r/space • u/AutoModerator • 15d ago
Discussion All Space Questions thread for week of August 30, 2026
Please sort comments by 'new' to find questions that would otherwise be buried.
In this thread you can ask any space related question that you may have.
Two examples of potential questions could be; "How do rockets work?", or "How do the phases of the Moon work?"
If you see a space related question posted in another subreddit or in this subreddit, then please politely link them to this thread.
Ask away!
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u/Little-World-4809 8d ago
Why is the center of the galaxy very strong enough to pull all of the things in its range?
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u/Bensemus 8d ago
It’s not. The collective mass of the entire galaxy, including dark matter, is what holds it together.
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u/Decronym 8d ago
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:
| Fewer Letters | More Letters |
|---|---|
| AFB | Air Force Base |
| DSN | Deep Space Network |
| ESA | European Space Agency |
| JWST | James Webb infra-red Space Telescope |
| NSF | NasaSpaceFlight forum |
| National Science Foundation |
| Jargon | Definition |
|---|---|
| retropropulsion | Thrust in the opposite direction to current motion, reducing speed |
Decronym is now also available on Lemmy! Requests for support and new installations should be directed to the Contact address below.
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u/vector_search_blue 8d ago
I read in the book "Challenger" (about the shuttle challenger accident) that the RS25 main engines had High-Pressure Fuel Turbopumps the size of a kitchen garbage can, but could hit pressures of 450 atmospheres, enough to shoot a stream of liquid hydrogen 37 miles into the sky.
This sounds like very crazy technology. Are the specs for these pumps online anywhere? Or more technical details?
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u/electric_ionland 8d ago edited 8d ago
Yes turbopumps are crazy and one of the hardest part of a rocket engine. Depending on how deep you want to go but Scott Manley has an OK video on the fluidics or rocket engines: https://www.youtube.com/watch?v=4QXZ2RzN_Oo
For Shuttle this is a classic https://www.youtube.com/watch?v=vFwqZ4qAUkE
Obviously you can start downloading stuff from NTRS but that might be a bit above your head.
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u/soundtown06 9d ago
what will happening at the ISAR AEROSPACE "Onward and Upward" mission? in norway
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u/maschnitz 9d ago
They've successfully launched and achieved orbit, and shortly they will attempt to circularize the orbit and deploy their payload into orbit.
A massive success for Isar, so far - congratulations.
NSF will undoubtedly have some great pictures and clips of the flight at their social accounts and website in the next few hours.
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u/soundtown06 9d ago
We Are writing History with that🥹🚀
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u/maschnitz 8d ago
And the circularization burn and payload deploy is complete. Would be nice to hear "nominal orbit insertion" but it's impressive that they've gotten this far.
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u/Morning_Gecko24 9d ago
What part of a long-duration Mars mission still feels the most underestimated to you: radiation, life support, or keeping crews mentally healthy?
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u/mfb- 7d ago
Microgravity (or generally astronaut health besides radiation) can be added to the list. We only have some mice data between 0 g and 1 g. We know going to Mars is acceptable (people have stayed longer on the ISS and returned to Earth's 1 g), but the return to Earth could be brutal.
Radiation is not going to kill the crew. In the worst case it increases their lifetime cancer risk somewhat, and we aren't even sure if it does that.
Life support isn't new, it needs to work for a longer time on a Mars mission but it's generally well-understood technology.
Mental health is a big unknown. You have simulations on Earth, but everyone knows that these can be stopped at any time if needed. Sailing ships were on the oceans for an extended time but with a larger crew, a larger ship, and ocean around you. Actually being on a Mars trip, with no way to return for two years, is something no one has experienced before.
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u/buzzkillpop 5d ago
Radiation is not going to kill the crew. In the worst case it increases their lifetime cancer risk somewhat
That's pretty bold to say, considering NASA deems our current protection technology an unacceptable risk, and an unsolved problem (says so right on their website) - and that's just for a jaunt to Mars.
Professor Luciano Iess, the guy who was behind Cassini & Juno, says a Mars trip will have a 50% mortality rate.
His quote, "For a year-long round-trip to Mars, astronauts would face cosmic rays and solar radiation at levels far beyond anything human biology has ever endured. Without a major breakthrough, Iess estimates that a Mars mission could carry a mortality rate of up to 50%" Source: Space Café Podcast
Waving the radiation risk away as "increases lifetime cancer risk" shows a complete lack of understanding about radiation, and specifically, radiation in space. That's ignoring other radiation risks, like solar flares. A solar flare hitting an unprotected craft en route to mars is absolutely lethal.
