Justy

I read a novel in the early 1990's about a supertanker collision, oil spill, and firestorm off the coast of British Columbia. It was, shall we say, not the greatest piece of literature ever penned by man. But as a last-ditch measure to try to avoid the collision, the novel's brand new top of the line bigger than ever supertanker did feature emergency braking rockets to try to bring its stopping distance down to something reasonable. (of course, it wasn't enough. It'd be a short novel if it was.) Safest rocket ever... the ignition will never work!

This is a great tool; I'd been doing a lot of these calculations on paper. I had been doing some of the minimum & maximum orbit calculations on paper, hadn't gotten around to spreadsheeting it yet... and coincidentally was looking for how to calculate darkness time for satellite batteries. But could you please explain what you're showing with "Optimal Field Of View" on the Satellite Relay tab?

Heh. So I did; I gave a link to the article but I was working from memory. Whoops. I'm glad to hear that actually. I then wonder why, in addition to the very appropriate step of confiscating ID, we took the additional misguided step of physically screening the air crew.

You have a good point with Pacific Southwest Airlines 1771, but you need to take it further to find the real lesson, which I really wish the global security community would learn. Summary: A man recently fired for theft from the employer is allowed back on that employer's aircraft the same day, without confiscating the company ID that allows him to bypass screening. He brings a gun on board, shoots the manager who fired him who happened to be on the same plane. Flight attendant opens the cockpit door to tell the pilots there is a problem onboard. Man shoots the attendant, pushes past the open door and shoots both pilots; may also have shot another pilot who was in the cabin as a passenger trying to get to the cockpit to save the plane. Plane crashes killing 43 in all. Possible Solutions: Take away the company ID that gives him those special privileges. Leave the cockpit door locked. Tell the disgruntled fired airline employee he's not allowed on the airline's planes anymore and he can take the bus home. What We Did: Air crew must be screened for dangerous baggage. ...which doesn't solve the problem. Crew don't NEED dangerous baggage if they want the plane to crash. They already have what they need for that: the ramp crew can bring down an airliner with duct tape (and has, accidentally: Aeroperu 603) or a poorly latched baggage door or stuffing a ham sandwich in the fuel port, the flight attendant has a heavy bucket of scalding hot coffee, the pilot has control of the plane for goodness' sake. All the pilot has to do to cause a crash is STOP DOING HIS JOB, and we're worried about him having a pistol or a metal dinner knife. The problem was that this guy held on to his trusted status as air crew even after being fired because he couldn't be trusted. So I say the problem isn't just that we only address problems as reactions... PSA1771 shows that when we do react, we often address the wrong problem.

Dharak1, your profile says you're in Edmonton, I would strongly recommend you get in touch with the Canadian Association of Rocketry. They have people dedicated to home-made motors ("EX" or "Experimental") and safe testing of rocket motors (Motor Certification Committee). The Tripoli Rocketry Association is even more involved in experimental rocketry (in addition to the famous LDRS events, they organize BALLS, a three-day all-experimental launch in the States) but their website is down. To start with, you might start with microhybrids using whipped cream dispenser N2O cartridges. They're roughly equivalent to D-class solid motors. Aerocon Systems' "S'Creamer" microhybrid is a ready-built unit with sections of acrylic pipe for fuel. You can find similar motors in kit form requiring some metalworking skill elsewhere, and if you want to scratchbuild one from Rene Caldera's original microhybrid design you can get the plans for $10 from Art Applewhite Rockets. I have a G-class hybrid from a manufacturer I won't name. I've never fired it, because shortly after I bought it, one from the same batch exploded on the test stand, throwing pieces at least twice as far as the listed minimum safe distance (which is, itself, a couple times farther than pieces from a failed motor are supposed to fly; make sure the ENDS of the motor are weakest, so if it blows up on the pad, pieces go up and fall back down, not outward towards you!). I see that same manufacturer has a G-class available once again for just under twice what I paid; I assume he re-worked the design. This is why I suggest you start with known designs as a learning exercise before you strike out on your own, and for your first couple attempts, ask if the CAR Motor Certification Committee will let you park your motor on their test stand during their next testing day and push The Button from the safety of their blockhouse.

