KG3

There is an awful lot to keep up with, but I do enjoy trying!

Question about things landing on Mars. This article from August 2009 has been in the back of my mind for almost 10 years. A meteorite the size of a large watermelon was found on the surface of Mars. https://www.nasa.gov/home/hqnews/2009/aug/HQ_09_186_Mars_meteorite.html The microscopic imager on the arm revealed a distinctive triangular pattern in Block Island's surface texture, matching a pattern common in iron-nickel meteorites found on Earth. "Normally this pattern is exposed when the meteorite is cut, polished and etched with acid," said Tim McCoy, a rover team member from the Smithsonian Institution in Washington. "Sometimes it shows up on the surface of meteorites that have been eroded by windblown sand in deserts, and that appears to be what we see with Block Island." "At about a half ton or more, Block Island is roughly 10 times as massive as Heat Shield Rock and several times too big to have landed intact without more braking than today's Martian atmosphere could provide. "Consideration of existing model results indicates a meteorite this size requires a thicker atmosphere," said rover team member Matt Golombek of NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Either Mars has hidden reserves of carbon-dioxide ice that can supply large amounts of carbon-dioxide gas into the atmosphere during warm periods of more recent climate cycles, or Block Island fell billions of years ago." Please bear with me here. In this video from Demolition Ranch (a guy who really likes to shoot things with various guns to see what happens) he shoots at dry co2 ice with his .50 cal. BMG (he's particularly found of this gun) at about 3 min 30 seconds in (you can FF past his "bullet proof T-shirt" plug if you like). The dry ice explodes into a cloud of vapor like he had hoped for but https://www.youtube.com/watch?v=Cnvw_5JlIcs&t=34s instead of the bullet passing through the blocks of dry ice, the water melon and off into the woods (like the bullets that went through the safe in the background) it stopped at the dry ice. The bullet wasn't deformed at all but it did have the copper jacket scoured off! Is there something about dry ice that makes it particularly good at stopping and polishing projectiles? Could the Block Island meteorite have landed on dry ice which sublimated away leaving it sitting on the surface rather than travelling through a thicker atmosphere? I'm sure the meteorite was traveling much faster than the bullet.

I think that for most people who aren't scientists science can't be proven. When the public hears conflicting arguments and are told that both are true people throw up their hands and say "scientists are crazy and just make things up". For example, smoking (not here to argue the merits of smoking). People were told that if they smoke they are more likely to die of lung cancer. Then they were told that there is no evidence that any particular chemical in cigarettes alters any particular cell in the lung to become cancerous, and here is an octogenarian who has smoked 3 packs of cigarettes a day since he was six and he can still dance hornpipes. Conflicting messages from people wearing lab coats, one group passionate the other emphatic, and neither technically wrong. For people (like myself) who can't do math beyond balancing a check book, we just have to rely on faith that we're not being lied to. For instance, "science has discovered a new element". Well I'm a black smith, let's put some of this new stuff in the forge, smack it with a hammer, work it on the anvil and see what we can do with it. Then I'm told than only about a dozen or so atoms of the stuff has been conclusively made and it only lasts for a millionth of a second! How do you prove to me that the stuff actually exists? (Actually, I usually just say "cool, new element" and assume somebody's double checked it.) Then you get the person who really does lie, comes up with a ridiculous idea and calls it a ground breaking, paradigm shifting new theory. When the general scientific community debunks this persons "proof" a complete gibberish then he/she can claim that they are being persecuted by an entrenched anachronistic establishment whos members either lack the intellectual capabilities to understand or are simply to afraid of loosing funding and don't have the nads to embrace brilliance of this new "theory". Just to confuse things this person will find five other people in lab coats that will hop on the band wagon. They don't understand anything but will hedge their bets and agree with the guy. If it turns out the guy actually is right these five people in lab coats hope to look really really smart. Enough said about pseudoscience, I think we've all seen it. But I will say be careful what you call proof. To many of us it really does look like gibberish.