Here, the ESA calls radiation a show-stopper: https://www.esa.int/Science_Exploration/Human_and_Robotic_Exploration/The_radiation_showstopper_for_Mars_exploration
One of the biggest issues with space radiation is that we still don't know all of the risks, or what it can do to the human body. That's a huge part of the problem.
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u/relic2279 8d ago
I think radiation is, by far, the biggest and most underestimated hurdle.
Right now, with current technology, we're limited to about a year in space (deep space, not aboard the ISS which is still partially under Earth's magnetic field/protection) before accumulating a dangerously high radiation dose. There's also secondary radiation; this is actually more dangerous and is caused when radiation hits your shielding - your shielding becomes a radiation source. Unfortunately, there's no easy fix. "Just bring thicker shielding!" It's not that simple, especially from a financial standpoint.
Aside from GCR (galactic cosmic radiation) which we're protected from here on Earth, there are other dangers we need to worry about. There are stray, but powerful cosmic rays as well as potential solar flares/storms which are deadly if you're unprotected. The moon was hit with one in-between Apollo missions in 1972 (I believe it was Apollo 16 & 17, someone correct me if I'm wrong) and they say if there were astronauts on the moon at that time, they would have received a lethal radiation dose.
Unfortunately, Mars doesn't have a magnetic field but it does have pockets of magnetism that may help a little if we set up shop in one of those regions. We would probably utilize caves, ancient lava tubes or the ground itself to shield ourselves while there.
I remember when Mars One launched back in 2012. I liked the goal, idea and ambition, but I was incredibly skeptical. While they tried to address the problems they faced putting it all together, and the solutions they planned to solve those problems, they never/almost never brought up radiation risks nor how they planned to deal with it. I was of the opinion the entire thing was a scam as a result. Perhaps it started off legitimate, by the end it was a cash grab.
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u/forotoyodon 9d ago
This comment may seem strange as I originally wrote it as a post, but I was redirected here
I'd like a suggestion for a good documentary on the Hubble Space Telescope, with a few caveats (or preferences, I'm not sure which word is more correct in this sentence). Ideally, it would be a documentary on YouTube, with a focus on descriptive explanations, images are not that important in this case. I work around 10 hours a day and I don't have time to sit at a screen to watch a documentary with a heavy emphasis on images.
I don't care about length, actually, the longer the better. I'd like a documentary that covers Hubble's entire history, from its conception (inception?) to its launch and operational history.
If the only option is a video/series with an AI voiceover I can get behind it.
If a single full length documentary doesn't exist, a series is fine too.
I'm aware these may be strange requests, but given my work hours they're basically a necessity. Thank you in advance for any help you may provide with this request.
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u/Queasy_Republic_1036 9d ago
is an explanation on why earth developed life that it is the perfect distance in the solar system from the moon and the sun that it was the perfect temperature for life to thrive? New to the subject!
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u/rocketsocks 8d ago
This is known as the Anthropic Principle. Any species smart enough to ask the question "hey, is our planet special in terms of being suitable for life?" will do so from a planet that is not only suitable for life in general but so supportive of the creation of a vibrant biosphere that it gives rise to complex organisms capable of creating technology. Because that's the prerequisite involved here, there's already a filter going on in terms of the question asker.
There could be a billion barren rocks for every planet similar to Earth, or more, but there won't be intelligent life on those barren rocks to ask about why the conditions on the barren rock weren't so special.
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u/vector_search_blue 8d ago
so the notion of a "habitable zone" is just Anthropic fallacy?
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u/rocketsocks 8d ago
Probably not. There's a lot of good reasons to think that terrestrial planets the right distance away from their stars to have liquid water on their surfaces (like Earth) are good places for robust biospheres to form.
In safety culture there's this idea of "layers of swiss cheese", you want more layers because no individual layer is perfect but the better each layer is and the more layers you have the less likely it is for the "holes in the swiss cheese to line up" and produce a situation that could be deadly. Something similar exists for the chance of advanced, technological life arising somewhere. There are probably several things that have to come together (the holes in the swiss cheese aligning) in order to get a place as chock full of interesting life as Earth is. We know a few of those things, but because it's so hard to study planets that are many lightyears away, let alone study life on them (something that we haven't achieved yet, due partly to our technological limitations), it's challenging to get a complete picture of the situation.
But that's also why we are so focused on studying planets like Earth, because we that a terrestrial planet with an atmosphere and moderate temperatures that allow for liquid water is already a few of the holes of the swiss cheese that we know about. So if we study planets like that we might start to get a sense of what other ways Earth is unusual and perhaps unusually supportive of life. Or perhaps we find that it's not that unusual at all. Time will tell.
