Aerobot
They tend to be expensive and have limited range, and due to the communications time lags over interplanetary distances, they have to be smart enough to navigate without disabling themselves.
Flying above obstructions in the winds, a balloon could explore large regions of a planet in detail for relatively low cost.
They can cover a great deal of ground, and their view from a height gives them the ability to examine wide swathes of terrain with far more detail than would be available from an orbiting satellite.
A solar Montgolfiere will sink at night, and will have a guide rope attached to the bottom of the gondola that will curl up on the ground and anchor the balloon during the darkness hours.
Alternatively, a balloon may carry a thicker instrumented "snake" in place of the gondola and guiderope, combining the functions of the two.
Once operational, the aerobot will be largely on its own and will have to conduct its mission autonomously, accepting only general commands over its long link to Earth.
The aerobot will have to navigate in three dimensions, acquire and store science data, perform flight control by varying its altitude, and possibly make landings at specific sites to provide close-up investigation.
The Montgolfieres flew at an altitude of 35 kilometers, where the atmosphere was as thin and cold as it would be on Mars, and one spent 69 days aloft, circling the Earth twice.
Unfortunately, although considerable development work was performed on the balloon and its subsystems, Russian financial difficulties pushed the Mars probe out from 1992, then to 1994, and then to 1996.
PAT concepts envisioned a reversible-fluid balloon with a 10-kilogram payload that would include navigation and camera systems, and eventually would operate under autonomous control.
While these tests and experiments were going on, JPL performed a number of speculative studies for planetary aerobot missions to Mars, Venus, Saturn's moon Titan, and the outer planets.
As its name implies, MABTEX was primarily intended to be an operational technology experiment as a precursor to a more ambitious efforts.
MABTEX might be followed in turn by a small solar-powered blimp named MASEPA, for "Mars Solar Electric Propelled Aerobot".
Prototype balloon envelopes have been fabricated from polybenzoxazole, a polymer that exhibits high strength, resistance to heat, and low leakage for light gases.
The vessel is designed to tolerate pressures of up to a hundred atmospheres and maintain internal temperatures below 30 °C (86 °F) even on the surface of Venus.
The vessel is set at the bottom of a hexagonal "basket" of solar panels that in turn provide tether connections to the balloon system above, and is surrounded by a ring of pipes acting as a heat exchanger.
[5] In April 2021 it was reported that NASA allocated work to design and test robotic balloons for future exploration of Venus.
An aerobot would be able to penetrate this haze to study the moon's mysterious surface and search for complex organic molecules.
After entry into Titan's atmosphere, the aerover would float until it found an interesting site, then vent helium to descend to the surface.
No matter what form the Titan Biologic Explorer mission takes, the system would likely require an atomic-powered radioisotope thermoelectric generator module for power.
Solar power would not be possible at Saturn's distance and under Titan's smog, and batteries would not give adequate mission endurance.
[10] A Jupiter aerobot might operate at altitudes where the air pressure ranges from one to ten atmospheres, occasionally dropping lower for detailed studies.
It would make atmospheric measurements and return imagery and remote sensing of weather phenomena, such as Jupiter's Great Red Spot.
Winged airplane concepts have been proposed for robotic exploration in the atmosphere of Mars,[2][11] Venus,[12][13] Titan,[9] and even Jupiter.
[16] A number of advantages of a viable rotorcraft design were noted, including the ability to pass over difficult Mars terrain yet still visit multiple sites in situ.
[17] The aircraft was deployed from the Perseverance rover, and initially flew five times during its 30-day test campaign early in the mission.
