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Hot answers tagged

21

tl;dr: No chance, not even close! The escape velocity from the surface of a round (spherically symmetric) body is given by $$v_{esc} = \sqrt{\left(\frac{2 GM}{r_0} \right)}, $$ showing that it is the $\frac{mass}{radius}$ ratio that's key here, not just the surface gravity given by $$a_{g} = -\frac{GM}{r_0^2}. $$ So since $$v_{esc} = \sqrt{a_g r_0}, $...


19

Could they be harvested? Sure. Could they be harvested in an economically profitable way? Probably not, for all the reasons you listed. There's a lot of unknowns to this question — while the chemistry they mention certainly makes sense, there's lots of stuff about the atmosphere we don't know. A harvesting ship would need to find exactly what ...


16

Cassini's INMS, the Ion Neutral Mass Spectrometer, is an in situ instrument that measures the neutral and plasma gas composition of what it ingests. It was intended for the measurement of Titan's atmosphere, Saturn's magnetosphere plasma, ring composition, and in fact the composition of icy satellite effluents. Here is a good presentation on the basics of ...


15

If we were going to send a probe into Saturn's atmosphere and were concerned about contamination of a potential ecosphere there, we would sterilize the probe first, e.g. with dry heat microbial reduction, to make sure that nothing viable was on the probe. Cassini has no protection from the entry heat like a probe would, and will be entering at an incredible ...


13

For Jovian and Saturnine moons, the simplest answer is no, at least not much more habitable than our own Moon is, because none of these moons have their own magnetic field or sufficient mass and their atmosphere would eventually thin out via the ionospheric hydrogen loss due to the solar wind. A bit more difficult answer is how many of these moons would be ...


12

No. Fermi estimate: Mimas' gravity is 0.064 m/s2, you need gravity to be about 1/20 of that to escape using a bike and a ramp (going by Deimos' surface gravity of 1/20 that of Mimas), lower still to escape by jumping :


11

For a Hohmann transfer to Saturn, I get 15.7 km/s for both burns. The transfer time is also a simple formula. I obtain roughly 6 years. Compare to the lunar ice. It is roughly 2.8 km/s to get to, and the trip time would be a few days, even from Low Earth Orbit. As suggested by the other answer, you could compare to Earth's surface. If we're using some ...


11

Can Dragonfly make it to one of Titan's Lakes? tl;dr: Yes! It could be doable in 2-3 years. According to your linked document Dragonfly will use a Multi-mission radioisotope thermoelectric generator or MMRTG: The MMRTG design incorporates PbTe/TAGS thermoelectric couples (from Teledyne Energy Systems), where the TAGS material is a material incorporating ...


10

Define "destroyed". It will no longer be able to maintain attitude control due to torque from the atmosphere at a radius of about 61,700 km. From there we will get no more data from the spacecraft since it can't point the antenna. From our point of view, at that moment, Cassini is buh bye.


10

It is not being overlooked. There are studies which are being carried out about the feasibility of life on Titan based on methane. It is true that Titan has all the necessary conditions for life: It is not in thermodynamic equilibrium It has more than enough of carbon based molecules It has a fluid environment (ethane/methane) for chemical reactions to ...


9

To answer the question, 'is Cassini running out of fuel': As you'd expect, NASA has monitored Cassini's fuel levels. In 2014 JPL published a study, 'Ensuring Cassini’s End-of-Mission Propellant Margins': With three years left and only 2.5% of its loaded bipropellant and 37% of its loaded monopropellant remaining, the Cassini project actively manages the ...


9

The solar flux at 1 AU (Earth's distance from the sun) is ~1361 W/m2. Flux falls off as the square of distance. Saturn, on average -- and thus Titan, on average -- is about 9.58 AU from the sun, so the falloff factor is 1 / 9.582 or 0.0109. Titan should average about 1361 x 0.0109 = 14.8 W/m2 when not shadowed by the gas giant. When Saturn is at its ...


8

3-5% of the speed of light would only be achievable for a really long duration mission. It just isn't efficient enough to do that kind of acceleration, and it takes a really long time to achieve. Okay, so how long would it take? The math is pretty easy, it's just speed/ acceleration. c=300,000,000 m/s, g= 9.8 m/s^2, so just find the speed, divide by 9.8, and ...


8

After reading this blog post and skimming through this paper1, it seems like it's just the stabilization of a standing waves caused by the difference in angular velocity. Basically, as you go outwards from the poles, there is an increase in the velocity as the system moves with a constant angular velocity. This creates some shear on the gases present ...


8

This is purely a speculation, as I have not found any official sources to confirm it, but I think they want to be able to view Saturn's pole during the fly by. The trigonometry works out at least: If you want to get a close-up of the polar regions with a lower inclination, like 40, 50 or 60 degrees, the altitude required is larger than the gap between ...