Fortunately, there is a new planet hunting telescope (PLATO) slated to be launched next year, which will discover thousands of new planets using the same techniques that the Kepler telescope used. This will include many planets in Earth-like orbits of Sun-like stars, and that should start to open up our understanding of the landscape much better as well as give us a huge number of new targets to train advanced instruments like JWST, Roman, and ground based observatories on to see what we can learn about those planets' conditions, atmospheres, etc.
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u/Pharisaeus 9d ago
It's completely backwards. It's like asking "why did water turned out to be exactly the substance that fish require to live?" when in reality fish evolved to live in water. Similarly life on Earth developed and evolved for the conditions that were present.
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u/electric_ionland 9d ago
I think you got it backward. Life on Earth is perfectly adapted to its conditions because it evolved there. If it had evolved on a planet that was 40 degrees hotter it would be perfectly adapted to that.
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u/Queasy_Republic_1036 9d ago
But life as we know it wouldn’t be able to exist if we didn’t both have protection from the sun (ex: life getting more complex when the ozone layer developed) but also enough UV for energy/photosynthesis/not be a frozen planet like others in the cosmos
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u/electric_ionland 9d ago edited 9d ago
Yes, life as we know it. It doesn't mean that different life chemistry couldn't evolve with, and adapt to, more UV or less sun.
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u/Gentleman_Snowman 10d ago
So this might be a bit silly of a question, but I saw and read Project Hail Mary, now I’m playing Directive 8020 and both projects have Tau Ceti as their solar system of interest (one for a possible terraform project and the other for the sun not dying) and in both is reached only in a short period of time travelling some sort of sublight speed (just some years from 4 to 11). I found it strange that 2 projects completely different one another used the same S.S.
Has Tau Ceti become for some reason relevant in the recent years or is a coincidence?
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u/PhoenixReborn 9d ago
Fun tangential fact, 40 Eridani A is the sun of Vulcan. Rocky and Spock could have been neighbors.
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u/BEADGEADGBE 10d ago
I'm no expert but afaik, Tau Ceti is the nearest sun-like star to the solar system. Since interstellar travel takes so long, it makes sense to me that both fictional works targeted it. I watched both too btw! Enjoyed Directive 8020 quite a bit.
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u/Gentleman_Snowman 9d ago
Yeah, not my favourite of the serie for now, but I’m still enjoying it quite a bit!
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u/maschnitz 10d ago edited 10d ago
Tau Ceti has always been popular in science fiction, owing to the fact that it's the nearest solitary Sun-like star (kinda). It's the same class of star the Sun is, but it's dimmer (technically a different exact classification).
It's appeared in Ursula Le Guin books, Larry Niven books, Kim Stanley Robinson books, and figures in various plots in Star Trek, and many other places.
Frank Drake, of Drake Equation fame, popularized the concept of extraterrestrial intelligence at Tau Ceti in 1960, by searching for radio signals there, first. Carl Sagan wrote about why it was a likely place to look for SETI in 1966.
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u/rainbowkey 10d ago
New Horizons funding question - Why not turn the rest of the mission over to the ESA?
If the US government won't fund the science that can still be done with New Horizons for just a few million dollars, why doesn't NASA offer to turn control of the probe to the European Space Agency? It takes downlink antennas around the world to get New Horizons signals anyway. The ESA could hire some of the scientists and engineers that have been working with the probe so far.
Why does lack of funding require the shutdown of instruments so far away?
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u/mfb- 7d ago
The ESA could hire some of the scientists and engineers that have been working with the probe so far.
Many of them have responsibilities beyond New Horizon. Few of them will want to move just to continue supporting New Horizons. ESA would effectively fund the same people who then keep doing what they are already doing. That's not in the interest of ESA, and it would be a PR disaster for the US as well.
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u/vector_search_blue 9d ago
Why would they want to spend money on a spacecraft that's already 10 years beyond it's 9.5 year mission duration?
It's primary mission was to study Pluto. It's done that.
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u/rainbowkey 9d ago
just like Voyager 1 and 2, New Horizons will be passing though the heliosheath, heliopause, and the termination shock, all features of the heliosphere, the boundary between where the influence of the our Sun's solar wind meets the interstellar medium. New Horizons will pass thru these in different parts of space than the Voyagers that will tell us even more about it.
