It’s a very interesting planet in its way, but we have vast amounts of data to be going on with. And available funds for solar system exploration are obviously limited.

I would like to see the same scale of resources allocated to some of the more interesting corners of the solar system – e.g., Titan. Imagine a new generation of self-controlled rovers and multiple orbiters returning the same quality of data that we get from Mars from a much stranger and, in its way, richer place like Titan.

Methane seas and their eroded shores, active dunefields, interesting weather with rainfall, all kinds of organic chemistry. A Martian-scale investigative effort would return far more fascinating vistas than even a horrendously expensive manned mission to Mars, in my opinion.

Bubblecar said:

It’s a very interesting planet in its way, but we have vast amounts of data to be going on with. And available funds for solar system exploration are obviously limited.

I would like to see the same scale of resources allocated to some of the more interesting corners of the solar system – e.g., Titan. Imagine a new generation of self-controlled rovers and multiple orbiters returning the same quality of data that we get from Mars from a much stranger and, in its way, richer place like Titan.

Methane seas and their eroded shores, active dunefields, interesting weather with rainfall, all kinds of organic chemistry. A Martian-scale investigative effort would return far more fascinating vistas than even a horrendously expensive manned mission to Mars, in my opinion.

There’s a joke about a drunkard who is looking for his keys under a lamppost. A policeman helps him look for a while before asking “Are you sure you dropped them here?”. “No,” said the drunkard, “I dropped them over there near the gutter.”
“So why are we looking here??”
“The light is much better.”

Mars is a very attractive target, partly because of its intrinsic interest (varied geology, hydrology, possible former life etc), but also because it is nearby, easy to get to, and well-lit.

A surface mission to Titan also has intrinsic interest (lakes, rivers, presumably rain) but the problems are huge.
The light reaching the Saturn system is only 3% that which reaches Mars, strictly because of distance. The light reaching Titan’s surface is about 0.1% that reaching Mars’s surface.
This means longer exposures for detailed images but mainly it means you can’t use solar power on the surface.
To transmit from the Saturn region to Earth also requires about 30 times more power than transmitting from Mars to Earth. It’s about 40 times from Titan’s surface, due to absorption by the atmosphere.
You also need to expend more power warming the electronics on Titan than you do on Mars because it is so damn cold, about -180 degrees Celsius on average.

So that’s the maths: you need much more power, but hardly any power is available.
Radionuclide power generators would be required for any Titan surface mission to last more than a few hours, and NASA is already seriously strapped for plutonium, and they’d need much more plutonium for an extended Titan mission than they would for a relatively passive deep space mission.
(http://www.wired.com/2013/09/plutonium-238-problem/)
Add to that the uncertainty of the requirements because we have relatively little data about long term weather on Titan. You would either over-engineer, or take a risk.

I’m not trying to poopoo it but the costs and difficulty of a Titan surface mission are so much higher than an equivalent Mars mission. The Cassini mission cost $3.3 billion dollars, and the total cost of the two MER rovers was 820 million dollars.

I’d love to see more outer solar system missions but I wouldn’t want to see fewer Mars missions to pay for it. If anything I’d prefer that money came from the manned program, which to my mind does not give much bang for buck.

> Do We Need Any More Mars Missions, For Now?

Remember ALSEP, the scientific experiment Apollo placed on the Moon. And the scientific experiments on Lunokhod. There still has never been an equivalent of ALSEP on Mars.

1. There has never been a good seismometer placed on Mars, so we don’t know anything about the deep interior of Mars.
2. There has never been a cube corner reflector placed on Mars, so we don’t know accurately how far away Mars is.
3. There has never been an experiment to measure the heat flow out of the interior through the surface of Mars, or even subsurface temperatures.
4. Even Luna 16, 20 and 24 returned rock and soil samples to Earth, there has never been a sample return from Mars.

So, to answer your question: hell, yes.

mollwollfumble said:

> Do We Need Any More Mars Missions, For Now?

Remember ALSEP, the scientific experiment Apollo placed on the Moon. And the scientific experiments on Lunokhod. There still has never been an equivalent of ALSEP on Mars.

1. There has never been a good seismometer placed on Mars, so we don’t know anything about the deep interior of Mars.
2. There has never been a cube corner reflector placed on Mars, so we don’t know accurately how far away Mars is.
3. There has never been an experiment to measure the heat flow out of the interior through the surface of Mars, or even subsurface temperatures.
4. Even Luna 16, 20 and 24 returned rock and soil samples to Earth, there has never been a sample return from Mars.

So, to answer your question: hell, yes.

5. There has never been a magnetometer on the surface of Mars. There was on ALSEP and Lunokhod.
6. Even off the surface, the low density of Phobos remains a mystery, it’s too low for Phobos to be made from solid rock, so what is Phobos really made from?
7. The Vega program to Venus released two balloons into the atmosphere. There has never been a balloon released into the atmosphere of Mars.

OK then, thanks for the information.

Bubblecar said:

It’s a very interesting planet in its way, but we have vast amounts of data to be going on with. And available funds for solar system exploration are obviously limited.

I would like to see the same scale of resources allocated to some of the more interesting corners of the solar system – e.g., Titan. Imagine a new generation of self-controlled rovers and multiple orbiters returning the same quality of data that we get from Mars from a much stranger and, in its way, richer place like Titan.

Methane seas and their eroded shores, active dunefields, interesting weather with rainfall, all kinds of organic chemistry. A Martian-scale investigative effort would return far more fascinating vistas than even a horrendously expensive manned mission to Mars, in my opinion.

