NASA's Juno spacecraft has been mated to an United Launch Alliance Atlas V 551 rocket ahead of its forthcoming trip to Jupiter. The "most powerful Atlas rocket ever made" is sitting on the launchpad at Cape Canaveral Air Force Station while technicians carry out "a final flurry of checks and tests" to see if all is well for a …
I'm no astonomer, but..
Does Jupiter generate its own light? Its got a chemically active atmosphere. Once the probe gets out as far as the Jovian system, won't Jupiter be the brightest object in the sky?
No it's dark
No light but AFAIK it does generate more heat that it receives. So does the Earth.
Jupiter would need to be considerably more massive to get hot enough to shine.
What happens if the US reaches its debt ceiling before the launch ?
A dodgy bloke with a fag hanging from his lip comes round and clamps the rocket.
Atlas for manned spaceflight?
It's been done.
All the manned orbital flights in Project Mercury used an Atlas rocket.
But about the only thing to have stayed the same is the name.
And the engines on this beast happen to be Russian, originally developed for the N1 super rocket of the 1960s.
And it's amazing how that never happens to get into the press releases... The AJ-26 engines on Orbital's Taurus II are also Russian, being renamed NK-33 engines from the same N-1.
This is after 4 different NASA engine dev programs crashed & burned, including FASTRAC. So we buy kit from the Russians. Who won the space race, again?
An extraordinary early advance
It's amazing to think that -- while the N1 was an over-complexly plumbed dead-end (30 engines in the first stage alone!), the NK-33 engines (which led to the RD-170 and RD-180 technologies) were decades ahead of their time. I remember a Horizon programme that followed the US engineers in the 90s (who'd been approached by the Russians), who just couldn't believe the thrust-to-weight figures the Russians claimed, until they actually witnessed a test. They were astounded that closed-cycle engines had been developed, so early on. It's also amazing to think that it was only because one of the chief engineers on the project disobeyed a direct instruction to destroy the stock of NK-33s that the technology survived; no-one else was even looking at closed-cycle engines with O2-rich preburners.
That's just because US keeps on off-shoring engineering while retaining lawyers and accountant who also refuse to pay any tax increase over their huge incomes... if US had more engineers to tax it could reduced the debit better, engineers are far less able to lobby the Congress than lawyers and their accolades.
... you mean 'acolytes', not 'accolades', but the general point that the US has been in thrall to a minority of unproductive traitors who are intent on grabbing and keeping its wealth for themselves is just accurate history.
We in the UK found that too...
... and left them to their own devices a long time ago.
Fraught time for mission specialists
The riskiest time for the probe is the launch, they must be eating their nails big time. And then there's the huge solar array unfurl, fingers crossed that goes OK.
If it were me I would have built two: "First rule in government spending: why build one when you can have two for twice the price?!" - SR Hadden, "Contact"
Nah, the riskiest time is those pesky close manouvres; you know, flybys, orbital capture and insertion, orbit circularisation, etc.
And at the time, people are trying to remember....
...did I use metres or feet and inches?
When life gives you lemons.....
.....OK...I'm old fashioned, with a hankering for things that go bang...sorry BANG!!!!!....and leave the survivors/spectators with a healthy glow.
<stop wittering man, and get to the point>
OK...I'm stark raving mad, and I've found a use for Fukushima.....
Come on folks...it's already radiated to hell and back, so who would notice the extra???
Waste(?) not, want not....You know it makes sense.
Weeell, the thing is that it's not irradiated.
Give it six months and you won't even be able to tell that anything radiation-related happened at all.
Aside from the hysteria that is.
Still pissed off at the whole "WE'RE ALL GONNA DIEE!!!!!" hysteria whenever something radioactive is even slightly involved.
Why not RTG
Given the distance of the object from the Sun, it would seem that a Plutonium RTG would make much more sense than solar panels. No?
Not enough around, really.
The breeder reactors to make that nasty crap are mothballed now, and working with Plutonium is one of the scariest things in the world. It also decays rather quickly, and it's not something you just keep sitting around...
RTGs are also rather inefficient, but could be made with 1960s technology. We've got better solar cells, that don't involve the potential of spraying several kilos of REALLY toxic metal in the upper atmosphere if things go bang.
What's wrong with Plutonium-238?
Nothing wrong with Pu-238
Do you have any spare Pu-238 kicking around? Down the side of the couch perhaps, or out in the shed behind the lawnmower?
The US doesn't have a lot of Pu-238 left, and most if not all of that is now committed to their spook satellite and submarine RTG military projects. The last lot of civvie-street Pu-238 they had left is sticking out of the back of the Curiosity Mars rover as solar cells weren't considered sufficient to keep it alive and operational through a Mars winter, never mind the much larger power consumption of this vehicle compared to the previous rovers.