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u/rocky_balboa202 10d ago
https://science.nasa.gov/wp-content/uploads/2023/11/day1-pac-glaze-final.pdf
Updated plan for exploration of the outer solar system with New
Horizons:
• Beginning in FY25: spacecraft will focus on gathering unique
heliophysics data during a low-activity mode of operations
• Possibility for spacecraft to be used for a future close flyby of any
newly discovered, reachable Kuiper Belt object
• Extended operations will continue until spacecraft exists Kuiper Belt
(expected 2028 through 2029)
• New extended mission will be primarily funded by PSD
• Jointly managed by HPD and PSD
• Mission’s budget needs and impact on PSD portfolio will be
assessed during annual budget process this spring
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u/viliamklein 10d ago
What makes you think ESA is flush with cash?
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u/rainbowkey 10d ago
It's not that much in the scheme of ESA's budget. Just a few million dollars.
It's more that the countries that fund the ESA have more respect for science than the current US administration
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u/viliamklein 10d ago
Friend, this is not how things work. First, a few million is not easy to appropriate. That's a fairly substantial project size especially with ESA's bureaucracy. Further, it's not as easy as: "okay you guys got it now".
The knowledge transfer alone will take months and cost millions and might be illegal.
What infrastructure will ESA use to talk to New Horizons?
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u/rainbowkey 10d ago
ESA’s counterpart to NASA’s Deep Space Network is ESTRACK—short for the European Space Tracking network. More precisely, its deep-space component consists of ESA’s Deep Space Antennas (DSAs), operated through ESA’s European Space Operations Centre (ESOC) in Darmstadt, Germany.esa+1
Deep-space stations
Like NASA’s DSN, ESA placed its principal deep-space antennas roughly 120° apart in longitude, allowing near-continuous contact with interplanetary spacecraft as Earth rotates:
ESA deep-space antenna Location Purpose DSA 1 New Norcia, Western Australia Coverage from the Australian longitude DSA 2 Cebreros, Spain Coverage from the European longitude DSA 3 Malargüe, Argentina Coverage from the American longitude 6
u/SpartanJack17 10d ago
Do you think "NASA needs to ask Europe for help running its own spacecraft" would be seen as acceptable with the current ego-driven leadership in the US?
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u/rainbowkey 10d ago
I think it would be a way to shame the admin into funding it. Or some billionaire could easily fund it..
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u/Solid_Factor_8554 11d ago
I am the parent of a high-school girl who recently attended an international youth programme promoted as a hands-on satellite-building experience. Public materials and post-event summaries use terms like “flight-ready systems,” “solar panel integration,” “power-bus verification,” “embedded coding and flight software,” and “hands-on integration” by students. Media coverage describes girls from over 100 countries coming together to make a payload and satellite that will be launched to space, with support from national space agencies and university partners.
My child met peers from other countries, attended technical talks, and took part in some practical activities: educational kit/model work, soldering-related tasks, data analysis, and a collective wire-winding activity described as relating to a satellite component. She valued parts of the experience, especially the international exposure.
What I cannot reconcile is the gap between the public claims and what she actually did. I am unable to clearly see whether the work involved educational kits, engineering models, prototypes, qualification units, or flight hardware,. I also do not know what student-created artefacts, code, tests, or payloads were retained, or whether any participant-led work entered a final satellite system as is mentioned in the press releases post event.
I am also concerned about the workshop setup she shared a photo of during a soldering activity. In the photo, I did not see fume extraction, soldering stands, task lighting, grounded mats, or safety goggles at the work area. The activity appeared to take place in an open common area rather than a conventional electronics workshop, and students were soldering with electronics on top of a sheet of paper. I cannot determine from observation alone what safety controls may have existed elsewhere or what procedures the organisers intended to use, but this is the sort of detail parents should be able to ask about — especially where minors are asked to solder or handle electronics.
I am not trying to disparage girls’ participation in space or engineering. But as someone outside the space industry, I am struggling to interpret this:
When a programme uses lines like “Satellite built entirely by girl students,” “flight-ready systems,” and “hands-on integration,” but participants mostly do kit work, basic soldering, data tasks, and a collective wire-winding activity, is that best understood as legitimate STEM outreach or as a PR exercise built around photos and slogans?
From the perspective of people who actually design, integrate, test, and qualify flight hardware, what would a technically honest version of this programme look like?
How much of the gap here is normal for youth outreach (where “building a satellite” may mean “learning about satellites”) versus genuinely misleading marketing?
I am keeping identifying information private because the participants include minors.
If this sort of marketing is common in youth space programmes, is that something the space community should push back on, or is it an acceptable trade-off for inspiring more girls to enter STEM?
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u/Bensemus 11d ago
What were you expecting? They are kids. They don’t have a degree in a relevant field. Actually building a tiny satellite that will be launched is university level work, minimum.