Let me check if there’s a Titan mission already planned.

I don’t see one. Or one to Enceladus. Or any follow-up to Cassini-Huygens. Perhaps I haven’t looked far enough. There is a plan to do detailed observations of Titan with the James Webb Space Telescope, but that’s not the same.

You may be interested in this paper, http://www.mdpi.com/2075-1729/6/1/8/htm called “Titan as the abode of life”. It doesn’t say anything new, but does summarise the prospects for finding life on Titan.

mollwollfumble said:

Bubblecar said:

It’s a very interesting planet in its way, but we have vast amounts of data to be going on with. And available funds for solar system exploration are obviously limited.

I would like to see the same scale of resources allocated to some of the more interesting corners of the solar system – e.g., Titan. Imagine a new generation of self-controlled rovers and multiple orbiters returning the same quality of data that we get from Mars from a much stranger and, in its way, richer place like Titan.

Methane seas and their eroded shores, active dunefields, interesting weather with rainfall, all kinds of organic chemistry. A Martian-scale investigative effort would return far more fascinating vistas than even a horrendously expensive manned mission to Mars, in my opinion.

Let me check if there’s a Titan mission already planned.

I don’t see one. Or one to Enceladus. Or any follow-up to Cassini-Huygens. Perhaps I haven’t looked far enough. There is a plan to do detailed observations of Titan with the James Webb Space Telescope, but that’s not the same.

You may be interested in this paper, http://www.mdpi.com/2075-1729/6/1/8/htm called “Titan as the abode of life”. It doesn’t say anything new, but does summarise the prospects for finding life on Titan.

The paper “Scientific rationale of a Saturn probe mission” from 2014, explaining why we need another spacecraft to Saturn after Cassini-Huygens, doesn’t even mention Titan or Enceladus, which is a massive oversight.

There are a few proposed missions to Titan around

Is Titan submarine the most daring space mission yet?

Titan Saturn System Mission

Titan Mare Explorer

Thanks CN.

CrazyNeutrino said:

There are a few proposed missions to Titan around

Is Titan submarine the most daring space mission yet?

Titan Saturn System Mission

Titan Mare Explorer

Ta.

“To transmit from the Saturn region to Earth also requires about 30 times more power than transmitting from Mars to Earth. It’s about 40 times from Titan’s surface, due to absorption by the atmosphere. “

How hard would it be to have a relay satellite/probe or a series of them and retransmit the signal to each one in turn until it reaches Earth.

Cymek said:

“To transmit from the Saturn region to Earth also requires about 30 times more power than transmitting from Mars to Earth. It’s about 40 times from Titan’s surface, due to absorption by the atmosphere. “

How hard would it be to have a relay satellite/probe or a series of them and retransmit the signal to each one in turn until it reaches Earth.

It’s an option but obviously each of those adds to the mission cost.

dv said:

Cymek said:

“To transmit from the Saturn region to Earth also requires about 30 times more power than transmitting from Mars to Earth. It’s about 40 times from Titan’s surface, due to absorption by the atmosphere. “

How hard would it be to have a relay satellite/probe or a series of them and retransmit the signal to each one in turn until it reaches Earth.

It’s an option but obviously each of those adds to the mission cost.

also the satellites have to orbit the sun, i presume to form a relay, so they wouldn’t always be in the right spot. unless you had a few of them.

ChrispenEvan said:

dv said:

Cymek said:

“To transmit from the Saturn region to Earth also requires about 30 times more power than transmitting from Mars to Earth. It’s about 40 times from Titan’s surface, due to absorption by the atmosphere. “

How hard would it be to have a relay satellite/probe or a series of them and retransmit the signal to each one in turn until it reaches Earth.

It’s an option but obviously each of those adds to the mission cost.

also the satellites have to orbit the sun, i presume to form a relay, so they wouldn’t always be in the right spot. unless you had a few of them.

Yes I was wondering about them lining up

Cymek said:

“To transmit from the Saturn region to Earth also requires about 30 times more power than transmitting from Mars to Earth. It’s about 40 times from Titan’s surface, due to absorption by the atmosphere. “

How hard would it be to have a relay satellite/probe or a series of them and retransmit the signal to each one in turn until it reaches Earth.

Very difficult. The real joy of listening directly on Earth is that it costs next to nothing to make a radio dish 32 metres in diameter. Putting a radio dish even 10 metres in diameter into Mars orbit or further away is out of the question. Even ignoring the dish size, the amplification needed would require impossibly large amounts of power.

So no, direct transmission from deep space to Earth is definitely the way to go.

Relays satellites have been used in the past, but the purpose there is quite different, it’s mostly to keep radio contact when there’s no line of sight. And it also made sense for Apollo where low power could be used from the surface to local orbit.

Cymek said:

ChrispenEvan said:

dv said:

It’s an option but obviously each of those adds to the mission cost.

also the satellites have to orbit the sun, i presume to form a relay, so they wouldn’t always be in the right spot. unless you had a few of them.

Yes I was wondering about them lining up

I was developing something like that for a completely different purpose. Most interferometers are limited by the diameter of the Earth. Even those in Earth orbit.

So I was looking at the optimal way to arrange satellites in constellations at different solar orbits to best use the whole of the solar system as a interferometer. It’s an interesting mathematical problem because these satellites would need to be in intersecting orbits. Four satellites on two perpendicular circular orbits is a good start, but you need a lot better than that for a perfect interferometer.