Astronomy at Home
Satellite Science Activity: How does Speed and Gravity Affect Orbit?
All satellites, including our natural satellite Moon, and the moons of other planets, are in elliptical motion around their planets. At each point along their trajectory (the path that they follow i.e. their orbits), they are falling towards the planet. The force that keeps them from shooting away from the planet in a straight line in the direction of their speed and into their orbit, is the Gravitational force, or gravity.

The higher the gravity of a planet, the faster the satellite will orbit at any given height. For artificial satellites, the higher the speed with which it is launched, the farther away it will orbit the planet. With enough speed, it may even escape the gravitational pull of the planet. Thus, the speed of a satellite plays an important role in deciding its orbit.
Age Group: IX onwards
Materials Required:
  • MDF board, square (60 x 60 cm) – 1 (Any wooden/plywood or cardboard sheet will do)
  • Pencil, Scissors, Metric Ruler – 1
  • Insulating Tape, Cellophane tape – 1
  • Modelling clay – 250 g (approx.)
  • Chart paper, white – 1 sheet
  • Marbles – 5 or 6
  • Liquid food colouring – Red, Orange, Green (any 3 colors)
  • Gloves – 1 pair
  • Cylindrical cardboard tube – 1 (inner tube of an aluminium foil wrap)
  • Paper towels/newspapers – to keep activity area clean
Fig 1- Materials required
Step 1:
Tape a sheet of white chart paper on the MDF board. Leave a margin of around 2 cm at each side. Mark a horizontal line on the top of the chart paper with pencil, leaving a margin of 2 cm on the top. The launching tube will be placed along this line.
Step 2:
Draw a vertical line from the top to the bottom on the right side of the chart paper. Mark the line at a distance of every 5 cm as shown in Fig. 2. This line will be used to measure the deviation of trajectory from horizontal.
Fig. 2: Vertical line with markings to measure the trajectory deviation from horizontal
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