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  • Writer's pictureMatt Russell

#169 Mercury Special

This week we have a Mercury Special, and we also talk about TRUTHS, Cookies in Space, Impact Crater Yarrabubba, and why Turtles are Turtles.

I had rather be Mercury, the smallest among seven planets, revolving round the sun, than the first among five moons revolving round Saturn.

Johann Wolfgang von Goethe


NASA’s Commercial Crew Program News

NASA and SpaceX completed the launch escape demonstration of Crew Dragon and Falcon 9 rocket Sunday. The final major flight test of the spacecraft before it begins carrying astronauts to the International Space Station under.

NASA Administrator Jim Bridenstine. “We are thrilled with the progress NASA’s Commercial Crew Program is making and look forward to the next milestone for Crew Dragon.”

“As far as we can tell thus far, it’s a picture-perfect mission. It went as well as one can possibly expect," said Elon Musk, Chief Engineer at SpaceX. “This is a reflection of the dedication and hard work of the SpaceX and NASA teams to achieve this goal. Obviously, I’m super fired up. This is great.”


UK Space Mission to save the planet!!!

The tellingly monikered TRUTHS is short for Traceable Radiometry Underpinning Terrestrial- and Helio- Studies.

Reported on BBC, and approved for development by ESA with a £27.7m budget, targeting for a launch in 2026 and probable total cost of about £260m

Proposed by the UK, the mission would establish an international system (SI) of measurement traceable space-based climate and calibration observing system to improve confidence in climate-change forecasts – a kind of ‘standards laboratory in space’.

To do this, TRUTHS would carry a hyperspectral imager to provide benchmark measurements of both incoming solar radiation and outgoing reflected radiation with an unprecedented accuracy achieved through a novel on-board calibration system conceived by the National Physical Laboratory the UK's "keeper of standards"

Meeting this week at Harwell the scientists and engineers from Britain, Switzerland, Greece, the Czech Republic and Romania to discuss how to get a cryogenic radiometer and a hyperspectral camera into space to measure and make a detailed map of the sunlight being reflected off Earth's deserts, snowfields, forests and oceans. But the real goal is to do this in such detail and quality that it becomes the benchmark instrument, that all other earth observation satellites can correct errors against. This even applies to data stretching back into the past in the archives.

This refined data will allow us to use the climate fingerprint and as explained by Nigel Fox

"By doing that we'll be able to detect subtle changes much earlier than we can with our current observing system,This will allow us to constrain and test the climate forecast models. So we'll know earlier whether the predicted temperatures that the models are giving us are consistent or not with the observations."

But will it all be too late!!!

ESA News

launched on last August, the second satellite in the European Data Relay System AKA the “SpaceDataHighway” has reached its intended orbit and completed its in-orbit tests. The system uses laser comms technology to enable Earth-observation satellites to speak to users on the ground in near real-time, great if you want to respond quickly to emergency situations, like floods and wildfires. and opens the door to the development of new services.

Cookie News

2 weeks ago splashing down in the ocean aboard the dragon cargo capsule were a bunch of space cookies, baked on the ISS in december by Luca Parmitano, he’s Italian so that kind of makes sense.

A special Zero-G oven was sent to space the month before in November. Zero-G Kitchen is a company founded by a couple, Ian and Jordana Fichtenbaum from new york, whose passion is to get a kitchen in space, so astronauts can have decent grub on their way to the moon and to mars. They have a unique skill set Ian is a Canadian Space businessman who loves Montreal Bagels and book lover Jordana was a Social Media expert for hotels and restaurants. Mix them up in a Kenwood chef and what do you get? A business that can build space station kitchens by leveraging marketing opportunities from foodie business. Helping them with this endeavour is the great company Nanoracks, who helped build the oven, LuigiLab, using their “plug and Play” interface for the ISS. And the space Oven was born.

DoubleTree by Hilton supplied the cookie dough and Parmitano got to work.

Amazingly the first cookie was super undercooked, eventually, Parmitano managed to make a cookie but it took over 2 hours to bake, so what is going on with Zero-G cooking? The cookies were not eaten and remained in the packets, which must have been very cruel for the astronauts, pictures show Koch hanging around salivating at the thought. They are back on earth and will be tested to see if they are even edible and what is going on!!!

Impact Crater

Yarrabubba, In western Australia, lies a crater that is the oldest known impact crater on Earth in a complex granite-greenstone area called Yilgarn Craton It has been known about very recently, in the early 2000s and Aeromagnetic images revealed features at diameters between 11 and 25 km putting the diameter of the fully eroded crater at about 30–70 km (19–43 miles) ie taking out London to the M25.

