Posts by cray74 1041 posts • joined 29 Nov 2011
Repair? They launched a spacecraft with less than pristine components?
Very tight aerospace requirements are going to generate lots of quality failures during manufacturing. Repairs are one of several ways of addressing such failures. It's just part of the industry.
Common means of fixing defects include Repair, which (in my facility) means fixing something so that it works as required, even if it doesn't look exactly like the blueprint. Rework: fixing something so that it works and matches the blueprint. Scrap: give engineers a conversation piece for their desks. Not a Defect: the quality control inspector was being too uptight and imagined the problem.
Capacitor blew during a test of a $50,000 circuit board? Remove and replace (rework). Solder has more voids than tolerated? Resolder it to print (rework) or, if that risks damaging the board, put a dab of sealant on it and notify the client of the blueprint deviation (repair). Platinum-cured silicone RTV didn't cure because someone used a wooden stick to mix it? Clean off the dripping goop, scrub the bonding area, apply correctly-mixed silicone per print, update work instructions and remove wooden mixing sticks from work area (rework). New aluminum parts don't have the golden sheen of hexavalent chromium chemical conversion coat (Iridite or Alodine)? Not a defect: engineering changed the part to use new eco-friendly, transparent trivalent chromium chem film so Erin Brocovich didn't sue the company but didn't warn the factory that the parts would look different, like bare aluminum.
You're never going to get everything right the first time during manufacturing, but with good quality control checks and final product testing then you can be sure that you deliver hardware that works to spec.
Of course, some perfectly sensible repairs don't cause problems for years. Apollo 13's explosion was caused by a repair: a dropped liquid oxygen tank was replaced with an older spare. The spare had internal damage that wasn't apparent until Kevin Bacon stirred the cryotanks. Sentinel 1B worked fine for 5 years with that soldering repair.
but damping it so that it doesnt spring straight back out would be a challenge
Shock absorbers and dampers are old, established technologies. Use a piston to launch your hopper and then separate legs with damping to cushion the landing.
electronics are not normally fans of bouncing.
Solid state electronics are pretty good about bouncing. If you don't have spinning rust in the system and take care to prevent the components from flexing such as by potting them in epoxy then you can get functional electronics launched from cannons at thousands of Gs.
I work with aircraft systems that can handle 11Gs in hard landings with a safety factor of 2 and an additional customer-is-antsy factor of 1.5. There are additional flight turbulence and operational requirements to handle more sustained bouncing than a brief hard landing. The microchips, components, and other circuit board doodads don't have weird aerospace-grade packaging, either. In fact, most of the electronics aren't even shock-mounted unless they incidentally share a mount with more delicate systems like optics.
You talking about the UK or Florida??
UK or Texas? Texas can't handle cold or heat .
Florida can handle a long run of hot days. Despite the abject stupidity in the Crystal River nuclear plant shutdown and the recent utility push to undermine solar panel owners, Florida has enough gas- and coal plants to meet extended summer demands. The grid is also relatively robust unlike, say, Texas and its experiment in deregulation. High CO2 and now less renewable friendly, but stable.
"I want to replace the windows before I consider solar" for various reasons.
Definitely, insulation can work wonders for electricity bills and it's generally cheaper than solar panels.
I have solar panels on my roof but the real electricity savings on my new home are heavy insulation and low-E double glazed windows. Without the benefit of solar panels, my electricity bill is just 1/3 what my parents paid in the late 1980s (same part of Florida, same size home, no inflation adjustment.) All the insulation I added to my home above the builder's minimum is about 1/4 the cost of the solar panels.
"Unsurprisingly all this "Smart" techy shite is turning out to be rather less smart and in reality no better, if not worse than the long-lived things they have replaced."
I was annoyed when the homebuilder stuffed my new house with smart everything - garage door opener to thermostat - but the gizmos have worked out well. My elderly father, who also lives there, has vision issues. The smart devices let me check the home's status and fix settings from my office desk. I've been able to change the air conditioning from my father's accidental selection of "emergency heat" to "cooling" on several summer mornings.
But, no, the smart controls haven't radically altered my home or utility bills. They just work well for my particular home situation.
Bill Gates has been backing nuclear power for years. He's targeting cost-competitiveness with other sources of power, not expensive ones.
You know by 2030 you should own nothing.
I'm not a billionaire being targeted by the World Economic Forum's proposals for reducing income inequality.
Liquid cooling is fine, but there will still be radiators. Maybe they'll be outside ?
