, but would be a ...


3

This seems like a relevant paper from 2017: Development of a 50,000s, Lithium-fueled, Gridded Ion Thruster. Diagram shows a laboratory setup, so not something that will actually fly. I found no examples of those. Details are not given for how an actually deployed system might differ. It looks pretty much like a lab setup described in 2001 paper, Lithium ...


3

The engines aren't particularly heavyweight, but we're handling lots of power in a very tiny volume. Lots of power means cooling. Gas accelerated to these energies becomes an extremely corrosive plasma, best held at bay by magnetic fields because otherwise the engine will be burning through itself. So - heavy electromagnets to guide the propellant. The ...


3

Electrical thrusters that use particles rather than ions exist. Most seem to be lower-performance (but higher-thrust) devices than the typical xenon ion thruster. In general, these devices seem to use sprayed liquid droplets rather than solid particles. https://en.wikipedia.org/wiki/Colloid_thruster


2

The SPT-100 thruster is described along with several others in the paper: Electric Propulsion Activity in Russia; IEPC-01-05, Presented as Paper IEPC-01-(05) at the 27th International Electric Propulsion Conference, Pasadena, CA, 15-19 October, 2001. Table 2 lists its specifications: Nominal operation mode power, kW: 1.35 Nominal thrust, mN: 80 ...


2

The description given matches that of the NERVA/Timberwind style nuclear thermal rocket, but it also applies to a more complex hybrid nuclear-thermal-electric engine described partway down this page (the section titled 'The True Hybrid'). In this scheme, hydrogen makes two passes through the reactor: in the first pass it's heated in order to drive a turbine ...


2

Would this engine produce any thrust? Yes, but not in the way you envision. Ice in a vacuum sublimates to steam, which will create a tiny bit of pressure (on the order of a few Pascals, barely enough to even measure). As the steam escapes down the tube and out into space, it will produce a slight thrust in the opposite direction. The fact that the sun is ...


2

You have to calculate the deltaV that these thrusters can provide you. You can do this by using the Rocket Equation. You need the ISP value of those thrusters and the starting and final mass of your cubesat (i.e. mass when you are deployed in LEO and mass after you have expended all your Xenon). That will give you the maximum available deltaV. This needs to ...


1

You can get a very approximate answer just from fundamental physics. Your ions probably have $e$ unit of charge (ie they are missing one electron), so in dropping through a potential $V Volts$ they will acquire $Ve$ Joules of energy. So if they have mass $m$ and exhaust velocity $v$ you will get $$1/2 mv^2 = Ve$$, so $$v = \sqrt{2Ve/m}$$ Now suppose the ...


1

I'm not sure if it's the first use of ion propulsion, but it's the first I know - and it's possible to argue it's a yet different propulsion because the principles differ from most ion engines used nowadays... Zond 2 launched on 30th November 1964, used six Pulsed Plasma Thruster motors for its attitude control. Unlike typical modern ion engines, where ...


1

Your formula is Power = 0.5 * Thrust * Exhaust velocity/efficiency. This equation gives to the beam power for all forms of propellant based propulsion. There could be several terms for efficiency, e.g. describing losses from the engine to the beam, electrical power conversion within the engine, power conversion from an external power source (e.g. the sun) ...


1

Ion thrusters need a power source. And power sources can be massive. This was a major objection to Franklin Chang Diaz' claim that VASIMR could get to Mars in 39 days. He assumed an alpha of .5 kg/KWe. Which isn't doable with present day state of the art. So what would a power source look like that cranks out a kilowatt electricity per half kilogram? I ...


1

Recently, I am also looking into this approach. It seems that carbon nanotube (CNT) fibers might be a promising option in the near future of 'rocket-launch-via-cable', due to its excellent conductivity and high strength. --------- Here are some ideas and calculations ---------- Consider the electric cable made of Carbon Nanotube Fibers with diameter $1mm$ ...


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