At 04:03 UTC on Monday, February 10th (23:03 EDT, USA), the European Space Agency’s Solar Orbiter is due to be launched atop a United Launch Alliance Atlas V from Cape Canaveral Air Force Station, Florida. Referred to as SolO, the mission is intended to perform detailed measurements of the inner heliosphere and nascent solar wind, and perform close observations of the polar regions of the Sun, which is difficult to do from Earth, in order to gain a much deeper understanding of the processes at work within and around the Sun that create the heliosphere and which give rise to space weather.
The launch will mark the start of a three 3-year journey that will use a fly-by of Earth and three of Venus to use their gravities to help shift the satellite into a polar orbit around the Sun. Once there, and at an average distance of some 41.6 million km, SolO will move at the same speed at which the Sun’s atmosphere rotates, allowing it to study specific regions of the solar atmosphere beyond the reach of NASA’s Parker Solar Probe and Earth observatories for long periods of time.
Our understanding of space weather, its origin on the Sun, and its progression and threat to Earth, comes with critical gaps; the hope is by studying the the polar regions of the Sun’s heliosphere, scientists hope they can fill in some of these gaps. The outflow of this plasma interacts with the Earth’s magnetic field and can have a range of potential effects, including overloading transformers and causing power cuts, disrupting communications and can potentially damage satellites. Further, the disruption of the Earth’s magnetic fields can affect the ability of whales and some species of bird to navigate.
We don’t fully understand how space weather originates on the sun. In fact, events on the sun are very hard to predict right now, though they are observable after the fact. We can’t predict them with the accuracy that we really need. We hope that the connections that we’ll be making with Solar Orbiter will lay more of the groundwork needed to build a system that is able to predict space weather accurately.
– Jim Raines, an associate research scientist in climate and
space sciences engineering
Specific questions scientists hope SolO will help answer include:
- How and where do the solar wind plasma and magnetic field originate in the corona?
- How do solar transients drive heliospheric variability?
- How do solar eruptions produce energetic particle radiation that fills the heliosphere?
- How does the solar dynamo work and drive connections between the Sun and the heliosphere?
To do this, the satellite is equipped with a suite of 10 instruments, some of which will be used to track active solar regions that might explode into a coronal mass ejections (CMEs), a major driver of space weather. When a CME occurs, SolO will be able to track it and use other instruments to be able to break down the composition of the energetic outflow (and that of the outflowing solar wind in general).
Knowing the composition of this outflow should help determine where energy is being deposited and fed into the solar wind from eruptions on the Sun, and how particles are accelerated in the heliosphere – the bubble of space where the Sun is the dominant influence, protecting us from galactic cosmic radiation.
Combined with the work of the Parker Solar Probe, launched in August 2018 (see: Space Sunday: to touch the face of the Sun) and which gathers data from within the Sun’s corona, and observations from Earth-based observatories such as the Daniel K. Inouye Solar Telescope (DKIST), Solar Orbiter’s data should dramatically increase our understanding of the processes at work within and around the Sun.
Like the Parker Solar Probe, SolO will operate so close to the Sun it requires special protection – in this case a solar shield that will face temperatures averaging 5,000º C on one side, while keeping the vehicle and its equipment a cool 50º C less than a metre away on the other side. This shield is a complex “sandwich” starting with a Sun-facing series of titanium foil layers designed to reflect as much heat away from the craft as possible. Closest to the vehicle is a aluminium “radiator” that is designed to regulate the heat generated by the craft and its instruments. Between the two is a 25-cm gap containing a series of titanium “stars” connecting them into a single whole. This gap creates a heat convection flow, with the heat absorbed by the titanium layers venting through it, drawing the heat from the radiator with it, allowing Solar Orbiter to both expect excess solar heating and present itself from overheating.
SolO’s primary mission is due to last 7 years, and those wishing to see the launch can watch it livestreamed across a number of platforms, including You Tube.