thinktank Neowin ThinkTank #2 -- Design, Plan, and Launch a "Two Decades" Science Set / Mission Programme to the four Gas Giants by 2020 or earlier

[Blue-Vision]

Hello, science buffs, independent researchers and armchair nerds! (And yes, that's a good thing!)

I welcome all of you to the second Neowin ThinkTank.

In this ThinkTank, we'll explore how a motivated Company, Partnership of Companies, or even a Governmental Space Entity like ESA, NASA, Roscosmos and others could (and probably should) pursue an extended, committed, "Two Decades" Probe + Multiple Landers* mission set to the Solar Systems' "Gas Giants" -- Jupiter, Saturn, Uranus, and Neptune.

(*Number of Landers per Probe depends on the destination, obviously)

In this ThinkTank, we should strive to explore every aspect of what a committed, motivated effort like this will require to succeed. We should also be mindful of a budget, since financial concerns are of (usually) vital importance before a project of any scale is given the green-light. We also should consider whether to use "flight-proven" designs such as Cassini and simply update them with the latest hardware & software (then modify that design to accommodate the additional Landers), or if we should "start from the ground up" with an all-new design.

We will also actually plan the Mission(s) themselves. That's a key part of any Probe mission -- where are we going? The science packages, even the very hardware and software itself, depends on that answer. Since each Probe will be going to one destination only, we can dedicate each Probe to its' destination as well as which Landers or Atmospheric Entry Probes we equip it with. Come on, you know you want to send AEP's down into Saturn, Uranus and Neptune! Now's the chance to actually plan those kinds of Missions!

Then we will actually decide which launch hardware should be used for which platform, and when it can be launched. We have the means to simulate the entire flight(s). And yes, it'll be Kerbal Space Program. (Just kidding....? )

For anyone not familiar with the Neowin ThinkTank, it's a very special study that the entire Community is invited to contribute to. Think of it as an exercise, an "Intellectual Interest Topic", where those members with the know-how, the fortitude, the moxy and the savvy can pool their collective talents into one "Grand Objective". Our last ThinkTank, "Establish Mars Colony One (and Two, and Three, and ...)" can be found here: https://www.neowin.net/forum/topic/1259650-neowin-think-tank-mars-colony-one-and-two-and-three-and/ 

Edited November 20, 2015 by BetaguyGZT
Added reference to ThinkTank One

[Blue-Vision]

So ... let's start off the festivities with important information about each of the four Mission Destinations. We'll need to be familiar with each location, intimately, in order to:

1) Identify the best flight plan for each Mothership, including Point of Orbital Insertion, and the fuel requirements to achieve the optimal POI, identify the desired Mission Length (ML) and account for additional RCS propellant requirements for the desired ML versus how much we can actually get to the destination;

2) identify desired Science Objectives as well as a healthy list of secondary Science Objectives; additional Objectives can be assigned on an as-needed/desired basis, as the opportunities present themselves or if new Scientific findings demand further study;

3) finally, design each Primary Probe (Mothership), it's Landers and Atmospheric Entry Probes (AEP's) that each Mothership will carry (including number), and the science suites that each item will carry to each destination within the requirements of (1) and (2).

With that in mind, let's get familiar with our destinations.

[Blue-Vision]

Jupiter - https://en.wikipedia.org/wiki/Jupiter (all images courtesy of Wikipedia/Wikimedia)

Size: 71,492km x 66,854km (flattening at Polar Regions due to high rotation speed)

Rotation: 9h 55m | Axial Tilt: 3.13°

Gravity: 24.79 m/s^2 | 2.528 g at surface (relative to Earth) | Mass: 1.8986 × 10^27 kg | Density: 1.326 g/cm^3 | Escape Velocity: 59.5 km/s

Distance from Sol: Aphelion: 5.458104 AU (816,520,800 km) | Perihelion: 4.950429 AU (740,573,600 km) | Orbital Speed: 13.07 km/s | Inclination: 1.305° (Earth) 6.09° (Sun)

Primary Moons: Io, Europa, Callisto, Ganymede

 

(Left: Cutaway view of Jupiter's interior expanding outward to the Ring System. Right: Infra-Red image of Jupiter taken by the VLT at the European Space Observatory ... WOW!)

(End Part 1 of Jupiter Presentation ... Editor glitching again.)

[Draggendrop Veteran]

Do we have until tomorrow at lunch for final submissions.....    just kidding...

....now where did I leave the cat...need to dust off a few books.......

[Blue-Vision]

Absolutely.  In fact, I'm going to try something on my end that'll let me draft posts -- that way I can post here in the thread with awesome data, not fight with the troublesome editor aside from simple edits, and let me research information at my pace (since I have a household to run, I'm called away from my computer frequently).  Win-win.