The scientific research reactors that made Pu-238 in the past have all been shut down or reworked to make medical radio-isotopes. The Soviets have some Pu-238 kicking around from their own scientific reactor programmes and they were selling it to the Yanks under a "civilian-use-only" licence then they discovered that the US DoD was comandeering the existing stocks of home-grown Pu-238 with the excuse that the civilians could use the Russian Pu-238 instead. This did not go down well in Moscow for some reason.
Another MSR win
This is a potential win for liquid fuel reactors with on-line reprocessing.
Depending on the fuel mix and the eagerness of the on-line reprocessing, a lot of the Pu recovered would be 238. In a solid fuel reactor, the 238 still forms, but by the time reprocessing can get at it, it's been joined by fissile Pu isotopes and chemical separation won't work.
"ride the thrust of five mighty strap-ons"
Do you also write articles for Gentlemens Specialist Journals?
What about radio
Jupiter , outside of Sol, is the largest radio emitter in our solar system. Why not have a power system that turns the radio emissions into power? either as a main or secondary power source.
Also Jupiter has a quite large magnetic field (partially responsible for the radio noise) you have a metallic object circling through it - cant you generate a few watts that way too?
now where is that lightening bolt icon.....
Re: What about radio
They'd probably changed to DAB+ on the way and then we'd be stuffed!
It'll be in the right orbit for it but to extract enough electricity from Jupiter's radio emissions I suspect a comically large antenna would be required.
To extract energy from a magnetic field you have to move a conductor through it, and then what you're really doing is converting the kinetic energy of the conductor's motion into electrical energy. That kinetic energy needs to come from and be replenished from somewhere, e.g. the liquid fuel stored onboard, or your orbit will decay. If you're doing that, you might as well use a fuel cell.
In comparison, electricity from solar panels is free as far as spacecraft are concerned.
And if it relies upon Jupiter for its electricity generation, what does it do for electricity before it reaches Jupiter?
@Richard 12 - that'd be nice if it was true
cesium without a capital and "half a million disintegrations per second"? I'm somewhat sceptical of this source with BS like that
Hahahaha, that site is comedy gold. Mind if I share it around my colleagues? They could do with a good laugh.
Reason for end-of-mission de-orbit?
Can't find one - anyone know?
I expect it will be collecting useful data as it drops out of orbit.
Re:Reason for end-of-mission de-orbit?
Probably the same reason Gallileo was deorbited. There's a small chance that any dead spacecraft around Jupiter would impact Europa, and, if there's anything alive down there we should do everything we can to avoid contaminating it.
Come on you Reg
Oi, where's the Reg's own First Earth Trojan story?
Bloody big rocket?
Of course it's bloody big! Would you prefer a damp squib?
We are talking about Jupiter, right?
As to powering the electronics, it is a LOT of Solar Panels. If one does the math, it is easy to estimate the solar-size-needed as well as the light-density from the Sun near Jupiter. The large solar panels would seem to be an issue if aero-braking or hi-g gravity assists were part of the plan. I guess that they aren't.
The total amount of electricity needed is quite low. There aren't any visible light sensors on Juno. It is all about measuring emissions from Jupiter and studying its atmosphere and core. They are trying to find out about the chemistry and dynamics of this large beastie.
This is another of the New Horizons craft that cost ~$1Bn to build/launch/operate over the six-year lifespan. That makes them 'relatively' less expensive than some of the grand projects over the past 10-20 years (TMO, Galileo, Cassini, etc.).
Now that's something of a User Guide! Kick your thrust bells every 5 trillion miles or 2 orbital launches, whatever comes first, etc...
Always remember to RTFM folks!
After the 33rd orbit?
Key things to know about Juno:
▪ Spacecraft scheduled to launch between Aug. 5 and Aug. 26, 2011
▪ Five-year cruise to Jupiter, arriving July 2016
▪ Spacecraft will orbit Jupiter for about one year (33 orbits)
▪ Mission ends with de-orbit into Jupiter
Or they'll just keep it going for years and say what a great success it was vastly outlasting its 'design lifetime'. On a tourist visit to JPL in Pasadena I asked the tour guide why NASA always so underestimated the functional design lifetimes of their orbiters / landers and why didn't they make the design lifetimes longer*. Didn't get a straight answer, they usually get questions about aliens and whether the Moon is made of cheese.
*doesn't make any difference to the actual lifetime of course
Argumentum Ad Hominem
NASA designers quote nominal lifetimes for missions. It creates budgets and cost structures that are used to justify the activity. If things are 'going well', then NASA possibly continues the work. It is financial stuff...
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