All posts by Tom

A Square Corner

Did you ever notice just about every crater is at least a little rounded, some a bit elongated sure but rounded and most are just plain circular. Well “square” corners do occur and while they can be fodder for conspiracy theories, there are perfectly reasonable explanations for their formation.

The lunar crater above (NASA/GSFC/Arizona State University) is a good example. The name of the crater is Lavoisier, named for the famous French Chemist Antoine Lavoisier.

The crater is about 70 km across (42 miles), pretty large and can be seen with even a small telescope – yhe image width is only about 10 percent of the entire crater. The thing about Lavoisier is the location, Longitude: 81.253° West, Latitude: 38.169° North puts it on the northwestern limb so you need something steady to see it well. Yes binoculars would work but not for a decent examination. Plus the moon probably needs to be pretty well full. I will definitely have a look in a couple of weeks.

So how do we get to the squared off corners? Here’s what the LRO / NASA website had to say:

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Sentinel 3B Launching Today

Launching later today (if all goes well of course) from the Plesetsk Cosmodrome in Russia is ESA’s Sentinel 3B. Coverage begins at 17:30 UT / 14:30 ET.

ESA’s caption: The Copernicus Sentinel-3B rocket at the top of the launch tower. The Copernicus Sentinel-3B satellite is scheduled for liftoff on 25 April 2018 from the Plesetsk cosmodrome in northern Russia. Its identical twin, Sentinel-3A, has been in orbit since February 2016. The two-satellite constellation offers optimum global coverage and data delivery for Europe’s Copernicus environment programme.

Image: ESA–S. Corvaja

BepiColumbo Plasma Sim

BepiColumbo is going to use electric propulsion thrusters to create an ion beam to travel to Mercury.  What sci-fi fan cannot love that?

Wow, science fiction comes to life again.  BepiColumbo is going to be a great mission!

Here’s the caption with the animation links intact from ESA:

When the Mercury Transfer Module of the BepiColombo mission fires its electric propulsion thrusters an ion beam is extracted. This is created through the ionization of xenon propellant, generating the charged particles that can be accelerated further using an electric field.

Together with gravity assist flybys at Earth, Venus and Mercury, the thrust from the ion beam provides the means to travel to the innermost planet.

After escaping the pull of Earth’s gravity with the Ariane 5 launcher, the spacecraft is on an orbit around the Sun. The transfer module then has to use its thrusters to brake against the mighty pull of the Sun’s gravity. It also has to tune the shape of its orbit in order to make a series of nine gravity assist flybys at the planets before finally delivering the mission’s two science spacecraft into Mercury orbit.

This image is an excerpt from a supercomputer simulation that models the flow of plasma around the spacecraft just after the high energy ion beam is switched on. An outline of the composite spacecraft with its extended solar arrays is included for reference.

The simulation tracks the particles in the beam as well as those that diffuse around the spacecraft, which are created by the interaction of the high energy beam ions with the neutral xenon atoms that also flow out of the thruster.  It shows the density of the plasma flowing around the spacecraft and its evolution: red represents high density, blue is low density (see animation for detailed scale).

Although the animation is several seconds long it has been slowed down, representing a mere eight milliseconds of real time – the time necessary for the plasma to reach a steady state.

The simulation was performed to demonstrate that the plasma produced by the thruster is not damaging to the spacecraft: its materials, including solar arrays or instruments, for example, or to the electric propulsion system itself. The simulations also confirmed there are no spurious or dangerous charging events.

Inflight measurements will verify the simulation results and help improve ways in which the generated plasma, spacecraft and space environment interactions can be better modelled.

BepiColombo is a joint endeavour between ESA and JAXA. After their seven-year interplanetary journey, the two science orbiters – the Mercury Planetary Orbiter and the Mercury Magnetospheric Orbiter – will start their main mission to provide the most in-depth study of mysterious Mercury to date.

The spacecraft begin transferring to Europe’s spaceport in Kourou this week, where an intensive period of preparations will ready the mission for launch later this year.

The simulations were performed by Félicien Filleul as part of ESA’s Young Graduate Trainee programme.

Copyright:   ESA/Félicien Filleul

 

 

The Great Red Spot

Beautiful work! Check this and other great submissions to the JunoCam site, not to mention the original images from Juno for anybody who wants to try their hands at processing.

Original caption:

This image of Jupiter’s iconic Great Red Spot and surrounding turbulent zones was captured by NASA’s Juno spacecraft.

The color-enhanced image is a combination of three separate images taken on April 1 between 3:09 a.m. PDT (6:09 a.m. EDT) and 3:24 a.m. PDT (6:24 a.m. EDT), as Juno performed its 12th close flyby of Jupiter. At the time the images were taken, the spacecraft was 15,379 miles (24,749 kilometers) to 30,633 miles (49,299 kilometers) from the tops of the clouds of the planet at a southern latitude spanning 43.2 to 62.1 degrees.

