# Questions tagged [energy]

Questions addressing the energy requirement for space/orbit/interplanetary missions.

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### Rocket Turbopump Energy Balance

The exhaust velocity of a rocket is given by: $v_e = \sqrt{\frac{2k}{k-1} \cdot R \cdot T_c \cdot (1-(P_e/P_c))^{\frac{k-1}{k}}}$ The velocity tends to a finite asymptote as $P_c$ increases. Therefore,...
1 vote
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### What is the relationship between the power supply system and the thermal control system?

According to Wikipedia, the solar panels of the ISS produce an average of about 120 kW of electrical energy, which is then used by the station's systems. Can it be converted into something other than ...
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### Calculation of the total energy of a spaceplane

I am trying to calculate the total energy change of a spaceplane during its flight time. From the data I have and the calculations I made, I created an excel table in which I included: flight time : ...
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### How much of a rocket energy is needed to overcome aerodynamic drag?

this question How much of a rocket's energy is used to achieve altitude vs horizontal velocity? addresses the energy split of kinetic vs. potential energy to get to space - and to stay there. We ...
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### Does the Orbital energy of a satellite in an elliptical orbit depend on the semi-major axis of the orbit?

I am learning about Space exploration and I have the following question: Does the Orbital energy of a satellite in an elliptical orbit depend on the semi-major axis of the orbit? Thanks!
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### best way to generate electricity on any planet's dark side

What options are available for generating electricity in a space colony if it is at the planet's darkest point all year around without help from nearby outposts?
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### Icy Hot Astronauts [duplicate]

According to the specifications of the Apollo 13 lunar module where the astronauts were during their emergency return to Earth, the walls were about the thickness of a coke can so how were they able ...
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### What's the point of characteristic energy?

My understanding of orbital mechanics is that delta-v is the most useful notion of ability to change orbits in space, akin to energy being the most useful notion of the ability to do work. But if ...
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1 vote
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### Energy to "nudge" a planet to a smaller orbit

Suppose we wanted to move a mass-$m$ planet to a much smaller new orbit around our mass-$M$ Sun. We'll assume the initial and final orbits are circles of radii $r_i,\,r_f$ with $r_f\ll r_i$, so GPE is ...
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### What are the energy requirements to reach Earth orbit and Mars orbit assuming no efficiency losses?

Suppose some magic propulsion method exists which directly converts electricity into kinetic energy. And its efficiency is 100%. And its weight is 0. What is a way to calculate the energy requirements ...
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### Energy from Earth's magnetic field using space tether

The NASA's space tether experiment in 2001,called for a scientific payload--a large, spherical satellite--to be deployed from the US space shuttle at the end of a conducting cable (tether) 20 km long. ...
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### Why are RTGs so inefficient?

I recently learned about how an n-type and p-type "sandwich" with different thermal properties can create a potential difference in the presence of a temperature gradient. The subsequent ...
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### Can we generate electricity from Martian sandstorms? If so can it be used for powering colonies?

Rapidly varying electric fields inside dust storms have been observed and studied for years. The winds in the strongest Martian storms reach 60 miles per hour.
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### Most energy efficient food production for sustainable human life support

Say you want to build a base at a place where conventional food deliveries from Earth would be very expensive. What will be the most energy-efficient food production process that could feed humans, ...
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### Can I "tack" towards a laser beam from which I am powering my 100% efficient & massless ion engine?

As far as I know, for light and particles taking special relativity into account: \begin{align} E^2 &= (T + m_0c^2)^2\\ &= p^2 c^2 + m_0^2 c^4 &\text{ (particles)}\\[1.5em] E &= p ...
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### What are the nuclear energy challenges specific to the moon?

What are moon specific hurdles to a fission reactor? low gravity no atmosphere Apparently it's more difficult to shed heat in a vacuum. Are some coolants more advantageous on the moon than others? ...
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### How much of the energy of a rocket ends up as a noise?

Rocket launches are notoriously loud. So much so that measures are taken to prevent the noise/vibrations from damaging the rocket, the pad, or basically anything else within a few hundred meters. How ...
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### How much does launch costs have to come down to make chemical fuel deep space probes feasible?

Considering that NASA have been running short of plutonium for their RTGs, it makes sense to consider alternatives. For the inner solar system up to Jupiter, solar cells have been demonstrated on ...
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### Most efficient method of storing energy with water on the moon?

I found a large cavern under my lunar homestead. It is several hundred feet (a couple hundred meters) deep and fairly large. There is a large ice deposit at the bottom. I am able to warm it to ...
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### Why is there no concerted effort to collect solar energy on a global scale?

edit and update: the assumption here is that necessary batteries for storing solar energy simply aren't available on a global scale (without intending to get into the veracity of such a statement).) ...
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### Would capture of a uranium-rich asteroid open new possibilities?

It seems that energy production in space is a limiting factor. We can use photovoltaics, but they're of minimal value past Mars, and many interesting places (like the moon) have very long nights. The ...
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### Challenges to building a human habitat on Titan (Saturn's Moon)?

I have been studying Titan for a while, reading documents from Cassini and Huygens (probes). On Titan there is an atmosphere, layer of clouds, seas of hydrocarbons (fuel and plastic for many centuries)...
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### How do Stirling radioisotope generators maintain a temperature differential in a vacuum?

I was reading the wikipedia page on RTGs and happened to stumble upon the section about efficiency. There were three methods that seemed to rely on direct conversion of thermal energy into electrical ...
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### Rocket explosion compared to kT of TNT; has one ever knocked something over at a distance?

The energy equivalent of 1 gram of TNT is about 1 kcal or large Calorie. For reference, 1 gram of carbohydrates gives us almost 4 Calories of energy (if we are lucky enough to use it and not store it)....
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### What is the largest energy stored in a spring or other stress-based energy storage device that's ever been put in space?