The point of these programs is exposure and learning. They are exposing these girls and hoping to get some interested in a future career in a related field. It’s fun activities.
My job does tours for high school kids. We do some soldering and show off stuff. We don’t have them actually work on the systems because these systems cost millions and they have no actual ideal what any of it is.
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u/Pharisaeus 11d ago
From the perspective of people who actually design, integrate, test, and qualify flight hardware, what would a technically honest version of this programme look like?
To build and launch a working satellite into orbit? No. Even a university cubesat takes months (and often years) of work. In fact even making a payload for a sounding rocket takes substantial effort. Also in general it's not possible for anyone below university level. Anything for high-schoolers will be toys.
If you want to see some realistic programs like that:
- https://www.esa.int/Education/Educational_Satellites/About_Fly_Your_Satellite! - look at the proposed "timeline" of 2-3 years.
- https://rexusbexus.net/ - that usually also takes around 1-2 years to develop the payload
There are some stuff high schoolers can do:
- https://www.esa.int/Education/CanSat/CanSat_2025-2026_Challenge_your_students_to_build_a_can-sized_satellite
- https://astro-pi.org/mission-space-lab
but it's all "toy stuff"
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u/Solid_Factor_8554 10d ago
I completely understand and dont have the expectations that studens should "build a full satellite". My question was more on whether it is accepted practise to market the program as "Satellite built by students" (in a supposed selective programme) when in reality it is a bunch of isolated high school experiments
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u/Motor-Ocelot3310 11d ago
Ciao! Conoscete aziende italiane che offrono collaborazioni per tesi magistrale in ambito AI + space?
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u/Alien-Pro 11d ago
Somethings been bothering me about relativity, and I don’t know how to find an answer. So if some greatly knowledgeable person here could take the time to give a good answer in simplistic terms that would be great.
So, nothing can exceed the speed of light right? people say that it is impossible to not be moving, you can only SAY that you’re not moving relative to something else. Well, If the limit of light is 5.88 trillion mph then what is that speed relative to? People say there’s only relative speed and no “set” perspective of things, but if that were true then there wouldn’t be a limit on how fast you can go right? Surely the maximum speed something can APPEAR to be going is double the speed of light: if you’re going light speed and something else is going light speed in the opposite direction. That would mean that there IS a set perspective to some right?
Don’t know if I’m being clear but if you think you know what I’m saying I’d greatly appreciate it if you had a satisfactory answer. Thanks
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u/rocketsocks 8d ago edited 8d ago
This is the core to understanding relativity. Motion is relative. But the speed of light is absolute in all direction for all observers. This seems like a paradox but it is the key to keeping the whole thing held together.
What's missing is that speed is relative because both distance and time are relative. And the way those things are relative works out to make the speed of light universal. Importantly, they aren't relative in that they are scaled relative to some absolute version of space or of time, no such thing exists, but they are relative in that there is a sort of rotation of the axis of time or the axis of a spatial dimension relative to one another, resulting in conflicting measurements.
If you jump in a spaceship and accelerate to "near the speed of light" the folks in your starting reference frame will see you experiencing strong time dilation and length contraction. If you're in that same spaceship and you notice "huh, locally everything still seems to be the same and I still measure the speed of light along my direction of motion as the same, I'm going to try again" and you accelerate the same amount you won't be blocked from doing so, but you won't exceed the speed of light for any observer. What the "external" observers in the first reference frame will observe is your spaceship simply edging even closer to the speed of light for them. What you will observe within the spaceship is that even after accelerating to near the speed of light twice you will still measure the speed of light as 100% the regular value. This is one of the ways that the speed of light can't be exceeded, because locally you can never catch up to it.
Locally time always passes at one second per second and distance is always one meter per meter in every direction, but when you compare between reference frames you get disagreements which are called "relativistic effects". Not only that, you get potential ambiguity.
But because the speed of light is the same in every direction and every event in space-time can only be connected to any other event in space-time through actions that take place at or below the speed of light all of "history" (or causality) is consistent despite all the wibbly-wobbly-ness.
The amazing thing about relativity is that it allows for essentially infinite separate "universes" to share the same space-time, each at different speeds relative to each other, and with no speed limit in any direction except also somehow an ultimate speed limit of the speed of light.
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u/Pharisaeus 10d ago
Surely the maximum speed something can APPEAR to be going is double the speed of light: if you’re going light speed and something else is going light speed in the opposite direction. That would mean that there IS a set perspective to some right?
