The thread for space cadets!
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hobbsyoyo
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NASA sent their final commands to the Opportunity rover on Mars. If they don't hear back from it this morning, they will stop listening for it.
Unfortunately the deep space antennas used for these efforts are few and far between and they can't afford to continue listening to a dead rover when they have active probes and rovers that need attention.
Unfortunately the deep space antennas used for these efforts are few and far between and they can't afford to continue listening to a dead rover when they have active probes and rovers that need attention.
Broken_Erika
Play with me.
It only exceeded it's planned operation length by over 14 years......
Silurian
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If the sea level rose by 2 miles (3000m) the ice on the lower areas would float off.
This would reduce the load on the bedrock so it would rise hundreds of meters lifting the remaining ice higher.
Thorgalaeg
Deity
An interesting video about the Soviet space shuttle:
Pros: more payload than the Space Shuttle, capable of flying unmanned and autoland, Energia rocket was an independent launch system (potentially even more powerful than Saturn V), no lift rockets in the Buran itself which were dead weight for the rest of the mission in the SS, instead it had two small turbojets! So it could actually fly, not only glide to the runway, and it had a very robust heat shield. (important point as we know now)
Cons: none, except it was six times more expensive than Soyuz and being at the wrong place at the wrong time.
Pros: more payload than the Space Shuttle, capable of flying unmanned and autoland, Energia rocket was an independent launch system (potentially even more powerful than Saturn V), no lift rockets in the Buran itself which were dead weight for the rest of the mission in the SS, instead it had two small turbojets! So it could actually fly, not only glide to the runway, and it had a very robust heat shield. (important point as we know now)
Cons: none, except it was six times more expensive than Soyuz and being at the wrong place at the wrong time.
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I remember the day when it landed after unmanned flight. We watched it on TV and it looked absolutely fantastic, like a technology from 21-st century.
Wouldn't turbojets be deadweight on the way to orbit, which (I assume) costs more than dead weight on the way back down?
hobbsyoyo
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They did not install the turbojets in the flight vehicle and there's a strong chance they would not have ever been used. IIRC they removed it from the design altogether at a late stage.
The Buran is awesome but it's also one of those projects that is very easy to look on with rose colored glasses. It's very easy to talk about its performance because on paper it was impressive but in the end it was never really given a chance to be proven out. This also conveniently means that whatever non-obvious flaws it has (and here, spotty field joints in the space shuttle come to mined) were never uncovered. On paper at least, it had attractive features that made it better than the shuttle. Again, the spotty field joints on the shuttle come to mind because the Buran didn't have them in the first place as an all-liquid rocket.
On the other hand, it shared the same lack of escape options as the shuttle and despite claims of obvious superiority in heat shield design, the Russians did not and do not have a strong heritage of design experience with non-ablative heat shields. Not re-using the engines would have made it likely more expensive to launch and the lack of a TDRSS (in-space relay network) equivalent would have limited the amount of science it could perform and made it harder for ground control to help the astronauts in emergencies.
I don't mean to throw shade at the Buran - I prefer it to the shuttle myself - just point out that it is easy to mythologize a system that only flew once and compare it favorably with systems that had all their flaws exposed through constant use. We also have to acknowledge that despite all the flaws of NASA, they are very upfront with their failures and development woes. With Buran, for the most part it was a black box that the West didn't know much about except what the Russians chose to tell people. Unsurprisingly, they chose to mostly tell us all the great things about it rather than an honest, full assessment. We do know more about it now than we did in the 90's but a whole generation grew up learning about it bits and pieces at a time.
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Berzerker
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supposed to be a comet out there tonight, a green one visible with binoculars. Wont be back until AD 3300 or 3900 (cant remember)
r16
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awright , once again with the essentials . Some Russians , with their Lomosonov satellite in case ı spelled it correctly , notice powerful flashes in the atmosphere . Prefereably at exact 40 kilometers or thereabouts of altitude . Say it's newly discovered natural phenomenon . Say , Renaissance started examining the Human Body 500 odd years ago and they just discovered a new organ last year , making it 82 , ı think . But "obviously" it's Alien conscripts brought in fast instead of sneaking in over a week , right out of mini jumps , under optic stealth and course corrected by the oft reported Dark Knight . Stargates are cool but hard to disguise , so the system one is just off Neptune .
