Well, crap....
So I guess the Juno mission is going to be a bit of a what-could-have-been. That's disappointing, after all the successes that NASA has had in the last few years with Curiousity, Dawn, New Horizons and other missions
Jun-OH-NO! NASA's Jupiter probe in busted helium-valve drama
NASA's Juno probe will not venture any closer to Jupiter, and will stay in its current 53-day orbit for the remainder of its mission. That's due to faulty helium valves in the propulsion system, space boffins announced today. The spacecraft has been circling the gas giant since July 2016. NASA scientists had planned to fire …
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Saturday 18th February 2017 07:06 GMT bazza
Re: Well, crap....
Maybe, it sounds like it's the rate at which they get to do interesting science is reduced (once every 56 days), rather than a complete cessation. That's not so bad really, considering.
I agree, they most certainly have been very successful indeed. I think that the entire run of missions going back to the 1960s, 70s, including the European, Japanese, Russian and others, has overall been a stunning display of just what engineers and scientists can pull off when given the chance. The value for money, even including the failures and difficulties, has been very good indeed.
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Saturday 18th February 2017 07:12 GMT Anonymous Coward
Re: Well, crap....
So I guess the Juno mission is going to be a bit of a what-could-have-been. That's disappointing, after all the successes that NASA has had in the last few years with Curiousity, Dawn, New Horizons and other missions
Unless something else goes wrong (which of course it might), Juno should still be able to achieve all of its primary science objectives - although it may take longer than initially planned. I think writing it off as a failure is a bit premature.
I also find it useful to think about it in terms of money: Juno mission cost is about US$1.1 billion (US billion, not the UK one). This sounds like a lot, but it is only 15% of the annual military budget of a country like Indonesia (which happens to be the 30th-highest military spender in the world). It is also less than 17 hours worth of the US military spending, and less than 6 hours worth of the military expenditure by our planet as the whole.
Think about what we could have achieved if instead of pointlessly arming ourselves to the eyebrows (the stage of arming ourselves to the teeth has been passed a long time ago) we would have invested at least a fraction of these resources into science, technology, environment preservation, and social justice.
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Monday 20th February 2017 14:18 GMT tiggity
Re: Well, crap....
Not official but in (I think) 74 Gov UK stats started to use US billion instead of UK billion.
But as most UK govt stats are a dubious work of fiction (e.g. lots of convenient ways to make jobless totals far less than they actually are) and need various mental gymnastics to process I still use "proper" UK billion and just treat UK stats as Amercianised when calculating what they really mean.
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Saturday 18th February 2017 07:35 GMT lawndart
Re: Well, crap....
The failed orbital reduction manoeuvre does not affect the closest approach to Jupiter, so there will be no reduction in the quality of the spacecraft's data collection. The data will be arriving in 53.5 day intervals instead of 14 day. The spacecraft is in a 90 degree polar orbit intended to cover the entirety of Jupiter's surface during the 14 day orbit part of the mission so it may take many more passes to successfully complete the mapping. I'm wondering whether Jupiter's moons and other bits of gravel it has orbiting it will perturb Juno's path by much. The current orbit's apoapsis is in a gap between a pair of the major moon groups.
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Monday 20th February 2017 03:57 GMT Tom 64
Re: Well, crap....
Was always a bit dubious about the success of this mission tbh.
Seems almost like they chucked this one together from off-the-shelf parts on a shoestring budget.
I mean, why not fit this probe out with a RTEG powerplant and ion drive? Less working parts, more efficient use of fuel and waaay longer lifespan in spaaace.
Mine's the one with flame-retardant lining.
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Monday 20th February 2017 07:42 GMT Anonymous Coward
Re: Well, crap....
I mean, why not fit this probe out with a RTEG powerplant and ion drive?
At least two reasons: the mission launch has about 1% probability of failure, with a high likelihood of the RTG being damaged or destroyed upon reentry. The resulting cleanup can be rather expensive (just ask Canadians about Kosmos 954 - and that thing fell in the middle of nowhere). Unless there is no technically viable alternative, using RTG or nuclear reactors is just a little too risky these days.
The second, and less important reason is that NASA has nearly exhausted its stock of the preferred RTG fuel - Pu-238. The US has not produced any for a while: it has been much cheaper to buy Pu-238 and other isotopes (including Po-210 and H-3) from Russia, which invested heavily in isotope production and separation facilities. With the current relations being what they are, the chances of the Congress authorizing more purchases are rather slim.
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Sunday 19th February 2017 18:43 GMT John Smith 19
Note while it's in a stable orbit NASA can look at safe ways to lower its orbit
without firing the main engine. Possibly by some tricky solar sail effects on the solar wind, maybe attitude thrusters, if Juno has any.
JPL put a lot of work in engine design for hypergols during the 1960's and 70's that's served them pretty well. Valve sticking is one of the areas they spent a lot of work on . It's quite tricky. You want a hard coating to resist attack by aggressive chemicals (and both propellants are aggressive) but you'd like a soft coating like a rubber O ring to seal well and stop leakage.
They also developed some of the baseline ways to model injector sprays and develop injectors capable of 10:1 thrust modulation.
Biting the hand that feeds IT