“Precise radiometric age establishes Yarrabubba, Western Australia, as Earth’s oldest recognised meteorite impact structure,” by a team led by Timmons Erickson of Curtin University of Western Australia analyzed the shock recrystallization neoblasts minerals zircon and monazite found at the site using uranium-lead (U–Pb) dating, which allowed them to pin down the exact age. 2.229 billion years ago, placing the impact at the end of the first period when the Earth was mostly or completely frozen, commonly called snowball earth or the Huronian glaciation.

Erickson said

“The age of the Yarrabubba impact matches the demise of a series of ancient glaciations. After the impact, glacial deposits are absent in the rock record for 400 million years. This twist of fate suggests that the large meteorite impact may have influenced global climate.

“Numerical modelling further supports the connection between the effects of large impacts into ice and global climate change. Calculations indicated that an impact into an ice-covered continent could have sent half a trillion tons of water vapour – an important greenhouse gas – into the atmosphere. This finding raises the question of whether this impact may have tipped the scales enough to end glacial conditions.”

A timely reminder that Global Climate not only has long term and medium-term trends but can be switched on and off with catastrophic asteroid strikes!!!!

From Alex Li,

Turtles nickname for the new/first class of Artemis astronauts. "Astronaut group nicknames are generally selected by the members of the preceding class and very often poke fun at some characteristic that is common to the new trainees. In the case of the "Turtles," that was Hurricane Harvey, which flooded major portions of Houston within a week of the 14 astronaut candidates ("ascans") reporting for their first day on the job at Johnson Space Center on Aug. 21."


Three and a half thousand years ago an Assyrian astronomer was marking into a clay cuneiform tablet observations of a very unusual star or as they called it “The jumping Planet” how mysterious this must have seemed, not at all like the other stars which appeared like an unmoving painting, the whole canvas moving high overhead, this one was moving on the canvas.

A little later, further south the Babylonians similarly obsessing over star catalogues, would call this fast-moving object Nabu, the god of literacy, the rational arts, scribes and wisdom, messenger to the gods. Meanwhile, the Greeks were calling this fast-moving object Stilbon “the gleaming” and later Hermes, while the Romans settled on their equivalent god, the fleet-footed Mercury again the messenger God. The Maya, like the Romans and the Assyrians thought Mercury to be a messenger god, an Owl who communicated with the underworld.

Over in China, as is always the way, they had come up with a more poetic name the Hour Star, in the far east Mercury is often referred to as the Water Star.

Budha graha was the Hindu god who presided over Wednesday as did the germanic god Odin, in what must be a coincidence, both associated with Mercury.

Around about the time of Jesus, legendary genius greek Claudius Ptolomy would realise that maybe Mercury would pass in front of the Sun, a transit, but realised that it would be hard to spot and also a rare event! 1000 years later. In another startling revelation astronomer, Abū Ishāq Ibrāhīm al-Zarqālī in the 11th century described the deferent of Mercury's geocentric orbit as being oval, like an egg or a pine nut, but didn’t follow up!!

Fast forward 600 years and Galileo himself was the first to observe, and record these observations of Mercury, through a telescope. He was unable to see the phases of Mercury, the cresent shape, as it is sooo small. 1631 Pierre Gassendi was the first person to see the transit of Mercury, predicted by Ptolomy and the timing of which predicted by Kepler. 7 years later Giovanni Zupi discovered that the planet indeed had orbital phases similar to Venus conclusively proving that Mercury orbited around the Sun

An even rarer event observed by John Bevis at the Royal Greenwich Observatory was an occultation of mercury by the planet Venus May 28, 1737, this won’t happen again till 2133

Telescopes were improved allowing In the 1880s, Giovanni Schiaparelli to actually map the planet and he suggested that Mercury's rotational period was 88 days, the same as its orbital period due to tidal locking. The maps of mercury by Eugenios Antoniadi were published a book in 1934.

Hard-won knowledge over thousands of years, by dedicated scientists that ushered in the era of modern astronomy.

