Never Say Never
Bond: Commander Pederson, are you equipped with the new XT-7Bs?
Cmdr: That's top secret. How do you know about them?
Bond: From a Russian translation of one of your service manuals.
105 posts • joined 22 Aug 2009
NOx was in the exhaust streams of hypergolic fueled rockets, and this was an ozone depleter. So moving from hypergolics stopped that problem. Today there is still concern about Cl present in solid rocket exhaust as it attacks ozone and the effect (ozone hole) lasts an hour or so. Could become a global issue if rocket launches increase in the future.
Apparently they have developed the Long March series, from types 5 on up, to use LOX/RP-1 (Kerosene) for the boosters and LOX/H2 for both the first and second stages.
These propellants are so much cleaner than what they have been using until very recently, that is, hypergolics for all stages (nasty, polluting chemicals). The new propellants, being mostly cryogenic (except for the RP-1) are harder to handle. But pretty much everybody else, India included, uses the relatively non-polluting propellants almost exclusively these days. Maybe we'll soon be seeing the end of hypergolics for rocket stages.
But if the spacecraft hit the ocean with any of its thruster fuel intact, yeah, that would have been polluting.
I just attended a fantastic presentation on Juno last night at Purdue University, by a young woman alumnus, now a JPL engineer on the flight dynamics team for Juno. I had many of the same questions you do, and learned some interesting things!
Regarding the burn to go from the 53 day capture orbit to a 14 day "science orbit," indeed it didn't happen yet, because of concerns with a check valve not operating as quickly as it should (minutes not seconds). They're still studying it. The current orbit is a good one, just a bit slow. They might do a lower power (lower ISP) burn at some point and put it into a 21 day science orbit using the engine in "blowdown" mode, where they don't pressurize the propellant tanks, and sidestep the check valve issue. But that's just one option they're apparently considering.
Jupiter, as you probably know, has a daily rotation of about 10 hours and has a pretty pronounced oblateness...so there is a substantial "J2" term in the gravity model of the planet; it can't be treated as a point mass at all times. So during the close-to-Jupiter, perijove part of the orbit, the J2 effect changes the orientation of the orbit. This is well known to those who follow this mission, and was planned for. What it means, is perijove, currently closer to the equator, will gradually move toward the north pole after several orbits, and the high point (apojove) will move further and further south. Why does this matter? The orbit was planned to avoid the intense radiation fields surrounding Jupiter like a doughnut. But due to this orbit shifting effect, eventually the probe will be flying (during part of its orbit) through some pretty intense radiation, off its original path that minimized radiation dose. So toward end of life, she said Juno will have had something like the equivalent of 100 million dental x-rays.
They always plan any orbit changes (burns) to occur when the icy moons (Europa etc.) are as far away from potential harm as possible. Apparently they're obeying the Monolith. They also plan to de-orbit, at end of life, into Jupiter itself, which is apparently relatively OK. (Although my wife points out, we're now contaminating Jupiter with Earth microbes, but maybe they're not expected to survive.) One option they've considered for EOL is to maximize science near the end: lower perijove to skim very close to the north pole, maybe a few hundred km. Then as the orbit naturally shifts perijove to be more and more south, eventually the probe, even if uncontrolled at this point due to electronics failure or lack of fuel, will eventually hit that equatorial bulge around Jupiter and deorbit. That's pretty good flying.
I used to be a little annoyed at the truly oddball issues found by my former company's software testing team. I wondered "why on earth would they even think to do that..."
Then I've also noticed my young son's strange way of playing video games...jumping all the time, trying to walk through walls, etc. As if he's trying to break the software.
Reading this article it dawned on me that maybe this is precisely the kind of thing we could use more of in software testing. In additional to testing the usual and expected behaviors, and as many "not expected but still possible cases" as you can dream up, also doing some *truly odd things* to the software from time to time may prove really useful!
I used to live in an apartment building on a busy street in the CA bay area. The cars were pretty noisy driving by, and yet it seemed they were particularly noisy on rainy days. It was the usual engine and tire+road noise with a high pitched "hissing" sound overlaid on it.
Perhaps they will design a sound sensor to detect this hiss and its intensity (more hiss = more moisture)...?
I've always felt bad about the Apollo 15 crew getting into hot water with NASA and Congress over the Postage Stamp Incident...their attempt to make a little money on the side through a private deal with a German stamp dealer. Several of the private deal stamp covers were brought along to the moon (presumably into orbit only, not down to the surface) together with a sheaf of "official" ones. The fallout once the private sale was discovered has tainted the crew for a long time.