My concern for Juno was that they might have needed to do some tracking & fine tuning to make sure it ends up outbound on the right course. In a post above, I quoted someone actually working on Juno who says they're still on the job monitoring spacecraft operations. Border services are by no means "skeleton crews;" so far, they're pretty much unaffected. Heck, there's only 5 minute lineups both directions at the four crossings between Vancouver BC & Seattle this morning. Only 14% of the Dept of Homeland Security is furloughed and they're mostly in law enforcement training and FEMA non-disaster services. I wonder. On one hand, the closest approach will be nearly 600km up, and in the Earth's shadow. But it's got a massive 650 square feet of solar panels -- that's a bigger cross-section than the European ATV cargo ship, and I saw that with the naked eye -- and maybe it'll still be far enough of the horizon before crossing into shadow to be seen from Cape Town. I hope someone gets to see it.

The earliest big news story I was old enough to be aware of was the Challenger explosion, and later I read the story of Apollo 13 in school -- in French! But THE MOMENT space became awesome was exactly 8:52pm Pacific Standard Time, December 5, 1993. STS-61 was the first Hubble service/repair mission. For those not old enough to remember a time before the Hubble Space Telescope, when it was first launched, it was an embarrassing failure, practically blind. But it had been designed from the start to be serviced by humans. During STS-61, my local cable company aired NASA TV on the next available channel... which coincidentally was channel 61. I was watching during the second spacewalk when Thomas Akers unplugged one of the solar panels, the one that was stuck and couldn't be rolled up to return to Earth. And more importantly, at 8:52pm my time, I was watching when Kathryn Thornton let go of it. As I remember it, the camera stayed on the solar panel for a very long time as Endeavour moved away from it. And I watched for the rest of the orbit, until panel and shuttle entered the Earth's shadow. And it was beautiful. And I stayed watching through the shadow, and when it was back in daylight the camera panned over to it now and again, still slowly drifting away. I missed spacewalk #3, I was a Scout at the time and Mondays were meeting nights. But I watched as much as I could of the last two walks, including the installation of the "contact lens" to fix Hubble's vision; I do believe I remember Story Musgrave hand-cranking one of the new, boxier solar arrays. A month later NASA released the photos showing how Hubble's vision had improved. And manned spaceflight was the most awesome thing ever.

The principal engineer for Juno's WAVES instrument replied to my question on a ham radio forum asking if the event was still on: Good news, Juno is taken care of. Better news, I'm going to transmit a signal to a probe on its way to another planet!!

Man, I sure hope so. Hard to get info. I'm pretty sure the ham radio project is off the table though. During the flyby, NASA was organizing a coordinated effort of ham radio operators to send a very slow speed morse code "HI" message (four dits, pause, two dits... where each dit is 30 seconds long!) to see if Juno's radio detector would pick it up. I might try broadcasting anyhow.

I was about to post that a contractor had posted to Reddit he was pretty sure work on MAVEN was one of the few projects still continuing, but the Planetary Society is a whole lot more trustworthy (if less hopeful), and the official @MAVEN2Mars twitter feed makes it pretty clear: "#MAVEN is shut down right now. Work at gov't facilities is undergoing orderly shutdown. Hardware will be put into known, stable, safe state." Damn. I guess we can be happy it's not RTG-powered; safely stowed, its solar panels should be just as good two years down the road as they are now. I can think of a bigger tragedy than delaying MAVEN, though. In a week, Juno does a slingshot past Earth, its closest approach just 559 km above surface. If the shutdown should mess up that maneuver...

My reason for trying Readyboost was that I thought the rhythmic micro-pause hiccups was being caused by disk access... I've since read up on it more, and I see that's not the case. But hey, it was worth a shot. Thing is, though, I thought the worst that would happen would be that I'd have wasted a couple bucks on a thumb drive; I was surprised that it actually seemed to retard performance. The effect of enabling/disabling MSSE is small, but it's there, especially later in the flight. Disabling MSSE only adds a few FPS, but you can see it's sped physics up quite a bit, I'm better than ten seconds of game-time ahead after ~470 seconds of real-time. By this point I'd done several practice runs and I think I had my staging pretty smooth, I don't think that ten second gap is human error, but I guess to be certain I'd need to do a few identical runs and average them. Comparison below is with old video drivers. I am kind of surprised how well my i5 2320 3.0 GHz keeps up with the i5 2500k 3.3 GHz, especially in the first half. Of course, the advantage of the 2500k is that, as shown, it can be cranked up to speeds that blow my system out of the water, while mine is stuck. Replacing my CPU for more speed would cost nearly as much as I paid for the whole system, even before additional cooling.