Incredibly the Russians and the Americans began bouncing radar of Mercury, and Gordon Pettengill and R. Dyce, using the 300-meter Arecibo Observatory radio telescope in Puerto Rico, showed conclusively that the planet's rotational period was about 59 days. This was such a revelation, everyone had bought into the idea that Mercury was tidally locked!! Schiaparelli’s observations were so good! What was the deal, Italian astronomer Giuseppe Colombo noted that 59 is roughly ⅔ of 88, so that Schiaparelli’s good observations were made every second orbit when the viewing was good, so indeed would have seen an unchanging face of Mercury, coincidentally, Mercury's rotation period is almost exactly half of its synodic period with respect to Earth

Mariner 10 confirmed this 3:2 resonance.

Counterintuitelvty A trip to Mercury requires more rocket fuel than that required to escape the Solar System completely. As a result, only two space probes have visited it so far, with a third on the way.

Here’s the problem, imagine being a roller skater on the edge of a giant deep bowl, you are on earth looking down the gravity well of the Sun, you are travelling around the edge of this bowl at the Earths orbital speed, 19miles/s but you got to get your speed up to 30 miles per second to chase down a skater zipping around the inside of the bowl further down the side of the well, This is going to use a huge change in velocity for you, called Delta V, Delta V costs fuel, lots of it, the bloody rocket equation. But worse still as you go down the sides of this very steep bowl to get to the level of the other skater, you are turning your potential energy from being at the top to kenetic energy as you move down, you are just going to wizz past unless again you use your rocket motors and lots of fuel to compensate, and you can’t grab the skaters clothes because Mercury is naked it has no atmosphere, so Aerobraking is out of the question.

The Glory of Mariner 10

The Image Processing Lab at NASA's Jet Propulsion Laboratory produced this photomosaic using computer software and techniques developed for use in processing planetary data. The Mariner 10 spacecraft imaged the region during its initial flyby of the planet. The Mariner 10 spacecraft was launched in 1974. The spacecraft took images of Venus in February 1974 on the way to three encounters with Mercury in March and September 1974 and March 1975. The spacecraft took more than 7,000 images of Mercury, Venus, the Earth and the Moon during its mission.

Launched on November 3rd 1973, Mariner 10 overcame all these difficulties by becoming the first spacecraft to ever use a gravitational slingshot manoeuvre on a planet, essentially stealing energy from the orbit of Venus, Venus left forever going faster around the sun after February 1974 as Mariner 10's velocity around the sun dropped by 10,000 mph to 72,215 mph. This changed the shape of the spacecraft's orbit around the Sun so that the perihelion now coincided with the orbit of Mercury. The spacecraft now flew past Venus 3 times, Owing to the geometry of its orbit – its orbital period was almost exactly twice Mercury's – the same side of Mercury was sunlit each time, so it was only able to map 40–45% of Mercury's surface, taking over 2,800 photos. It revealed a more or less Moon-like surface

Mariner 10 discovered evidence of a tenuous atmosphere consisting primarily of helium with a magnetic field and a large iron-rich core. Reading suggested that Mercury has a nighttime temperature of −183 °C (−297 °F) and maximum daytime temperatures of 187 °C (369 °F).

It ran out of orbital manoeuvering fuel and was switched off in 1975, and presumably orbits the sun to this day, but no one knows. The mission boss was the late Bruce Churchill Murray one time director of JPL and co-founder of The Planetary Society with Carl Sagan and Louis Friedman. Curiosity went across the knobs of Murray Buttes on it’s way to Mount Sharpe.

MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging), was launched on August 3, 2004. It made a fly-by of Earth in August 2005, and of Venus in October 2006 and June 2007 to place it onto the correct trajectory to reach an orbit around Mercury.

A first fly-by of Mercury occurred on January 14, 2008, a second on in October, and a third in September 2009. The probe successfully entered a 12hr elliptical orbit around the planet in March 2011 after a 15-minute velocity changing burn in deep space. Only a small portion of each orbit was at a low altitude 120 miles (perihermion), where the spacecraft was subjected to heating from the hot side of the planet and allowed to cool when it got 9300miles away at aphermion. The probe finished a one-year mapping mission and then entered a one-year extended mission into 2013.

MESSENGER crashed into Mercury's surface on April 30, 2015 leaving a crater estimated to be 16 m in diameter

2008, the MESSENGER team announced that the probe had discovered large amounts of water present in Mercury's exosphere, which was an unexpected finding. In the later years of its mission, MESSENGER also provided visual evidence of past volcanic activity on the surface of Mercury, as well as evidence for a liquid iron planetary core. The probe also constructed the most detailed and accurate maps of Mercury to date, and furthermore discovered carbon-containing organic compounds and water ice inside permanently shadowed craters near the north pole

BepiColombo is a joint mission of the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA) to the planet Mercury. The mission comprises two satellites launched together: the Mercury Planetary Orbiter (MPO) and Mio (Mercury Magnetospheric Orbiter, MMO) with an arrival at Mercury planned for December 2025, after a flyby of Earth, two flybys of Venus, and six flybys of Mercury ...for another show.