ı usually don't do the links , but this one indeed merits one . ı have chanced upon this fabled "Ancient Aliens" kind of programmes only this week , surfing around on TV and am seriously appalled and guess what whom the article includes , lo let you sleep sound and tight ...
https://www.iflscience.com/space/ru...hey-have-spotted-mysterious-light-explosions/
ı usually don't do the links , but this one indeed merits one . ı have chanced upon this fabled "Ancient Aliens" kind of programmes only this week , surfing around on TV and am seriously appalled and guess what whom the article includes , lo let you sleep sound and tight ...
https://www.iflscience.com/space/ru...hey-have-spotted-mysterious-light-explosions/
Thorgalaeg
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Of course, but small turbojets weighted a fraction of several huge lift rockets. The turbojets were just enough to keep the Buran in the air, obviously with such relatively tiny engines it couldn't never take off by itself or even do a touch and go landing.
http://www.buran-energia.com/bourane-buran/bourane-consti-reacteur.php
The engines were Saturn AL-31, originally made for the Su-27 fighter. It could install up to four. Modifications were needed so they could withstand spaceflight.
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About Opportunity exceeding its planned lifespan by a factor of like 50:
Does NASA intentionally understate the planned lifespan for spacecraft, at least the ones that don't have clear endpoints? Hindsight bias notwithstanding, 90 sols seems pretty short given the design of the rovers. Granted, they did expect that the solar panels would be coated with dust and not periodically cleaned, so I can see a reason not to expect they'd live more than an Earth year or so. Curiosity is an even more obvious case: it has an RTG and so could reasonably be around for decades, but its mission was said to be for only one Martian year/1.9 Earth years. Is this deliberate, and if so is it related to funding or to inflating the odds of success and/or how successful a mission is perceived to be?
Does NASA intentionally understate the planned lifespan for spacecraft, at least the ones that don't have clear endpoints? Hindsight bias notwithstanding, 90 sols seems pretty short given the design of the rovers. Granted, they did expect that the solar panels would be coated with dust and not periodically cleaned, so I can see a reason not to expect they'd live more than an Earth year or so. Curiosity is an even more obvious case: it has an RTG and so could reasonably be around for decades, but its mission was said to be for only one Martian year/1.9 Earth years. Is this deliberate, and if so is it related to funding or to inflating the odds of success and/or how successful a mission is perceived to be?
hobbsyoyo
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A bunch of things apply.
They have to pick a mission success criteria and they will pick a reasonably softball one. They have nothing to gain from setting the mission success criteria to be more aggressive than it needs to be and lots of incentive to make it an easy target to hedge against unforeseen circumstances.
There is always quite a bit of uncertainty in missions like this. Spirit and Oppy were the first big, independent rovers to go to Mars and while NASA simulated and prepared for the mission environment, in the end they couldn't be sure that everything would work as intended. You can see this in the faulty wheels that Curiosity has - despite three previous rovers worth of experience, NASA still underestimated the wheel erosion that their larger, nuclear-powered rover would experience. NASA has adapted the way they drive it to compensate but the problem was very serious and quite a concern when it was noticed.
Even when everything goes right, certain parts and instruments have limited life spans. The drills that Oppy and Spirit used to sample rocks were a good example of this as it was known that the bristles they used to chew into rocks would wear out. So if you have instruments and parts with limited life spans, you are inherently putting a timer on success that can only get worse, not really any better.
Let's say you have two instruments, a chemical sensor with a theoretically infinite life span and a drill with a life span of 45 days of heavy use. Now when you get to Mars, you find that due to an unknown design flaw, the chemical sensor dies. This means you have a useful scientific life of 45 days for your rover. If you have tied your mission success criteria to say, 180 days of useful scientific observations, you will all of a sudden find your hardware struggling to meet a goal that the supposedly immortal chemical sensor could have easily met. You want to avoid boxing your mission in unfavorably and provide plenty of margin for success. Under promise and over deliver.
