Sylvie Willis
Satellites are fascinating pieces of technology that have been used for decades to gather information and data from space. They are powered by solar energy and fuel, the latter of which is used to operate thrusters in a variety of situations. The amount of fuel a satellite carries depends on its mission and the length of time it is expected to operate. Modern satellites use hydrazine-based fuel, although this is toxic and the space industry is researching safer alternatives. Some satellites are launched with 3 tons of fuel and oxidizer each and are expected to last 15 years, although this number may vary depending on the satellite's total mass.
| Characteristics | Values |
|---|---|
| Fuel used by satellites in orbit | Hypergolic fuel |
| Fuel used by satellites out of orbit | Liquid hydrogen, kerosene, liquid oxygen |
| Fuel for station-keeping | Electric propulsion with xenon propellant |
| Fuel for satellite launch | 3 tons |
| Fuel for a satellite's intended orbital velocity | Depends on the equation of orbit: v = sqrt(GM/r) |
| Fuel for satellite disposal | Raised into a 'graveyard orbit' |
Explore related products
What You'll Learn
- Satellites use hypergolic fuel, not liquid hydrogen, kerosene or liquid oxygen
- Hydrazine is toxic, so the space industry is researching safer fuels
- Power isn't needed to keep a satellite in orbit, only for tasks like photography
- Solar energy helps with day-to-day tasks, but fuel is needed for movement
- Fuel is required to reach orbital velocity and overcome air resistance
Satellites use hypergolic fuel, not liquid hydrogen, kerosene or liquid oxygen
Satellites are launched with some fuel, which is used to operate thrusters in a variety of situations. For example, fuel is used to move the satellite into the intended orbit, increase the speed and altitude of a low Earth orbit (LEO) satellite, and avoid collisions with other satellites or space debris.
Satellites in orbit do not use liquid hydrogen, kerosene, or liquid oxygen. Instead, they use hypergolic fuel. Hypergolic propellants are fuels and oxidizers that ignite spontaneously when they come into contact with each other and do not require an ignition source. This makes them uniquely suited for spacecraft maneuvering and well-suited for upper stages of space launchers like the Delta II and Ariane 5. The most common hypergolic fuels are hydrazine, monomethylhydrazine, and unsymmetrical dimethylhydrazine (UDMH), and the oxidizer is nitrogen tetroxide. These hypergolic fuels are all liquid at ordinary temperatures and pressures, so they are sometimes called "storable liquid propellants".
Liquid oxygen (LOX) is the main oxidizer used in most modern rocket propellants. It is typically combined with either liquid hydrogen, refined petroleum (RP-1), or liquid methane to create powerful rocket fuel combinations. However, these fuel combinations are not used by satellites in orbit. LOX is safe to handle compared to other substances, and it can be kept at cryogenic temperatures for long periods, making it suitable for use in rockets that must be kept launch-ready for extended periods.
Kerosene-burning engines produce enough residue to limit their operational lifetimes. Kerosene is also not suitable for use as a hypergolic propellant when combined with cold hydrogen peroxide. However, when hydrogen peroxide is run over a catalyst, it decomposes into free oxygen and steam at over 700 °C, which is hypergolic with kerosene.
The trend among Western space agencies is moving away from large hypergolic rocket engines and towards hydrogen/oxygen engines or methane/oxygen engines for various advantages. However, hypergolic propellants are still used in upper stages when multiple burn-coast periods are required and in launch escape systems.
Business Jet Fuel Efficiency: Burning Questions Answered
You may want to see also
Explore related products
$170.22 $209
Hydrazine is toxic, so the space industry is researching safer fuels
The amount of fuel a satellite carries depends on its total mass, expected lifetime, and specific mission requirements. On average, a satellite with a total mass of 3 tons can carry 3 tons of fuel and oxidizer, with a 15-year expected lifetime. However, the type of fuel used is just as important as the quantity.
Hydrazine-based fuels are currently the standard propellant for satellites. They are highly predictable and stable, with a flat pressure profile during firing, making them ideal for space missions. However, hydrazine is highly toxic, and exposure to high levels of it can cause severe health issues, including damage to the liver, kidneys, and central nervous system. Its explosive nature also poses a significant risk during ground operations. As a result, handling hydrazine requires special precautions, including specialized space suit-like clothing to protect workers.
Recognizing the hazards of hydrazine, the space industry is actively researching and developing safer alternative fuels. One example is the HyproGEO project, coordinated by aerospace company Airbus, which has developed a non-toxic hybrid propulsion system for satellites in geostationary orbit. This system uses a highly acidic form of hydrogen peroxide as fuel, which breaks down into oxygen and water without releasing harmful fumes.
Other promising alternatives to hydrazine include nitrous oxide-based propellant combinations, with companies like Dawn Aerospace, Impulse Space, and Launcher leading the development. In 2021, D-Orbit successfully flew the first nitrous oxide-based system in space onboard their ION Satellite Carrier. Additionally, NASA's Green Propellant Infusion Mission (GPIM) will test a non-toxic alternative fuel on a SpaceX Falcon Heavy rocket.
The transition to new propulsion systems and fuels requires disrupting existing procedures and infrastructure, which can be challenging. However, the potential health, safety, and environmental benefits of adopting non-toxic and less hazardous fuels for satellites strongly motivate the space industry to explore these alternatives.
Billion-Dollar Fossil Fuels: Who Profits From Our Planet's Peril?
