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The Chapman probes are designed to reduce construction, and design costs for missions throughout the solar system, by using a common design, much in the same way that modern rockets like the Atlas V do. Since all the probes use a common body, with the same instruments, the probes can be build at a much reduced cost, and it also allows for a better comparison of different bodies throughout the solar-system.
The probes are separated into 3 categories. Chapman Inner-1 and Chapman Ion-1 are designed for work in the Inner Solar System between the orbits of Mercury and Mars. Chapman Inner-2, and Chapman Ion-2 are designed for work in the asteroid belt. While Chapman Outer is designed for work out past the asteroid belt.
Most of the Chapman probes are powered using solar panels ranging in size from 8.6 meters, to 32 meters. Inner-1 and Ion-1 use solar panels with an efficiency of 21% (i.e. at 1Au they can absorb 286.86W/m2 of the Sun's energy from the 1366W/m2 available), and can approach as close as 0.2 Au without overheating. Inner-2's and Ion-2's solar panels have a greater efficiency, running at 32%. Because their solar panels are more sensitive, Inner-2 and Ion-2 can only approach as close as 0.6 Au without damaging them.
The Chapman Outer, uses two Radioisotope Thermoelectric Generators (RTGs) that provide 375W of electricity each at launch. Powered by 238Pu, they have a half-life of 87.7 years, meaning they will provide enough energy for the spacecraft for about 18 years, when the power output drops too low to sustain normal operations.
The Chapman probes utilize either a 5000N bipropellant engine, or a 154mN Hall effect thruster. Since the Hall effect thruster requires 2.2kW of electricity to run (plus another 100W to maintain spacecraft systems), there is no Outer version of the probe that uses the Hall effect thruster, since the RTGs only have a total of 750W at launch. For a Chapman Outer to have enough energy to power a 2.2kW thruster, it would require at least 7 RTGs to power it.
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Chapman Outer |
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Empty Weight: | 784kg |
| Fuel Weight: | 980kg | |
| Total Weight at Launch: | 1764kg | |
| Propellant Type: | N2O4/N2H4 | |
| Maximum Thrust: | 5000N | |
| Delta V available: | 2732m/s | |
| Minimum Operating Distance: | 0.2 Au | |
| Power Source: | 2 Radioisotope Thermoelectric Generators (750We at launch, 87.7yr Half-life) | |
| Lifespan: | 18 years | |
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Chapman Inner-1 |
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Empty Weight: | 679kg |
| Fuel Weight: | 980kg | |
| Total Weight at Launch: | 1659kg | |
| Propellant Type: | N2O4/N2H4 | |
| Maximum Thrust: | 5000N | |
| Delta V available: | 3009m/s | |
| Power Source: | 6 large panels, + 2 small panels with a 21% efficiency | |
| Individual Panel Size: | 2.0m x 0.7m | |
| Minimum Operating Distance: | 0.2 Au | |
| Max. Operational Distance: | 2.0 Au | |
| Max. Hibernation Distance: | 5.3 Au | |
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Chapman Inner-2 |
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Empty Weight: | 691kg |
| Fuel Weight: | 980kg | |
| Total Weight at Launch: | 1671kg | |
| Propellant Type: | N2O4/N2H4 | |
| Maximum Thrust: | 5000N | |
| Delta V available: | 2974m/s | |
| Power Source: | 14 large panels, + 2 small panels with a 32% efficiency | |
| Individual Panel Size: | 2.0m x 0.7m | |
| Minimum Operating Distance: | 0.6 Au | |
| Max. Operational Distance: | 3.7 Au | |
| Max. Hibernation Distance: | 9.5 Au | |
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Chapman Ion-1 |
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Empty Weight: | 694kg |
| Fuel Weight: | 850kg | |
| Total Weight at Launch: | 1544kg | |
| Propellant Type: | Xenon | |
| Maximum Thrust: | 0.154N at 2.2kW | |
| Delta V available: | 22741m/s | |
| Power Source: | 16 large panels, + 2 small panels with a 21% efficiency | |
| Individual Panel Size: | 2.0m x 0.7m | |
| Minimum Operating Distance: | 0.2 Au | |
| Max. Distance for Engine Use: | 1.7 Au | |
| Max. Operational Distance Without Engine: | 3.2 Au | |
| Max. Hibernation Distance: | 8.2 Au | |
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Chapman Ion-2 |
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Empty Weight: | 735kg |
| Fuel Weight: | 850kg | |
| Total Weight at Launch: | 1585kg | |
| Propellant Type: | Xenon | |
| Maximum Thrust: | 0.154N at 2.2kW | |
| Delta V available: | 21854m/s | |
| Power Source: | 22 large panels, + 2 small panels with a 32% efficiency | |
| Individual Panel Size: | 2.4m x 1.175m | |
| Minimum Operating Distance: | 0.6 Au | |
| Max. Distance for Engine Use: | 3.5 Au | |
| Max. Operational Distance Without Engine: | 7.5 Au | |
| Max. Hibernation Distance: | 16.8 Au | |
