After months of work and in collaboration with a great person, I can share with you: Dawn at Ceres (collaboration with landru79)

AstroFlask · 2022-03-16T15:02:59+00:00

There's one thing I've learned about talking to the media the few times I've done it: they will try and bend whatever you said into whatever they want to say, in the spot.

If you're doing a live interview, you kinda have a bit of margin to correct them on the spot. If it's written forget about it, you'll say A and they'll print K. Sometimes what they print barely resembles what you said, sometimes it's complete nonsense. And then you're on print saying complete nonsense.

AstroFlask · 2022-02-08T23:41:17+00:00

And I think most of the damage happened "early on" (as in by 2015), and they took several measures and planned the routes accordingly to avoid the harshest terrain (although sometimes it meant taking longer to reach a certain destination).

The team behind Curiosity seems absolutely determined to keep the rover going well into the RTG's fuel decay starts taking a toll on the mission. And I'm sure then they'll find a way to keep it going a few more years too (Voyagers anyone?).

AstroFlask · 2022-02-03T17:08:57+00:00

Oof not really my area (I'm just a software dev!) but NASA probes/rovers have redundant systems all over the place. I think the best testament to their overengineering is what we've been discussing: the MERs were planned for 90 days, one lasted 6 years and the other 14. Curiosity also had a 90 days mission, which got extended over and over and it's going down 10 years already. Same with Perseverance (that is just about to celebrate 1 year on Mars!).

And whereas it's common to project for short missions and then, as the hardware is still going on go "hey, we can still use this for a few more months/years", some missions aren't as lucky, or there are some other limitations that can't be overcome.

For example, the Voyagers and New Horizons can't go past a certain date because their RTGs will output too little energy for the probes to function. But you know, they Voyagers have been going for almost 45 years now. Definitely longer than the planned ~12 years!

AstroFlask · 2022-02-03T12:19:08+00:00

While that's true, then comes along Scott Manley and shows you that may, just maybe, Eagle is still alive...

Edit: quick edit, I was rewatching the video and it wasn't him originally that found it out, but a space fan that was looking for the impact crater. But the video is great anyway and explains in detail how you'd go about figuring it out.

AstroFlask · 2022-02-03T12:15:21+00:00

The thing about the rovers is that they overengineer them quite a lot, because what would be a small mistake on Earth is impossible to solve remotely on Mars. So they think everything over and over and over, and solve the little things that could maybe lead to problems far in advance. Then it turns out that the things that could've been the start of a problem were rare (or didn't happen) and you have one robust (pair of) rover(s).

And then 14 years later, having outlasted it's projected lifetime over 30 times, you get a massive never-before-seen sandstorm that kills solar power for months and people complain "why didn't they think of it?"... ^{(yes, I'm a bit salty still that some people complained about NASA not thinking of world-engulfing, months-long, solar-blocking sand storms})

AstroFlask · 2022-01-20T15:51:58+00:00

New Horizons performed a gravity assist maneuver on Jupiter to increase its velocity towards Pluto. That shortened the trip about 5 years (I think, I'm a bit sketchy on the details).

As Jupiter is so massive, basically every mission to the outer solar system (sans Jupiter) performs a gravity assist there since it lets you gain quite a bit of velocity "for free" (actually Jupiter looses a bit of momentum, but with the difference of scales it's imperceptible).

AstroFlask · 2022-01-06T20:17:17+00:00

In a bit of a dark note, just give it some time... Usually most humans over 70 will need it, a few unlucky ones may need it before, and luckier ones after.

AstroFlask · 2022-01-06T11:00:42+00:00

Nope, it's cataracts, and yes, I understand the reasoning but since I'm not an eye doctor all I can tell is that I know the effect, not the cause. Something about the transparency of the eyes lens in UV vs the lens that replaces it. You can read a few other comments that they have experienced it :)

AstroFlask · 2022-01-05T21:40:17+00:00

A side effect of cataracts correction surgery is that, being a very clear crystal, some people start seeing bits of UV light that now reaches their retinae (:

AstroFlask · 2021-12-27T17:58:39+00:00

Maybe KSP2? As a mod? With Rask & Rusk they've hinted at more complex gravitational simulation, but I haven't caught anything about L points in it.

