Gram-scale StarChip components | Battery

Battery design is one of the most challenging aspects of the mission. Currently under consideration for the energy source onboard are plutonium-238, which is in common use, or Americium-241. 150mg has been allocated for the mass of the battery. This includes the mass of the radioisotope and the ultra-capacitor. As the isotope decays it will charge the ultra-capacitor. Then, at the appropriate time, the StarChip components will be switched on and begin to operate. The power budget is informed by the available energy in the battery. An innovative approach could take advantage of the heating of the frontal surface of the nanocraft through its interaction with the interstellar medium. The heat supply, at a rate of 6mW per cm2, could provide a thermoelectric energy source during the interstellar cruising phase.

It may be possible to coat the lightsail with a thin film of photovoltaic material, which was demonstrated on the IKAROS mission. This could be extremely useful during approach to the host star. The photovoltaics will be able to supply significant energy when they are within 2AU of the target star. Even with just 10% efficient photovoltaics, the energy supplied would be nearly 2kW at 1AU. This is more than 100,000 times the power of the radioactive energy source, and could conceivably allow much higher data rates for laser communication. This is one option that will be explored.

Coating the StarChip itself with PV would allow for high efficiency, and potentially gain several Watts just from the StarChip. These options open up a host of possibilities to greatly enhance functionality at the host star in the crucial data and imaging phases.

Research:

Jul 07, 2022 05:34 aabuckler@hotmail.com Posted on: Breakthrough Initiatives

Has any consideration been given to using a conductor(s) to generate current as the craft passes through the interstellar magnetic field? I am not competent to attempt the math, but a speed of 100 million mph should make a pretty good armature. Any energy extracted from the conductors would come from the kinetic energy of the vehicle and would also serve to slow it down, but that may not matter during cruise when power levels would be low. Not sure if the power extracted could be increased to reduce velocity enough for a capture vs. a flyby. I also saw elsewhere the transmitted beam power was 100 GW. But at 300 MW/ Newton (150 with ~100% reflection?) I figure that is around 300-(600) Newtons of thrust, or 65-(130)lbs. If this is right, how many Gs is the acceleration run? I must have missed the takeoff mass. I ask, because if it only takes a few weeks to get to cruising speed there is lots of time for temperature to drop to superconducting levels. Then maybe power could be extracted at a high enough level for dynamic braking to work at the end of the trip. Possibly using the current to pull in hydrogen and direct it against the sail? Just asking ...

Feb 01, 2024 09:46 Vittorio Palmieri Posted on: Breakthrough Initiatives

Our recent publication hints at the possibility of building high power 90Sr beta voltaic batteries with plain silicon (https://doi.org/10.1016/j.nxener.2024.100101) This would allow integration of the battery with other electronic components saving weight.

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