Yes. Specifically, they're saying they don't use chillers to reduce coolant temperatures below ambient. Heat is still removed from the coolant by using outside air.
If you're someplace with a moderate peak air temperatures (e.g., Britain or Tennessee) then you can lower coolant temperature to something well below the servers' preferred operating temperature just by using outside air, no additional chilling required.
For example the new Frontier supercomputer uses 85F (29C) water cooled by ambient external air. This eliminates the megawatts required by chillers and saves about $1 million annually in electricity costs.
The MMRTG used by Curiosity and Perseverance generates 110 watts of electricity (at mission start) from a 45-kilogram assembly. While you said, "ignoring weight," 45kg is a significant chunk of a Mars mission's payload and well outside the boundaries of a 1.8-kilogram drone like Ingenuity, which also needs up to 350 watts.
If I understood correctly that you were suggesting putting the RTG elsewhere (e.g., a ground-based carrier like the Perseverance rover), there are a couple of issues depending on how you arrange things:
1. If you want the carrier to also do some science and trundle about then you've got hot competition for those 110 watts. Perseverance and Curiosity are golf cart-sized vehicles that can demand up to 900 watts during their peak activities.
2. If you diminish the carrier's science role to support the flying drones then you're sharply limiting the scientific payload the mission. Perseverance carries 59kg of scientific gear, which is not something you're going to fit on modestly up-sized versions of Ingenuity.
There's the additional issue that if you repeatedly land the flying drone(s) near or on the carrier then you need to convince engineers that it won't damage the carrier during a bad landing. A 350-watt motor spinning counter-rotating propellers will do a good job blending exterior equipment on a rover.
That said, there's probably room for compromise in power budgets and activities. Now that Ingenuity has proven that a helicopter mini-drone can work on Mars, you can bet something like it will be tried again, but bigger and with some real scientific payload. That might call for a power sharing arrangement between rovers and aerial drones.
But why is video quality so bad, then?
Low wattage camera, processor, and communications systems, and limited bandwidth.
From this link: "The end-of-life battery power is estimated at 35.75 Wh. Of this,10.73 Wh is reserved for improved battery life and emergencies, 21 Wh is reserved for night time heater use. This leaves 10 Wh for flight per day, assuming flight is done to still allow some charge."
You have to fit any camera work into that budget.
Video is also competing for bandwidth from the 17 cameras on Perseverance, plus the science payloads.
Is it not against the Geneva convention to publicly identify fallen solders ?
Article 4 of the 1929 Geneva Convention indicates that combatants should strive to identify and report deaths. Subsequent Geneva Conventions say the same thing. [Ref. 1] So, the Ukraine's claim of doing this to alert parents is legally correct, if non-traditional. Given the Ukraine's likely additional motivations of trying to demoralize Russians, the matter's more questionable.
On that note, the Washington Post (among others) is arguing that showing the bodies of fallen soldiers violated the Geneva Conventions' requirement to protect POWs from "insults and public curiosity." The idea behind this clause was that POWs shouldn't be paraded through streets where they could be beaten, humiliated, showed with unpleasant materials, etc. This clause pre-dated widespread photo journalism and TV broadcasts, leading to the UK's guidance for journalists [Ref. 2]. The general idea is, "Don't show living POWs, particularly if their dignity is compromised." The US raised a fuss about the 2016 incident where Iran captured sailors and released images of them [Ref. 3]. The Ukraine's release of videos of Russia POWs earlier in March falls afoul of this rule.
However, most material on "insults and public curiosity" emphasize treatment of the living. The Geneva Conventions' guidance on bodies of the dead is more nebulous with respect to sharing photographs [Ref. 4]. The Conventions are pretty clear that fallen soldiers' bodies should not be mutilated and should be treated with dignity. It's likely that someone could formally object to the Ukraine's use of Clearview and alerting (or taunting) parents of fallen soldiers as a violation of the bodies' dignity.
Note: my search was not exhaustive so I might've missed precedents where photographs of the dead constituted a war crime.
REFERENCES
[1] International Red Cross's position on identifying war dead
[2] UK's interpretation of insults and public curiosity
we might - just might - wake up and fix the mess we made...
Cheer up! The ozone layer is on a path to recovery, acid rain has dropped across North America and Europe, forests are recovering in North America and Europe (North America is more forested than it has been in decades), waterways are recovering, China's air pollution is dropping, global extreme poverty is down, global literacy rates are up, whale populations are bouncing back, and, until late February of 2022, deaths due to war were at historical lows.
