As I noted a couple of weeks prior to this article (see: Space Sunday: 3D printed rockets; pi for a planet and solar cycles), our Sun is now entering its 25th (in terms of when formal record-keeping began) cycle of activity. Over the next few years it will become increasingly active with sun spot, flares and their associated events, reaching a peak in about 2025/26, before things once again start to settle down in the second half of this 11-year cycle.
Such events have the potential to interfere with modern life on Earth, particularly in disruption electronic and electrical systems, and present a very real radiation threat to astronauts. Fortunately, however, the Sun is mild-aged and so even its wilder outbursts are not now as bad as they could be, and a number of factors have to line up in order for them to directly affect us on this planet (as happened with the Carrington Event of 1859). Which is not to say we’re entirely safe: the Sun could decide to throw a particularly violent tantrum when Earth happens to be in (for us) the wrong place.
Solar activity is important, as it offers insight for the potential for life forming on other worlds. Take M-class red dwarf stars, for example. They are the most populous class of star in the galaxy, and many have been found to harbour planets (the TRAPPIST-1 system being the most famous) some of which occupying the so-called habitable zone around these stars that should make them good candidates for harbouring life.
It has been known for some time that solar flares can impact the atmospheres of exoplanets, as shown in this ESA video. The new study shows they can do much more
However, such is their size, M-class stars can host solar eruptions that can be 10,000 times more violent that the “average” solar event (flare + coronal mass ejection, or CME) experienced by the Sun and because of the convective nature of such small stars, they are more the norm than the exception. As the normal light / heat output from these stars a much lower than the Sun’s, any planets around them must orbit correspondingly close to the star than is the case within our own solar system. This means that they are potentially more prone to being impacted by these massive super flares, up to and including physically ripping away their atmospheres over time, raising the question as to just how this might affect their surface conditions and habitability for life as we know it.
A study of almost 30 of these M-dwarf stars just published in the Astrophysical Journal reveals that overall such super flares extremely limit the potential for anything but the hardiest micro-organism – although their presence early in a star’s life could actually initially help give life on a planet a helping kick-start,
The study used two sources to study the flaring of some 27 M-dwarf stars: NASA’s TESS “planet hunter” satellite, and the Evryscope Telescope array located at the Cerro Tololo Inter-American Observatory in Chile and operated UNC-Chapel Hill, North Carolina, USA. Both the telescope array and TESS were tasked with observing the candidate stars at the same time, allowing any flare activity on them to be simultaneously recorded.
As a super flare – which could last up to 15 minutes – occurred, measurements were taken every 2 minutes, generating a temperature profile for the flare from start to finish. This revealed a strong, if complicated, correlation between the overall temperature output of a super flare and the amount of deadly ultra-violet radiation it contained. In turn, this allowed the team to conclude that it is extremely likely that planets in close proximity to these stars will receive so much UV radiation, they are unlikely to support the survival all but the hardiest of micro-organism.
The report also notes that in particular, such super flares would likely quickly wreck any protective ozone layer that may form within a planet’s atmosphere, further limiting the development of life – but that conversely, they may initially be required to help impact ozone formation, in order to allow sufficient radiation to reach the surface of a planet in order to power pre-biotic chemistry that in turn may kick-start living processes.
The team behind the study point out that their data is a relatively fine sampling thus far, and more work is needed. They also note that the super flares captured in the study can be classified as “classic” – an event rising to single peak in terms of radiation, temperature, and outburst in a similar manner to our own solar flares – and “complex”: a solar flare that essentially “pulses” with multiple peaks of energy. The cause of these “complex” super flares is unknown, although they appear to be in the majority based on the sample recorded. The fact that they “pulse” with output means that their physical impact on planetary atmospheres is also liable to more complicated than a direct cause / effect correlation seen with “classic” flares.
Even so, the findings open up a new avenue of study for understanding the potential habitability of exoplanets close to M-dwarf stars, and the result have already tended to correlate a 2018 study that suggests the planet found orbiting our nearest stellar neighbour, Proxima Centauri is unlikely to be life-bearing due to it being impacted by similar super flares.
Spaceflight Round-Up
Crew-1 Delayed
The first operational flight of the SpaceX Crew Dragon to the International space Station has been delayed.
The flight, which will carry a crew of four – NASA astronauts Shannon Walker, Victor Glover and Mike Hopkins, and JAXA astronaut Soichi Noguchi – to the ISS, had been scheduled to lift-off from Kennedy Space Centre on October 31st. However, on October 10th, NASA announced the flight will be held over until at least mid-November.
No formal reason for the delay has been given; however the scrubbing of a Falcon 9 launch just 2 seconds before lift-off is being seen as a possible cause. That launch, on October 2nd, of a GPS 3 satellite, was aborted due to what Elon Musk, SpaceX CEO described as an “unexpected pressure rise in the turbomachinery gas generator.” It has yet to be rescheduled.
The first stage units of both that rocket and the one for the Crew-1 flight have never previously flown, so some have theorised the delay to Crew-1 is to give time for SpaceX to evaluate the problem and ensure it is not something endemic to newer Falcon 9 boosters. Certainly, the GPS 3 launch scrub didn’t prevent SpaceX from launching a further batch of its Starlink Internet satellites using a previously-flown Falcon 9 first stage.
Inara Pey: Living in a Modemworld 