So do your thing, DD (and everyone else). Remember to "show your work", as they say in Science.

[Blue-Vision]

Moving along -- Jupiter Presentation Part 2 -- Io (Images and Data courtesy of Wikipedia. Wikimedia, NASA and others) https://en.wikipedia.org/wiki/Io_(moon)

    

Radius: 1,821.6 ± 0.5 km (28.6% of Earth) | Mass: (8.932 ± 0.000018) × 10^22 kg (0.015 Earth) | Density: 3.528 ± 0.006 g/cm^3 | Surface Gravity: 1.796 m/s^2 (0.183 g) | Escape Velocity: 2.558 km/s

Orbital Distance: 350,000 km from cloud tops / 421,700 km avg. | Orbital Speed: 17.334 km/s | Orbital Period: 42.46 hours / 1.77 days | Inclination (to Jupiter): 0.05° | Rotation: Tidally-locked

Nomenclature / naming convention criteria: https://en.wikipedia.org/wiki/Io_(moon)#Nomenclature | Observational History: https://en.wikipedia.org/wiki/Io_(moon)#Observational_history 

Summary: Io is the most distinct, recognizable Moon in the Solar System (aside from our own Moon). The intense geological activity on Io is literally the stuff of science fiction -- if there's an amalgam of a "Hellscape", this would be half of the picture simply from the geology alone. This is due to the extreme proximity to Jupiter's magnetic field as well as the gravitational "tug of war" between Jupiter and the three larger, outer Jovian Moons that constantly knead and flex Io during the orbital resonance forces at play throughout the Jovian system. In fact, Io plays a significant role in shaping the Jovian magnetic field, acting as an electric generator that can develop 400,000 volts across itself and create an electric current of 3 million amperes, releasing ions that give Jupiter a magnetic field more than twice the size it would otherwise have.

Io orbits within a belt of intense radiation known as the Io Plasma Torus. The plasma in this doughnut-shaped ring of ionized sulfur, oxygen, sodium, and chlorine originates when neutral atoms in the "cloud" surrounding Io are ionized and carried along by the Jovian magnetosphere. Unlike the particles in the neutral cloud, these particles co-rotate with Jupiter's magnetosphere, revolving around Jupiter at 74 km/s. Like the rest of Jupiter's magnetic field, the plasma torus is tilted with respect to Jupiter's equator (and Io's orbital plane), so that Io is at times below and at other times above the core of the plasma torus. As noted above, these ions' higher velocity and energy levels are partly responsible for the removal of neutral atoms and molecules from Io's atmosphere and more extended neutral cloud. The torus is composed of three sections: an outer, "warm" torus that resides just outside Io's orbit; a vertically extended region known as the "ribbon", composed of the neutral source region and cooling plasma, located at around Io's distance from Jupiter; and an inner, "cold" torus, composed of particles that are slowly spiraling in toward Jupiter. After residing an average of 40 days in the torus, particles in the "warm" torus escape and are partially responsible for Jupiter's unusually large magnetosphere, their outward pressure inflating it from within.

Jupiter's magnetic field lines, which Io crosses, couple Io's atmosphere and neutral cloud to Jupiter's polar upper atmosphere by generating an electric current known as the Io flux tube. This current produces an auroral glow in Jupiter's polar regions known as the Io footprint, as well as aurorae in Io's atmosphere. Particles from this auroral interaction darken the Jovian polar regions at visible wavelengths. The location of Io and its auroral footprint with respect to Earth and Jupiter has a strong influence on Jovian radio emissions from our vantage point: when Io is visible, radio signals from Jupiter increase considerably. The Juno mission, currently en route to Jupiter with a planned orbital insertion in June 2016, should help to shed light on these processes. The Jovian magnetic field lines that do get past Io's ionosphere also induce an electric current, which in turn creates an induced magnetic field within Io's interior. Io's induced magnetic field is thought to be generated within a partially molten, silicate magma ocean 50 kilometers beneath Io's surface. Similar induced fields were found at the other Galilean satellites by Galileo, generated within liquid water oceans in the interiors of those moons.

Io is slightly larger than the Moon. It has a mean radius of 1,821.3 km (1,131.7 mi) (about 5% greater than the Moon's) and a mass of 8.9319 × 10^22 kg (about 21% greater than the Moon's). It is a slight ellipsoid in shape, with its longest axis directed toward Jupiter. Among the Galilean satellites, in both mass and volume, Io ranks behind Ganymede and Callisto but ahead of Europa.