There are challenges ahead, but we've dealt with a lot of other long-term challenges in the last 50 years.
On one hand, having 40 satellites junked would be rough for almost any other constellation. On the other hand, at least these cleaned themselves up rather than becoming space junk for decades. Those low orbits were deliberate and part of how Starlink proved to the FCC that over 95% of the constellation would controllably drop from orbit at their ends of life.
For a brief while, my father ran a cleaning service. He called in the whole family to clean the walls of one apartment that had been occupied by a chain smoker for 15 years. The white walls had been turned yellow by tar. We had nothing that could dent the tar without also stripping the paint, which was outside our remit. The owner ended up repainting.
If you can put a tenacious layer of cigarette' tar on walls then it seems reasonable that an office of chain smokers could cover other surfaces.
My 6 year old monitor works fine
I didn't realize they made CRTs for computers 6 years ago, I thought everyone went LCD by then. Personally, I have no trouble believing that the static on a CRT screen could attract an extra helping of tar and ash. They were always dust magnets.
Geez, isn't it time to give up on monoliths and launch a larger swarm based telescope
Swarm telescopes are dependent on optical interferometry, which is a pain to get working correctly. Only a handful have ever been functional, and even fewer are working. This means the process of operating a swarm of optical-infrared-UV satellites isn't as simple as slapping some 1-meter telescopes on a Starlink chassis, launching 60 on a Falcon 9, and then laughing as old school astronomers are left in the dust. Rather, it'd likely be an effort of several decades with one or more pathfinder missions proving out the technology.
Besides requiring the novelty of optical interferometry, a swarm of astronomical satellites focusing (hah) on multiple, small platforms would lack the total "light bucket" capacity of a single, large telescope. For example, while the Navy Precision Optical Interferometer can resolve the shapes of oblate stars and geosynchronous satellites it does so with just six 50-centimeter telescopes. (Currently supplemented by 4 non-interferometric 1.8m "outrigger" telescopes, with plans to add 1-meter interferometric optics). That's a grand total of 11.3 square meters of collection area (mostly in the outriggers). The James Webb has 33 square meters of collection area. That's just better at seeing faint, distant objects than a swarm with less collection area.
Ultimately, yes, a swarm of large telescopes in space could be awesome but, for now, monolithic and segmented telescopes like Hubble and James Webb are easier to implement.
Iodine's not just space storable, but a room temperature solid that will vaporize easily (184C). Compared liquid and gas containers that have to deal with the stresses of pressurization, an iodine tank could be very light. Just boil a bit off at near-vacuum pressure for the low demand of an ion engine.
And the density! 4.93g/cc is about four times denser than any common liquid or solid propellant, to say nothing of a gas like xenon. The propellant tank would be so light for the delta-V you could cram in it.
Finally, iodine ionizes at a lower energy than xenon, so it's got that advantage.
Cool stuff.
And when the flight is aborted? Big rocks dropping from high altitudes. No thanks.
Back in the days of yore (late 80s, as I recall), a Titan launch planned for Canaveral Air Force Station was delayed because a Floridian congresscritter had discovered that the Titan was launching with sand for ballast. Beach sand, on a $250 million tech rocket delivering a high-tech spy satellite to space!
So the USAF pulled the Titan back into its hangar, quickly slapped together some ballast weights out of aluminum plate, and launched the rocket several million dollars later.
Had the Titan blown up during launch (as they liked to do), that would've been tons of aluminum plate dropping around Cocoa Beach rather than a cloud of sand.
Hundreds of tons of CO2 produced by every launch
Yup. And the total, global annual launch industry produces about as much carbon dioxide as 1 day's operation of Heathrow or JFK International. Or fewer than 100,000 cars.
for what? So some billionaires can satisfy their egos.
That was the moral panic last month involving a suborbital race between Bezos and Branson. SpaceX's Starship is addressing market interest from (at least) NASA, who sees the StarShip as worth a $2.9 billion investment.
Musk might be personally weird and have his own motives, but SpaceX isn't just a vanity project for him. Just glance at the Falcon 9 launch manifests: they're not filled with ego gestures, they're carrying payloads for paying customers.
Space habitats are supposed to spin
The ISS was designed strictly as a micro-gravity research laboratory. Out of the countless design variations of Space Station Freedom and the International Space Station, one of the dominating criteria was protection the laboratory modules from acceleration, tidal forces, vibrations, and even crew movement. Quite a few cost-cutting designs were tossed because they didn't protect the lab modules' microgravity conditions. For example, the simple gravity-gradient stabilized Power Tower concept for Freedom was dropped because by using lab modules as ballast at one end of the tower they were subject to some tiny G-forces.
