Precision D-I-Y.

The one-second window that could make or break mission to Jupiter Experts working on the Juice project reveal the short timeframe its craft has to get into orbit – or it could go wrong By Sarah Knapton, SCIENCE EDITOR

The Juice mission, which is looking for signs of extra-terrestrial life on the Jovian moons Europa, Ganymede and Callisto, has a miniscule one-second window to get into orbit when it launches in April.

The European Space Agency orbiter needs to harness the gravitational forces of Earth, Mars and Venus to slingshot it towards its target, and the planets must align perfectly, or the spacecraft could end up way off course.

In comparison, when the Artemis I mission launched to the Moon last November, it had a leisurely two hours to get off the ground.

Juice, which stands for Jupiter Icy Moons Explorer, is due for launch on April 13 from the European spaceport in Kourou, French Guiana, onboard an Ariane 5 rocket.

Jupiter lies around 391 million miles from Earth, on average, and it will take eight years for the spacecraft to reach its destination.

The system is believed to be one of the best places to look for extraterrestrial life because its ice moons are believed to contain vast icy oceans.

Once there, the orbiter will fly 125 miles above Callisto, observing the oldest moon in the Solar System, before making two flybys of Europa.

Beneath the ice crust of Europa is thought to lie a huge ocean of liquid water or slushy ice, that contains twice as much water as Earth's oceans combined.

Jupiter Icy Moons Explorer Juice space Solar System mission European Space Agency Engineers preparing the spacecraft for the Juice mission CREDIT: Charly Triballeau/AFP via Getty Images This vast and deep body of water is widely considered to be the most promising place to look for life in the Solar System, and instruments on board Juice will be hunting for biosignatures like methane, which could hint that life is thriving beneath the icy surface.

On Earth, extremophile lifeforms have been found thriving near subterranean volcanoes and deep-sea vents, raising hopes that it could also exist in the underground oceans of Jupiter's moons.

After Europa, the mission will spend eight months circling Ganymede, the first time a spacecraft has orbited any moon other than our own.

Ganymede is the only moon in the Solar System known to generate its own magnetic field, so scientists are keen to work out how that is being achieved.

Just like Europa and Callisto, it harbours a hidden ocean, so researchers will also be looking for signs of habitability.

Jupiter Icy Moons Explorer Juice space Solar System mission European Space Agency An artist’s impression of how the Juice spacecraft will orbit Jupiter’s moons CREDIT: Nasa/ESA Hubble Space Telescope The magnetic field surrounding Ganymede has proved challenging to spacecraft engineers who had to construct a lead-lined centre to protect the electronics.

Mr Byrne added: “It has a massive magnetic field, 10,000 times stronger than the Earth, so it’s really the worst place to be putting a spacecraft. If you wanted to kill it, this is what you'd do.”

In all, Juice will make 35 fly-bys of the three moons, before finally carrying out a controlled crash into Ganymede. The team also wants to learn more about Jupiter, in particular why its famous Red Spot is shrinking.

Experts believe that the one-second window is achievable, but are worried that weather could scupper the launch. Too much wind or storms could cause delays and would mean waiting for the next time the planets align.

If the first window is missed there are several more opportunities in April, but after that the team would need to wait until August.

Tim

Well, most missions tend to use gravity assist to get them where they are going. Its not new. I would have said that this is a false quote, in that course corrections en route are nearly always required as the Solar system is not clockwork and indeed the strength of the solar wind over the years will vary and hence corrections are needed. The current Nasa probe Juno had several course corrections, and even now with such large solar panels is purtibated by it as it orbits.

It may be that the ability to have enough fuel for a full mission might be compromised if its off by more than the quoted time, but without more info, its hard to say. Nobody would fund a project if it was expected to revolve around such a small error. If they needed a bigger rocket then I'm sure these exist. Also you would expect the spacecraft cruise stage to have a surplus of fuel. Brian

Otr the journalist got the wrong end of the stick which happens quite a lot.

I doubt NASA would risk the cost of such a project if it relied on a 1 second accuracy for success or failure.

I thought it was a bit odd that the story started by saying "all space travel depends on split second timing" and then went on to say that this mission "had a 1 second window", as though that was tighter than split second ...

The question is why? I mean, unless it was subsidised as a show case, no education authority would go anywhere near that sort of cost. Brian

That is the width of the launch window.

For a couple days in a row, at a certain time of the day, the window for multiple slingshots will open. With minimal fuel burns needed, to tune the slingshots.

If you miss the window, then the satellite does not have the fuel, to correct for the error.

On the James Webb mission, Ariane 5 demonstrated what a precise puppy it could be. So I can see why they're doing this. On James Webb, Ariane had to put the vehicle in just the right orbital path, and then it took very little fuel by Webb, to complete the trip to Lagrange.

Now, this is a different kind of mission, and they provided the satellite with a piss-weak engine. The ion engine on this thing, ran for a total of 5.9 years. And you can see the spiffy lane changes it did. But that adds a lot of weight to the satellite, to pack enough Xenon to run an engine for 5.9 years. The launch window for a satellite with a piss-weak engine like this, could be a lot wider. If you leave the engine running long enough, you can make quite large corrections.

It launches today at 12:30, streamed live on iPlayer. If it misses today's 1 second window, then it tries again tomorrow, and the day after, etc.

ALL THESE WORLDS ARE YOURS – EXCEPT EUROPA. ATTEMPT NO LANDING THERE.

It's funny, I was looking at the viewing figures (under 200k) and remembering another Clarke quote, in response to the comment "Earth is decadent"

"Oh no, we're not decadent. But our children will be"

(Ghost from the Grand Banks, and I'm quoting from memory).

Andy

Seems it got away on day 2. Can't figure out how it only has a 1 second window, yet this 1 second window repeats every day for a fortnight? Surely the rest of the solar system just ploughs on, regardless of earth's rotational speed?

it's a /different/ 1 second?

One second seems a bit tight, but it's prolly to do with the number of slingshots they need to do to reach Jupiter. It's what happens when you use a sixpenny rocket instead of a shilling one.

I v much doubt they are 1 second windows in the sense that the mission fails if launched outside them. I could never cope with the maths of mission design but I suspect it's more that the fuel required for the mission /to/ Jupiter increases rapidly if an optimum launch time is missed and they want to keep as much fuel as possible for manoeuvres after it gets there.

Whatever the detail of the 1 second window, at least the Juice project managed to squeeze its way through the window yesterday (Sorry!).