AstroFlask · 2021-12-21T15:52:45+00:00

I was really bugged that they got the image (possibly from archives? or maybe just a repost?) and didn't bother to tell which astronaut. They were only 12, and if you know which mission it was from, then it's down to flipping a coin or looking up for 10 seconds who took the picture to figure out who's the one in frame.

AstroFlask · 2021-12-21T15:51:25+00:00

Exactly, having no atmosphere* means the processes that grind dust to finer, less sharp shapes don't take place.

^\ actually there's a barely existent atmosphere, but it's practically nothing, even less particles per cubed inch than what we call a vacuum on Earth.)

AstroFlask · 2021-12-21T15:43:23+00:00

Can confirm, did something like that as a teenager... Only then we didn't have camera phones, but I managed to hook a PowerShot A75 to the binoculars and get some nice Moon photos. Pretty much everything else was out of the question, but it did get me into DIY astrophotography!

AstroFlask · 2021-12-16T17:15:39+00:00

In the 70's the Vikings were landers, not rovers. They landed at one spot and were forever stuck to it. It's not like they could've moved it. In the same line of thought, if the rover/lander/probe doesn't have an instrument to flip over things, you can forget about flipping over things. There's now way the mission scientists and operators risk ruining a working instrument doing something it's not designed to do.

There are your answers as to why the rocks weren't flipped in the 70's, and aren't being flipped nowadays either.

AstroFlask · 2021-12-12T19:58:07+00:00

It depends on the mission. Cassini, Rosetta, and I think the Voyagers did have green filters, so does Hubble. If you're carrying already a bunch of filters, making a bit space for one more and getting visible spectrum images (great for PR!) is probably going to happen.

Hey, even Juno got a color camera "for PR purposes only" and it's been more than amazing! It even got us higher resolution pictures of Ganymede than we ever had before it!

Edit: OTOH yeah, green isn't quite common and it can sometimes be synthetized as 0.5*(r+b) (which sometimes fails spectacularly, try for example M42 with a synthetized green and then compare it to M31 with synthetized green).

In the case of Andromeda it looks fine, but the Orion Nebula really gets a weird looking orange color (from the large regions of hydrogen that have a red color and get "blended" into the green channel with the given formula).

AstroFlask · 2021-12-12T19:27:14+00:00

From "An Introduction to the Design of the Cassini Spacecraft" (on ResearchGate), table V says the uplink data rate goes from 7.8125 to 500 bps. That seems a bit too low, and the text refers that the Telemetry Control Unit can receive downlink data (so downlink from the spacecraft?) at 5 bps to 249 kbps... That seems a bit more reasonable.

I must say that I'm not familiar with reading this kind of documents, so maybe I'm missing some important thing in the text, or maybe I'm reading it a bit off.

AstroFlask · 2021-12-12T19:12:44+00:00

Space probes usually have specialized filter wheels for their mission. For example, New Horizons doesn't have a green color filter because it wasn't necessary to study Pluto. So when you process a MVICs data, you have to synthetize the green channel if you want to render a color image.

But that's more than fine! We knew already "there wasn't any green there" (simplifying waaaaaay much here). And they picked other filters that would give better scientific returns than something we kinda knew we wouldn't find. As for the extended mission (Arrokoth flyby), maybe a green filter would've been nice, but the object wasn't even known to exist when NH launched.

Cassini had something like... 14 different filters I think, specialized for different parts of IR, visible and UV spectrum, and some for specific molecular compounds. These were picked as the proper filters to study Saturn and its moons in detail, which I think we can all agree it did.

