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Gas giant dipper

Transatmospheric satellite based on thermal or Bussard ramjet
  [vote for,

I propose a science satellite concept for gas giants: The satellite dips into, say, Jupiter's atmosphere at each perijove, to gather detailed data on the atmosphere and climate.

Obviously this will incur aerodynamic drag losses, so these are compensated for by collecting some of the atmosphere and using it as propellant. After being collected by a scoop, either it will be heated by a nuclear reactor or decay (thermal ramjet) or the hydrogen component of the atmosphere will be fused with itself (Bussard ramjet), and then ejected out the back of the satellite. If it's a thermal ramjet, the heat used can be waste heat from the RTG or reactor (which I assume the satellite will have, solar panels not being very useful out near this solar system's gas giants).

Jupiter's atmosphere, for reference, is 86% by number H2.

The advantage of this over using stored propellant is that the propellant is unlimited, and thus the number of orbits achievable is unlimited by propellant. (It will still be limited by decay of other components such as nuclear fuel, electronics exposed to strong magnetic fields, etc., but those things can probably more easily be made to last longer.)


notexactly, Oct 24 2016

Bussard ramjet https://en.wikipedi...wiki/Bussard_ramjet
For anyone unfamiliar with the concept [notexactly, Oct 24 2016]

GOCE https://en.wikipedi...irculation_Explorer
Prior art: satellite that orbited within Earth's atmosphere, with an ion engine to offset drag [notexactly, Oct 24 2016]

Some discouraging light math https://space.stack...propellant-feasible
Apparently this is not likely to be very feasible anytime soon, and would probably be a struggle to fease even with nuclear rocket technology, because your exhaust velocity has to be greater than your orbital velocity. (Not my question—I don't participate in Stack Exchange stuff.) [notexactly, Jul 13 2019]

On the other hand, ESA seems to think an air-breathing electric thruster might be feasible https://www.esa.int...g_electric_thruster
They've tested one, anyway. [notexactly, Jul 13 2019]

Triple-alpha process https://en.wikipedi...riple-alpha_process
Helium burning to carbon [Voice, Jul 14 2019]


       I have since realized that this might be more suited to gas harvesting applications than scientific applications. For example, most of the rest of Jupiter's atmosphere is helium. We happen to not be able to hold onto our helium here on Earth, so we will eventually need another source of it. This type of spacecraft could then be used to collect helium from Jupiter.
notexactly, Oct 26 2016

       Aye aye skipper. We'll try full ahead.
wjt, Oct 28 2016

       I think the expression is "go with throttle-up."   

MaxwellBuchanan, Jul 13 2019

       // we will eventually need another source of it. //   

       The main exhaust product of a fusion reactor is Helium. Build fusion powerplants, stuff in Deuterium, get lots of energy and the Helium is a bonus .. There's no downside !
8th of 7, Jul 14 2019

       I thought one of the benefits of fusion was that it used very little fuel, and therefore produced very little helium, for a given amount of energy output?
notexactly, Jul 14 2019

       Then treat the helium as the "product " and use the "spare" energy to extract CO2 from your atmosphere (possibly via a biomass route) and reduce it to carbon - amorphous, or crystalline.   

       Graphite blocks have all sorts of uses too.
8th of 7, Jul 14 2019


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