What computing power is required for space travel? Understanding processing needs for manned space missions.

Context

This question aims to understand the level of computing power needed for manned space missions, particularly in the context of historical comparisons (e.g., toasters having more power than early spacecraft computers). It explores whether space travel is possible without computers, relying solely on physics and electrical controls, and seeks a simplified explanation of relevant terms and concepts.

Simple Answer

• Think of computing power as the brain of the rocket, telling it where to go and how to get there.
• Early space missions used computers, but they were much less powerful than your phone today.
• Computers help with navigation, controlling the engines, and communicating with Earth.
• You could theoretically launch a rocket using just physics, but it would be very hard to control and land safely.
• Electrical controls like thrusters do use some computing, but mostly just to turn them on and off; the computer decides *when* to turn them on or off.

Detailed Answer

The computing power needed for a space mission isn't just about having a powerful computer; it's about having a reliable and accurate system that can perform specific tasks critical to the mission's success. These tasks include navigation, guidance, control, communication, and life support. Navigation involves determining the spacecraft's position and velocity in space. Guidance involves calculating the trajectory needed to reach the destination. Control involves adjusting the spacecraft's orientation and thrust to follow the calculated trajectory. Communication is crucial for transmitting data to and from Earth, and life support systems need constant monitoring and adjustment to ensure the safety and wellbeing of the astronauts. Early space missions like the Apollo program relied on relatively simple computers compared to modern technology, but they were specifically designed and rigorously tested to perform these essential functions reliably. Therefore, the measure isn't solely clock speed or memory, but the system's ability to handle the specific requirements of space travel. Redundancy and fault tolerance were also vital considerations. This meant multiple systems to back each other up, which in many ways made the computers of that time bulkier and seemingly more complex.

The comparison between the computing power of a modern toaster and the Apollo guidance computer is often used to illustrate the rapid advancement of technology. While it might be technically true that a modern toaster contains a processor with more raw processing power than the Apollo guidance computer, this comparison is misleading. The Apollo guidance computer was designed for a specific purpose: to guide the Apollo spacecraft to the Moon and back. It was built with components that were lightweight, power-efficient, and resistant to radiation, all critical considerations for space travel. A toaster, on the other hand, is designed for a completely different task and prioritizes different characteristics, such as cost-effectiveness and ease of use. The Apollo Guidance Computer (AGC) was innovative in its software design. It was one of the first computers to use integrated circuits, which significantly reduced its size and weight. The software was written in assembly language and had a real-time operating system that could handle multiple tasks simultaneously. This allowed the astronauts to interact with the computer and make decisions during the mission. The computer also had a sophisticated error-detection system that could alert the astronauts to potential problems.

The role of physics in space travel is fundamental. We rely on Newton's laws of motion and gravity to calculate trajectories and understand the forces acting on a spacecraft. Without this knowledge, space travel would be impossible. However, even with a thorough understanding of physics, computers are essential for accurately implementing these calculations and making real-time adjustments. A purely physics-based approach, without any computer intervention, would be exceedingly difficult to execute successfully, especially for a manned mission with complex maneuvers and landing requirements. Imagine trying to calculate the precise thrust and timing needed to dock two spacecraft manually, without the aid of computers to constantly monitor and adjust the trajectory. This is where the concept of closed loop control is used. A set of sensors feed information into the computer, the computer does a calculation of what is necessary and applies a control signal, often to a thruster. The system monitors the new state and compares it to the target state. The difference results in a new control signal. This process continues until the target state is achieved, resulting in a highly accurate state.

Electrical controls, such as thrusters, do involve some level of computing power, but it's typically quite basic. The primary function of these controls is to execute commands from the central computer system. For instance, a command might be to activate a specific thruster for a certain duration. While the electrical system handles the actual activation and deactivation of the thruster, the central computer determines when and for how long that activation should occur, based on calculations and sensor data. The computer acts as the brain, making decisions based on incoming information and sending commands to the electrical system, which acts as the muscles, carrying out those commands. Therefore, the electrical controls themselves don't represent significant computing power; it's the central computer that provides the intelligence and coordination needed for complex tasks like navigation and trajectory control. In many of these cases, the electrical signals are sent using data protocols which use the language of zeros and ones. Computers are particularly adept at working with this data and manipulating it as needed.

In summary, while the Apollo missions used computers with far less raw processing power than modern devices, the crucial factor was their reliability, specialized design, and ability to perform the specific tasks required for space travel. A purely physics-based approach is theoretically possible, but highly impractical for manned missions. Electrical controls like thrusters contribute only minimally to overall computing power; it is the central computer that handles navigation, guidance, control, and communication. Modern space missions now rely on significantly more advanced computing power for tasks like automated docking, complex trajectory calculations, and advanced data analysis, reflecting the increasing sophistication and ambition of space exploration. It is important to also consider that the software developed has also improved significantly over the years. Artificial Intelligence will likely be a factor in space exploration in the coming years. This will require an even larger increase in computing power on the rocket.