You don't get a microgravity environment by spinning the entire space station. You don't get a clean microgravity environment in a lab if part of the station is spinning, leaving the rest of the station shaking, shivering, and suffering gyroscopic precession as it orbits Earth.
goin up there to lose muscle and bone mass is the most poorly thought out thing that ever came out of the 60's and it's amazing that we haven't figured that out yet.
The ISS's research work is dominated by two fields: biology and materials science. A great many of the biology studies coming out of the ISS, like the Twins Study, are all about that bone and muscle loss. The whole point of 6-month and 1-year tours on the ISS is to find out what spaceflight does to humans because the 1960s left a lot of blanks.
The 1960s and 1970s 3-year Martian roundtrips or 14-month Venus flybys envisaged at the time would've crippled and incapacitated the astronauts and cosmonauts because space agencies of the era were clueless about long-term spaceflight effects.
The ISS's non-spinning environment has answered a lot of important questions over the last two decades of service, questions that would not have been answered with a spinning space station.
Other reports indicate that Nauka wasn't just spinning the station:
"...[Scoville] soon realized that it was not and that Nauka was not only firing its thrusters, but that it was trying to actually pull away from the space station that it had just docked with. And he was soon told that the module could only receive direct commands from a ground station in Russia, which the space station wouldn't pass over for over an hour."
The severity of the situation is summarized by Scoville's later tweet that he had never "been so happy to see all solar arrays + radiators still attached."
Well, here's a toast to the engineers that dealt with the Nauka's excitement with calm and poise.
I think it's the definition and visibility they're talking about.
And that's fine if that's the author's point. The Lunar Reconnaissance Orbiter is mapping the moon to 18-inches resolution such that that foot trails of astronauts are visible. LRO's fantastic work mildly complicates moon landing deniers' conspiracy theories.
But then you get claims like "only 5% of the oceans have been mapped" that are taken for granted, even though every inch (or, well, tens of square kilometers) of the sea floor have been mapped since 1977.
Hence my curiosity about the ambiguity.
we have mapped the Moon more than our planet's deep oceans.
I've heard variations of this claim frequently on the internet, but the Earth's ocean floors were thoroughly mapped by 1977. There are dozens of oceanographic institutes, militaries, and oil companies mapping and studying the seafloor for purposes ranging from primary science to profits. From the Antarctic ocean seafloor to the the Arctic Ocean seafloor, we've got the seafloors mapped in depth. (sorry)
So, what definition is being used when it's claimed that we've mapped more of the moon's surface than Earth's seafloors?
never realised space had to demonstrate a profit back then.
NASA (and thus US taxpayers) paid for Mercury, Gemini, Apollo, and the shuttle, but NASA didn't build those spacecraft. Alan Shepard's first flight was in a Mercury capsule built by the McDonnell Aircraft Company, which was lofted by a Redstone rocket built by Chrysler's aerospace division.
Michael Collins, Buzz Aldrin, and Neil Armstrong went to the moon in a capsule built by North American Aviation, used a lander built by Grumman Aircraft Company, and launched in a rocket with stages built by Boeing (Saturn IC), North American (Saturn II), and Douglas Aircraft Company (Saturn IVB). Their A7L spacesuits were made by ILC Dover and Hamilton Standard. Launch pad services were supplied by Bendix.
NASA didn't have to show a profit (though it tries to show financial benefits for American taxpayers), but all those private space companies weren't going to the moon "for the exposure." Government cheese like NASA contracts was a good source of profits while the Space Race lasted.
Is the replacement spectrometer the same instrument they originally had to sacrifice in order to fit COSTAR?
Nope. The original sacrificed for COSTAR was considered the least important of the main Hubble instruments. It was a photometer, not a spectrometer, meant to assess the brightness and polarity of celestial objects. This is useful if, say, you wanted to determine the distance of celestial object, spot transiting exoplanets, or estimate the rotational periods of stars. The replacement instrument COS was a spectrometer meant to figure out the "mass, distribution, motions, temperatures, and compositions of matter in the Universe."
"Every picture you’ve seen that took your breath away is courtesy of COSTAR..."
After 16 years of producing incredible pictures, COSTAR was removed from Hubble in 2009 during the STS-125 servicing mission. You can now see COSTAR in the National Air and Space Museum. Since 2009, all instruments in Hubble have their own, built-in corrective optics. COSTAR's bay is now occupied by the Cosmic Origins Spectrograph.