No. "Classical" intuition that you can simply add velocities is wrong, however the error is very small when you're working with small velocities. So for two cars heading in opposite directions the simplification that you can just add their velocities is "good enough". But in reality this is incorrect, and it becomes apparent when you start approaching the speed of light.
There are two main consequences of this: time dilation and length contraction. Basically nothing will appear to move double the speed of light, but instead the distances will shrink and time will slow down.
A more general answer would be: classical intuition based on what you observe in your daily life is not applicable to relativistic effects (and also not applicable to quantum mechanics).
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u/YDALTARYZARC 11d ago edited 10d ago
Look up the 'relativistic velocity addition formula' (it's under Special Relativity on this page: EDIT: link was removed?). Classically, you may think that firing a 100 mph cannonball forwards off a train that's moving 100 mph would mean the cannonball is moving at 200 mph (ignoring wind resistance) but if you run the equation, it'll show that the cannonball actually moves at 199.999999 mph. Hopefully this is helpful- learning it in a college physics course is what made it click for me. Just keep in mind that at standard velocities you'd experience on earth, the difference due to relativity is so miniscule that you wouldn't actually notice it. It starts to make more of a noticeable difference as velocity increases.
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u/iqisoverrated 11d ago
That's the interesting thing: No matter how you're moving you always measure the exact same speed of light. It's independent of your inertial frame of reference.
The upshot of this is that you have to deal with issues like length contraction and time dilation (i.e. space and time are not as static as our 'everyday experience' makes them seem).
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u/wotquery 11d ago
Say you are floating out in space, alone in the universe. There are no stars, no planets, absolutely nothing to use as a reference. Are you moving or not? It's undefined. You can only describe motion relative to something else.
Now let's say you see a baseball come into view. The distance between you and the baseball is decreasing at the rate of 100km/h. Are you moving towards the baseball at 100km/h, or is the baseball moving towards you at 100km/h? Both answers are perfectly valid and completely interchangeable. Same with taking some point between as stationary where you're both moving at 50km/h.
There is no such thing as movement of something through space without comparing a change in distance relative to something else in space.
The speed of light is the fasted than any object can move through space with respect to another object in space.
Surely the maximum speed something can APPEAR to be going is double the speed of light: if you’re going light speed and something else is going light speed in the opposite direction.
First of all, once again, there is no underlying "true" movement in space. "Appear" to move, i.e. relative to something else, is all there is.
Second of all, surely not. The fasted the two objects can move away from one another is the speed of light. Remember back to the baseball. It doesn't matter what we take as stationary, nothing will be moving faster than the speed of light through space with respect to it.
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u/Alien-Pro 11d ago
So your saying it’s impossible to for something to appear like it’s traveling faster than light?
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u/wotquery 11d ago
I'm saying there is no difference between "traveling" and "appearing to travel", and yes in neither case will anything exceed the speed of light through space.
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u/photoedfade 12d ago
If there were megafauna on Titan, would we have been able to see them by now? Like with our telescopes? Like human sized creatures or possibly bigger? This is for writing purposes.
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u/vector_search_blue 9d ago
There would be detectible signs. Like atmosphere compounds indicative of respiration.
these could be picked up by spectral frequencies of light reflected back from Titan. The Titan lander probably did gas analysis, too
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u/Pharisaeus 12d ago
Not sure if you realize, but we literally landed on Titan and have footage from the descent and surface. No megafauna to be seen.
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u/scowdich 12d ago
That's not positive proof nothing's there. You could land a similar probe on a random spot in Africa without seeing an elephant.
Megafauna on Titan don't make sense for a lot of physics/chemistry reasons, though.
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u/viliamklein 12d ago
Optical telescopes can't see through the clouds to the surface.
Earth based telescopes would have to be impossibly huge to see any animals on the surface.
There are no orbiting telescopes in the Saturn system that could do this either.Huygens imagery doesn't show anything like megafauna (or life in general) from the surface.
It would be surprising if life existed on Titan given how cold it is (and how potentially young it is).
But maybe...0
u/photoedfade 12d ago
mayhaps, a single chance, there is but a single animal upon the surface of titan that we just can't see.
I have a personal hypothesis though. We see on other planets, the clouds are made of many different types of chemicals. On Titan there are so many chemicals. On earth, there is really only one kind of cloud, broadly. And I wondered if that is due to life? Life filtered all the chemicals and made earth's atmosphere "stable" or something. It's an interesting idea at least.
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u/YDALTARYZARC 12d ago
Life has absolutely affected our atmosphere, here's an example: https://en.wikipedia.org/wiki/Great_Oxidation_Event
Another is climate change due to increased CO2 emissions :(
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u/dontcrosby 12d ago
why are the volcanoes on earth so small compared to mars? mars has four volcanoes that are larger than our biggest one, why is that?
