Tethers are ropes or chains that are used to tie something down. They are often used to keep animals in a particular area, or to hold a boat in place.
A counterweight is something that is used to balance something. It's usually a big, heavy object that is placed on one side of a scale to help balance the weight.
A catapult is a device that is used to launch objects high into the air. It is usually powered by a person or animal walking or running back and forth, and the object is thrown using a lever or a bow.
A meteorite is a piece of rock that has been pulled from outer space and landed on Earth. It's usually a very rare event, and it's usually found in remote areas.
When you're talking about the weight of something, you can use the word payloads to refer to the weight of the object itself, as well as the weight of the material that the object is made of.
Airliners are large, commercial airplanes that are used to travel across the world. They are usually filled with people, luggage, and cargo.
When something is interplanetary, it is located or occurring between the planets in our solar system. Sometimes interplanetary refers to things that are beyond our own planet, such as outer space.
Comparably means in the same way, or at least as good. When you say that something is comparably priced, you mean that it is not very expensive compared to other things of the same type.
To perk up is to make something more cheerful or enjoyable. When you perk up someone's day, you make them feel better.