Listening to Syzygy from a garden in France

This morning – Bertrand Pinel, a keen amateur radio-astronomer who’s shared his work with us before – was awake to listen to Phobos making is Syzygy occultation of Mars Express.

Bertrand Pinel's 3.5m backyard antenna. Image credit: B. Pinel

Bertrand Pinel’s 3.5m backyard antenna. Image credit: B. Pinel

At 01:11 UT (03:11 CEST), Mars Express was occulted by tiny Phobos, a roughly potato-shaped body measuring 27 km across its longest axis and 18 km across its shortest.

Bertrand (the same gentleman who gave us the Phobos sound recording) captured the drop in signal (as Phobos blocked the direct line of sight between MEX and Earth) using his own radio dish antenna in his garden in France. Some screen shots are included below from his signal processing equipment – you can see the gap and the times of occultation.

MEX-Phobos occultation Credit: Bertrand Pinel

MEX-Phobos occultation Credit: Bertrand Pinel

Thanks, Bertrand, for sharing!

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Mars Express, Phobos and the occult … ation

Today’s post contributed by Michael Khan, a mission analyst at ESOC and an avid amateur astronomer – Ed.

Imagine you’re playing Scrabble. The tiles on your rack don’t look as if there is much you could do with them. No vowels. Three ‘Y’s, a ‘Z’, and a ‘G’. Oh no! You might as well pass and exchange all tiles for new ones, Right?

You think you're good at online Scrabble? Well, I just put "syzygy" on the board - see if you can beat that! Credit: E. Yourdon CC BY-NC-SA

You think you’re good at online Scrabble? Well, I just put “syzygy” on the board – see if you can beat that! Credit: E. Yourdon CC BY-NC-SA

Wrong! (Don’t quit yet!)

Just look for a letter ‘S’ somewhere on the game board and you can append five of your tiles to spell the word SYZYGY (preferably such that it covers a triple word score). Thus you get rid of the ‘Z’ and the ‘Y’s and you earn heaps of points. There will be complaints around the table, but you can relax and let them complain: You really cleaned their clocks with this one. You win!

In astronomy, a syzygy defines a situation where at least three bodies are aligned. Eclipses, such as the 15 April lunar eclipse, are a perfect example of a syzygy in action.

Via Flickr E. Yourdon

In spacecraft operations, syzygies abound, and our Mars Express is no exception. Often, they are regarded as an unavoidable nuisance. When the spacecraft passes through the shadow of Mars and has to run on batteries, that is a syzygy of Mars Express, Mars and the Sun. When MEX is occulted by Mars and communications are interrupted, that is a syzygy of MEX, Mars and the Earth.

Other syzygies, however, offer real science opportunities. Stellar occultations by bodies in the Solar System have led to very important scientific discoveries.

To name but a few:

Fabulous view of Mars 15 May 2014

Today’s post contributed by Michael Khan at ESOC. UPDATED 8.04 – corrected date for Mars & Spica to 17.07, and fixed several minor typos  – Ed.

Once again, it’s opposition time. While the Earth requires one year1 to complete a full revolution, a Mars year, due to the planet’s wider orbit, lasts 687 days. As Earth and Mars are plying their separate orbits with different speeds, the distance between each varies considerably with time. But once in a period of just over two years, they are aligned in what astronomers call an opposition. On that date, seen from Earth, Mars is located almost exactly in the direction opposite from the Sun, so stargazers can see the Red Planet high in the sky at midnight, and closer and brighter than at any other time.

Earth-Mars distance

The distance from Earth to Mars during the years 2000 to 2019

Because the Mars orbit is eccentric (i.e., it is elongated rather than circular), not all oppositions are equal. Many of you will remember the one in the autumn of 2003, when Mars approached Earth to as close as 56 million kilometres. It appeared like a surprisingly bright red star. In 2014, opposition will take place on 8 April, but again because of the eccentricity of the orbits, closest approach will in fact be a few days later, on 14 April. The distance from the Blue to the Red Planet will then be 92 million kilometres – two-thirds more distant than in 2003, so Mars will appear only a third as bright as it did 11 years ago.

Admittedly, observing Mars in the night sky is a lot less spectacular than it was, and it will again be, as soon as the year 2018. But still, you should have a look. It’s impossible to miss, all the more so because right now it is close to the star Spica in Virgo; Spica is special, because it is in fact not one, but two stars – and big ones at that – that are orbiting a common centre of mass at very close quarters. Spica is interesting, it’s massive, it’s bright… and it’s blue! So you currently have the brilliant blue Spica and the brilliant red Mars both in approximately the same direction in the sky.

Surely you don’t need any more coaxing than that to get you to do some stargazing  – or do you? All right then… let’s see which celestial bodies Mars will encounter in the course of the year. (Of course, we are talking about apparent encounters only, where the bodies involved appear to be separated by only a small angle. In terms of actual spatial distance, the distances will still be ‘astronomical’, with the exception of comet C/2013 A1 Siding Spring, which will buzz Mars on 19 October 2014. But as avid readers of our blog, you already know that).

Here is a list of star parties to which Mars has been invited this year. You are welcome to join – no need to feel like a gate crasher. All these events will be easily visible to the human eye. Using a pair of binoculars or a telescope is optional, but not mandatory.

On 14 April, the full Moon encounters Mars and Spica

On 14 April, the full Moon encounters Mars and Spica

This is an easy one for starters. And what’s more, it happens on the day, 14 April, when Mars is closest to the Earth. Directly in the south around midnight (all times in the star charts below are given in GMT) the full Moon will intrude between Mars and Spica.

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Comet Siding Spring flyby cancelled?

In the closing weeks of March, astronomers worldwide were surprised to see a sudden increase in brightness for comet C/2013 A1 (Siding Spring). At the same time, try as they might, it was not possible to detect even the remnant of a nucleus in the rapidly expanding cloud of dust that had replace the previously still very small tail.

Is this a comet breaking apart? Credit: NASA, ESA, H. Weaver (APL/JHU), M. Mutchler and Z. Levay (STScI)

Is this a comet breaking apart? Credit: NASA, ESA, H. Weaver (APL/JHU), M. Mutchler and Z. Levay (STScI)

At the same time, the control team in Baikonistan reported that contact was lost with the Uranus-bound international spacecraft Behemoth, the first truly global attempt to explore our Solar System.

Aptly named, this spacecraft was launched three years ago, and – with a mass over 100 tons – is easily the largest (not to mention most expensive) space probe ever built. One moment it was still transmitting, the next moment it wasn’t.

All efforts to re-establish contact with Behemoth have, alas, turned out to be fruitless. However, astronomers and engineers mapping the paths in space of the vessel and comet Siding Spring believe the trajectories may have intersected at a fateful point still far beyond Mars orbit. We may never know – but the laws of probabilities lead us to conclude that Siding Spring’s sudden brightening and the equally sudden silence of Behemoth are not unrelated.

However, every cloud has a silver lining, as the saying goes. Astronomers have informed the Mars Express control team that due to the apparent disintegration of comet C/2013 A1 (Siding Spring), its potentially dramatic encounter with Mars on 19 October 2014 is therefore called off and all preparations for the event can cease, as no preventive measures will now be required. In fact, the MEX team have all headed off to the pub for a jolly celebration…

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