Here’s looking at you, Saturn: global project will study auroras

We still haven’t seen Saturn’s auroras in all of their forms. Every time we look, we see something new. Hopefully, in addition to knowing what is happening, we can now begin to understand more about why these phenomena are taking place.
Dr Tom Stallard
An international team of planetary scientists organised by academics at the University of Leicester is ready to launch a month-long observational campaign to learn more about the northern and southern lights of another planet. The project, which is the largest-ever observation of its kind, will employ European Space Agency (ESA), European Southern Observatory (ESO) and NASA instrumentation in order to make detailed observations of Saturn’s auroras.

The team will utilise both space- and ground-based telescopes to make observations of Saturn’s auroras from a variety of wavelengths and viewpoints. The researchers are confident that this multilateral approach will provide the most comprehensive dataset ever collected in relation to the phenomenon.

To find out more about this ambitious undertaking, I spoke to participating scientist Dr Tom Stallard, Lecturer at the University of Leciester’s Department of Physics and Astronomy. Dr Stallard, who will lead the ground-based observations from NASA’s InfraRed Telescope Facility (IRTF) in Hawaii, believes that having so many eyes trained on Saturn simultaneously will uncover a wealth of new information about extraterrestrial auroras.

"Planetary scientists around the world have made some really interesting discoveries about Saturn, especially during the last decade," he said. "Essentially, we want to tie this knowledge together. The difficulty has always been that Saturn’s auroras are very dynamic – they are constantly changing. We are still trying to understand all of the different aspects that these auroras possess. They take on lots of different morphologies and it can be difficult to fully encapsulate exactly what is going on. Consequently, relating all of the different pieces of information to one another has posed a significant challenge in the past, because we haven’t all been looking at the same time.

"By making lots of different observations at roughly the same time, we hope to learn more about Saturn’s magnetic field, what its auroras look like and how they affect the planet’s atmosphere," Dr Stallard continued. "We still haven’t seen Saturn’s auroras in all of their forms. Every time we look, we see something new. Hopefully, in addition to knowing what is happening, we can now begin to understand more about why these phenomena are taking place."

Whilst this project offers clear opportunities to learn more about Saturn’s northern and southern lights, the researchers believe that their results could also provide new insights into Earth-based auroras.

Drawing analogies

Auroral formation on Saturn
The above image shows auroral formation on Saturn
Credit: Jonathan Nichols, NASA, ESA and the University of Leicester
"Previous studies of extraterrestrial auroras have demonstrated that although many of their features differ to those of Earth, the underlying physics is basically identical," explained Dr Stallard. "The types of effect that are observable on Earth, Jupiter and Saturn, are all – to some extent – analogous. For instance, a couple of years ago, I found a weak auroral feature on Saturn that looked very similar to one that had previously been observed on Jupiter. Jupiter has a volcanic moon called Io that strongly drives the planet’s auroras. Saturn’s auroras have similar features, but without the same driving force, they are much weaker. Likewise, Earth – luckily – doesn’t have a volcanic moon, so these effects are also much weaker here than they are on Jupiter.

"By conducting such a comprehensive study of Saturn’s auroras, we increase our chances of identifying effects that are present on Earth but which haven’t yet been observed because they are too weak," he continued. "Often, when planetary scientists study Earth-based phenomena, they do so in great detail. They use a lot of spacecraft and they collect large quantities of information. However, this can make it hard to see the big picture. When you compare multiple datasets collected at distinct locations, it is possible to gain a much broader perspective than one obtained through the study of a single object."

During the course of their study, the researchers will make use of the Hubble Space Telescope (HST), the Saturn-orbiting spacecraft Cassini, the Very Large Telescope (VLT), the W M Keck Observatory and the IRTF. As Dr Stallard explained, it is extremely difficult to make so many instruments look in the same direction at exactly the same time.

"We have done our very best to synchronise all of the telescopes, but to do so exactly is almost impossible," he said. "One of the biggest planning challenges that we have encountered is connected with the Hubble Space Telescope. The problem with Hubble is that it is very close to Earth: it is so close that it is being constantly slowed by our planet’s atmosphere. The satellite’s orbit is in a state of continuous degradation, which means that to keep it in its orbit, it has to be pushed outwards every few weeks. This means that it is very difficult to predict the orbit in which the satellite will find itself more than a few weeks in advance.

"At the same time, the observations that we will be making using the ground-based telescopes had to be planned six months to a year in advance," Dr Stallard explained. "Planning differences such as these make it impossible to achieve total synchronicity. Even so, through a lot of hard work and persistence, we believe that we have come as close as possible to getting all of the instruments to observe Saturn’s auroras at the same time."

Once the observations have been carried out, the team will begin to collate the findings of each instrument. At this stage, the academics will be able to compare data on Saturn’s auroral events obtained from a multitude of angles. The pooling of resources offers a variety of benefits – both economic and qualitative – across the entire spectrum of scientific research. Of course, coordination on such a large scale also involves extensive preparation. Even so, the scientists participating in this observational campaign hope that by joining forces, they will learn more about how Saturn’s auroras are formed and the way in which energy flows from the planet’s solar wind and magnetic field into its ionosphere and atmosphere.

Power in numbers

Dr Stallard is optimistic that the hard work that he and his colleagues have invested into organising their month-long observation will pay off. I ended our conversation by asking whether he believes that multilateral strategies represent the future of planetary science research.

"It is definitely an approach that is being considered more and more," he said. "The real problem is connected with how difficult it can be to tie multiple observations together. I’ve been conducting support observations with Cassini for a decade now, so I have quite a lot of experience in this area. Our upcoming project began with just one telescope – the IRTF – but over time, we have been building towards this observational crescendo. It has been very difficult and it has required the involvement of many scientists, so we’re all really hoping that everything goes to plan.

"Similar collaborations have been successful in the past, but these have typically taken place in conjunction with other important missions," Dr Stallard concluded. "It can be very difficult, but I think it’s really important to get these projects to work. The potential rewards are definitely worth the time that it takes to get them off the ground. The same can be said of plenty of other areas within planetary science. It’s just a matter of bringing people together in a way that enables each participant to do the work that they want to do."

The month-long campaign will begin on 19th April 2013. Observations will be live streamed through the W M Keck Observatory website, and a podcast featuring Dr Stallard is available via SoundCloud.



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