ESA: Venus probe doomed to fiery death on weird planet's surface The European Space Agency has administered the last rites to its Venus Express probe, saying that the spacecraft is now out of control and has gone "gently into the night." "The available information provides evidence of the spacecraft losing attitude control most likely due to thrust problems during the raising maneuvers," …
> "Venus had slowed down 6.5 minutes in the last 16 years – which makes our leap year look like a very minor affair". C'mon ElReg this is not Fox News.
Agreed - but I don't even understand the original comment. Earth has leap years because the period of its orbit is not exactly divisible by an integer number of days, not because it is slowing down.
And even if the author got the wrong end of the stick, one day every 4 years is far larger than 6.5 minutes in 16 years.
Probably confusing the leap year with the leap second, which is applied to UTC (whose second is not based on rotation) to re-synchronize it with GMT (which is a solar time). Leap seconds are because the earth's rotation is slowing down oh so slowly and this is our way to keep our reckonings stable for the time being.
IOW, I don't think a leap second is going to help correct a Venusian reckoning that's off by that much.
Given that the Venus Express was measuring for just 9 out of those 16 years, could some of the discrepancy be down to inaccuracies in the earlier missions' equipment? Or is this extrapolating backwards from just the measurements from VE?
The article reads as if it's the former, in which case my sceptical hat needs a run-out.
The fuel isn't being pulled to the bottom of the tank. There is some spin to point the instruments at Venus, and some rotation to point the comms at Earth, but surface tension is stronger. Until the engine fires, the fuel is probably in a blob somewhere inconvenient for starting the engine. Even when the engine is firing, the fuel sloshes about in a determined effort to avoid being measured.
The 'fuel gauge' works by firing the engine and measuring how much the mass of the fuel reduces the acceleration of the spacecraft. As the spacecraft has been repeated tearing through the top of a corrosive atmosphere it is surprising that any fuel was still inside the tank.
Maybe the rotation is so slow that there is a significant differential between the rotation speed of the core and the surface, with layers of the upper mantle moving like an atmosphere (due to the differential and not just heat convection)? Then the surface rotation speed could change like the average windspeed in the upper atmosphere. Patterns or eddys in the motion could follow a cycle that speeds or slows the surface at regular intervals.
Or perhaps the absence of a moon means that the gravitational bulging due to the Sun is not countered, and results in greater friction and slowing of the planet's rotation relative to other planets?
Or the lack of a moon's disruption to the gravitational field allows small currents in the mantle to grow uninterrupted resulting in the effect I first mentioned?
Or could the slowdown be a countdown to another resurfacing event?
I borrowed the space shuttle Atlantis from the visitor complex at Cape Kennedy and deployed an orbital sun screen to darken Venus express. That is why the stars and the space ship are visible in the same photo. Ivan borrowed the Бура́н prototype from the Technik Museum. He followed behind Venus Express with a big lamp so the back of the communications dish is not completely black.
We're dropping a big chunk of metal on them, after all...
More seriously, kudos to ESA. They designed it so well that it lasted a lot longer than the original mission length and it continued to tell us about Venus. Here's hoping they send another one to continue the good work, at higher resolutions and for even longer and I'd say the ESA team has earned a day off, with beer.
On a more speculative note, wouldn't it be better to send a very radiation-hardened long-lifespan high-orbiting satellite to Venus whose only job would be to relay signals from the various (I can dream) orbiters & landers doing Venus studies. Such a satellite would mean that the others wouldn't have to worry about sending their data themselves, just a short, and hopefully high-bandwidth, signal to the relay and then a very secure, very high-bandwidth signal back to Earth. The laser signalling technology they've started testing for high-bandwidth satellite communications would be good for this...
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