6,900 tons of Merican Diplomacy can do this: Admittedly, not as impressive as a yuuuge marine mammal 'getting air' while getting air, but hey.....they had a head start. We've only been at this for about a hundred and twenty years. In any case, I believe it's the 713 boat (Houston) above. I have a copy of the 718 boat's EMBT blow following her virgin dive in my office taken from the original negative as I knew one of the photogs on Honolulu. Being ship's photographer was one of the more............."interesting" collateral duties on US boats back in the day. Sadly....they use other sensors and equipment these days, and more is the pity. Too bad about the Sanfranlulu thing. Honolulu was a pretty good boat.....
Kessler eh? I didn't realize it had a name, thanks. I encountered a fascinating fictional account of it in Neal Stephenson's novel Seven Eves.
or Asteroids..... c1979.... Saylut space station c-1971 Skylab.... Mir.... ISS... We've had space stations and lots and lots and LOTS of functioning, intentionally orbited satellites in LEO for a pretty long time now. They call it SPACE for a pretty good reason. Mostly because there's an awfully LOT of it up there, so some perspective is warranted. Some 5,000 satellites are currently operational....according to the Googles which cites the Index of Objects Launched into Outer Space maintained by the United Nations Office for Outer Space Affairs (UNOOSA.) Who knew, right? the UN. Anyway, there are obviously lots of other hunks and chunks of junk for the UNOOSA to get UNEASA about - but as I said before, India kinetically de-orbiting a 300km, pickup-truck sized object is......at worst.....slightly unfortunate and believe it or not there are plans and procedures for dealing with holes that get knocked into manned facilities. That's why they get hazardous duty pay. Probably Family Separation Allowance too, if they're federal employees...... Quite frankly....science has bigger fish to fry these days.
Hoped for a sub breaching photo and was not disappointed . I do believe that their centers of mass remain below surface though. Otherwise: a) a rough landing b) might reveal secret top speed capabilities. == Without doubt, largest ever mobile items beneath seas are there right now. When in photic zone I fancy that blue whales would say something like "what the heck was that?"
@ photic zone.... Subs are almost always creeping along too slowly to disturb the plants.....'cept in the back. They're also fairly smoooooth. It IS a concern though for more than one form of mammal.....but submarines usually operate in the trackless yonder of the open ocean. If you know one is in the neighborhood, then the boat is at a yuuuuuge disadvantage. The rough landing part has been fully explored....sorta. Following WW-twice, we tinkered with GUPPY or Greater Underwater Propulsion Power Program - Wikipedia. Lotsa lessons learned. Few near misses. Things like lead-acid batteries, ballast, dept control and trim tanks, gyros, (later) reactors, lube systems, Wardroom pantry china.....all like it when the deck is on the bottom and the overhead is on the top. Also....they discovered things best explored in aircraft (snap rolls, stalls, jammed control surfaces) Still....boys will be boys. Every boat skipper wanted his very own Emergency Main Ballast Tank Blow picture for the "I Love Me" wall resulting in a few near hull-loss incidents. ...I'm told..... Finally......COMMSUBGOD had to be a buzz-kill and enforce....ah.....limits on the fun. Boats are still required to perform EMBT blows periodically - like when visiting CongressCritters are aboard but safeguards are SUPPOSED to be in place to avoid bad things. Unfortunately....it doesn't always work. -------------------------------------------------------------------------------------------------------- Top Speed is less worrysome now that submarines are mostly equipped with propulsors instead of propellers...... One can still count and measure....but it's a lot harder to do. Seawolf and Connecticut are SPEEDY and DEEP DIVING but....like the F22 and the Zumwalts.....too expensive.....so we're buying "better" stuff (wink-wink!) in bulk. YMMV. If you ever get a check ride in an SSN-21....TAKE IT!!!! and.....INVITE ME!!!
Quite far away (55 million light years), in center of galaxy M87, there is a black hole. A very large one. By combining signals from radio telescopes across Earth, this thing has been imaged. Rather than possibly violating copyright law, just search "event horizon telescope" to see the image. Doesn't look like much, right? A blurry donut? Yet, astronomers are stoked because it is only 70 micro arcseconds across. This is far better resolution than any single telescope (radio or 'vis') could attain. Now, living in times of very accurate clocks, such resolution can be attained. With petabytes of data, hundreds of astronomers, computational power like you can scarcely imagine. But how fine is this resolution, really? My favorite way to describe it is with another (possibly copyrighted) image: Put one of those at a distance equal to Moon's from Earth. That tiny. Sweet eh?
Falcon Heavy with 3 firesticks ascended and those 3 made their landings. No cars were sent up this time. Israel's lunar lander was still moving 130 meters/second when it got to moon, so that will not be called a landing.
That would be a little over 260 mph. Even at 1/6th Earth's G, not terribly survivable. The Chinese still have the most recent Lunar landing. Bob Wilson
Aw c'mon Bob, lunar gravity is not a factor in decelerating Beresheet from 130 to 0. Mass 180 kilograms. 1/2 mv^2 Maybe a bit of a crater, maybe just aerospace rubble pile.
Yeah for Sapcex! 3 fer 3 is actually fairly non-trivial. World's largest operational rocket is now fully operational - and not just op-tested. Can't wait until squishier cargo is lofted, since it's now very PC to dislike Earth's current sole extraterrestrial squishy-cargo haulers.... ----------------------------- Too bad about ISA's crater-ops, but that's the space-biz for you. Much celebrating by terror agencies starting with "H" and maybe certain US legislators.