The question What is the largest delta-v ever produced in space from mechanically stored energy? asks of course about the delta-v produced, but here I'm asking about the largest amount of stored ...
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### Titan crude oil equivalent in Gbbl?

Despite the cost, what is the crude oil that is hydrocarbons energy equivalent which Titan could provide as referred to crude oil Gbbl compared to Earth? (Joules as common denominator) Here is what ...
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### Does it take more energy to get to Venus or to Mars?

Let's assume we use the ideal positions of those planets relative to Earth for launch. And let's assume the spacecraft is launched from the same place on Earth. Also let's assume the goal is to get ...
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### Why satellite’s solar panel wattage is often listed in specifications?

What is the purpose of listing the power output (Wattage) from solar panel, without the energy/power specification of batteries or other electrical storage devices? Do satellites often use the power ...
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### Can a solar mirror increase an ion engine 's output?

Could an ideal size solar sail work as a parabolic mirror to increase the out put of an ion engine? Would the extra weight encumber the ion engine nullifying the increases sunlight on the ion engine? ...
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### How much D2O does it take to power an interstellar generation ship O'Neill cylinder for 10,000 years?

Did I do the math right? I'm using full precision but write only 2 sig figs. https://en.wikipedia.org/wiki/Nuclear_fusion#Criteria_and_candidates_for_terrestrial_reactions ...
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### How feasible is wind energy generation on Mars? [duplicate]

Spacecrafts and rovers tend to have dust settled on their panel which leads to reduced power generation. If wind turbines could power the instruments, then the seasonality of solar power generation ...
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### What are the tradeoffs of circularly unfurling solar panel over linearly deploying solar panels?

Martian landers like Phoenix and Insight uses circularly unfurling solar panels. The regular satellites make use of linearly unfurling panels. What are the primary reasons why linear unfurling ...
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### "Free energy" moving the space elevator possible?

In this other question I have found the following: A space elevator can climb at a low, constant vertical speed (albeit for a very long climb), and gets its orbital speed for free [borrowed from ...
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### How come we don’t put a huge windmill-like machine in space? [closed]

I am new to this sight, but since space being a vacuum there is little to no air resistance at all making a windmill spin forever. There is no wind in space however, if you spin it once, it should ...
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### Can an Earth like planet support life by building a Dyson Sphere across a White Dwarf? [closed]

(Hypothetical Concept) But is it possible to depend on a white dwarf as our power source? Provided we harness its 99% of energy? Can life be sustained?(If it is possible we can easily colonize an ...
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### What are the energy-to-mass ratios of some fuels/oxidizers, when including the oxidizer?

Energy-to-weight ratio is an important parameter. We would like it to be high so we don't have to carry around much fuel. Maybe you've heard some of the numbers for common fuels. Hydrogen is about ...
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### Solar Flux on Mars Surface

Considering that the Solar Flux on top of Mars' atmosphere is 590 W/m2 (following the 1/r^2 relation for sunlight), how much of this incident light actually arrives to Mars. In other words, what is ...
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### Energy needed to open/close entry points in a rocket

In general, how often are air locks opened on a rocket? How much energy is needed to open and close the entry point?
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### Energy solutions for space [closed]

One of the primary methods of creating power in space is by solar panels. However upon reading more about silicon based solar panels I got to know how even small dust particles can ruin the whole ...
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### What does Specific power [W/kg] of a Solar Array exactly mean?

I am trying to size (weight and surface) a Solar Array for a Mars Base (university project) and the main specification I get is Specific Power [W/kg]. However, I need to relate both weight and surface,...
910 views

### In the absolute vacuum of Space, will an electric dynamo still work? [duplicate]

In the absolute vacuum of Space, will an electric dynamo still work? Can it produce an electric current if it is not inside (or being affected by) a magnetic field (like earth's magnetosphere)?
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### What type of electrical wiring provides the longest life in space?

It sound like standard electrical wire as you would use in earth bound transportation would have a significantly shorter life in the vacuum of space. (See related Do plasticizers evaporate in space?) ...
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### What is the distribution of ∆V amongst different stages of rocket flight?

How is rocket energy (or fuel consumption) is distributed between gaining orbital velocity gaining orbital height fight aerodynamic drag
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### 'Space Transit Habitat' source(s) of energy

What are the sources of energy for a Space Transit Habitat(manned) in terms of both propulsion( after passing over the Low Earth Orbit) and required electric facilities)through a 6-8 month voyage to ...
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### Power to grow food per person

Can I get a rough estimate of the power (in watts) needed to produce light to grow enough food for one person, using vertical farming of the kind proposed for space habitats? Any reasonable outpost/...
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### In an ion thruster, does the temperature of the plasma drop after acceleration?

In the last discussion on why ion thrusters are so energy hungry(Why are Ion Thrusters so energy hungry?), people said that the system is not only supposed to ionize the gas but also heat it to ...
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### Why don't ion thrusters use exothermic reactions directly to ionize the gas and heat up the plasma?

Ion thrusters require a lot of energy because of their high exhaust velocities. But why can't they just pump a mixture of hydrogen and xenon into the chamber, mix it with oxygen and burn it? Doesn't ...
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### What is the relation between the rocket equation and work, energy and power?

Say, I'm given the data typical to the Rocket equation in its many variants: $\Delta v, I_{sp}, m_f, m_0, ρ, T$ (thrust) and the likes. And someone asks me "What's the horsepower of the space shuttle ...
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### Why are Ion Thrusters so energy hungry?

Ion thrusters need a lot of energy. But I don't understand why. So, one thing I understand is that it takes a lot of energy to achieve a high exhaust velocity (since kinetic energy is proportional to ...
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