Conversation so far:
What was the first artificial satellite?
History changed on October 4, 1957, when the Soviet Union successfully launched Sputnik I. The world's first artificial satellite was about the size of a beach ball (58 cm.or 22.8 inches in diameter), weighed only 83.6 kg. or 183.9 pounds, and took about 98 minutes to orbit the Earth on its elliptical path.
What are the types of satellite orbits?
There are essentially three types of Earth orbits: high Earth orbit, medium Earth orbit, and low Earth orbit. Many weather and some communications satellites tend to have a high Earth orbit, farthest away from the surface
What are the important classes of artificial satellites?
Common types include military and civilian Earth observation satellites, communications satellites, navigation satellites, weather satellites, and space telescopes. Space stations and human spacecraft in orbit are also satellites.
How do satellite navigation systems work?
Satellite Navigation is based on a global network of satellites that transmit radio signals in medium earth orbit. ... The signal contains data that a receiver uses to compute the locations of the satellites and to make other adjustments needed for accurate positioning
What is the Galileo system and why is it important?
Galileo is to play an important part of the Medium Earth Orbit Search and Rescue system (MEOSAR). Galileo satellites will be able to pick up signals from emergency beacons carried on ships, planes or persons and ultimately send these back to national rescue centres.
Why did the Galileo system create tension with the US?
Since Galileo was designed to provide the highest possible precision (greater than GPS) to anyone, the US was concerned that an enemy could use Galileo signals in military strikes against the US and its allies (some weapons like missiles use GNSSs for guidance). The frequency initially chosen for Galileo would have made it impossible for the US to block the Galileo signals without also interfering with its own GPS signals.
What are Cubesats?
A CubeSat is a type of miniaturized satellite for space research that is made up of multiples of 10 cm × 10 cm × 11.35 cm cubic units. CubeSats have a mass of no more than 1.33 kilograms per unit, and often use commercial off-the-shelf components for their electronics and structure.
What are Cubesats' advantages?
Their small size makes it possible to rapidly build and test, making CubeSats an ideal and affordable way to explore new technologies and ideas.

Question: What are they used for
Self-contained rewrite: What are Cubesats used for?