Language
Country/Area
No result found
Spacecraft Returning to Earth: How Difficult is a Reusable Future?
In aerospace engineering, the concept of single-stage-to-orbit (SSTO) spacecraft has been the holy grail of space technology exploration. The ideal of this design is that a spacecraft can be launched from the Earth's surface into space and used again without loss upon return. While successful single-stage-to-orbit examples have emerged on other celestial bodies, such as the Moon and Mars, on Earth, such technology remains stuck in the theoretical and conceptual stages.
Reusable spacecraft have significantly reduced the cost of space missions, but realizing this concept faces huge technical challenges.
Historical background
In the 1960s, as the space boom took off, many early SSTO designs began to surface. One of the early designs was the disposable single-stage orbital space truck (OOST) proposed by Douglas Aerospace engineer Philip Bono. Since then, Bono has also proposed a reusable version ROOST.
Another early SSTO concept was Krafft Arnold Ehricke's proposed NEXUS, a design that could carry 2,000 short tons of cargo into Earth orbit and was planned for missions deep into the solar system.
Technical Challenges
Although the concept of SSTO has attracted the attention of many designers, in fact, single-stage spacecraft face various difficulties in the design and implementation. First, Earth's high gravity requires propulsion systems during flight to handle higher energy demands than other planets.
On Earth, the SSTO spacecraft needs to reach an orbital speed of 7,400 meters per second, which poses a great challenge to propulsion technology.
Propulsion system and fuel considerations
In terms of fuel selection, hydrogen fuel is favored because of its high specific impulse. The combination of hydrogen fuel and oxygen can provide the highest propulsion efficiency, but there are many difficulties in its storage and use.
In comparison, other higher-density fuels such as aviation kerosene are also receiving attention because they are easier to store and use and can provide better performance in some designs. According to research, fuels of different densities have little difference in performance in launch systems, making fuel selection an important design consideration.
Future Outlook
In the 21st century, with the advancement of rocket technology, launch costs have dropped significantly. As a result, the initial advantages of SSTO are no longer so obvious. Although many concepts, such as Skylon and DC-X, have received widespread attention, none have yet reached actual operation.
With the advancement of material technology, realizing the dream of SSTO that was once considered impossible is now possible.
Conclusion
Single-stage to orbital systems remain an important issue for future space exploration. Faced with high design and engineering costs, propulsion system requirements and technical requirements, these make it very difficult to achieve reusable spacecraft. However, with the advancement of technology, especially the development of materials and propulsion methods, the future may still be full of possibilities. Facing the current challenges, can mankind overcome numerous difficulties and truly realize a reusable spacecraft that returns to Earth?