Is there a source of helium on Mars? I know that helium on Earth is produced by natural radioactive decay of uranium and is trapped in pockets of natural gas where it can be collected in commercial quantities. Mars does have occasional and mysterious burps of methane gas but could there be productive pockets of helium too?

Maybe this has been discussed here already but what kind of air would people on Mars be breathing? I mean in whatever pressurized environments they will be living in? It seems like the nitrogen we enjoy so much here on Earth is a bit scarce on Mars. Would they be breathing pure oxygen at low pressure like they did in Apollo or will they have to import nitrogen from Earth or some other place?

I think a couple problems with digging a tunnel in Los Angeles is the earthquakes and the oil fields! https://en.wikipedia.org/wiki/Salt_Lake_Oil_Field The Salt Lake Oil Field is an oil field underneath the city of Los Angeles, California....The field is also notable as being the source, by long-term seepage of crude oil to the ground surface along the 6th Street Fault, of the famous La Brea Tar Pits....The field is one of many in the Los Angeles Basin. Immediately to the west is the San Vicente Oil Field, and to the southwest the large Beverly Hills Oil Field. To the east are the Los Angeles City Oil Field and Los Angeles Downtown Oil Fields,

Iridium comes to mind as well. But I thought the whole point of mining asteroids was the fact that the stuff was already in space. I mean does a pound of platinum on earth cost more than putting a pound of... well anything into space? Lets see, according to Wikipedia as of 2011 the price of platinum was about $2050 per troy ounce which comes to about $24,600.00 a pound. What does it cost to put a pound of payload into orbit these days? I do see your point. Just the environmental benefit of not mining and processing the stuff on earth would be helpful. Cheap fuel cells would be good too.

It seems like the article doesn't speculate much on engine or nozzle design. I wonder how a aerospike engine might work at this? "Propulsion: Engine bell stiffness and structural dynamics, induced by interactions with the flow before engine start, followed by reverse pressure after start are areas needing further characterization. Severe variation in the pressure environment may drive structural dynamics. If an SRP engine configuration includes embedded engines, heat rejection could also be a challenge. For SRP configurations utilizing the same engines for both high thrust maneuvers and soft landing, deep throttling and thrust vector control may be required beyond the current state-of-the art to provide a low velocity landing and prevent site alteration at landing."

Wow, thanks for posting this paper! I guess this paragraph says it all. "Mission Infusion Potential: Propulsion is the only Mars entry, descent and landing technology that is intrinsically scalable across a wide range of missions. While not explicitly required for today’s robotic science missions, one can envision the potential use of supersonic retropropulsion on a next decade robotic Mars mission in an architecture that accommodates significant propellant mass or as a robotic precursor to eventual human Mars exploration. Architecture-level parametric assessments have demonstrated that SRP is likely required to enable safe landing of Mars landed payload masses above approximately 5 t. As a result of the large gap between current capability (payload mass of approximately 1 t) and that needed for Mars human exploration missions (payload mass above 20 t), a progression of analysis and flight testing is required to mature SRP into a viable capability ready for infusion into a human exploration mission." Are they saying in this paper that supersonic retropropulsion (SRP) should exclude the use of heat shields and parachutes for Mars landings above 5 t?

So what happens when you fire an engine to slow your craft down from a super sonic speed? I'm thinking like when the first stage of a Falcon 9 reenters the atmosphere. Does the exhaust distort or even punch through this bow shock or somehow become part of the boundary layer around the rocket? Can they even fire the engines into a super sonic head wind or do those waffle fins slow it down to subsonic first? I just ask because I've read there is some consideration of atmospheric pressure when it comes to rocket nozzle design.

So where do you suppose the wiggle room is for making your design stick out from all the others? I mean are there any innovations possible to the heat shields, parachutes, rockets, or how the craft hits the ground that have been used before? Or is this a packaging/materials problem? Are most of these entries going to be a scaled up version of the Viking landers? Or just allot of very fine tweaking of all of the above?

Would it be at all possible to make better use of the mass of the atmosphere the spacecraft passes through on the way to the surface? Could it somehow be scooped up and redirected forward, maybe somehow added to the rocket exhaust that is slowing the vehicle down?