The System: Acer Aspire M3970 CPU: Intel Core i5-2320 @ 3.00 GHz (CPU-Z: core speed 3193 MHz under load, bus speed 99.77 MHz) RAM: 6 GB DDR3 667 MHz GPU: ASUS ENGT430 (NVIDIA GeForce GT430), 1 GB OS: Windows 7 Home Premium 64-bit, Service Pack 1 Passmark: 5837 Cinebench: 4.93 The CSVs are in this Dropbox folder. I did several tests; the most relevant are in the folder called "New Drivers," which was a run I did after all the rest, when I noticed nVidia posted new graphics drivers last week. The rest I did to compare a few things to see if they'd affect performance: "Baseline Condition" has MS Security Essentials running. "No Antivirus" has MSSE's Real Time Protection switched off. "USB3 Flash Drive" moves the KSP folder from the local hard drive to a Kingston 16GB USB 3.0 "DataTraveler 100 G3" flash drive. "With Readyboost" uses two of those same flash drives dedicated to Readyboost disk cache. "New Drivers" is, as I said, Baseline Condition re-done with the most recent nVidia update. In each case, I tilted the camera until I couldn't see the water tower anymore, throttled up, enabled SAS, hid the navball, started FRAPS monitoring, and waited until FRAPS' green square vanished before launching. All runs were in the default 1024x768 window on a 1920x1080 monitor, with the required tweaks to physics delta-time and V-sync. It looks to me like disabling MSSE's Real Time Protection increased performance slightly, as did using the latest video drivers; running KSP from the USB drive had little effect, and Readyboost actually hurt performance. The differences were all pretty small, though. Edit: I did full-to-burnout runs with antivirus disabled at various resolutions, in both fullscreen & windows, as well.

"Little" white men? Are you kidding? They're, like, two meters tall! And long arms and legs so they can run you down, pick you up and crush the green right out of you! Run for your lives, the humanoids are coming for you! Or so the stories go. Don't get me wrong, I've always enjoyed Edgar Rice Kerman's stories, where the veteran falls asleep on Kerbin and wakes up on Erf, and ends up uniting the white, black, red and yellow humanoids to defend themselves against fearsome, warlike, slave-trading quadruped beasts called "kittens". Very entertaining escapism, but that's science fiction. I'm all for a kerbed presence on Dres, but don't try to drum up budget support by claiming it's to protect us against some threat from imaginary humanoids!

Way to go, HueHue. I was playing with the shortwave tonight, and I got the Voice Of Kerplodistan from the United Kermunist Kerbal Republics. Turns out they took your challenge as a threat and decided they had no choice but to produce an equivalent system in response! I'm a bit rusty with the language, but I think they're calling it the "Nukabombik Transportsionnaya Sistema 2U." They've already conducted a partially successful test flight, including dropping a bomb in a remote part of one of the UKKR's vassal states, Kaboomistan. The Antiquing Week & Space Technology website has the latest leaked specs: 2060 m/s at 31,000 meters, one nuclear weapon, and while it has some control problems with regards to landing, they expect to prove circumnavigation and landing within days proven circumnavigation ability. There was also some bluster about how UKKR airspace is defended by atomic-powered radar satellites that can detect aircraft all the way down to the surface, and the same high altitude interceptors that shot down Tarmenius' plane on Thursday... though my copy of Jeb's Fighting Aircraft doesn't show anything like that. You know, I think they might be trying to take credit for shooting down a plane that actually broke up by ACCIDENT! +50 pts for speed & altitude requirement +50 pts for one NTR-bomb +100 for circumnavigation & landing =200 pts total

