## How much energy is needed?

The amount energy a EPM-spacecraft consumes mainly depends on the mass
of the spacecraft, its propulsion and electronics and time it needs to
reach the speed of light and return to its base.

## Mass of the EPM-spacecraft

The
EPM-spacecraft does not have to be large. Its sole purpose is to
break the light barrier. It needs electromagnets (1+2), solid state
switches (3+4), control unit, navigation and commnication equipment
(5), batteries (6), a generator (7) and a fuel tank (8). The fuel tank
works like the

external space shuttle tank and stores the bipropellant fuel (liquid oxygen + kerosene) for the generator.

The total weight EPM-spacecraft specified by its parts:

- Two CER-20 electromagnets, capacity 1,050 Watts each, lifting capability 5,250 kg each, combined weight 560 kg
- Lithium-ion batteries, 16 kWh storage, weight 170 kg
- 20 kW generator, fuel consumption 6.5 liters per hour at full load, weight 500 kg
- Light weight hull, solid state switches, control unit, navigation and communication equipment, weight 700 kg.

- Fuel for the generator: 250 kg (± 275 liters) liquid oxygen, 650 kg (± 795 liters) kerosene
- Allowing 650 kg for fuel tank

Total weight: 3,480 kg
## Energy consumption propulsion and electronics

The two CER-20 electromagnets consume 1,050 Watts each. The
energy consumption of the other electric hardware, like for instance
the navigation and communication equipment, fuel pump, solid state switches is not likely to exceed 5 kWh.

To give you some reference point: the instruments on the

mars rover Opportunity could work for up to 4 hours on the 140 Watts generated by Opportunity's solar arrays.

Therefore a 20 KWh generator should be sufficient.

## Duration of the trip

As was shown in the "Speed of light"-section on the previous page, it
would take the EPM-spacecraft less than 21 hours to reach the light
barrier. This kind of acceleration might be a bit too much ;-). So we
give it 3 hours more.

It will take the EPM-spacecraft 24 hours to reach the speed
of light. In order to return to its launch pad, it has to decelerate
24 hours to a full stop, 24 hours to reach the speed of light again and
has to decelerate again for 24 hours to a full stop at the launch pad. This means the
electromagnets and the other equipment have to be powered for four days
non-stop.

>> To be continued<<