I’ve read a lot of articles on planetary exploration. Quite a few of these have been on alternatives to rovers: different methods for exploring great areas up close that don’t rely on wheels or tracks.

The “hopper” option has been popular. Nuclear thermal hoppers have been proposed for Mars. Hayabusa 2 has delivered hoppers to the asteroid Ryugu and they seem to be working nicely. Seems an easy way to get over rough terrain (but there are also disadvantages).

Among planets with some kind of atmosphere, airborne options such as dirigibles, free floating balloons, gliders and even powered heavier than air craft have been seriously considered.

Much of the earth’s surface was explored using sailboats. Unlike rovers, hoppers, aeroplanes, or dirigibles, they don’t need a power supply, and unlike balloons they can be steered and one can use both the air currents and liquid currents as needed.

I never saw articles on this and in fairness that’s because until about 10 years ago it would have seemed like a pointless notion but then hydrocarbon lakes were found on Titan! Lakes 1000 km across, hundreds of metres deep. There’s a river 400 km that flows through a steep canyon: imagine all the data you’d obtain from a craft sailing down that, observing the layers on the sides of the canyon.

Bad news is that average windspeed at the surface appears to be low, in the realm of 6 km/h. Good news that the atmosphere is dense: some 5 times denser than Earth’s at the surface. So the pushing power would be like a 30km/h breeze on Earth.

In terms of liquid currents, I have no data… the big lakes are similar in size to the Caspian sea which has currents are around 0.5 km/h max.

The major lakes on Titan all have large islands in them so within a single lake you could explore different terrains.

And also I think it would be cool.

“Bad news is that average windspeed at the surface appears to be low, in the realm of 6 km/h. Good news that the atmosphere is dense: some 5 times denser than Earth’s at the surface. So the pushing power would be like a 30km/h breeze on Earth.”

Does that scale linearly? I have no idea.

Interesting idea but what sort of temperature is this liquid?

sibeen said:

“Bad news is that average windspeed at the surface appears to be low, in the realm of 6 km/h. Good news that the atmosphere is dense: some 5 times denser than Earth’s at the surface. So the pushing power would be like a 30km/h breeze on Earth.”

Does that scale linearly? I have no idea.

Doesn’t scale linearly. Scales roughly as pressure proportional to density times speed squared. So that 6 km/hr scales up by the square root of density, to 13.5 km/hr. But that’s not at all too slow. It is hugely faster than every Mars rover.

I like the idea of a sailboat. A sailboat on other planets has been mentioned in SciFi, but I had never thought of it as a viable option until now.

Would still need to have some means of steering. A sailing rover would need to be able to discern where the current was flowing, obstacles, possible obstacles and hidden obstacles, and make corrections as required, on its own in real time without any input from from a human operator would might be a couple of hours away by radio message. Plus it will need some kind of propulsion to get it out of a jam if it gets stuck.

party_pants said:

Would still need to have some means of steering. A sailing rover would need to be able to discern where the current was flowing, obstacles, possible obstacles and hidden obstacles, and make corrections as required, on its own in real time without any input from from a human operator would might be a couple of hours away by radio message. Plus it will need some kind of propulsion to get it out of a jam if it gets stuck.

Easy peasy. That’s hardly any different to the problems facing every rover.

mollwollfumble said:

party_pants said:

Would still need to have some means of steering. A sailing rover would need to be able to discern where the current was flowing, obstacles, possible obstacles and hidden obstacles, and make corrections as required, on its own in real time without any input from from a human operator would might be a couple of hours away by radio message. Plus it will need some kind of propulsion to get it out of a jam if it gets stuck.

Easy peasy. That’s hardly any different to the problems facing every rover.

I thought the rovers on Mars just stopped and sent back pictures to the control room on Earth, where a committee then decided the next few metres of travel and sent instructions back to the rover.

Bubblecar said:

Interesting idea but what sort of temperature is this liquid?

Presumably the same as the general surface temperature, -180 degrees C.

Shouldn’t be a problem if the vehicle is liquid-proof and adequately heated.

party_pants said:

mollwollfumble said:

party_pants said:

Would still need to have some means of steering. A sailing rover would need to be able to discern where the current was flowing, obstacles, possible obstacles and hidden obstacles, and make corrections as required, on its own in real time without any input from from a human operator would might be a couple of hours away by radio message. Plus it will need some kind of propulsion to get it out of a jam if it gets stuck.