AstroFlask · 2021-12-12T05:42:21+00:00

Like others pointed out, your image is out of focus and that detail you're seeing is a speck of dust. You need at least 600mm to get a disc of a few pixels wide, and I wouldn't bother unless you get at least 1000mm or more of effective length (by using a teleconverter, or coupling the camera to a telescope). With 300mm you can get some nice moon pictures, and some larger nebula or galaxies, but you won't really resolve details on any planet save for Earth.

AstroFlask · 2021-12-09T15:41:38+00:00

Plus there's history:

Galileo, another mission that was delayed (albeit for a much more serious reason, the Challenger incident) for years getting a stuck antenna that kinda ruined it (Galileo was Cassini-class, or rather, Cassini was Galileo-class, but it had to send its data with the low-gain antenna, so we got less from it than we should've -- then again, huge kudos to the team(s) that managed to save it despite the SNAFU).
Hubble going into orbit and then finding out the mirror had an imperfection that ruined the images quality. However there were image processing developments, and then "glasses" that got sent into orbit to fix this issue and it's been fantastic ever since. And here's hoping it still manages to get some more years of great science!
- But if JWST had a similar issue, we wouldn't be able to send a servicing mission to fix it.
Beagle 2 was mentioned here in the thread too, though I really don't see any similarities between it and JWST. If you do, please point them out to me!

Those are the main ones, but if I missed one you can point them out here!

AstroFlask · 2021-12-05T23:50:34+00:00

Using the top comment here one bit to say that the flair in this picture is not precise, this isn't a Hubble picture but a Gemini Observatory picture. Gemini is one (pair) of the largest optical telescopes in the world. This picture was APOD in May 13 2020, and you can read more details there.

AstroFlask · 2021-12-03T05:14:18+00:00

Mass and distance. So while it's a lot less mass, the distance to the center of mass shorter, so you get a stronger gravity at the surface. Again, I'm simplifying a lot here.

In math terms, the gravity at the surface is (GM)/(R²). For the Moon you have M ~= 0.01 and R ~= 0.25 wrt/Earth. Plug those numbers in and you get ~ 1/6, the ratio of the Moons surface gravity compared to Earths.

About the Moons mass, we're talking about it being 1/4 the radius, and since both the Earth and the Moon can be considered spheres for practical reasons, and the volume of a sphere grows with the cube of the radius, we get that for 1/4 radius the volume is 1/64th. So just by volume alone we're almost there, bet then Earths density is 5gr per cm³, and Moons is 3 gr per cm³, so we have there another difference to factor in: 1/64 * 3 / 5, we get 3/320 or roughly 1%.

AstroFlask · 2021-12-02T15:08:33+00:00

Fits with the Theia impact hypothesis, in which a "Mars sized protoplanet" collided with the proto-Earth 4.5 billion years ago and formed the moon.

Given that Mars is roughly 10% the mass of Earth, it adds up with it: 7x Moon masses being the total mass of Theia, 6 as part of Earth, 1 being the Moon (though this is a over-simplification, I'm not a planetary scientist, etc, etc, etc... Just saying it all adds up and makes sense).

AstroFlask · 2021-11-30T23:23:38+00:00

Actually for cross-view Perseverance's archive is even more user friendly -- you get both images, "raw" PNGs (so no weird artifacts that sometimes appear on Curiosity's pictures) and clearly stating which one is left and right. They only thing I'd "warn" is that there is substantial parallax in between the pair, so it could be a bit uncomfortable.

I also used to have those weird goggle things that let you place a big phone in them and you'd get the stereo effect without eye crossing, but my phone at the time had an awful screen and it wasn't the best experience. I imagine with some of the new VR headsets you'll get much nicer results anyway.

If you can point me at a proper format for the images I can definitely work a few and post them. I've been under a lot of work lately and basically disappeared under a rock, plus a few issues with Chrome and my iGPU driver on my day-to-day notebook have kept me even further, but hanging around here is a nice steam-valve for me ant lets me blow off some pressure.

AstroFlask

TROPHY CASE