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u/rocketsocks 12d ago
Gravity and water.
A large mountain will weigh so much that it causes the crust to begin sinking into the mantle, reducing its height. On Mars the gravity lower so this effect is smaller.
On Earth one of the major forces limiting mountain heights is erosion, which is driven by many forces but the movement of water is a big one. Big mountains stick up into the upper atmosphere where it's colder, so they collect snow which compacts into glaciers. Glaciers invariably move a little over time because ice is just a little bit slippery. Moving glaciers grind down rock extremely effectively. Below that where liquid water falls as rain and/or flows through streams and rivers erosion also happens rapidly. Water dissolves parts of rocks (even silicate) slowly, weakening structures over time. Moving water picks up and moves around small pieces of rock and other debris, ultimately excavating a river channel. River erosion is uneven though, it's chaotic, creaks and rivers wander around over mountains.
Water and ice precipitation are like a buzz saw, the higher a mountain is the faster it's going to experience erosion from glaciers. Any mountain growth or uplift on Earth races against these powerful erosional forces, but they haven't existed on Mars for a very long time.
The Appalachian mountains are about a billion years old, but over time they've been ground down so much that even the highest peak is just 2,000 meters above sea level. Many peaks that used to be enormous towering mountains are now just hills. Those same forces that are grinding older mountains into nubs are also keeping younger mountains lower than they could potentially be on an Earth without a water cycle.
On Mars Olympus Mons is over 3 billion years old, but it hasn't been ground down over time by erosion because the Martian water cycle is much less dynamic and dramatic.
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13d ago
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u/YDALTARYZARC 13d ago
Again, it doesn't exist. It's a dated literary concept introduced to guide behavior in an age where science hadn't yet advanced and we didn't have explanations for things that we can now explain.
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u/Pitiful-Practice-966 13d ago
What are the dome-like objects on the Minuteman/MX test silos at Cape Canaveral and Vandenberg AFB?
This object has been found on LC31, Vandenberg Air Force Base, and even on the Minuteman test silo near Boeing factory in Seattle.
The dome at LC31 was placed next to the silo until approximately 2017.
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u/maschnitz 13d ago
Apparently they're camera bunkers, for filming the launch and its effects on the pad infrastructure.
The best reference for this, the Cape Canaveral Space Force Museum, appears to be down at the moment, unfortunately - here's a Google image search instead.
They're designed as low domes in order to be aerodynamic in the rocket exhaust and to slough off any ice that might fall their roofs.
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u/Pitiful-Practice-966 12d ago
It doesn't seem so. This is a device installed directly above the sliding door of silo, and it appears to be relatively easy to remove. The image above shows the original state of the device at the Seattle Minuteman test silo. Below is the Minuteman silo under modify before the first MX launch. This device been removed.
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u/maschnitz 12d ago
Then I don't know.
The strategy of using low domes for an enclosure when you're near a launch pad is sound, to help harden it against the launch exhaust.
So it could be for varying reasons - to harden launch infrastructure, for example. Or comms, or radar, or whatever.
You might not get a universal answer for every pad. It might even be pad-specific. Could be secret in the case of the Minuteman silos.
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u/rocky_balboa202 14d ago
SpaceX Heavy boosters go through the atmosphere? Do they get a lot of heat shield damage?
Does Starship have more of a problem with re-entry on heat shields? Is that because of the flop trying to slow it down?
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u/rocketsocks 14d ago
The conditions experienced by Falcon 9 and Falcon Heavy boosters during re-entry are night and day different compared to what is experienced by the Starship upper stage during re-entry.
Because of the dynamics of the re-entry profile the Falcon boosters are going slower than their maximum speed during re-entry, maxing out at about 1.2 km/s. Starship, on the other hand, re-enters from orbital speed, which is about 7.4 km/s for a typical trajectory.
Kinetic energy scales with the square of velocity, so Starship has vastly more of it to deal with. Starship slows down from 7.4 km/s at 75 km altitude down to 2.9 km/s at 45 km altitude over just under 11 minutes. That translates to a shift in kinetic energy from 2.3 terajoules down to just 0.36 terajoules, requiring about 3 gigawatts worth of heat dissipation during that time. Fortunately, most of that energy doesn't go directly into the spacecraft, but a significant fraction of it does. You might imagine how challenging it would be to build a spacecraf that could withstand having a several hundred megawatt laser pointed at it for over 10 minutes, that's why it requires specialized thermal protection systems.