My fourth attempt, Munfrod died of a freak life support failure despite having plenty of oxygen and nowhere near maximum CO2. Looks like the CO2 built up in the pod and, under time acceleration, didn't properly shift over to the fully empty CO2 storage in the recycler. Darnit. My fourth-and-a-half attempt, never going beyond 10,000x acceleration, has reached Eeloo (year 2 day 119) and MUNFROD IS STILL ALIVE!! Woo! Rejoice! The comm sats and mapping/kethane sat are deployed, and Munfrod will be making his two week surface expedition once mapping is complete. Synapse, that is a clean, sharp, stable looking ship. How have you got the drop tanks set up, two batches of four tanks? I did four batches of two tanks, and I'm not sure the extra complexity is really worth it. I hope that's a probe body I see just forward of the batteries on the CM, does the ship have enough dV to rescue Bill? If you get a chance, I'd appreciate a copy of your notes on gravity assists too. I get the basic concept of how I can use one to add velocity, I just don't understand how to line one up so it takes me someplace I want to go. I always end up adding more dV to a midcourse correction than I save on ejection. Hejnfelt, that's a lot of greenhouses you're sending to Eeloo, which as I understand it is meant to one day become an ice moon around a Saturn-like planet. Will you be adding Freeman Kerman to you crew list? He even comes with !

Well, I made my first couple tries at this. The challenge for me is that I'm using Ioncross life support. I learned after my first two attempts that the air recyclers don't deal well with full (100,000x) time acceleration, so I kept running out of air. So I developed a process where I'd cruise for ~100 days of game time at full speed while Kermrade Kerbonaut Munfrod Kerman filled the recycler's CO2 storage, started the recycler, babysat the progress for a while at 1000x, stopped the recycler, and repeat. So orbital assembly (1: NTR tug with drop tanks. 2: life support & refueling for NTR. 3: two stage tunacan lander with one crew) and the flight out to Eeloo encounter took, all together, something like four hours. It wasn't the greatest, it won't score anything like some of what you guys have going, but darnit, it was mine and I was proud of it. I was especially proud of the communication satellites, I'd never done a constellation like that before. I put the ship in a 7h12m (1.33 Eeloo days) equatorial orbit with the Pe at 684 km; the plan was to drop one satellite at each pass of the Pe, then have it circularize and change inclination (30deg) on its own. That would leave me with three satellites each spaced 1/3 of the way around an Eeloosynchron-ish orbit, with the poles covered by each satellite one at a time. The fourth comsat was in a lower, high inclination mapping orbit. After the first comsat completed orbital insertion, I couldn't switch ships. Or get back to the Space Center. Or quicksave. All I could do was kill the program and hope to restore from an autosave. Nope! Back to Year 1, Day 1. But lessons were learned, and I'll try again next weekend.

That, sir, is actually very nice photo.

The version I had read about used underground tunnels. They would be burned right through the rock using a tunnel boring machine, powered by a nuclear reactor, heating a large tungsten probe to melt and vitrify (glass) the rock. This was desirable because, once you built the machine, the cost of digging tunnel was tiny. aside from land use concerns, an advantage to going underground was the low energy needed to operate the train itself. Gravity would do nearly all the work, both accelerating and braking. A ground level tube will have to use more power for that.

I love the idea of vactrains. And the idea of atomic powered tunnel boring machines burning sealed tubes of vitrified rock, how cool is that? The floating tunnel under the ocean makes a lot of sense, though if it sways at all, won't that be a problem for the ultra fast train rattling around on its track or, worse yet, the walls? The version I'd read about started with a coast-to-coast backbone, LA-DFW-NYC, with branch lines of slower vactrains, conventional high speed trains in vactrain-like tunnels but without the vacuum, and local surface commuter trains. The eventual expansion of this Planetran train into a world-spanning (well, northern hemisphere spanning) transit system was of course inevitable, but hey, let's keep focused on immediate and practical things, like LA to NY in 54 minutes in a spaceship floating on magnets in a glass tunnel through solid rock dug by atomic moles. So cool! Hey, we should write that into a song about nostalgic views of the future or something. On that train, all graphite and glitter, Undersea by rail, Ninety minutes from New York to Paris, Well, by '76 we'll be A-OK... What a wonderful world it will be, What a glorious time to be free. --Donald Fagen, "I.G.Y." The coolest part was that the trains were unpowered. They were propelled by rolling downhill out of the station, and slowed again by rolling uphill into the next one. Vacuum tunnel and maglev, so no resistance, right? One day I will read that paper ("Trans-Planetary Subway Systems, A Burgeoning Capability," Rand Corp, 1978). And I will see if it can answer my fiancee's biggest question. You see, the way I geek about rockets, aviation and trains, she geeks about weather systems, earthquakes and volcanoes. So when I described Planetran to her, her first reaction was, "But what about fault lines?" Instantly I started to imagine the westbound train from Dallas crossing into California at 3000mph where a segment of perfectly smooth glass tunnel had shifted six inches to the right. There's also the fact that "nuclear" is a bad word now, and it might not be as economically viable using conventional tunnelling equipment to dig a path across the whole continent. The undersea floating tunnel faces neither of those challenges though...

