I had this same sense when I saw the 'Powers of 10' short movie for the first time in the 70s.

Yes, it's all deliciously fantastic - and time under a clear sky at night is time well spent.

A nicely sintered landing pad would do the trick.

Berms / shields around landing sites are worth looking at.

Daedalus was still an Orion-esque engine, but with thermonuclear (not fission) 'devices'.

Bussard ramjets are out of favour as nobody is sure that they make nett thrust.

> yet we can find a tiny plaque?

And will be till we put a dome over it.

Not quite in the same vein, but there are graffiti in various places:

https://eeggs.com/items/9064.html

And, I'm told, on a PCB of Beagle2's avionics there's "We come in pieces".

<such trenchant wit>

No agency as such, but a great many skilled workers and companies.

One instrument I worked on in the 90s had a crucial element (four titanium wires as thin as hairs stretched across a gap of 50mm, and all that inside thin-walled titanium cans with walls no thicker than playing cards) that was made in Poland.

<TIL: the first head of Polsa, Prof Banaszkiewicz, is the lead scientist of this very device I'm describing! He's done well!>

Perhaps.

But you still need to launch that junk from its current orbit to wherever you want it to go, and then soft-land it (if you're aiming for the Moon).

The average satellite will lack;

a) Fuel/engines to perform such a task

b) the same for capture/soft-braking manoeuvres

c) structures/resources to allow it to land safely (legs, power, etc.)

It's like saying I could go down to the beach, and cobble together a boat from discarded plastic and wood.

I could.

Or I could build a ship.

In the bad old days (early 90s) I used a patched conic solver.

I wager that there are tools to do that kicking around.

&#x200B;

Paths with a gravity assist (handy!)

https://www.mathworks.com/matlabcentral/fileexchange/39462-gravity-assist-trajectory-design-and-analysis?s_tid=blogs_rc_5

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Someone's thesis (Matlab, again)

https://repositories.lib.utexas.edu/handle/2152/ETD-UT-2011-12-4849

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More Matlab (just adjust Mars till Saturn)

https://github.com/chicomcastro/optimized-Earth-Mars-transfer

etc.

And there are half a dozen antique TDs about FORTRAN codes kicking around on the NASA TRS.

And Inkscape is free and fabulous.

This is not true.

I worked (in the early 90s) on satellites for EUMETSAT, writing and testing code for the latest Meteosat constellation of remote observation craft.

The imagers did not use a 'fish eyed lense'.

The Earth, like all planets, is essentially spherical as a quick trip to the seashore can demonstrate.

I'm a chartered physicist, and that just means that I can plot my ignorance on a chart with fancy-pants axes, such as log-linear space.

And it's still a straight line vs. time.

The older I get, the less I know as a fraction of all that is knowable.

For that exact purpose I used to have;

a) A tile from Buran (and a propane torch)

b) A Sokol-KV glove

c) A 3kg lump of campo-del-cielo

d) Some JSC-1 lunar regolith simulant

e) some Mars-1 martian regolith simulant

f) A bit of Etna (compare and contrast with the above!)

&#x200B;

JSC ought to be able to help out with d) / e) - worth dropping them a line.

&gt;Has anyone every traveled to a launch

Yes, many tens of thousands of people have travelled to see launches.
But to make them the focus of the trip is to court disappointment.

Build a trip that has other goals alongside that - see KSC, travel to Key West, explore the coast.

All of these are (depending on where you're flying from) fair reasons to visit Florida - especially if you're currently enduring frigid temperatures.

<I saw an STS launch in the 90s - got a chance to hear Michael Foale, and had a whale of a time>

Here are some of the best models we have of Jupiter's near-core:

https://arxiv.org/pdf/1812.07436.pdf

p12 allows for both a sharp discontinuity and a gradual 'fade' from metallic hydrogen to rock. The data we have cannot distinguish between those models.

"The existence of a diluted core, or a steep heavy-element gradient inside Jupiter is actually consistent with formation models of Jupiter (see section 4.3 for details). Giant planet formation models in the core accretion scenario (e.g., Pollack et al., 1996) suggest that once the core mass reaches ∼ 1 − 2M⊕ the accreted solid material (heavy elements) vaporise and remain in the planetary envelope (e.g., Stevenson, 1982). This leads to a structure in which the deep interior is highly enriched with heavy-elements, with no sharp transition between the core and the inner envelope (e.g., Helled & Stevenson, 2017 and references therein)."

We can walk on things because they're rigid solids.

But I doubt that there's a nicely defined discontinuity between the metallic hydrogen ocean and some rock.

It is a good question - I suspect that the sound of a breaking wave arises from the bubbles made by the impact 'ringing' - the fundamental mode of which will vary with T and the ratio of specific heats (gamma).

So I'd expect breaking waves on Titan to have fewer large bubbles (weaker gravity) but on the other hand the syrface tension of N2/ethane is lower than that of water, so might not bubbles be larger?

Either way, the speed of sound is 2/3 that of that at Earth's sea level - so a vibrating bubble ought to have a lower tone - if bubble sizes are like those on Earth, then the speed of sound alone will make crashing breakers sound deeper in pitch.

I think.

-fun!-

<polishes nails: I calibrated the speed of sound sensor (API-V) on the Huygens probe>

The speed of sound varies only with temperature and composition of the gas.

If you know the temperature (trivial) then you can infer the composition from the time taken for a 'ping' to traverse a small gap - from a transmitting element to a microphone.

Pressure affects only the 'loudness' of the ping, not the speed.

It's a good question how a waterfall might sound - or a breaking wave. That's not a trivial matter - as anyone who has poured hot and cold water into a glass and listened will attest.

Over which is an ocean of hypercompressed hydrogen at essentially the same density as the rock below.

The only transition is one of composition (mumble: and both seismic speeds) rather than density - which we seen in the terrestrial oceans.

<nods>

A positive-pressure suit purged with your favoured blend of N2/O2 will suffice.

ie, a calibrated microphone.

Yes - it's not a trivial piece of engineering - and depends entirely on the altitude region of interest.

And you're best off integrating this onto a sonde/entry probe of some sort - a bare microphone in a tube will need a further other non-trivial items.

<power source, transmitter, etc.>

It depends on the altitude at which you conduct this courageous experiment.

It is a gas giant after all, so there are locales with pressures of 1bar, and altitudes with temperatures of 300K.

Sadly those regions do not overlap.

It is - for certain definitions of habitable.

If you don't mind living in a balloon-lofted city, and having a somewhat higher radiation does, it's quite the place.

No - they didn't "just go through" - they encountered gas that became increasingly denser as one sinks into Jupiter.

There probably is a solid core of rock, but before then you encounter multi-bar pressures, and densities exceeding that of common fluids here.

The spectral content of the noise would be an interesting question to study.

It's probably a power law (most/many things are) but with what index?

That's a good and non-trivial question. Thank you!

Only three qualities alter the speed of sound.

The mean molecular mass (ie, what the gas is made of) and temperature (and the ratio of specific heats, gamma). Pressure has no effect on speed of sound, but (of course) the density of a gas will dictate how much acoustic energy may be found.

Gravity influences the density profile of a gas, but that's all.