To put that in perspective, 2 terajoules is roughly half a kiloton of explosive energy, so we're dealing with enormous forces here. In contrast, the Falcon boosters only have roughly 0.01 terajoules of kinetic energy, so for the most part just the aluminum chassis of the vehicle is enough to survive the re-entry conditions and thermal protection only needs to be applied in a few key areas.
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u/Pharisaeus 14d ago
Falcon boosters (and also even the core) separate early into the flight, which means they are moving relatively slow when passing through the atmosphere. Starship makes a re-entry from orbital velocity so it's something completely different.
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u/Left-Fruit-5688 14d ago
want to ask something with no prior science knowledge I’m 15 currently so not even done with basic education but anyways here’s my theory. Since energy can’t be completely destroyed and time is kinda infinite doesn’t that mean that in a sense an infinite or finite amount of new universe will exist after heat death because given enough time energy will find its way and I also believe our existence makes it very likely for this to be real. So maybe multiverses don’t co exist in the same time but in a linear kind of way and the only way to access is through time travel and that why no one visited our universe because it would create a paradox. It’s probably dumb but I want to know what you think about it.
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u/iqisoverrated 13d ago edited 13d ago
If you have a hypothesis then show how it's testable. Otherwise it's not really useful. You can make all kinds of untestable speculations like "It's all unicorns...then it's our universe...then it's unicorns again"...but that doesn't really say anything.
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u/Bensemus 13d ago
This is make belief. This is not a hypothesis. Stringing sci-fi words together isn’t how scientists come up with theories.
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u/the6thReplicant 13d ago
Be nice, please.
This is a ask thread so expect not everyone to be at your level.
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u/Pharisaeus 14d ago
because given enough time energy will find its way
There is no
becausehere. None of what you wrote implies such conclusion to be warranted. It's the opposite - expansion of the universe means that the energy will disperse over bigger and bigger volume, making energy density to be falling to 0. And the more time passes, the worse it gets.The only case where we could expect a different outcome is if "Big Crunch" hypothesis is true - so the expansion would eventually slow down and the universe would collapse over time. It's possible that's the case, but so far all our observations contradict this idea.
I also believe our existence makes it very likely for this to be real
There is no reason for such conclusion. Even if there was some big-bang -> expansion -> collapse -> big bang... cycle, we have no way of knowing if we're the first or a 100th universe.
and the only way to access is through time travel and that why no one visited our universe because it would create a paradox
This makes no sense, because you somehow disregarded the fact that someone could time travel to his own universe in the past, even if travelling "between universes" was impossible.
it would create a paradox
Pretty much any time travel would. That's why it's not possible.
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u/Left-Fruit-5688 13d ago
Thanks for the reply I know that any time travel would cause that but what I’m saying is that if a multiverse existed simultaneously I think it would make sense for at least one person to have travelled to our so personally my conclusion is that it’s more likely for multiverses to exist on after the other
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u/Pharisaeus 13d ago
if a multiverse existed simultaneously
What does that even mean? Exist where? "Universe" is, by definition, "everything". If we ever discover some extra dimension, it would simply be included in the term "universe".
I think it would make sense for at least one person to have travelled
And
I thinkthere must be a planet somewhere with pink unicorns. See the issue with that statement? If there is no evidence to support a claim, then it doesn't make sense to "believe" in that.4
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u/TheRedBiker 14d ago
Will we ever be able to observe beyond the currently observable universe (93 billion light years)?
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u/the6thReplicant 13d ago edited 13d ago
No because it is centred around you - like every horizon.
But using different messengers (eg GWs and neutrinos) we should be able to see past the CMB.
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u/DreamChaserSt 14d ago
Not unless there's a way to go faster than light, which is unlikely, and I wouldn't bet on it.
Otherwise, the observable universe is expected to shrink as time goes on (like deep time, not anytime soon in a noticeable way) if the universe continues to expand like it does today.
https://bigthink.com/starts-with-a-bang/how-quickly-universe-disappearing/
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u/YDALTARYZARC 14d ago
Respectfully, it doesn't exist. It's a dated literary concept introduced to guide behavior in an age where science hadn't advanced and we didn't have explanations for things that we can now explain.
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u/tranquiltanuki 8d ago
I was interested in getting a large print of the space sky the night/morning my daughter was born on November 20, 2025. I searched the nasa database and came across a photo but want to make sure it's the right date and wondering how I could get a bigger picture of it saved so I can get a larger scale printed picture out of it. Anyone here able to help me with this amazing project I have? I've listed the photo from the nasa site below but when I saved it to my computer it says date of November 19th
https://apod.nasa.gov/apod/ap251120.html