Space Sunday: conjunctions, radio signals and budgets

Jupiter (bottom and brighter) and Saturn as seen between the sails of the post windmill at Brill, Buckinghamshire, UK. Credit: Jim Dyson / Getty Images

Monday, December 21st, the winter solstice, saw Jupiter and Saturn reach their closest point of mutual approach to one another when viewed in our evening skies, in what is referred to as a great conjunction.

I covered the event in some detail in my previous Space Sunday report, noting that 2020 would see the two planets appear to come with 6 arc minutes of one another as they lay low over the south-western horizon in last light following sunset.

Caught via a camera with telephoto lens is Jupiter (l) with the Galilean moons also visible (from top left: Calisto, Io, Europa, and furtherest out, lower right, Ganymede). Saturn, to the right, appears as a distinct oval due to its ring system not being sufficiently resolved by the camera lens. Credit: Peter Jay / Getty Images.

Unfortunately, British weather being what it tends to be, I didn’t get to see things on the night thanks to cloud and rain.  To add insult to injury, the skies were clear just 40 km away, allowing friends to witness the event on the night, while the rain and cloud continued here most of the rest of the week, preventing me from getting a further look at the two planets as they dropped ever closer to the horizon. Ho hum.

Not of this Earth: Jupiter and Saturn with rings visible, as seen on December 21st from lunar orbit in an image captured by NASA’s Lunar Reconnaissance Orbiter. Credit: NASA

Fortunately, however, many around the world did have clear skies and captured the event using cameras equipped with telephoto lenses or attached to telescopes. I’ve included a handful of my favourites shots here.

The event was also captured on film by Jason De Freitas, who captured the space between Jupiter and Saturn being neatly “cut” by the passage of the International Space Station.

ET Probably Isn’t Radioing Us

A radio signal detected in a part of the sky that neatly aligns with our closest stellar neighbour,  Proxima Centauri, is unlikely to be of extra-terrestrial origin.

The radio burst was detected in  April-May 2019 by the Parkes Radio Telescope in  Australia, one of two radio telescopes used by the Breakthrough Listen project, which since 2015 has been listening to the one million closest stars to our own in an attempt to pick up artificial radio signals that might indicate extraterrestrial intelligence.

The primary 64-metre radio telescope dish of the Parke observatory, New South Wales. Credit: John Sarkissian

At the time the signal was detected, the telescope was engaged in radio observations of Proxima Cantauri, some 4.2 light years away, and a star known to have two planets orbiting it, one of which – Proxima b – is a rocky world about 1.7 times the size of Earth that sits within the star’s  habitable zone.

Parkes wasn’t listening for radio signals at the time they were picked up, but was engaged in radio observations of flare activity from the star. However, when detected, the signal was immediately intriguing due to its relatively narrow frequency – 982.002Mhz – which ruled out it being caused by known natural phenomena. In order to verify it, the Breakthrough Listen team received permission to “nod” the telescope dish.

This is a common technique used to verify radio signals that involves deliberately swinging the receiving dish away from a signal for a period of time, and then back towards it in order to see if it can be re-acquired (indicating it is not an artefact of the telescope itself), and to measure whether the signal has moved relative to the dish (which would indicate the source is likely in Earth’s orbit). In this case, the signal was reacquired, with measurements suggesting it could be emanating from Proxima b.

When news of the signal, and the on-going analysis to try to determine it’s likely point of origin / cause, was anonymously leaked recently, it was picked up by a number of media outlets and caused something of a stir. However, before ET Hunters get too excited, there are a number of additional facts to consider.

Firstly, it is devoid of any modulation – and so is likely devoid of any meaningful data, were it indeed to by an extra-terrestrial, which makes sending it a little pointless. Secondly, it was entirely transient; following the period of initial detection in April / May 2019, it was “lost”, and has never been re-acquired. Were it a deliberate signal, it would not be unreasonable to expect it to remain fairly constant in terms of detection, either by Parkes or (preferably) other centres around the world.

But the biggest counts against it being ET “‘phoning home” (or at least us), lies with the fact that the signal came from the general direction of Proxima Centauri. As our nearest, and oft-observed stellar neighbour, the star has been under observation for decades, and nary a once have we received anything amounting to an peep out of it that might suggest aliens are playing with radio systems there.

More particularly, however, is the fact that Proxima Centauri is a red dwarf star. As I’ve noted numerous times in these pages, these  M-class stars are prone to exceptionally violent solar flare. Given the close proximity of Proxima b to its star, these flares would likely, at a minimum, be bathed in hard radiation, and at worse, completely rip away the planet’s atmosphere within a period of around 100-200 million years. Therefore, it is highly unlikely the planet really is the point of origin for the signal.

An artist’s impression of Proxima b with Proxima Centauri low on the horizon. The double star above and to the right of it is Alpha Centauri A and B. Credit: ESO

instead, the most likely explanations for the signal are that it might either be something like the carrier wave from a long-forgotten piece of orbital debris of human manufacture or – mostly likely – actually originated on Earth, with conditions in the upper atmosphere serving to “bounce” it into the Parkes Telescope sphere of detection.

The Breakthrough Listen team and their partners certainly lean towards the latter as an explanation, although as noted,  they are still analysing the data gathered on the signal.

This is not a natural phenomenon—I haven’t seen the data, but if it passed BL’s tests then it’s too narrowband to be natural. It’s definitely caused by technology. But it’s almost certainly our own technology.

– Jason Wright, Professor of Astronomy and Astrophysics at Penn State University

But, Radio Emissions May Reveal Exoplanets

Over the last few decades we have discovered thousands of exoplanets and potential exoplanets orbiting other stars. All of them have thus far been discovered using visible light using of two methods: the radial velocity method (aka doppler spectroscopy) and the transit method.