I know it's possible to exit a gravity assist with as much as 200% the target object's velocity plus the velocity you started the encounter with, but that's assuming the target object is so much bigger than you that you can pretend it's infinite and immovable. I also know gravity assists are less efficient the further you are from the target object, and that if Earth and Venus get too close they'll start tearing chunks from each other (that's not a bad thing when you're trying to destroy planets, but it is if you want to throw one in a particular direction), so there is going to be an upper limit. Is 60% reasonable? Too high? Too low? Beats me, and I don't like to pull numbers from thin air. I don't deny that a Venus slingshot is a cheaper way to get to Jupiter than going directly, but the energy required, whatever system you use to put that energy into Earth, cannot possibly be less than disassembling Earth where it is. That is one way of accomplishing it, but I don't think it's going to be any more efficient if you put a certain amount of energy to fly an asteroid past Earth and accelerate Earth by a little gravitational coupling, than to just put that same energy into pushing Earth directly. I can't prove it though. I wonder if there are even enough asteroids; the entire belt put together only weighs 4% as much as the Moon. I only said that's how much energy it takes. It will take at least that much energy no matter what the technology is. I didn't say it would take any particular period of time, I just used days of the Sun's output as a way I could compare numbers for amounts of energy I can't possibly grasp otherwise. If you want to spread the matter of the Earth apart far enough that it doesn't pull itself back together again, whether in one blast or a slow push, it takes 2.2405*1032 kg*m2/s. That looks like a big number to me but I have no real idea what it means. The Sun puts out 3.86*1026 kg*m2/s every second, also big and scary and meaningless to me. But divide one into the other and you find the minimum energy for destroying Earth is equivalent to 540,440 seconds, or 6.7 days, of the Sun's total output. Do it in an instant or spread it over eternity, this is the absolute minimum it takes to overcome gravity. Similarly, to move Earth as far as Venus to set up that first slingshot takes a certain minimum amount of energy. Do it however you want: push the Earth, push asteroids that pull the Earth, push Mars and play interplanetary 8-ball, doesn't matter. No matter how you deliver the energy, it's still going to take nearly three times as much energy as blowing Earth apart just to get as far as Venus, with yet more energy needed to finish the job. We can make it LESS efficient if we want to, we can waste as much energy as we want, but we can't make it any more efficient than this perfect-world minimum. As far as method goes, I'm still partial to the massdriver idea. It's on the edge of current technology, I admit, but I'm with you on this point: long but efficient FTW. Centuries? Longer? Wait a second, maybe it WOULD use even less energy, since as you slowly reduce the mass of the remaining Earth, each shot needs less energy to overcome its gravity... nope, that's balanced out by the early shots having the entire planet dragging them back, it'll work out to the same as just scattering the whole planet in a single blast. You win again, physics!! Anyhow, the numbers and equations I used are mostly on this page, plus a couple numbers (mean distance of Venus from Sun, etc) looked up on Wikipedia.

