Energy Transmission

Overview: Once the power generators have topped off the energy storage systems(batteries), the power will be transmitted via laser power beaming from onboard - a Helium powered polymeric balloon platform(PB) - high-temperature batteries to high-temperature batteries on the space rover after de-ascending to a certain altitude suitable for engaging the PB with energy transmission ensuring a bare-minimum exposure to Venus’ harsh atmospheric conditions.

As soon as the rover’s batteries are charged/recharged, the PB carrying the power generation and storage technology will re-ascend back up to the upper reaches of Venus’s atmosphere where the temperature is max.36.85C(day) - min.-173C(night) to recharge its own batteries once again.

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In detail, Once the rover’s batteries are topped off(completion of energy transfer), the spacecraft will ascend back to the upper reaches of the atmosphere where the temperature conditions go like this - Venus's upper atmosphere extends from the fringes of space down to about 100 km (60 miles) above the surface. There the temperature varies considerably, reaching a maximum of about 300–310 kelvins (K; 80–98 °F, 27–37 °C) in the daytime and dropping to a minimum of 100–130 K (−280 to −226 °F, −173 to −143 °C) at night. - marking better conditions for power generation and long-term storage compared to the surface - ~480C.

The aircraft will settle 45-60 km above Venus as it is one of the most Earth-like environments in the Solar system. At 50km, the baseline altitude for both robotic and human concepts as studied by NASA are relatively gentle and supportive for energy regeneration and long-term storage.

Helium containers will be fixed on either side of the exposed area of the payload for helium removal and addition for de-ascending and re-ascending purposes.

This sequence has the potential of repeating throughout the life of the surface rover leaving it up to the surety of survival of the components of the surface rover itself.

→ Indirect advantage of having such a spacecraft - The platform is also capable of serving as a communications relay between Earth and the lander.

→ Indirect advantage 2 - The spacecraft can serve as a secondary science mission even after the space rover stops functioning.

The Polymeric Balloon:

The spacecraft consists of helium lifting gas keeping in mind the density of venus’ atmosphere where helium provides more lift capability than an equivalent volume on Earth itself. For propulsion and control, energy generation unit/s part of the payload inside of the ship distribute energy required to drive electric propellers and fin control surfaces-minorly partitioned compared to the major partition that is for transmitting to the space rover.

Tendency to float - With Venus’ atmosphere mostly being made out of CO2, and nitrogen and oxygen being lighter than CO2, breathable-air filled spacecrafts(balloon form) will float at a height of about ~60km from the surface. The energy generation unit will be present at the bottom of the envelope in the gondola.

Tendency to maintain control - During the atmospheric operation, the spacecraft will follow the longitudinal winds while using electric propulsion to counter the high wind speeds.

Aircraft Measurements:

Aircraft Operational Modes:

The aircraft is set to operate in one of two modes depending on the day or night cycle. The operational mode turned on during night time assumes the longest night(consistent with 85 m/s winds) of 66 hours. During this mode, the energy storage system powers the payload(the energy generation unit) and propulsion system capable of achieving 3 m/s. According to NASA, the poleward winds are approximately 5 m/s which means the airship will drift away from the equator during this time.

The operational mode turned on during day time assumes the shortest day (consistent with 110 m/s of winds) of 44 hours to transmit power to the space rover. Keep in mind: A certain amount of energy is saved for both regeneration of energy and powering the propulsion system to return back to the atmosphere for charging. Also, the propulsion system will be designed for a velocity of up to 15 m/s which means the aircraft will be able to overcome the poleward drift and reach the equator before the night time operational mode begins.

Engaging Laser Beaming Technology:

Energy loss graph below ~

Using this model, the loss factor between a ~45 km altitude and the surface of the venus was compared. It can be inferred that the lowest loss factor is 20% at 1022nm, as represented in the above figure.

Short wavelength and high-power lasers in the visible and near infrared coupled with high efficiency LPCs(laser power converters) derived from commercially available photovoltaic cells will enable power transfer(from an altitude below the Venus cloud deck ~20km from surface) to the surface.

The Transmitter -

For the power beaming transmitter, a 1022 nm laser of 450 W would maximize power transmission between below the clouds and the surface of Venus.

The Receiver -

Laser Power converter - GaAs

The bandgap of GaAs was plotted to be up to 300C and was linearly extrapolated up to 465C. The extrapolation means, a bandgap of 1069 nm is maintained at 465C. This makes GaAs a very good LPC candidate with a 1022 nm laser.

Re-emmitting the laser energy on the Surface Rover -

The laser beam energy will be collected by the LPCs placed on the exposed area of the surface rover & will directly supply the converted energy to the laser beam emitter on the surface rover directed towards the tesseract shield which will re-emit the laser beam energy at a high frequency of 1069nm at 450W which is sufficient enough for it to pass the first layer, the platinum shield of thickness 2.8mm. The laser beam energy re-emitted into the tesseract shield will be collected by LPCs present inside of the shield which will convert the energy into electricity which directly powers the battery. The main concern for powering the battery inside of the tesseract shield was the inefficiency of cabling energy transmission wires out of the shield. In this case, since we have the energy being emitted directly through the first phase of the tesseract shield, the laser beam converted into electricity by the LPCs inside of the shield can be directly wired within further(converging) shielding stages of the tesseract allowing us to directly power the battery from that point.

Efficiency - Assuming perfect pointing of a 1 kW laser beam at 1064 nm and a 65% efficient tuned laser power converter (LPC) receiver array, power beaming would provide 650 W to the surface rover for the first emission. For the re-emmission that takes place, approximately ~400W of energy is set to be transmitted into the battery considering the "Re-emission" & "Platinum thickness" factors.(Approximations could have been made even more specific if official NASA research/lab test results for "Re-emmitted Laser energy" were made public)

← Graph that shows the tendency of laser power to penetrate any material(in our case anodized platinum) given the laser power in Watts in varying with the penetration size(thickness of the material).

The platinum will be anodized to disengage possible reflection of the laser light.

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Last updated 3 years ago