So now we're talking about the very public sale of yet another Apollo 15 artifact. Seeing the article (before reading it) made me think maybe the Apollo 15 guys were in trouble again...
At last, El Reg comes to my part of the world. Perhaps I can help! To wit:
1. I've got a Cesaroni J engine (might be 3G) that's yours for the asking, and the usual adapters for fitting different dia. vehicles. Only hitch is that I'm up in Seattle. Can't get these at Walmart, but the courier delivery guy did drop it off at my house, only after I promised over the phone to lie to his boss and say I was physically present when he dropped off (this hazardous material). So yes it's relatively easy to ship these in US of A.
2. My folks live in New Mexico, unfortunately, way up in Santa Fe. But they have lots of friends and might find you a place to stay down in Las Cruces. How many of you will there be?
3. Why bother with the Caribbean after the flight? You've got one of the most interesting places in the USA to explore. For starters, White Sands missile range is close by, as is Alamogordo. Both have missile or space museums... Then there's El Paso TX, go to the ('murican) Taco Bell there, it's surreal... If you time your visit right you might even get to visit the Trinity Site.
The point is, they're training a new generation of rocket scientists / program managers / engineers how to fly spacecraft. Doesn't matter that this has been done before, you need to start with a smaller scale project.
They're being very methodical, more tortoise than hare ("Rabbit" notwithstanding).
If they could burn all that fuel quickly and be on their way in one go, I'm sure they'd do it.
But, a bigger engine might not have been available, or they chose a small one (that burns fuel more slowly) to save weight. With advance planning, it's really no big deal to make many small burns to increase the size of your orbit.
Exactly, it's like predicting the weather. A commenter above mentioned "120km" as the altitude of doom. True. But sometimes it's a bit higher, say, 130km, depending on atmospheric conditions. Which we don't know exactly at all points of the atmosphere at all times. Hence, you just can't know where a gradually decaying, circular orbit will come down.
Far better to do a big burn at the end of the sat's life, to target the orbit to intersect the Earth at a safe spot.
>>They said it had left the galaxy.
I just can't stop chuckling at that.
>> Actual speed is about 80 kips, or about 2.5x faster than a pocket calculator.
If it left the galaxy, then its actual speed is in excess of Warp 6.
In 1999, leaving Seattle in late November, I remember seeing a bunch of dodgy-looking people stepping off the little subway train on their way into the exit of the airport while I was boarding the same train to get to the terminal. One young lady was very clearly carrying a (probably dummy) metal grenade, and she had just stepped off an airplane. I suppose she was one of the WTO protesters gathering for the "battle in Seattle."
What stuck in my mind was that she had apparently been allowed to carry this on an airplane.
Interestingly, on my way from Japan to the US in about 1990, I had nearly had an iron bell (more a windchime) confiscated because it was about the same size and color as a grenade. I had to beg the security guy to let me keep my souvenir.
If there's a risk of colliding the cleaner sat with the target, then just setup the approach direction so this collision would at least slow down the target...and contribute to its de-orbiting.
Alternative technology idea for the Swiss: orbit a large, yellow rectangular bit of material to get in the way of orbiting satellite targets. The target sat would hit the material and slow down, leaving a hole in the material. After a while it would resemble...
I enjoyed Myst. It ran well on my PC, and I remember many pleasant hours spent solving the puzzles, with help from my brother (who in turn learned clues from his friends).
Fast-forward about 6 years, after my move to the Seattle area I learned the design team (Cyan) was from Washington State, and their Myst island had been inspired by one of the San Juan islands.
I've visited the spot by boat a few times (it's wonderful) and think about Myst when I do. The pictures here don't do it adequate credit:
The F1 engines in the Saturn V burned Liquid oxygen and RP-1 aka kerosene...basically jet fuel. So the exhaust was no more toxic than what you breathe at an airport.
LOX/RP-1 is nowhere near as toxic as the hypergolic fuel combos used by the Gemini's Titan II (pre-Apollo but only just), and by the Chinese space program even today for their Shenzhou manned missions. But after 44 years in the sea, I can't imagine any traces of the fuel would be left regardless of what type it was.
John Smith 19:
"9/11/01 was thirteen years ago."
12 years ago?
Steve Davies 3:
"Don't you mean 11th September 2001
Using the proper date format."
Interesting, I always though the attackers on that day chose the date "9/11" because it's the phone number Americans dial to get emergency services, 9-1-1, so that the date would be more memorable. So in this case the "correction" wouldn't be needed. Or I just missed the joke.
When Steve mentioned that die-rolling in video games just didn't have the psychological impact of real dice, I figured digital dice...with accelerometers and bluetooth...could be a great addition to such games.
Looks like someone already made a patent for it though:
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