Composed primarily of silicate rock and iron, Io is closer in bulk composition to the terrestrial planets than to other satellites in the outer Solar System, which are mostly composed of a mix of water ice and silicates. Io has a density of 3.5275 g/cm3, the highest of any moon in the Solar System; significantly higher than the other Galilean satellites and higher than the Moon. Models based on the Voyager and Galileo measurements of Io's mass, radius, and quadrupole gravitational coefficients (numerical values related to how mass is distributed within an object) suggest that its interior is differentiated between a silicate-rich crust and mantle and an iron- or iron-sulfide-rich core. Io's metallic core makes up approximately 20% of its mass. Depending on the amount of sulfur in the core, the core has a radius between 350 and 650 km (220–400 mi) if it is composed almost entirely of iron, or between 550 and 900 km (340–560 mi) for a core consisting of a mix of iron and sulfur. Galileo's magnetometer failed to detect an internal, intrinsic magnetic field at Io, suggesting that the core is not convecting.

Modeling of Io's interior composition suggests that the mantle is composed of at least 75% of the magnesium-rich mineral forsterite, and has a bulk composition similar to that of L-chondrite and LL-chondrite meteorites, with higher iron content (compared to silicon) than the Moon or Earth, but lower than Mars. To support the heat flow observed on Io, 10–20% of Io's mantle may be molten, though regions where high-temperature volcanism has been observed may have higher melt fractions. However, re-analysis of Galileo magnetometer data in 2009 revealed the presence of an induced magnetic field at Io, requiring a magma ocean 50 km (31 mi) below the surface. Further analysis published in 2011 provided direct evidence of such an ocean.[68] This layer is estimated to be 50 km thick and to make up about 10% of Io's mantle. It is estimated that the temperature in the magma ocean reaches 1,200 °C. It is not known if the 10–20% partial melting percentage for Io's mantle is consistent with the requirement for a significant amount of molten silicates in this possible magma ocean. The lithosphere of Io, composed of basalt and sulfur deposited by Io's extensive volcanism, is at least 12 km (7 mi) thick, but is likely to be less than 40 km (25 mi) thick.

Based on their experience with the ancient surfaces of the Moon, Mars, and Mercury, scientists expected to see numerous impact craters in Voyager 1's first images of Io. The density of impact craters across Io's surface would have given clues to Io's age. However, they were surprised to discover that the surface was almost completely lacking in impact craters, but was instead covered in smooth plains dotted with tall mountains, pits of various shapes and sizes, and volcanic lava flows. Compared to most worlds observed to that point, Io's surface was covered in a variety of colorful materials (leading Io to be compared to a rotten orange or to pizza) from various sulfurous compounds. The lack of impact craters indicated that Io's surface is geologically young, like the terrestrial surface; volcanic materials continuously bury craters as they are produced. This result was spectacularly confirmed as at least nine active volcanoes were observed by Voyager 1.

https://upload.wikimedia.org/wikipedia/commons/a/a5/First_Geologic_Map_of_Jupiter’s_Moon_Io.jpg 

Io's colorful appearance is the result of materials deposited by its extensive volcanism, including silicates (such as orthopyroxene), sulfur, and sulfur dioxide. Sulfur dioxide frost is ubiquitous across the surface of Io, forming large regions covered in white or grey materials. Sulfur is also seen in many places across Io, forming yellow to yellow-green regions. Sulfur deposited in the mid-latitude and polar regions is often radiation damaged, breaking up normally stable cyclic 8-chain sulfur. This radiation damage produces Io's red-brown polar regions.

Explosive volcanism, often taking the form of umbrella-shaped plumes, paints the surface with sulfurous and silicate materials. Plume deposits on Io are often colored red or white depending on the amount of sulfur and sulfur dioxide in the plume. Generally, plumes formed at volcanic vents from degassing lava contain a greater amount of S2, producing a red "fan" deposit, or in extreme cases, large (often reaching beyond 450 km or 280 mi from the central vent) red rings. A prominent example of a red-ring plume deposit is located at Pele. These red deposits consist primarily of sulfur (generally 3- and 4-chain molecular sulfur), sulfur dioxide, and perhaps Cl2SO2. Plumes formed at the margins of silicate lava flows (through the interaction of lava and pre-existing deposits of sulfur and sulfur dioxide) produce white or gray deposits.

Compositional mapping and Io's high density suggest that Io contains little to no water, though small pockets of water ice or hydrated minerals have been tentatively identified, most notably on the northwest flank of the mountain Gish Bar Mons. Io has the least amount of water of any known body in the Solar System. This lack of water is likely due to Jupiter being hot enough early in the evolution of the Solar System to drive off volatile materials like water in the vicinity of Io, but not hot enough to do so farther out.

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End Io Presentation

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