As such, theyre also the least understood planets in the Solar System.
Ourongoingresearchlooks at how to overcome the harsh entry conditions experienced during giant planet missions.
As we look forward to potential future missions, heres what we might expect.
Beinahegut
But first, what are giant planets?
Unlike rocky planets, giant planets dont have a surface to land on.
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The larger Jupiter and Saturn are gas giants.
Theyre also believed to have a small rocky core.
Still, there have been some past missions sent to the gas giants.
Flight times get even longer for the two ice giants, which are much further from the Sun.
Neither has had a dedicated mission so far.
NASA/JPL
While momentum is building for a return, it wont be simple.
A major issue is power.
The Juno spacecraft is the most distant object from the Sun to haveused solar panels.
It orbits Jupiter, which isfive times further awayfrom the Sun than Earth is.
Meanwhile, Uranus and Neptune are20and30times further away, respectively, from the Sun than Earth is.
This radioactive decay can damage and interfere with instruments.
And these speeds greatly heat up the spacecraft.
Proposed future probe missions to Uranus and Neptune would occur at slower entry speeds of22km/s and 26km/s, respectively.
While the material has been tested with afull-scale prototype, it has yet to fly on a mission.
Its planned NASAs HEEET material will be used for future ice giant entry missions.
There are plans for a jointNASA-ESA missionto visit one of the ice giants within the upcoming launch window.
But while there has beenextensivepreparation, its undecided which ice giant will be visited.
A single mission to both planets is being considered.
An entry probe is planned, too.
But if the mission visits both planets, its undecided which planetsatmosphere the probe would explore.
In other words, crunch time is coming.
This heat release can be detected for Jupiter, Saturn, and Neptune.
Uranus, however, doesnt seem to release heat and scientists dont know why.