Another big issue is budgeting. Big flagship missions are expensive both upfront and on an ongoing basis due to the teams of engineers and scientists you have to pay to continue flying/driving them. Because of this and the way our flaky, year-over-year spending bills are handled by Congress, NASA can't always budget all of the money they need for operating the mission long-term. They choose instead to rob Peter to pay Paul by taking money out of the future ongoing-operations budget to pay for the immediate construction and launch of the mission - or rather they construct the budget such that it's heavily front-loaded to begin with, even if it means they can only afford a short duration of operation. If you can claim success early into the life of the mission, it's easier to go back to Congress and ask more money to fund continuing operations than if you go back to them without total success already behind you.
Local conditions also play a role as well. The recent ESA mission called Rosetta is a good example of this in that the orbit of the comet it rendezvoused with was known to be nearly impossible to survive long-term. Similarly with Mars, yearly dust storms can range from very mild or even non-existent some years to absolute beasts that black out the sun for months. Given these kinds of uncertainties, you really want to make sure you get mission success fairly quickly so you design mission goals that can be accomplished in a short amount of time to avoid hazards. After that you can begin exploring more long-term investigations.
They have to pick a mission success criteria and they will pick a reasonably softball one. They have nothing to gain from setting the mission success criteria to be more aggressive than it needs to be and lots of incentive to make it an easy target to hedge against unforeseen circumstances.
There is always quite a bit of uncertainty in missions like this. Spirit and Oppy were the first big, independent rovers to go to Mars and while NASA simulated and prepared for the mission environment, in the end they couldn't be sure that everything would work as intended. You can see this in the faulty wheels that Curiosity has - despite three previous rovers worth of experience, NASA still underestimated the wheel erosion that their larger, nuclear-powered rover would experience. NASA has adapted the way they drive it to compensate but the problem was very serious and quite a concern when it was noticed.
Even when everything goes right, certain parts and instruments have limited life spans. The drills that Oppy and Spirit used to sample rocks were a good example of this as it was known that the bristles they used to chew into rocks would wear out. So if you have instruments and parts with limited life spans, you are inherently putting a timer on success that can only get worse, not really any better.
Let's say you have two instruments, a chemical sensor with a theoretically infinite life span and a drill with a life span of 45 days of heavy use. Now when you get to Mars, you find that due to an unknown design flaw, the chemical sensor dies. This means you have a useful scientific life of 45 days for your rover. If you have tied your mission success criteria to say, 180 days of useful scientific observations, you will all of a sudden find your hardware struggling to meet a goal that the supposedly immortal chemical sensor could have easily met. You want to avoid boxing your mission in unfavorably and provide plenty of margin for success. Under promise and over deliver.
Another big issue is budgeting. Big flagship missions are expensive both upfront and on an ongoing basis due to the teams of engineers and scientists you have to pay to continue flying/driving them. Because of this and the way our flaky, year-over-year spending bills are handled by Congress, NASA can't always budget all of the money they need for operating the mission long-term. They choose instead to rob Peter to pay Paul by taking money out of the future ongoing-operations budget to pay for the immediate construction and launch of the mission - or rather they construct the budget such that it's heavily front-loaded to begin with, even if it means they can only afford a short duration of operation. If you can claim success early into the life of the mission, it's easier to go back to Congress and ask more money to fund continuing operations than if you go back to them without total success already behind you.
Local conditions also play a role as well. The recent ESA mission called Rosetta is a good example of this in that the orbit of the comet it rendezvoused with was known to be nearly impossible to survive long-term. Similarly with Mars, yearly dust storms can range from very mild or even non-existent some years to absolute beasts that black out the sun for months. Given these kinds of uncertainties, you really want to make sure you get mission success fairly quickly so you design mission goals that can be accomplished in a short amount of time to avoid hazards. After that you can begin exploring more long-term investigations.
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Berzerker
Deity
"Rise of the Rockets" (human activity in space) is on PBS Nova tonight at 12 central
brought to you by David Koch
brought to you by David Koch
Estebonrober
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"Rise of the Rockets" (human activity in space) is on PBS Nova tonight at 12 central
brought to you by David Koch
Isn't it ironic. Killing the planet on one hand, celebrating humanity on the other.
Thorgalaeg
Deity
I don't think it is ironic. It is very admirable for a species to become capable of destroying its own planet. Stupid but admirable.
Berzerker
Deity
I'm not much into the technology but it was kinda cool watching them test the engine for their new sls rocket
I didn't know there were so many small start ups building rockets for the satellite delivery market
I didn't know there were so many small start ups building rockets for the satellite delivery market
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