It may not a great stretch to connect exploration and navigation to time. I enjoyed thinking about how time-keeping accuracy has been improved. Sundials, since about 1500 BC, have uncertainty of about 10,000 parts per million (ppm). This was improved with “equation of time”, about 1760, to 1000 ppm. On a separate path, pendulum clocks circa 1650 were telling time with uncertainty of 200 ppm. But you could not travel with them, not useful for navigation. Spiral-spring chronometers were most excellently represented by Harrison chronometer in 1761 with 30 ppm. Precision navigation at sea commenced. Mechanical watches did not (and could not) improve much on that. By 1970, quartz oscillators made consumers watches with inaccuracy of 6 ppm. Consumer GPS circa 2005, uses atomic clocks in earth orbit, with inaccuracy of 0.006 ppm. So move to parts per billion, 6 ppb. A stay-at-home atomic clock in 2000 achieved 0.000001 ppb. Quantum clock in 2010 was 10 times more accurate than that. Tired of typing zeroes. Your GPS is 1000 times more accurate than cheap wristwatch, 5000 x better than Harrison’s fabulous chronometer. Beats beats of pendulum clock by 35,000 times, and a nice sundial by about 170,000 x.
Highly accurate clocks are also required for very-long-baseline interferometry, such as was used to produce this week's first-ever direct image of a black hole. With regular telescopes, imaging to the theoretical limit requires that the entire optical surface be controlled to errors less than a quarter wavelength of the light or radio frequency being used. For VLBI, this means that the master clock errors or instabilities between the different telescope sites must be kept to similarly tiny values. VLBI has been around for several decades, but keeps getting better and capturing tinier targets as clocks improve.
That is just the thing, and I hope it's not only we two here - else we should just go 'private" For marine navigation, clocks better than 30 ppm would have been limited by functional resolution with star-sighting sextants. It boils down to about 1 kilometer of 'where am I?' == Time-aligning planet-scale VLBI signals has only now been done at this fabulous sub-100-microarcseconds scale. Which inverts to 0.000 ... many zeros ppm in time. It was by all accounts, very difficult work. I expect near-future targets will be: Not this tiny Still at 'radio' wavelengths, both because dust yonder and earth's atmosphere cause scatter of 'light' Among those appealing to media attention. == Closely time-aligning telescopes at earth's L4 and L5 could reveal a lot more about out yonder. Please realize that this changes exploration from going out to looking out (very very well). Our current going-out speed (~20 km/sec) is ... sadly low.
If you want to go out there...learn more about what's going on here first. One can use interference to look at things like tectonics, geology, geodesy, nutations...all kinds of neat stuff. We use interfarometry in the telecom biz, although not really for exploration outside of fairly small bits of glass. LIGOs are somewhat bigger and since there are observatories that folks on 2/3 of our coasts can visit, science can be used to explore something much MUCH more difficult to understand. US.
A quick geometry check suggests that VLBI observatories placed at Earth-Moon L4-L5 could produce a resolution improvement of approximately 50X, compared to the current ground based observatory placement. Without even any clock improvements, if the same wavelength is used. The current EHT-network telescopes operate at a wavelength of 1.3 mm, much shorter than the 21 cm hydrogen line observations being used when I first read about VLBI systems decades ago. (Minimum resolution angle is inversely proportional to wavelength). Optical use of this interferometry would represent a 2300-fold improvement in resolution, but would require equivalent improvements in clocks and data conversion and recording. It is going to be a while before we (or our grandchildren) reach thisgoal, but there should be plenty of value to find at each incremental step along the way. (Optical interferometry is done on much shorter baselines, where the telescopes are close enough for the collected light to be piped to a central combiner in real time. But resolution is inversely proportional to baseline too.) I hope we can see a similar picture of our own Milky Way central black hole (Sagittarius A*) soon. While it is much smaller than the M87 black hole pictured this week, it is also much closer. Comparing mass and distance estimates, it seems that its angular size should be about 30% larger than M87's BH.
Other things look very tiny in sky - like stars. Here is a clever way to 'size' them, using handy solar-system debris: Asteroids help scientists to measure the diameters of faraway stars: New technique doubles resolution of angular size measurements -- ScienceDaily Found angular dimension of 94 micro arcseconds, similar to black hole mentioned above.
Here is a sundial: Where I drew a red circle around shadow of tip. That point moves daily and monthly and could teach a lot if somebody put some markers in the lawn. Science outdoors! US' unappreciated gnomon! On cloudy days, just take kids to DC museums. Also good.
^Good school science project! Those in flyover country could use the interwebs and be virtually smart. -------------------------------------------------------------------------------------------------------- Oh oh....(?) I saw a very non-spacey-agey picture of a 30-ish foot rocket strapped to what looked like an old truck and trailer - heading TOWARDS what looked like a landfill area......(can't find that one bit did find another one...) However (comma!) one of Chna's youngest high-tech startup entrepreneurs is actually getting stuff done! Look familiar??? FEATURE-China's rocket start-ups go small in age of 'shoebox' satellites - Reuters China’s rocket start-ups go small in age of ‘shoebox’ satellites HERE there be dragons!