I don't see how quantum entanglement would contribute to justidutch's email situation.

If there is some sort of quantum effect going on wouldn't trying to prove it fail? Like the double slit physics experiment, if you simply observe which slit the electron goes through you collapse the wave form and the interference pattern goes away. So if you try to quantify your experience with your ex you will either find a cause for it or you will find it to be a statistically random event simply because you examined it. So, yes but no but yes. Maybe just try to enjoy these things when they happen but don't think about them too much.

Looks like star man forgot his wallet!

One science fiction question I have is about doors. The use of sliding doors in spaceships seems rather ubiquitous both on TV and in movies. I've seen them slide horizontally, vertically, diagonally, both for interior doors and air locks. It seems to me that the only sliding doors I've ever seen in real life have been at the supermarket or in houses going out to the patio. Does anybody know if a sliding door has ever been used in or proposed for an actual spacecraft? I'm sure it looks cool on screen and it must make things easier for the set designers and such but could/would they work in a pressurized vessel?

Avatar, for some reason folks in the theater got upset because I cheered when the space marines blew up the giant tree that the Navi lived in. What can I say? I guess I'm more of a lawn and garden guy than a tree and shrub guy.

Thanks for posting this. I remember when it happened but there were few details in the press.

I believe the missile strike was supposed to have caused a full blown Kessler syndrome type scenario. Like, lots of other stuff in orbit was getting shredded too. What I don't understand is why this caused them to loose contact with ground control.

I guess the guy hasn't read Down the Mississippi by Mark Twain. There's some descriptions of boiler explosions in that book that are probably good contenders for that one!

I'm confused. What record could this guy possible make with this contraption? Does this rocket have a recording studio in it too? Is he trying for a Grammy?

Are you in school for astronomy or engineering? Are you planning on doing any astrophotography with any of the scopes you are making? I'm amazed at how amateur astronomers team up with professionals these days to do real science. Sorry to hear about your hot plate.

Remember that Gene Roddenberry was trying to address social issues of the day by taking them out of the context of 1960s America and putting them in space hundreds of years in the future. I guess I should cut Star Trek some slack in the science department. I liked Gravity but honestly how much acceleration can you get from a fire extinguisher and what are the odds that she would have landed in water within swimming distance of land? But that's the movie business. The writers need to make everybody happy. The director wants to make something visually appealing, the big name actors want screen time, the editors want to make the story move at a pace, the producers want to find people to put up the cash and the investors just want to get people into cinemas and make money. Allot of fingers in pie!

My pet peeve is the 2009 Star Trek reboot film. Spock tries to keep the Romulan's sun from blowing up by injecting it with "Red Matter". Red Matter, really? I mean, you know there's Matter and Anti-matter. Also there's Dark Matter (not to be confused with Black Lives Matter). As well as the matter we don't know about or What's the Matter. And the stuff we don't care about or Doesn't Matter. Then there is Space and Counter-Space (counter space is where you are most likely to find your Ant-Pasto). But Red Matter? Come on. Then there is the whole traveling back in time thing which doesn't really bother me too much, artistic license and all. But they expect us to believe that a race of people who have figured out FTL travel haven't figured out stellar evolution? We figured out which stars go boom decades before we got Sputnik off the ground! All right, so the Romulans who survive and go back in time in a spaceship large enough to eat entire plants for breakfast do what? Start rescuing the inhabitants of their home planet now that there is time to get them to safety? No, instead they declare war on Star Fleet!! I can be very forgiving in the sciency department as long as SOMETHING in the movie makes sense.

My all time favorite bad sci-fi guilty pleasure movie is Dark Star which was made in 1974. It is totally unapologetic. I especially like the space suits which you can see are made of house hold items such as vacuum cleaner part, muffin tins and such. The alien in the clip I linked to here a beach ball with green feet! Still, it's an entertaining move. https://www.youtube.com/watch?v=T5YTXnnQjC4&t=20s