Ace Facts about Mercury

  • On average Mercury is the closest planet to earth.

  • Because of the 3:2 semi tidal lock An observer on Mercury would see only one day every two Mercurian years and could walk around the planet in a permanent sunrise or sunset if they liked.

  • It has the smallest axial tilt 1/30 degree

  • It has the most eccentric orbit of any planet (except if you still think Pluto is a planet), remember the pine nuts, and at perihelion is only 66% the distance of aphelion. Earth is 97% for example.

  • This varying distance to the Sun leads to Mercury's surface being flexed by tidal bulges raised by the Sun that are about 17 times stronger than the Moon's on Earth. Combined with a 3:2 spin-orbit resonance of the planet's rotation around its axis, it also results in complex variations of the surface temperature

  • It’s -173 °C at night and 427 °C in the day!!!

  • The poles are always below -93 °C

  • There are no moons!

  • Venus is hotter

  • Mercury is the second-highest after Earth in the Solar System, but if you were to remove the gravitational compression caused by Earths considerable bigger size, then Mercury would be quite a bit denser. So the Core must be very large and rich in iron.

  • Mercury's core occupies about 55% of its volume; for Earth, this proportion is 17%

  • Smallest Planet and even smaller than Ganymede and Titan.

  • More Massive though than Ganymede and Titan.

  • Only a little bit bigger than the moon.

  • The Moon is very similar in appearance with dorsa (also called "wrinkle-ridges"), Moon-like highlands, montes (mountains), planitiae (plains), rupes (escarpments), and valles (valleys)

  • Based on data from the Mariner 10 the crust is estimated to be 22 mi thick, and it looks like Mercury has a molten core

To be more of an average rocky body you would expect it to be 2.25 it’s current mass,

  • onetheory is that is was once a larger planet hit by another planetesimal of approximately 1/6 the mass that stripped the crust and mantle leaving a planet core behind.

  • Another theory was the Sun was just much hotter back when Mercury formed and vapourised forming an atmosphere of "rock vapor" that could have been carried away by the solar wind

  • O maybe and most likely at the moment the solar nebula caused drag on the particles from which Mercury was accreting, which meant that lighter particles were lost from the accreting material and not gathered by Mercury

  • The Messenger results are not favourable for the first two as there are higher-than-expected potassium and sulfur levels on the surface for this

  • BepiColumbo should clear this up.

Names of features

  • Names coming from people are limited to the deceased.

  • Craters are named for artists, musicians, painters, and authors

  • Ridges, or dorsa, are named for scientists who have contributed to the study of Mercury.

  • Depressions or fossae are named for works of architecture.

  • Montes are named for the word "hot" in a variety of languages.

  • Plains or planitiae are named for Mercury in various languages.

  • Escarpments or rupēs are named for ships of scientific expeditions.

  • Valleys or valles are named for abandoned cities, towns, or settlements of antiquity

Mercury's surface is more of a jumbled up mess than either Mars's or the Moon's

  • The sun is about 7 times brighter on Mercury than on Earth

  • Mercury use to have active Volcanoes

  • The icy regions are estimated to contain up to 100 billion tons of ice

  • The craters in the north pole have enough water ice to "encase Washington, D.C., in a frozen block two and a half miles deep" MESSENGER's principal investigator Sean Solomon

  • Despite having a low rotation speed there is a pretty big and very stable magnetic field generated by mercury (1.1% of Earths)

  • Probably caused by molten metal core sloshing around, kept liquid due to eccentric orbital tidal forces

  • The magnetosphere caused can trap the solar wind Plasma, increasing the weathering of the planet

  • Messenger discovered the magnetosphere had leaks in the form of magnetic "tornadoes" – twisted bundles of magnetic fields connecting the planetary magnetic field to interplanetary space – that were up to a third of the radius of the planet. These twisted magnetic flux tubes, technically known as flux transfer events, form windows in the planet's magnetic shield through which the solar wind may enter and directly impact Mercury's surface

  • This is 10 times more than on earth, scientists can work out why

  • Mercury's orbit is inclined by 7 degrees to the plane of Earth's orbit, transits of Mercury can only occur when the planet is crossing the plane at the time it lies between Earth and the Sun, which is in May or November. This occurs about every seven years

  • As the axial tilt is almost zero, the sun never rises more than 2.1 arcminutes above the horizon a hairs width held at arm’s length.