Easy peasy. That’s hardly any different to the problems facing every rover.

I thought the rovers on Mars just stopped and sent back pictures to the control room on Earth, where a committee then decided the next few metres of travel and sent instructions back to the rover.

Here I am with a brain the size of a planet and they ask me to pick up a piece of paper. Call that job satisfaction? I don’t.

Bubblecar said:

Bubblecar said:

Interesting idea but what sort of temperature is this liquid?

Presumably the same as the general surface temperature, -180 degrees C.

Shouldn’t be a problem if the vehicle is liquid-proof and adequately heated.

The Huygens probe that landed on Titan was liquid proof. Nobody knew at that time whether Titan’s surface was solid or liquid so Huygens was designed to work in both.

That said, -180 degrees C is pretty darn cold. I wondered recently how much greenhouse effect there is on Titan thanks to it’s thick atmosphere. I came to the conclusion that there is some, but not a heck of a lot. I couldn’t give a firm number for it.

party_pants said:

mollwollfumble said:

party_pants said:

Would still need to have some means of steering. A sailing rover would need to be able to discern where the current was flowing, obstacles, possible obstacles and hidden obstacles, and make corrections as required, on its own in real time without any input from from a human operator would might be a couple of hours away by radio message. Plus it will need some kind of propulsion to get it out of a jam if it gets stuck.

Easy peasy. That’s hardly any different to the problems facing every rover.

I thought the rovers on Mars just stopped and sent back pictures to the control room on Earth, where a committee then decided the next few metres of travel and sent instructions back to the rover.

A lot like DRS.

party_pants said:

mollwollfumble said:

party_pants said:

Would still need to have some means of steering. A sailing rover would need to be able to discern where the current was flowing, obstacles, possible obstacles and hidden obstacles, and make corrections as required, on its own in real time without any input from from a human operator would might be a couple of hours away by radio message. Plus it will need some kind of propulsion to get it out of a jam if it gets stuck.

Easy peasy. That’s hardly any different to the problems facing every rover.

I thought the rovers on Mars just stopped and sent back pictures to the control room on Earth, where a committee then decided the next few metres of travel and sent instructions back to the rover.

Curiosity is, in the short term, able to travel independently, dealing with obstacles somewhat intelligently.

I do think that tacking and plotting a course on a fairly still lake would be easier than roving a complex rocky terrain.

dv said:

I’ve read a lot of articles on planetary exploration. Quite a few of these have been on alternatives to rovers: different methods for exploring great areas up close that don’t rely on wheels or tracks.

The “hopper” option has been popular. Nuclear thermal hoppers have been proposed for Mars. Hayabusa 2 has delivered hoppers to the asteroid Ryugu and they seem to be working nicely. Seems an easy way to get over rough terrain (but there are also disadvantages).

Among planets with some kind of atmosphere, airborne options such as dirigibles, free floating balloons, gliders and even powered heavier than air craft have been seriously considered.

Much of the earth’s surface was explored using sailboats. Unlike rovers, hoppers, aeroplanes, or dirigibles, they don’t need a power supply, and unlike balloons they can be steered and one can use both the air currents and liquid currents as needed.

I never saw articles on this and in fairness that’s because until about 10 years ago it would have seemed like a pointless notion but then hydrocarbon lakes were found on Titan! Lakes 1000 km across, hundreds of metres deep. There’s a river 400 km that flows through a steep canyon: imagine all the data you’d obtain from a craft sailing down that, observing the layers on the sides of the canyon.

Bad news is that average windspeed at the surface appears to be low, in the realm of 6 km/h. Good news that the atmosphere is dense: some 5 times denser than Earth’s at the surface. So the pushing power would be like a 30km/h breeze on Earth.

In terms of liquid currents, I have no data… the big lakes are similar in size to the Caspian sea which has currents are around 0.5 km/h max.

The major lakes on Titan all have large islands in them so within a single lake you could explore different terrains.

And also I think it would be cool.

How big a sailboat? Huygens weighed 319 kg, which would make quite a sizeable craft.

Listen to the winds of Titan.

https://m.youtube.com/watch?v=36ffV-CI3Mo