It most certainly does (or at least its chums at ULA do) ... ULA even blocked sea launch on the basis that sailing 12 miles offshore to launch was an "export"
Good points: a commercial rival with less competitive products undermined opponents. ULA's parents, Boeing and Lockheed-Martin, certainly don't mind wielding lobbyists when their products fall short.
It was amusing to see SpaceX lawyer their way into national defense launches. ULA thought they had that locked up.
the whole design and 10 year delay of JWST was to avoid an Ariane launch,
As of 2008, NASA was planning to use an Ariane 5. 2008 was before most of the instruments had been built or mirrors finished. There were certainly many delays after that point like testing problems in the 2010s but they weren't related to avoiding the Ariane 5.
Were there also delays in the 1996-2007 period based on avoiding Ariane 5 use?
They use the Russian engines because they're cheaper
More significantly, the Russian kerosene-oxygen rocket engines have exceptional performance. While the US mostly ignored kerosene after the 1960s to focus on hydrogen-oxygen rockets (and solids, for military use), the USSR kept plugging away at kerosene-oxygen engines. Until SpaceX's Merlin series of engines the US had nothing like the thrust-to-weight performance of the RD-170 family. The fall of the Iron Curtain and revelation of Russian rocket engines caused some eye-boggling in the US.
Then the US started buying those engines because, y'know, capitalism trumped patriotism. In the 1990s the Russian engines were good, cheap engines that could substantially improve US rocket performance. When the engines became expensive in the 2000s the performance was still worthwhile.
Why not just have the Russians launch your payload?
Tricky question. A few follow-up questions:
1. If Boeing uses Rolls-Royce jet engines on its airliners, why not build the planes in the UK?
2. If Chrysler and Dodge used Japanese engines in its cars, why not build the cars in Japan?
3. What about all of NASA's flights to the ISS in Soyuz capsules?
US commercial satellite operators have gone outside US borders for their launches. The Ariane family was a workhorse for the world's launches until recently. A US communication satellite was on the Long March 3B that killed at least 6 if not several hundred people. When saving money matters to a US satellite operator they're certainly willing to chase a cheaper launch.
But in this restricted case, the Atlas rockets using Russian engines primarily have US government payloads. While NASA doesn't mind launching on foreign rockets if they get the job done (e.g., James Webb is going up on an Ariane V), the National Reconnaissance Office and Department of Defense will laugh themselves into hiccups and hernias at the idea of putting one of their satellites on a "Rooskie" rocket.
As the original capitalist economist Adam Smith noted, "There seem, however, to be two cases in which it will generally be advantageous to lay some burden upon foreign, for the encouragement of domestic industry. The first is, when some particular sort of industry is necessary for the defence of the country. ..."
The usual defense-related payloads of Atlas rockets are definitely cases where the customer will not chase the cheapest launch to foreign spaceports but will rather use a launch that suits the customer's idea of national security. Taking a modern NRO payload to Russia is basically inviting Russians into Lockheed-Martin's factories for a detailed inspection of US spy satellites.
Sadly, there are far too many device manufacturers who drop a whole Windows PC into their product. Then fail to update it.
Yes.
I stay gainfully employed with materials engineering problems at an aerospace factory, which is less a matter of software than trying to figure out why an epoxy had bubbles in it or paint didn't cure. But my mechanical, electrical, and optical colleagues have been complaining about the recent forced upgrades from Windows XP to Windows 7 on their CNC and test hardware.
Since the device manufacturers don't issue refits (at least not upgrades that make company security happy), we've been painstakingly figuring out how to convert software and drivers to Win7 by ourselves, or mating new computers to the factory gear.
Soon, soon we'll catch up with the world of 2009.
exposed for being the charlatans they are and be barred from practice?
Dr. Tenpenny has been a vocal anti-vaxxer for years. For example, in 2015 she was barred from entering Australia where she had been invited to speak to anti-vaccine groups. Despite spreading harmful information on a grand scale, she has retained her osteopathic license because it's an "alternative medicine" license. Facebook might've banned her, but the Ohio Board of Medicine has been steadily renewing her license every 2 years.