  • At certain points on Mercury's surface, an observer would be able to see the Sun peek up about halfway over the horizon, then reverse and set before rising again, all within the same Mercurian day

  • The hottest points on Mercury happen where the Sun seems to hang in the sky for 3 weeks overhead, although it is going alternatively between retrograde and prograde 3 times.

  • The center of small crater Hun Kal defines the 20° West meridian. A 1970 International Astronomical Union resolution suggests that longitudes be measured positively in the westerly direction on Mercury, The two hottest places on the equator are therefore at longitudes 0°W and 180°W, and the coolest points on the equator are at longitudes 90°W and 270°W. However, the MESSENGER project uses an east-positive convention.

  • Mercury attains inferior conjunction (nearest approach to Earth) every 105-129 Earth days on average. Close as it will get is 51.1 million miles, but in 28622 it could get as close as 50 million miles, stick it in your diary folks and hope it isn’t cloudy that day.

  • Simulations indicate that the orbital eccentricity of Mercury varies chaotically from nearly zero (circular) to more than 0.45 over millions of years due to perturbations from the other planets

  • Numerical simulations show that a future secular orbital resonant perihelion interaction with Jupiter may cause the eccentricity of Mercury's orbit to increase to the point where there is a 1% chance that the planet may collide with Venus within the next five billion years

Mercury and Einstein!!

Urbain Le Verrier was getting worried that a slow rotation of the perihelion point of Mercury's orbit around the Sun could not be completely explained by Newtonian mechanics and perturbations by the known planets.

Under Newtonian physics, a planet orbiting the sun would trace out an ellipse with the centre of mass of the system at a focus. The point of closest approach, the perihelion, is fixed. A number of effects in the Solar System cause the perihelia of planets to precess (rotate) around the Sun. The principal cause is the presence of other planets which perturb one another's orbit and a tiny amount from solar oblateness. Urbain Le Verrier analysed observations of transits of Mercury from 1697 to 1848 and showed that the actual rate of the precession disagreed from that predicted from Newton's theory by 38″ (arc seconds) per tropical century. He suggested, that another planet named Vulcan might exist in an orbit even closer to the Sun than that of Mercury, The success of the search for Neptune based on its perturbations of the orbit of Uranus led astronomers to place faith in this possible explanation, no such planet was ever found

So what gives. It turns out to be one of the best tests of Albert Einstein's general theory of relativity. Einstein's formula for the perihelion shift per revolution gives 42.97 arcseconds per century. This is in close agreement with the accepted value of Mercury's perihelion advance of 42.98 arcseconds per century, there are 532 arcseconds per century from perturbations so the effect is small but nonetheless important.

Observing Mercury

  • Mercury can be a very bright star around mag -2.78 brighter than Sirius but below naked-eye visibility

  • Observation of Mercury is complicated by its proximity to the Sun, as it is lost in the Sun's glare for much of the time. Mercury can be observed for only a brief period during either morning or evening twilight

  • Mercury can, like several other planets and the brightest stars, be seen during a total solar eclipse.[116]

  • Like the Moon and Venus, Mercury exhibits phases as seen from Earth. It is "new" at inferior conjunction and "full" at superior conjunction. The planet is rendered invisible from Earth on both of these occasions because of its being obscured by the Sun, except its new phase during a transit.

  • Mercury is technically brightest as seen from Earth when it is at a full phase. Although Mercury is farthest from Earth when it is full, the greater illuminated area that is visible and the opposition brightness surge more than compensates for the distance. The opposite is true for Venus, which appears brightest when it is a crescent because it is much closer to Earth than when gibbous

  • Mercury is more often and easily visible from the Southern Hemisphere than from the Northern. This is because Mercury's maximum western elongation occurs only during early autumn in the Southern Hemisphere, whereas its greatest eastern elongation happens only during late winter in the Southern Hemisphere

  • An alternate method for viewing Mercury involves observing the planet during daylight hours when conditions are clear, ideally when it is at its greatest elongation

  • The Hubble Space Telescope cannot observe Mercury at all, due to safety procedures that prevent its pointing too close to the Sun

  • Because the shift of 0.15 revolutions in a year makes up a seven-year cycle (0.15 × 7 ≈ 1.0), in the seventh year Mercury follows almost exactly (earlier by 7 days) the sequence of phenomena it showed seven years before

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