What technology enables spacecraft to navigate in space?

The appropriate technology for spacecraft navigation is based on inertial navigation systems and GPS technology. Inertial navigation systems work by measuring the spacecraft's acceleration and rotation over time, allowing it to calculate its position, velocity, and orientation without relying on external references. This makes it particularly useful in the vastness of space, where traditional navigation aids may not be available.

GPS technology also plays a crucial role for spacecraft operating within the Earth's proximity, such as low Earth orbit missions. By receiving signals from a network of satellites, a spacecraft can determine its exact location in real-time. For missions further from Earth, other navigation techniques must be used, but the combination of inertial navigation and GPS is fundamental for accurate navigation in various environments.

The other options do not apply effectively to spacecraft navigation. Astronomical telescopes are primarily for observing celestial bodies rather than navigation. Magnetic compasses are based on Earth's magnetic field, which is not applicable in space where magnetic fields may not provide reliable information. Radar systems can be used for tracking objects, but they are not the primary technology for spacecraft navigation in the way that inertial navigation systems and GPS technology are.