Space exploration has come a long way since the first satellite was launched in 1957. Today, spacecraft are powered by a variety of sources, including solar energy, chemical fuels, and nuclear power. Nuclear power is particularly advantageous for space exploration due to its compactness, long service life, and other attributes. In this article, we'll explore why nuclear power is so important for spacecraft and how it can be used to power both life support and propulsion systems. Nuclear-based systems have less mass than equivalent power solar cells, making them ideal for more compact spacecraft that are easier to orient and steer in space. This is especially beneficial for manned spaceflight, as nuclear power concepts can reduce both cost and flight time.
Nuclear fission derives energy from the division of atomic nuclei, while nuclear fusion does so by binding them together, releasing energy in the process. Webinar participants heard about systems that can use both fission and fusion for spacecraft propulsion, extraterrestrial surface power and energy for onboard spacecraft systems. Rockets taking off from Earth will rely on chemical fuels in the foreseeable future. However, once in orbit, nuclear engines could take control and provide propulsion to accelerate the spacecraft through space. Nuclear power reactors use controlled nuclear fission in a chain reaction. With the use of neutron absorbers, the reaction rate is controlled, so the power depends on the demand.
The Cassini spacecraft was carrying three RTGs (Radioisotope Thermoelectric Generators) that provided 870 watts of power from 33 kg of plutonium oxide 238 while exploring Saturn. Beyer added that in recent years, Congress has continued to fund the development of nuclear space technology at NASA with the aim of conducting a future flight test in space. With thermal nuclear propulsion, reactors heat propellants like hydrogen and then the gas from that reaction is expelled, creating thrust. DARPA is investing in nuclear propulsion for spacecraft in the hope of successfully demonstrating an engine that can fly great distances in cislunar space, the area between Earth and the Moon. One way to reduce crew exposure would be to use nuclear propulsion, significantly reducing transit time. Roskosmos director says development of megawatt nuclear space power systems for manned spacecraft is crucial if Russia wants to maintain a competitive advantage in the space race, including exploration of the Moon and Mars.
The next phases of the program will focus on the design, development, manufacture and assembly of a nuclear thermal rocket engine. Heat pipe power system (HPS) reactors are compact, fast reactors that produce up to 100 kWe for about ten years to power a spacecraft or planetary surface vehicle. UNOOSA recognizes that “for some missions in outer space, nuclear power sources are particularly suitable or even essential because of their compactness, long service life and other attributes” and “that the use of nuclear power sources in outer space should focus on those applications that take advantage of the properties of nuclear power sources.” The bimodal versions will operate electrical systems on board a spacecraft, including powerful radars, in addition to providing propulsion. The SAFE-400 space fission reactor (safe and affordable fission engine) is a 400 kWt 100 kWe HPS for powering a spacecraft using two Brayton power systems: gas turbines driven directly by the reactor's hot gas. Fusion rockets such as the Princeton reverse-field configuration reactor concept being developed at the Princeton Plasma Physics Laboratory would have the advantage of producing a direct fusion drive (DFD), which would directly convert the energy of charged particles produced in reactions from fusion to propulsion for the spacecraft. Compared to nuclear electric plasma systems, these have much more thrust for shorter periods and can be used for launches and landings. Nuclear power has many advantages over other forms of energy when it comes to powering spacecraft. Its compactness allows for more efficient designs that are easier to orient and steer in space.
It also reduces cost and flight time when used for manned spaceflight. Nuclear fission and fusion can both be used for propulsion and energy production onboard spacecraft systems. Heat pipe power system reactors are also compact and fast reactors that produce up to 100 kWe for about ten years to power a spacecraft or planetary surface vehicle. Fusion rockets have even more thrust than electric plasma systems and can be used for launches and landings.