New answers tagged

1

The answer is significantly dependent on how much aerodynamic pressure and heating you can tolerate, and whether it's possible to achieve high specific impulse from a rocket engine exhausting into Venusian atmosphere. At 10km above the Venusian "reference altitude", a speed of only 46 m/s (~100 mph) puts you at a Q of 39.5kPa -- a little higher than "max Q"...


1

One could obtain an upper bound by reducing it in the following way: The mass density of the atmosphere is 65 kg/m³, which combined with a 15.9km scale height means that the atmosphere has roughly Earth density at 4 scale heights, or ~60km. Which means we can just use Earth number from there and out. We do a simple delta-v cost estimation for climbing up to ...


1

But the article in Wikipedia is rather outdated. The sequence of flybys for actual Feb 2020 launch is different than for planned 2017 launch. The ratio of orbital periods of Earth and Venus can't be written as simple proportion (e.g 3/2) - actually it's about Te/Tv ~ 1.612. This means the configurations of Earth-Venus relative positions don't repeat (at ...


7

Peroxydisulfates and acid itself would be a bad choice for rocket oxidizers for several reasons: H2S2O8 is actually a solid with melting point of 65°C, therefore unsuitable for liquid fueled rockets, In pure form acid is even more aggressive and corrosive than sulfuric acid, it's like sulfuric acid on steroids. It can explode in contact with organic ...


4

Nothing changed. Note that your plot covers 10 years and not 7. You cited a line from Wikipedia, but didn't check the source given for it: The nominal mission of seven years will see a maximum orbital inclination relative to the solar equator of 25°. During the extended mission, additional Venus GAMs [gravity-assist manoeuvres] could allow the orbital ...


0

It is possible to cool with a fan below ambient temperature with the help of the thermoelectric cooler like these. From the other side, devices under the link only support about 70 degree temperature difference so five must be cascaded for Venus, using 150 W in total that is very demanding for a battery operated spacecraft. The outer devices are also not ...


3

As pointed out, a cooling fan cannot reduce the temperature below the ambient. That doesn't mean it's completely useless in this case. First, OP said "Venus-bound." In this case a fan could be used to transfer heat from sunward sections to shadowed sections, or even better to radiating heat sinks on the shadowed side. Even when on the planet, it could be ...


3

Heat is exchanged via three mechanisms: convection (transfer of heat in gases and fluids) conduction (transfer of heat between touching solid objects) radiation (transfer of heat via thermal radiation) In the presence of an atmosphere, transfer via convection is usually the most efficient, followed by conduction. Radiation is -- by far -- the weakest form ...


10

The effect of a fan in an electronic device is to accelerate the temperature exchange between circuits and atmosphere. But that temperature exchange works in both directions. When the atmosphere is even hotter than the electronics you expose to it, then improving the flow with a fan will make the part even hotter. That's the principle behind a convection ...


39

Fans work by moving cool air (or other fluid) over a warm surface. If there is no air, like in space, a fan will serve no purpose. Cooling things in space is actually a bit tricky because of this - objects on earth tend to lose most of their heat through conduction or convection, but in the vacuum of space, all you can do is radiate heat, which a fan will ...


Top 50 recent answers are included