As it’s name suggests, the former uses the doppler effect when observing other stars. If they are moving away from us, then spectroscopy will show the light from them shifted towards the red; if they are moving towards us, then the light from them will be shifted towards the blue. But what if their light keeps moving back and forth between a red and a blue bias? That indicates the star is “wobbling” at it spins – and the mostly likely thing to cause a star to “wobble” is the gravitational influence of one or more planets orbiting it.

The transit method – which has resulted in the discovery of the majority of exoplanets – measures regular fluctuations in a star’s brightness, the result of one or more planets passing between it and Earth, reducing the amount of  light we receive from it.

Bur now we may have a third means of detecting certain types of exoplanet – by using interactions between the star and any magnet field that might exist around a planet orbiting it.

We can see these interactions visibly in the form of aurorae above the polar regions of planets like  Earth and Jupiter, which each have a strong magnetic field. However, what may not be realised is that these interactions also give rise to radio emissions that can travel for light years before they attenuate.

This being the case, an American / French team of astronomers set out to “listen” to three  star systems known to have exoplanets within them – 55 Cancri, Upsilon Andromedae, and, notably, Tau Boötis – to see if they could detect radio signals caused by aurorae events above any of the planets. They did this using the Low-Frequency Array  (LOFAR), a highly-sensitive array of 20,000 small radio antennae clustered in 52 groups across Europe (38 in The Netherlands, with 6 in Germany, three in Poland, with Ireland, the UK, France, Sweden and Latvia having one array apiece, at present – further arrays are to be added across Europe) to listen to the stars and their planets.

Elements of the LOFAR array near Exloo,the Netherlands. Via Wikipedia

The Tau Boötis system, some 51 light years away, was of particular of interest. A binary star system, it is noted for being the home of a “hot Jupiter” gas giant roughly four times the mass of Jupiter, that orbits the larger of the two stars – the F-class Tau Boötis A – once every three terrestrial days. This is close enough for any magnetic field the planet might generate to likely be entangled with the star’s plasma, forming a strong radio source.

When on Tau Boötis A, LOFAR did detect very strong radio emissions – around one million times more powerful than the radio emissions associated with the aurora of Jupiter. Measurements of the degree of polarisation within the emissions demonstrated they were were consistent with the level of polarisation expected of planetary auroral radio emissions, and therefore entirely distinct from any radio emissions emanating from the star.

An artist’s impression of Tau Boötis Ab orbiting its parent star. Credit: ESO/L. Calçada

However, there is a very faint chance the detected emissions might be the result of some  new and complex interaction between the magnetic fields / solar winds of both Tau Boötis A and its much smaller dwarf companion, Tau Boötis B, which orbits the larger star at a distance roughly 7 times greater than that between Neptune and our Sun.  Thus, the team responsible for work are conducting further observations and analysis in order to eliminate this. providing they do, and their work can be independently confirmed, then this work means a further technique for finding exoplanets may have been added to our astronomical tool kit.

NASA to Receive US $23.271 Billion in Fiscal Year 2021 Omnibus Bill

the US Congress has agreed to fund NASA to the tune of US $23.3 billion through the 2021 fiscal year, after both the House and the Senate reached an agreement on the space agency’s budget. The amount is roughly US $2 billion less than NASA had requested, but it is enough to ensure a number of projects the Trump Administration wanted axed will move forward whilst also providing continued funding for the majority of the agency’s core projects.

Key points of the budget include:

  • Full, or above requested, funding for the Space Launch System (SLS), the Orion capsule and their associated Exploration Ground Systems, – all viewed as key elements in NASA’s Project Artemis return to the Moon.
  • One-quarter (US $850 million of $3.3billion) of the development funding requested for the Human Landing System (HLS) – the vehicle(s) that will actually land humans on the Moon and return them to orbit.
  • Continued funding for the Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) and the Climate Absolute Radiance and Refractivity Observatory (CLARREO) Pathfinder Earth science missions, the Nancy Grace Roman Space Telescope (formerly WFIRST), all of which the Trump Administration have been trying to kill over the last four years.
Nancy Grace Roman Space Telescope (formerly WFIRST) will provide astronomers with the most complete view of the cosmos to date. Credit: NASA Goddard Space Flight Centre / CI Lab
  • Continued funding for the Stratospheric Observatory for Infrared Astronomy (SOFIA), and for NASA’s education programmes (that latter of which the Trump Administration has also sought to end).
  • Continued reduced funding for the commercial low Earth orbit development programme, intended to assist commercial entities develop successors to the International Space Station ($17 million of a requested $150 million), and reduced funding for NASA’s space technology programmes ($1.1 billion against a requested $1.6 billion).
  • $156.4 million for “planetary defence programmes” such as the Double Asteroid Redirection Test (DART) and Near Earth Object Surveillance Mission (NEOSM) missions, intended to help identify and protect against asteroids that might impact Earth.

Whilst lower than the request 2021 budget, the Omnibus Bill does see spending on NASA increased by over half a billion compared to 2020. It also directs NASA’s activities in certain areas. Notably, the lion’s share of the $1.1 billion for space technologies is to go towards the development of On-orbit Servicing, Assembly, and Manufacturing 1 (OSAM-1), a robotic spacecraft equipped with the tools, technologies and techniques needed to extend satellites’ lifespans, and the development of nuclear thermal propulsion systems for deep space operations. In addition, the bill instructs NASA to launch the Europa Clipper on the SLS, but only if SLS is available and determined to be a suitable launch carrier for the mission. If not, only then can NASA seek a commercial launch vehicle for the mission.

However, the lack of funding for HLS likely means that any hope NASA had of returning humans to the surface of the Moon by the end of 2024 – always a highly ambitious goal, given the realities of space development – is now well and truly in the waste bin of aspirations.