# Basics of Spaceflight

• Spaceflight involves the use of space technology to achieve the flight of spacecraft into and through outer space.
• Spaceflight is used for a variety of purposes, including scientific research, exploration of celestial objects, and communication with spacecraft.
• The physics involved in spaceflight involves a complex interplay between gravity, force, mass, and acceleration.

# Laws of Motion in Spaceflight

• Newton’s First Law of Motion states that an object at rest will stay at rest, and an object in motion will stay in motion, unless acted upon by an outside force. In space, where there is no friction or air resistance, spacecraft continue moving in the same direction until an external force is applied.
• Newton’s Second Law of Motion states that the force applied to an object is equal to the mass of that object multiplied by its acceleration (F=ma). For spacecraft, the thrust of the engines must be enough to overcome the weight of the spacecraft and any cargo it is carrying.
• Newton’s Third Law of Motion is perhaps the best known in relation to spaceflight: “For every action, there is an equal and opposite reaction”. This principle is used to propel spacecraft forward.

# Stages of Spaceflight

• Launch is the initial phase of spaceflight. Mechanical systems, usually rockets, are used to accelerate the spacecraft beyond the Earth’s atmospheric drag and gravitational pull.
• Spacecraft in orbit remain in space due to their speed and the gravitational pull of the Earth. Through careful calculations and adjustments, satellites can be placed in a specific orbit, or path, around the Earth.
• Re-entry and landing are the final stages of a mission. The spacecraft moves from the vacuum of space into the Earth’s atmosphere, which puts a lot of heat and stress on the spacecraft.

# Factors Affecting Spaceflight

• The amount of energy required for a space mission depends on the mass of the spacecraft, the distance to the target, and the speed needed to reach the target.
• Microgravity is the apparent state of weightlessness experienced by astronauts in orbit. It affects human physiology and the behaviour of materials and fluids in space.
• Space radiation can pose a threat to humans and electronics in space. Exposure must be carefully monitored and mitigated to ensure the safety of the crew and the success of the mission.

# Spacecraft Propulsion

• Rocket engines work on the principle of action and reaction. They burn fuel to produce a high-speed flow of gas, which results in a force pushing the spacecraft forward.
• Ion engines use electricity to create charged particles of gas that are expelled to propel the spacecraft. They are much more fuel-efficient than chemical rockets but provide less thrust.
• Solar sails use the pressure of sunlight to move a spacecraft. This method requires no fuel but can only be used where sunlight is available.

Understanding the mechanics of spaceflight is essential for comprehending how spacecraft travel from Earth to space, how they remain in orbit, and how they return safely, providing valuable insights into the physics governing the universe.