NASA has high hopes for the moon of Jupiter, Europe, and the American space agency has just punctuated the i’s and crossed the t’s on the spacecraft that will fly there to see if it can really sustain life. Europa Clipper faces a long journey, with Jupiter orbiting the Sun on an elliptical path much more distant than Earth, but what he can find there can make it all worthwhile.
That’s because, unlike what we’ve seen from other planets and moons in the solar system, Europa shows signs of being highly conducive to sustaining life. There is twice as much liquid water there as there is on Earth, for example, mostly than a huge, salty ocean. It is heated by the heating of the tides and is expected to be supplied with minerals from the moon’s rocky construction.
In short, as potential places where life can develop or even thrive, Europa could be a paradise on our doorstep, astronomically speaking anyway. The Europa Clipper project is the way NASA plans to find out for sure, with the agency confirming that the spacecraft has already completed its Critical Design Review. This is the process by which the complete project – including everything from propulsion to scientific instruments and the complex radiation shielding that will be required – is assessed before the final spacecraft is approved for construction to begin.
This design is not simple. Europe can have a lot of water, but it also occupies a particularly treacherous part of space. Radiation levels are high and surface temperatures are low; this means that the Europa Clipper needs to be tough enough to survive these conditions, but also to carry instruments sensitive enough to get the data that NASA and its scientists need.
The plan is apparently straightforward. As soon as it arrives at Jupiter, Europa Clipper will orbit the planet in an elliptical trajectory, always grazing near the moon to take readings. “Science includes collecting measurements of the inland ocean, mapping the surface composition and geology, and searching for plumes of water vapor that may be coming out of the icy crust,” explains NASA.
Although the final design may only have been approved now, the construction of many of the individual components that go into the spacecraft has been underway for some time. That’s because NASA has already given the green light to some of the subsystems and instruments, such as the high-gain antenna that is almost 3 meters wide. This is the huge dish that will be used to communicate with Earth and send back the data that Europa Clipper collects.
Likewise, solar wings – 30 meters long and covering 960 square meters of solar panel surface – are also being built. The Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, is working on the propulsion module, with its 16 rocket engines, and everything will be set up at NASA’s Jet Propulsion Laboratory. There, computer hardware, as well as the armored vault that scientists hope will keep this hardware and other components protected from radiation, are being built.
There will be several different tools on board. Thermal image sensors measure surface temperatures, signs of hot ice and surface roughness; NASA hopes to use this to develop a future probe for Europe. A magnetometer will look at the direction, force and time-varying nature of the magnetic fields around the moon, in addition to measuring the depth and composition of Europa’s ocean.
The Europa Imaging System consists of two visible light cameras – a wide angle and a narrow one – to obtain high-resolution photos of the surface. With a resolution of approximately 20 inches, they will be able to locate evidence of recent or even current geological activities. An ultraviolet spectrograph will do the same with ultraviolet light, while the Mapping Imaging Spectrometer will collect infrared light and be used to detect the distribution of ice, salts and organic products.
A mass spectrometer will collect gases around the moon and discover its composition, while a plasma instrument will track things like ice sheet thickness, ocean depth and ocean salinity. Instruments for measuring surface dust scattered in the nearby space – and potentially water and other particles – will also be on board. Finally, there will be a radar system that can penetrate up to 18 miles into the ice, to try to find out what may be below the surface.
Ironically, in addition to ensuring that Jupiter radiation is not a problem, the Europa Clipper team must also ensure that the instruments it carries are not conflicting, either. “At the moment, we are ensuring that all instruments can operate at the same time without electromagnetic interference,” explains Robert Pappalardo, scientist for the Europa Clipper project at JPL.
By the end of 2021, all components – from instruments to solar panels and rockets – must have arrived at JPL. Starting in 2022, the challenge will be to put them together like a huge and very expensive puzzle. The launch is expected to occur in 2024.