Regan Brown
The Cassini-Huygens mission was a joint effort between NASA, the European Space Agency, and the Italian Space Agency. The spacecraft, which launched in 1997, was powered by 32.7 kg of nuclear fuel, mainly plutonium dioxide. It had a total of 6565 pounds of propellant at the start of its mission, and by the end, had used 6504 pounds, with only 1% of its fuel remaining. The nuclear fuel was essential to the mission's success, as it enabled the spacecraft to operate at significant distances from the Sun, where solar power would not be feasible.
| Characteristics | Values |
|---|---|
| Fuel | 6,565 pounds (2,978 kilograms) |
| Fuel used | 6,504 pounds (2,950 kilograms) |
| Remaining fuel when crashed into Saturn | 1% |
| Fuel type | Plutonium-238 |
| Plutonium-238 weight | 28.3 kg (62 lb) |
| Plutonium-238 type | Plutonium dioxide |
Explore related products
What You'll Learn
Cassini's fuel was a mix of plutonium dioxide and plutonium-238
The Cassini spacecraft carried 6565 pounds (2978 kilograms) of fuel when it launched on October 15, 1997. Its fuel was a mix of plutonium dioxide and plutonium-238. Plutonium-238 is a rare, radioactive isotope that does not emit neutrons. Instead, it emits alpha particles as it decays, and this radiation can be stopped with a sheet of paper. Plutonium-238 is not used in nuclear bombs, unlike its weapons-grade sister isotope, plutonium-239. Plutonium dioxide is produced by dissolving plutonium in a silver-catalysed process, separating the plutonium from americium/silver, separating americium from silver, and then recovering the silver.
Plutonium-238 is a vital power source for deep-space missions like Cassini. It has been used in NASA's Voyager probes and the New Horizons Pluto probe. Plutonium-238 is made by irradiating neptunium-237, which is recovered from research reactor fuel or special targets, in research reactors. This process takes place in nuclear reactors that are about as wide as a 55-gallon (208-liter) drum.
The plutonium-238 in Cassini was sealed inside shells made of iridium, a super-tough, and super-precious element. These shells were designed to contain the plutonium in the event that Cassini accidentally reentered Earth's atmosphere. Each RTG (radioisotope thermoelectric generator) wraps several kilograms of plutonium-238 with materials that convert escaping heat into electricity. Cassini's three RTGs provided the spacecraft with a steady electrical power supply of nearly 900 watts, enough to power a microwave oven.
The Cassini mission ended on September 15 to prevent losing control of the robot and contaminating watery moons that might harbour alien life. During the mission's ""Grand Finale," the plutonium-238 was expected to be the last part of Cassini to melt and disintegrate as the probe plowed through Saturn's atmosphere. The plutonium inside would sprinkle across Saturn like a radioactive shooting star, but it would quickly dissipate due to the extreme heat.
GFuel Shipping Costs: How Much Does It Cost?
You may want to see also
Explore related products
It carried 32.7kg (72lb) of nuclear fuel
The Cassini spacecraft carried 32.7 kg (72 lb) of nuclear fuel, mainly plutonium dioxide (containing 28.3 kg (62 lb) of pure plutonium). The fuel was in the form of iridium-clad pellets of plutonium-238, developed by the Department of Energy. This fuel was essential to the mission, powering the spacecraft and enabling it to operate at significant distances from the Sun where solar power systems would not be feasible.
The nuclear fuel provided the heat and electricity that kept Cassini responsive throughout its journey. This power source, known as a radioisotope thermoelectric generator (RTG), has been used successfully in previous US missions. The RTGs were lightweight and compact, allowing the spacecraft to carry out its mission without being weighed down by bulky power systems.
The Cassini mission, a joint effort between NASA, the European Space Agency, and the Italian Space Agency, lasted from its launch in 1997 until 2017, with several extensions. The spacecraft travelled a total of 4.9 billion miles, including 1.2 billion miles with respect to Saturn, and made 162 targeted flybys of Saturn's moons.
The mission came to an end when Cassini ran out of fuel and crashed into Saturn, burning up in a fireball. At the time of its demise, the spacecraft had about 1 percent of its fuel remaining. Despite this low fuel level, the Cassini team successfully navigated the spacecraft to the end of its mission, gathering valuable scientific data.
Wawa Fuel Service: Competitive Pay for Specialists
You may want to see also
Explore related products
It used 99% of its fuel before crashing into Saturn
The Cassini spacecraft had a weight of 12,593 pounds (5,712 kilograms) at launch, which included the weight of the fuel, Huygens probe, adapter, and other components. By the end of its mission, it had travelled about 4.9 billion miles (7.8 billion kilometres) with respect to the Sun and 1.2 billion miles (1.9 billion kilometres) with respect to Saturn.