Didn't forget, consciously ignored because I didn't think it could possibly reduce the energy required by 86%. But let's look at it... The question was, which takes more energy, moving Earth to Jupiter or blowing it up in place? Just the first step, pushing Earth to Venus orbit, still takes nearly three times as much energy (19 days of Sun's output) as just blowing Earth up where it is, so the Venus gravity assist has already lost before the rest of the math is finished. Beyond that, I don't know how to do math on gravity assists, Venus is LESS massive than Earth so what little I do know tells me the effect isn't going to be earth-shattering (heh) even if the planets pass so close they nearly tear each other apart with tidal forces, and there will still need to be more energy to make up the rest of the change from Earth-Venus transit orbit to Jupiter. So here's your revised chart: Deorbit whole Earth into Sun: 80 days Push whole Earth into Jupiter: 50 days Push Earth into Jupiter via Venus: no less than 19 days, probably much more Crashing Earth into Venus: 19 days Crashing Venus into Earth: 15 days Blow Earth apart in-place: 7 days The winnah, and still cham-peen!! Would an Earth-Venus collision even destroy Earth? I dunno. Venus is 81.5% the mass of Earth. Earth took a hit from a Mars-sized object (11% Earth mass) early on, and all it did was scuff off enough dust to make the Moon. Earth is a tough old girl.

There's nothing wrong with ruling them out for the challenge, but for what it's worth, there's good justification in history for SRBs in Apollo-to-Mars. Large SRBs were well established at the time, and the most realistic Saturn upgrades (ie, none of this "we'll duct-tape four Saturn V's together for a first stage and fly it back to a runway landing" crap) used them. 120 inch SRBs (a little narrower than Shuttle's 146 inch SRBs) were already in use for Titan; strapping four of them on Saturn V would give you 170 tons to orbit (vs. 118 for the Saturn V alone). Better yet, Aerojet tested their monstrous 260 inch SRB in 1965, and had built the factory to produce them in Florida (because they would be too big to ship!)... but the contract fell through and the factory closed. One of these would entirely replace the first stage on little Saturn IB, or cluster four of them to increase Saturn V's payload beyond 300 TONS (the inconveniently named Saturn V-D). Put fuel tanks on top the SRBs and crossfeed them into the Saturn V's first stage, dropping them at SRB burnout, and payload jumps to over 370 tons (Saturn V/4-260), enough to launch the entire ISS (up to 2009; it's too heavy now) in one launch! Aerojet was passed over in favour of Thiokol, with their cheaper, multi-segment boosters (Aerojet's were cast in one single giant piece, so no seams). You may remember Thiokol from such press releases as "Shut up, Roger Boisjoly, we don't care if it IS too cold, launch Challenger anyhow, it'll be-- hey, our contract protects us if anything goes wrong, right? Yeah? Great! Like I said, it'll be FINE!"

Kerbface, it turns out you're right. Here's how much energy is needed to destroy the Earth, expressed in terms of THE TOTAL OUTPUT OF THE SUN. Deorbit whole Earth into Sun: 80 days Push whole Earth into Jupiter: 50 days Blow Earth apart in-place: 7 days I am too lazy to do the math on this, but if you use massdrivers to hurl chunks of Earth as propulsion, you might be able to push *some* of the Earth (say, Australia) into Jupiter with less energy than blowing it apart, by grinding up the rest of the Earth and turning it into an "exhaust" trail consisting of buckets of rock in a deadly cloud of comet-like orbits. With each bucket thrown, the Earth's mass decreases, so like a rocket its TWR increases.

You're right. So instead of a pitiful laser pointing out the back of the spacecraft, you leave a gigantic laser at Earth, powered by solar panels and nuclear reactors and hydroelectric dams and windmills and natural gas and steam engines and hamster wheels and everything else, with no regard at all to how much it weighs, because who cares, it's not going anywhere. Then you point the laser at your very, very light solar sail spacecraft. Now you can use a laser putting out a thousand times practically nothing, and as long as the power supply keeps up on Earth (note to self: start hamster breeding program), you can keep it up for a very long time. On second thought, you probably don't leave it on Earth, you leave it in Earth *orbit*. You can't afford to lose laser output as heat before it leaves the atmosphere. So I guess we're down to solar and nuclear power only (note to self: hamster spacesuits). But still, not having to accelerate that power supply and giant laser is a big deal.

I think it's kethanol. We all know that kethane won't even stay liquid, let alone solid, at the temperatures in cismunar space. But kethanol -- that's a kethane molecule where you substitute one of the propellium atoms with a propellioxide group -- has a much higher melting point and might be stable. Or it could be frozen dodecane. Not just because it has a good freezing point (-10C), but because it has a funny name.