Citizen scientists Gerald Eichstädt and Seán Doran processed this image using data from the JunoCam imager.

JunoCam’s raw images are available at www.missionjuno.swri.edu/junocam for the public to peruse and process into image products.

Image credit and a hearty well-done to: NASA/JPL-Caltech/SwRI/MSSS/Gerald Eichstadt/Sean Doran

VividX2 Makes History

The VividX2 makes history as the world’s first commercial satellite able to provide full-colour video of life on Earth.

It is capable of taking ultra-high definition images of any location on Earth and can take two minutes of video at the same time.

The satellite is only about the size of a typical cloths-washing machine (a cubic meter) and weighs just 100 kg.

See more at www.earthi.space

Four Years of NEOWISE

Impressive four years of NEOWISE operation:

Asteroids detected or observed 29,000
Near Earth Objects: 788

About the video (NASA): The orbits of Mercury, Venus and Mars are shown in blue. Earth’s orbit is in teal.

Green dots represent near-Earth objects. Gray dots represent all other asteroids which are mainly in the main asteroid belt between Mars and Jupiter. Yellow squares represent comets.

Upcoming this week:

22 April 2018: Earth Day

25 April 2018 (Wednesday): ESA’s Sentinel 3B Satellite launches atop a Russian Rokot. I believe launch time is 17:57 UTC.

Also Mercury is heading towards maximum Western elongation (29 April @ 27 degrees), we might get a look at it just before sun up in the Eastern sky. If you do go looking for Mercury as always be very-very careful. The Sun isn’t far away and you could be badly injured if you look at the sun, especially if you are using any magnifying devices.

Waiting For Gaia

Every now and then you will read my lamenting how we need better distance measurements. You might think we know the distances to distant stars, after all we reference distances. The trouble is those measures are only accurate in the broadest sense – we really do need more accuracy.

Gaia aims to change all that! ESA just posted this excellent overview of the Gaia mission.

28 Years of Hubble

I like the Lagoon Nebula, I can see it from here when it is visible and it does make a nice telescope target. My best looks are usually from August, due south, not too late (22:00 on) and warm weather.

Click the image for a larger view here and the links from NASA’s Image of the Day caption from yesterday contains more links to both the image and about Hubble. 28 years, I feel old (lol) – what a great machine Hubble is! Congratulations to the Hubble team both current and past for a mission that started out a bit rocky but ended up being an icon. The team’s resilience and dedication to the project seems to get lost sometimes but without them the mission never would have never amounted to anything near what it has, so my hat is off to you folks!

From the NASA’s Image of the Day (yesterday):

This colorful image, taken by the Hubble Space Telescope, celebrates the Earth-orbiting observatory’s 28th anniversary of viewing the heavens, giving us a window seat to the universe’s extraordinary stellar tapestry of birth and destruction. At the center of this image is a monster young star 200,000 times brighter than our Sun that is blasting powerful ultraviolet radiation and hurricane-like stellar winds, carving out a fantasy landscape of ridges, cavities, and mountains of gas and dust.

This mayhem is all happening at the heart of the Lagoon Nebula, a vast stellar nursery located 4,000 light-years away, visible in binoculars as merely a smudge of light with a bright core.

The giant star, called Herschel 36, is bursting out of its natal cocoon of material, unleashing blistering radiation and torrential stellar winds, which are streams of subatomic particles, that push dust away in curtain-like sheets. This action resembles the Sun bursting through the clouds at the end of an afternoon thunderstorm.

Herschel 36’s violent activity has blasted holes in the bubble-shaped cloud, allowing astronomers to study this action-packed stellar breeding ground. The hefty star is 32 times more massive and 40,000 times hotter than our Sun, and is nearly nine times our Sun’s diameter. Herschel 36 is still very active because it is young by a star’s standards, only 1 million years old. Based on its mass, it will live for another 5 million years. In comparison, our smaller Sun is 5 billion years old and will live another 5 billion years.

The image shows a region of the nebula measuring about 4 light-years across.

Image Credit: NASA, ESA, and STScI

SENTINEL-3B – Deja Vu?

If you have a feeling of deja vu at the Sentinel-3B above don’t worry this is a twin. The first was launched in 2016 and this one is scheduled to be launched on 25 April 2018.

This great image is from ESA – S. Corvaja.

ESA’s caption — The Copernicus Sentinel-3B satellite being mated with the Rockot adapter at the Plesetsk Cosmodrome in northern Russia.

The satellite is being prepared for liftoff, scheduled for 25 April 2018. Its identical twin, Sentinel-3A, has been in orbit since February 2016. The two-satellite constellation offers optimum global coverage and data delivery for Europe’s Copernicus environment programme.