Cassini's mission came to an end on September 15, 2017, when it plunged into Saturn's atmosphere, transmitting scientific data until its small thrusters could no longer keep the spacecraft's antenna pointed at Earth. The decision to end the mission in this manner was made to ensure that Saturn's moons, particularly Enceladus and Titan, remain pristine for future exploration.
In its final months, Cassini was placed on an impact course that unfolded over five months of daring dives, including 22 orbits that passed between Saturn and its innermost ring. During these final orbits, Cassini's altitude above Saturn's clouds varied from 1,000 to 2,500 miles (1,600 to 4,000 kilometres). The final five orbits took the spacecraft through Saturn's uppermost atmosphere, resulting in a loss of signal at an altitude of approximately 1,500 kilometres above Saturn's cloud tops.
Cassini's fuel usage was carefully managed throughout its journey, with accurate spacecraft navigation and rigorous remaining propellant estimation. By the end of its mission, it had used 6,504 pounds (2,950 kilograms) out of its original 6,565 pounds (2,978 kilograms) of propellant, amounting to 99% of its fuel. This efficient propellant use allowed Cassini to complete its primary mission and multiple mission extensions, including the Cassini Solstice Mission and the Grand Finale.
Aviation Fuel Weight: 100LL Fuel's Weight Per Gallon
You may want to see also
Explore related products
Cassini was powered by radioisotope thermoelectric generators (RTGs)
RTGs are used on NASA missions where other power options, such as solar power, are impractical or incapable of providing the necessary power for a mission's scientific or operational goals. They are particularly useful for spacecraft that travel far from the Sun, such as the Pioneer 10 and 11, Voyager 1 and 2, Galileo, Ulysses, Cassini, and New Horizons missions. The first RTG launched into space by the United States was the SNAP 3B in 1961, which was powered by 96 grams of plutonium-238 metal. Since then, more than two dozen U.S. space missions have utilized RTGs.
The probability of an accident occurring that caused a radioactive release from one or more of Cassini's three RTGs during the first 3.5 minutes following launch was estimated at 1 in 1,400. The chances of a release later in the ascent into orbit were 1 in 476, and after that, the likelihood of an accidental release fell off sharply to less than 1 in a million.
RTGs are not fission reactors, and the plutonium they use is not the type employed in nuclear weapons. The radioactive material inside an RTG will decrease in power over time. For example, by the year 2000, 23 years after production, the RTG's power output had decreased by 16.6%. NASA has developed a multi-mission radioisotope thermoelectric generator (MMRTG) that uses skutterudite, a cobalt arsenide (CoAs3), which can function with a smaller temperature difference than current tellurium-based designs.
The Devastating Impact of Fossil Fuel Spills
You may want to see also
The RTGs were lightweight, compact, and enabled travel far from the Sun
The Cassini-Huygens probe, which launched in 1997, used three Radioisotope Thermoelectric Generators (RTGs) to generate electrical power. RTGs are used on NASA missions where other power sources, such as solar power, are impractical or insufficient for the mission's scientific and operational goals. RTGs are particularly useful for powering spacecraft that travel far from the Sun, as solar panels would be inefficient in these contexts.
RTGs are lightweight and compact, each with a mass of about 57 kg and an overall diameter of 0.422 m and a length of 1.14 m. They generate about 300 watts of electrical power at the start of a mission, using about 8.1 kg of Pu-238, which produces about 4,400 watts of thermal power. The plutonium oxide fuel is in 18 GPHSs, which are cuboid and contain cylindrical plutonium-based pellets. The use of RTGs allows for greater flexibility in landing sites and longer lifespans than solar-powered options.
The Cassini spacecraft also carried 82 strategically placed Radioisotope Heater Units (RHUs), which provided warmth in the form of one watt of thermal power each, using a pencil eraser-sized pellet of plutonium oxide. The Huygens probe used 35 similar RHUs to keep it warm during its descent to Titan.
While RTGs offer significant advantages in terms of power generation and compactness, they also pose a risk of radioactive contamination. If the container holding the fuel leaks, the radioactive material could contaminate the environment. However, the Cassini-Huygens probe took several precautions to minimise this risk, including storing the fuel in individual modular units with their own heat shielding, surrounded by layers of iridium metal, high-strength graphite blocks, and an aeroshell to protect against the heat of re-entering the Earth's atmosphere.
Brazil's Fuel Blend: Ethanol's Role
You may want to see also
Frequently asked questions
Cassini carried 6565 pounds (2978 kilograms) of fuel.
Cassini was powered by 32.7 kg (72 lb) of nuclear fuel, mainly plutonium dioxide (containing 28.3 kg or 62 lb of pure plutonium).
Yes, Cassini had enough fuel to complete its primary mission. However, the two extended missions drove fuel levels down to nearly zero. By the time the probe crashed into Saturn, it had about 1% of its fuel left.
Cassini's fuel was used to power the spacecraft and enable it to operate at significant distances from the Sun. The heat from the nuclear fuel's radioactive decay was turned into electricity.