You may want to see also
Explore related products
Power isn't needed to keep a satellite in orbit, only for tasks like photography
A satellite in orbit doesn't generally need power to keep orbiting. Power is only needed for tasks like photography, transmitting data to Earth, and receiving transmissions from Earth. The initial speed of a satellite when it is launched is usually enough to keep it in orbit for hundreds of years. This speed is maintained when the satellite detaches from the launch rocket and is fast enough to counter the downward pull of gravity.
Satellites do carry their own fuel supply, but this is not used to maintain speed for orbit. Instead, fuel is used for changing orbit, increasing the speed and altitude of a low Earth orbit (LEO) satellite, and avoiding collisions with other satellites or space debris.
The fuel used by satellites is generally hydrazine-based. However, hydrazine is toxic and must be handled with full-body protective gear. As a result, the space industry is researching safer alternatives.
Solar energy is another source of power for satellites. The first solar-powered satellite, Vanguard 1, was launched in 1958 and has now been in space for over sixty years. Solar energy is a reliable source of power for satellites because, unlike Earth-based solar panels, satellites don't experience reduced energy production on overcast days. However, satellites don't always have access to solar energy when the Earth is between the satellite and the sun, so they need an alternative power source for these periods of darkness.
Fuel Consumption of 5000-Watt Generators: How Much?
You may want to see also
Explore related products
Solar energy helps with day-to-day tasks, but fuel is needed for movement
Solar energy is an essential source of power for satellites, enabling them to carry out their daily tasks and communications. Satellites are equipped with solar panels that convert sunlight into electricity, powering their electronic systems and facilitating their designed functions. This clean energy source offers numerous advantages, including reduced interference with plant and wildlife, zero hazardous waste, and the absence of competition for scarce freshwater resources.
However, solar energy alone cannot fulfil all the energy requirements of a satellite. While solar power keeps the satellite operational, fuel is necessary for movement and specific functions. Satellites are typically launched with a certain amount of fuel, which is used for manoeuvring and addressing potential risks. This fuel, currently often hydrazine-based, is crucial for moving the satellite into its intended orbit, adjusting its altitude and speed, and avoiding collisions with space debris or other satellites.
The amount of fuel carried by a satellite depends on its mission and specifications. On average, a satellite with an expected lifetime of 15 years may carry around 3 tons of fuel and oxidizer. However, this figure can vary, and some satellites may carry less fuel, depending on their mass and specific requirements. It's worth noting that satellites don't rely on traditional fuels like liquid hydrogen, kerosene, or liquid oxygen; instead, they use hypergolic fuel, which doesn't require oxygen due to the challenges of long-term oxygen storage in space.
The satellite's orbit plays a crucial role in its fuel consumption. Satellites in low Earth orbit (LEO) experience atmospheric drag, causing their orbit to decay over time. As a result, they require occasional reboosting to maintain their orbit. On the other hand, a satellite in a higher orbit may not need as much fuel for station-keeping, as gravity and the lack of friction in space can keep it moving.
In conclusion, solar energy is instrumental in powering satellites and enabling their routine operations. However, fuel remains essential for satellite movement, orbit adjustments, and collision avoidance. The balance between solar power and fuel usage ensures the satellite's functionality and longevity in the vastness of space.
The Blue Angels' Fuel Costs: A Pricey Performance
You may want to see also
Fuel is required to reach orbital velocity and overcome air resistance
The amount of fuel a satellite carries depends on its mission. Satellites don't use much fuel for station-keeping, and solar energy helps them carry out day-to-day tasks and communications. However, fuel is required to move the satellite into its intended orbit and to maintain its orbit over time.
To reach orbit, a satellite must overcome air resistance and achieve orbital velocity. Orbital velocity is much harder to achieve than orbital height. To achieve a full orbit of Earth, a spacecraft must travel five times faster than the V-2 rocket, which had a top speed of about 3,500 miles per hour. To escape Earth orbit and head towards the Moon, a craft must reach 25,000 miles per hour, requiring a significant amount of fuel.
The rocket equation, developed by Tsiolkovsky, calculates the amount of fuel needed for a journey through space. The biggest challenge is boosting the "excess" mass, mainly the fuel required to transport the fuel burned later in the journey. The multistage vehicle was invented to address this problem, with powerful rockets dropping away sequentially when their fuel supply is exhausted.
In addition to fuel for orbital velocity, extra fuel is needed to overcome air resistance. The exact amount depends on various factors, including the rocket's flight profile, engine efficiency, and the weight of lower stages carried during part of the journey. For example, the Falcon 9 FT has a fuel capacity of 155,800 kg for the first and second stages combined.
To maintain their orbit, satellites use thrusters to increase their altitude and speed, counteracting the effects of atmospheric drag, which can cause their orbit to decay over time. Some satellites are launched with 3 tons of fuel for an expected lifetime of 15 years. However, this may vary depending on the satellite's mass.
Nuclear Energy: Superior Alternative to Fossil Fuels?
You may want to see also
Frequently asked questions
The amount of fuel a satellite carries depends on its total mass. Satellites launched with 3 tons of fuel and oxidizer each are expected to have a lifetime of 15 years. However, 3 tons is considered excessive, as many satellites have a total mass that is less.
No, a satellite in orbit doesn't generally need power to keep orbiting. Power is required for a satellite's electronic systems, such as photography and transmitting to or receiving transmissions from Earth.
Satellites in orbit use hypergolic fuel, such as hydrazine, and electric propulsion with xenon propellant.
The equation of orbit is: v = sqrt(G*M/r), where G is the gravitational constant of the universe, M is the mass of the Earth, and r is the radius or distance from the centre of the Earth.