Governor DeWine has an unimpressive political career filled with the usual 1990s-2010s Republican positions, but he has a few respectable points in his resume. He greatly accelerated criminal DNA testing, shut down "pill mill" dispensaries, and most recently showed a little common sense about medicine:
On Thursday, DeWine said he opposes House Bill 248 and asked Ohioans to think of the impact vaccines have had on society. "Before modern medicine, diseases such as mumps, polio, whooping cough were common and caused great, great, great suffering and death to thousands of people every single year."
What about making decomissionning of satellites internationally mandatory by sending them back to Earth for destruction in the atmosphere?
The major sources of artificial debris in space are less satellites and more upper stages. Low orbit satellites (those under 800km altitude) tend to clean themselves up with atmospheric drag within a few decades, if not a few months (under 400km) after running out of station keeping fuel. High orbit satellites (e.g., geosynchronous satellites) are moving much more slowly and generate less debris in collisions.
That leaves upper stages, particularly those that lobbed satellites into highly elliptical geosynchronous transfer orbits. These orbits do spend a fraction of their orbit screaming through crowded low altitude bands but not for long enough to experience much drag. Their residual fuel and aging batteries tend to explode after several decades in orbit.
Based on those points, most responsible satellite operators are finally taking steps to clean up space. The techniques utilized include:
1. Reserving some fuel for end of life de-orbiting of low altitude satellites. (Starlink had to demonstrate that 95%+ of its satellites would de-orbit under control at their end of life. If not, they're in low orbits that'll decay shortly.)
2. Now reserving some fuel for end of life boosts to graveyard orbits for high altitude satellites. (It takes a ridiculous amount of fuel to get from geosynchronous orbit to Earth's atmosphere, more than to go from geosynchronous to the moon. Most geosynchronous satellites are cash cows that try to use every available drop of fuel to hold station, so operators don't like saving lots of fuel for big maneuvers. Compromise: kick upward to a graveyard orbit, which requires little fuel.)
3. Reserving some upper stage fuel for a de-orbit burn, or at least arranging a perigee at an altitude that will decay quickly. SpaceX usually utilizes de-orbit burns on its second stages, though sometimes the burn fails.
4. Hiring a third party to extend satellite life with more fuel including a reserve to retire into a graveyard orbit.
The recent media panic about China's out of control upper stage de-orbiting was amusing considering just weeks earlier the panic had been about space debris. That behemoth would've been a large debris generator if left in orbit but, being a lightweight rocket stage, it burned up thoroughly on reentry and only weeks after being launched.
Thank you. I was here to say the same thing. Screens and screen doors are vital in Florida to let in winter and spring breezes without the clouds of mosquitos that can carry away small children.
Screens also keep out birds, even large sandhill cranes who defecate in quantities rivaling the bodyweight of a swallow anywhere they're allowed to access. Great fertilizer for the yard but not something I want on my back porch.
"Slidey chocobar phones were peak design."
I went from an LG enV Touch to the Droid 1 slider. While the jump in performance from a feature phone to a smart phone was impressive and the jump from 3G to 4G was great, I was not impressed with the slider and keyboard combination. The enV rotated the screen out of the way of my thumbs while the Droid kept it there like a speed bump designed interfere with the top row of keys.
Your mileage obviously varies, but I miss the flip-phone keyboard of my enV. I've had high hopes for the Gemini and Cosmo but they seem to need a little more refinement.
NASA has a lot of experience using the Peltier-Seebeck effect, I am surprised they haven't found a way to utilise it on the space station. No liquids and no moving parts, it has been used since the sixties on both satellites and rovers.
About 10 years ago, I worked on a project to replace a Peltier cooler from a rack of outdoor, all-weather satellite communications gear. Besides problems specific to this kit** and irrelevant to spacecraft, Peltier coolers have terrible efficiency. Even a small, rack-mounted vapor-compression refrigerator that compromised efficiency to fit into 2U was literally an order of magnitude more efficient in terms of watts of heat moved per watt of electricity. We went from about 400W peak draw on the Peltier for 400W of cooling to 120W draw for 350W of cooling. Spacecraft tend to have constrained power budgets so alternatives to Peltiers are probably welcome.
On the flip side, I did stumble over a problem that these Purdue students are tackling. Being a materials engineer rather than a mechanical or refrigeration engineer, I never thought about the circulating fluid in the refrigerator. When we were putting the vapor-compression chiller through its paces in environmental chambers for MIL-STD-810 "falling dust" and "blowing rain" tests, we'd flip our test box on all different sides to threaten the air intakes and exhausts. Well, there's a reason new refrigerators come with warning to let them sit upright for 24 hours: the liquid refrigerant depends on gravity and supplies lubrication to the moving parts.