8

Let's turn the question on its head and see what exhaust velocity we need to if Titan's entire (mostly nitrogen) atmosphere were used as a propellant. $\Delta v = v_e log(m_i / m_f)$ Wikipedia tells us that the atmosphere of Titan is about 1.19 times as massive as that of Earth so we get about 6.13e18 kg of atmosphere (propellant) in a total mass of about ...


7

Let's do a Fermi estimate: Rockets bring about 2-5% of their start mass to orbital velocity. To cancel out Titan's orbital velocity, you're looking at two orders of magnitude more fuel and oxidizer than Titan's mass. Earth's atmosphere weighs $10^{18}$ kg, or 1/200,000 of Earth's total mass. Titan's is 1.5 times as dense, so if Titan's atmosphere were ...


6

No, you can't fly through the rings you can see without hitting lots and lots of dust-sized ice particles at high velocity. Your vehicle will not fare well. The ring material is not sparse in that sense. There is a wide distribution of particle sizes from boulders to dust. There's a lot more dust-sized, so that's what you need to worry about. (I wouldn'...


6

I'm going to interpret "surface" to mean Saturn's upper atmosphere. It was recently discovered that ring particles are raining down on Saturn. It’s raining on Saturn. Each second, the planet’s rings shed perhaps thousands of pounds of water ice, organic molecules, and other tiny particles into the gas giant’s clouds. This is caused by particles ...


5

Concise version from the pre-flyby media teleconference announcement: Cassini scientists are hopeful the flyby will provide insights into how much hydrothermal activity is occurring within Enceladus, and how this hot-water chemistry might impact the ocean’s potential habitability for simple forms of life. If the spacecraft’s ion and neutral mass ...


5

Well, it's the sugarcoating blowing off the Saturn's doughnut, of course! Not far from the truth, but jokes aside still, the color dichotomy of Iapetus is due to the darker half, the Cassini Regio, being a result of the moon's accumulation of the dust in the Saturn's largest, yet extremely tenuous, diffuse dust ring called the Phoebe ring depositing onto ...


5

I don't know about multiple mission proposals, but I was able to find a fairly well spelled-out plan so I'll answer based on that. The proposal is based on the IceMole melting probe but I don't know if there's a name for the proposal itself. The best source of data I've found is this PDF from 2014. It indicates that at least for this proposed mission they ...


5

It is modeled that the dunes must form from chips of Titan's bedrock. Whether those chips are primarily hydrocarbons or primarily water ice, depends on what Titan's crust is presumed to be composed of. There are varying models, depending on what is known of Titan (such as the moment of inertia), and one model with a reasonable level of support involves a ...


5

Any picture of Cassini in space is an artist's conception, probably a computer rendering, although the Saturn backdrop may come from real Cassini photographs. I had thought it possible that the Huygens probe carried by Cassini to Titan might have taken one or more pictures of Cassini as it departed, but it's not possible, as the camera was enclosed under ...


5

The raw images of Cassini can be viewed online in reverse order https://saturn.jpl.nasa.gov/galleries/raw-images?order=earth_date+desc&per_page=50&page=0


4

Although I and many other authors of the 2007 Enceladus study would love to see such a mission happen, that seems very unlikely in the near future. The first issue is that Enceladus orbits only four Saturn radii out, so is in a very deep gravitational well. Second, assuming the probe orbits with its pariapsis at Enceladus and its apoapsis at Titan, the ...


4

The rings became flat over time as the trillions of particles in them collided over and over, slowly causing their vectors (direction of motion) to average out until they were all aligned in the same direction. See this short video from Minute Physics. A flat disk rotating in one direction is the only arrangement of these particles that is stable. The ...


4

No. The surface of Saturn is not solid. Saturn is too hot to support solid ice, and not just because of solar radiation: Also like Jupiter, Saturn gives off almost twice as much energy as it receives from the Sun, because it has its own internal heat source, powered by the slow gravitational collapse that started when the planet first formed. Given ...


4

(This image shows that the rear side of Saturn ring is dark ) (this image shows the variation of rings brightness as the distance from earth the more closer the more brighter) The Saturn ring consist of 99% of water and the remaining impurities** The water is in the form of water ice since ice is a crystalline structure it reflection and refracts light ...


4

The effect you are seeing is simply wind, not a twist. The reason for the diagonal direction is that the smoke is moving horizontally while the rocket is moving upwards, like this: How can I be so sure about this? Well, viewing the other side of the rocket is not necessary: If the smoke was indeed ejected sideways, it would continue in the same direction ...


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