The refrigerator's manufacturer was impressed that their little chiller worked at all angles but did have to replace an expensive custom-built compressor. They were rather nice about the whole thing, really.
Anyway, if these kids get this chiller working in zero-G then congratulations to them.
*********************************************************************
**The Peltier cooler and resistive heaters formed a 20-kilogram brick that was mounted on and through the top of the keg-sized electronics rack. The enclosure for the rack was thin aluminum that bent under the cooler, forming concavities that compromised the weather seal and funneled water into $50,000 of electronics. My vapor-compression cooler mounted in the rack with only a weather-resistant louver penetrating the front of the rack.
From the Soviet BOR-4 that caught NASA's eye in 1983 to the HL-20 mini-shuttle and the bigger HL-42 , this vehicle concept has had a long, twisting road to space. It almost flew on the on the International Space Station as the Crew Return Vehicle but was cut because of budgetary reasons. Sierra Nevada is running with the idea as the Dream Chaser with some cargo contracts to the ISS and now, maybe, finally, it'll get some people into orbit. Maybe it's time is finally here.
Cheers to Sierra Nevada for keeping this elegant space plane concept alive.
I wonder how they're managing that?
Same way as the US's solar-powered rovers: ATOMIC ENERGY! Well, a few watts from decaying radioisotopes, plus lots of insulation.
Yutu-2 also apparently learned from whatever "mechanical control" failure paralyzed Yutu on the nearside, and better addressed the extreme cold failures that damaged Yutu's solar panel closure motors. (The solar panels were supposed to close up at night and supply insulation to the body. More convenient than finding a tauntaun every night.)
If you have such a power source, why not just use it to drive the wheels instead?
It is challenging but not impossible to directly power automobiles with wind, solar, or nuclear sources. Generally, wind, solar, and nuclear are better arranged as stationary power plants that deliver electricity to trains and trolleys, to battery-powered vehicles, or to chemical reactors that produce hydrogen for cars.
The surface rock of the moon is twenty degrees below freezing, so whatever water is still inside the moon brechia will not escape.
Good start, but that's not how vapor pressure works. The frost line of a solar system is considerably colder than -20C because in a vacuum some evaporation will occur even to rather low temperatures. Generally, water ice is taken to be stable in a vacuum at -130 to -170C.
There are vast quantities of water and methane on Jupiter, Saturn, Uranus and Neptune,
There are indeed vast quantities of volatiles on those gas giants, but their escape velocities are vastly higher than the moon's. For example, at Earth's surface temperature water molecules move around the atmosphere at about 300m/s. Earth's escape velocity is 11,030m/s, so any water molecule popping up to the upper edge of the atmosphere will be inclined to fall back to Earth. Per Jean's Escape Mechanism a tiny fraction of those water molecules - or more likely UV-dissociated hydrogen molecules - will escape because they're moving fast enough to do so. As escape velocities climb, it gets harder for gases to escape. Hence large worlds tend to be ice giants or gas giants.
Pluto and Titan are cold enough that the average molecular velocity of any evaporated gases are well below escape velocity and, being big blocks of volatiles, they've got enormous reserves to stay icy for billions of years.
But Luna is in a bad position: low escape velocity, relatively high temperatures. Water can easily evaporate and escape from the moon.
I hope this regolith will be put in isolation for a while in case it comes back with some nasty, alien virus.
Viruses work by using RNA or DNA to hijack living cells. Viruses thus necessarily must have evolved closely with their target cells or their DNA/RNA packet will be so much nonsense to the cell, assuming they can even lock on to the cell's exterior.
Worrying about space viruses infecting Earth is like expecting a virus meant for the Burroughs MCP to work on Windows 10 machine.
The Hunter Biden macbook story would have been far more interesting, there was at least a modicum of IT involved.
Yes, Foxconn only went to Wisconsin to expand its widely known cheese division, not for anything IT related.
Regarding the Hunter Biden MacBook (probably with some Foxconn chips), there were some interesting aspects:
1. Hunter Biden lives in California.
2. The computer repair shop was in Delaware - admittedly, where members of the Biden family are.
3. The computer repair shop owner couldn't positively ID Hunter Biden as the MacBook's owner.
4. The leaked emails contain names and dates that don't match up with Hunter's itineraries
It has been a bad few weeks for US-based rocket fanciers as SpaceX, United Launch Alliance (ULA), and Northrop Grumman took turns at failing to get their respective rockets off the ground.
Generally, a rocket failure is not takeoff so much as a rapid unscheduled disassembly, which known to affect even senior aerospace companies. Failure to reach orbit is another common failure in the launch industry.
Launch scrubs and delayed takeoffs, on the other hand, are sensible precautions. Launch services aren't airlines trying to appease hundreds of angry, restive passengers with timely takeoffs. Instead, they have customers expecting that their billion-dollar hardware gets delivered correctly, intact, and operational.
The only thing the GOP understands is MONEY.
I'm not sure that's true given that long-term GOP politicians are addicted to voodoo economics: cut taxes, raise spending, wait for an economic miracle to avoid debt increase, and blame the Democrats for the debt when the miracle doesn't arrive. Rinse and repeat for the last 40 years.
The GOP's slur toward Democrats that they "tax and spend, tax and spend" sounds sensible in comparison.
What checks and balances exist on executive orders? What limits?
In an ideal world where the US government is working correctly, US executive orders are limited by the Constitutional powers of the Presidency. That is, the President doesn't write laws, doesn't set taxes, and doesn't set budgets because those are powers reserved for Congress. Accordingly, executive orders cannot create new laws and taxes, and can't change budgets issued by Congress (with caveats - a vague budget for a federal department gives a President a lot of leeway).
Further, executive orders are subject to judicial review just like Congressional laws. The Supreme Court can invalidate an executive order just like it can declare a new law to be unconstitutional.
The US President is basically a chief executive for the US federal government's bureaucracy. Presidents' job is to execute the laws and budgets set by Congress. Executive orders are thus directives from the boss to employees in the federal bureaucracies and must fit within existing laws and budgets.
To put it another way, executive orders should try to clarify or help implement laws, not make laws.
Some example executive orders:
George Washington cut the first executive order and it was a 1789 directive to heads of bureaucratic departments to (in so many words) "Tell me what's happening in your department." With that order, executive departments got a new rule to start keeping their boss informed of events. It seems like a fairly obvious order but apparently the new federal government was a bit haphazard and didn't have any prior written requirements for the new departments to tell their boss what they were doing.
President Lincoln's "Executive Order Establishing a Provisional Court in Louisiana" (1862) would normally have been completely outside a President's powers since the judicial branch handles the courts. However, Louisiana was in rebellion, had been captured by federal troops, and was under martial law. Presidents being the head of the US military, it was within Lincoln's wartime powers to set up courts to restore order in Louisiana. These courts ended when Louisiana returned to civil administration.
One of the most famous executive orders came from Lincoln and was again applied to rebellious states only: the Emancipation Proclamation. The constitutionality of freeing slaves elsewhere might've prompted a serious court fight over an executive order or even a Congressional law, hence the US eventually had to amend the Constitution to eliminate slavery.
On the other hand, Harry Truman's Executive Order 10340 attempted to federalize all US steel mills ahead of a disastrous strike and was slapped down by the Supreme Court. The reason for the decision was that this executive order attempted to make law, which is a power reserved to Congress, rather than to "clarify or further a law put forth by Congress."
Since that 1952 defeat, executive orders have been written to carefully cite laws or fundamental Presidential powers in the Constitution that allow the orders to work.
Clear as mud? :)
I'm not sure what existing laws give the President authority to shutdown specific websites, so I can't comment on the TikTok matter.
"Sad that in the decades since NASA has likely launched more paper across desks than useful payload"
While the Voyagers are epic probes for their endurance, they were flyby probes that only briefly visited their destinations. Since then, NASA has favored orbiters and landers like:
* Cassini and Huygens (with the ESA) at Saturn
*Galileo and and its atmospheric probe at Jupiter
*Juno, also at Jupiter
*Dawn, orbiting multiple main belt asteroids
*MESSENGER, orbiting Mercury
*OSIRIS-ReX, orbiting asteroid Bennu
*Magellan, orbiting Venus
*Numerous Mars orbiters, rovers, and landers
*Parker Solar Probe, diving through the Sun's corona repeatedly
And that's just a sampling of NASA's post-Voyager projects.
The main "could be worse" factor is that the perigee is quite low, so the orbit should decay reasonably fast.
Not as fast as a 400km circular orbit, unfortunately. With only brief dips to 400km, that second stage and its debris field could last decades. Recent Western practices for second stages are to get their perigees a bit lower or actively deorbit them (SpaceX) after payload release.
A nice database of debris entries and initial launch dates can be found here. Too many of those upper stages last decades in GTOs.
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