October 30, 2018 Zimmerman/Batchelor podcast
Embedded below the fold, in two parts.
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Year: 2018
Penny Dreadful
An evening pause: Ideal for Halloween.
Hat tip Jim Mallamace.
The vast northern plains of Mars
Cool image time! Actually, this image, found in the October image release from the high resolution camera of Mars Reconnaissance Orbiter (MRO), is not that interesting, in its own right. Context is all!
The image on the right is a small section cropped and reduced in resolution from the full image, which you can see by clicking on it. It shows one of the only interesting features in this long image strip, a small mesa sticking out all by itself in a flat featureless plain pockmarked by various small craters.
The release has no caption, though it is entitled “Northern Plains Survey.” The northern plains, while having a lot of interesting features that attract the attention of planetary scientists and thus get photographed at high resolution, is mostly featureless, at least at the resolution of the wide field survey cameras on many Mars orbiters. In order to know what is really there, they need to take high resolution images systematically, of which this image is obviously a part.
The problem is that there is so much ground to cover. This particular image was taken of a spot in the middle of the plains just to the north of the drainage outlets from Valles Marineris, as shown by the context map to the right. The tiny white spot to the right in the middle of the blue plains north of those drainage outlets is the location of this image.
To understand how much ground needs to be covered, to the right is a close-up of the area shown by the white box in the first image above, with red rectangles indicating where MRO has already taken images. The white cross is the subject image. As you can see, most of this immense plain has not yet been imaged. It is almost as if they threw a dart to pick this one location. Most everything around it remains unseen at high resolution. Thus, to understand the geology of this one image is hampered because the surrounding terrain remains unknown, in close detail.
Mars is a big place. It is an entire planet, with the same land surface as the Earth’s continents. It still contains many mysteries and unexplored places. It will take generations to see it all.
Early Milky Way collision uncovered by Gaia
Data from the space telescope Gaia has revealed a Milky Way merger event that occurred about 10 billion years ago.
Using the first 22 months of observations, a team of astronomers led by Amina Helmi, University of Groningen, The Netherlands, looked at seven million stars – those for which the full 3D positions and velocities are available – and found that some 30,000 of them were part of an ‘odd collection’ moving through the Milky Way. The observed stars in particular are currently passing by our solar neighbourhood.
We are so deeply embedded in this collection that its stars surround us almost completely, and so can be seen across most of the sky.
Even though they are interspersed with other stars, the stars in the collection stood out in the Gaia data because they all move along elongated trajectories in the opposite direction to the majority of the Galaxy’s other hundred billion stars, including the Sun. They also stood out in the so-called Hertzprung-Russell diagram – which is used to compare the colour and brightness of stars – indicating that they belong to a clearly distinct stellar population.
The sheer number of odd-moving stars involved intrigued Amina and her colleagues, who suspected they might have something to do with the Milky Way’s formation history and set to work to understand their origins. In the past, Amina and her research group had used computer simulations to study what happens to stars when two large galaxies merge. When she compared those to the Gaia data, the simulated results matched the observations. “The collection of stars we found with Gaia has all the properties of what you would expect from the debris of a galactic merger,” says Amina, lead author of the paper published today in Nature.
At the time, the two galaxies were both probably about the same size, approximately equivalent to the Magellanic Clouds.
Must I mention that there is some uncertainty here? The data is good, and the conclusions seem quite reasonable. At the same time, the data is still somewhat thin. We need a lot more Gaia-type telescopes mapping out the motions and positions of all the stars of the Milky Way in far more detail before the uncertainties here will shrink.
Timelapse movie of Supernova 1987A’s evolution from 1992 to 2017
Cool movie time! An astronomy graduate student in Toronto has created a movie showing the steady evolution of the shock wave from Supernova 1987A, the first supernova visible to the naked eye since the discovery of the telescope, during the past twenty-five years.
Yvette Cendes, a graduate student with the University of Toronto and the Leiden Observatory, has created a time-lapse showing the aftermath of the supernova over a 25-year period, from 1992 to 2017. The images show the shockwave expanding outward and slamming into debris that ringed the original star before its demise.
In an accompanying paper, published in the Astrophysical Journal on October 31st, Cendes and her colleagues add to the evidence that the expanding remnant is shaped—not like a ring like those of Saturn’s—but like a donut, a form known as a torus. They also confirm that the shockwave has now picked up some one thousand kilometres per second in speed. The acceleration has occurred because the expanding torus has punched through the ring of debris.
The animation, which I have embedded below the fold, uses images produced by an array radio telescopes in Australia.
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Oblique view of Hayabusa-2’s most recent landing rehearsal
Cool movie time! The Hayabusa-2 science team has released a small movie of images taken by a side-mounted camera of the spacecraft’s most recent landing rehearsal, showing the spacecraft ascend from its closest approach from an oblique angle.
I have embedded the movie from these images below the fold. As they note,
Images taken with the small monitor camera (CAM-H) during the Touchdown 1 Rehearsal 3 operation (TD1-R3). One image was captured every second from immediately after the spacecraft began to ascend (altitude 21m) on October 25, 2018 at 11:47 JST. The spacecraft was rising at about 52cm/s.
It appears the closest image was taken from about 21 meters away, about 65 feet, and gives a sense of scale. It also reveals once again how difficult that landing in January is going to be. Though this location is thought to be the smoothest spot on Ryugu, it is still littered with rocks that could cause problems.
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Shake-up in SpaceX’s Starlink satellite division
Capitalism in space: It appears that Elon Musk has done a major shake-up in SpaceX’s Starlink satellite division, firing a number of managers because he was unsatisfied with the slow pace of development.
The management shakeup followed in-fighting over pressure from Musk to speed up satellite testing schedules, one of the sources said. SpaceX’s Behrend offered no comment on the matter.
Culture was also a challenge for recent hires, a second source said. A number of the managers had been hired from nearby technology giant Microsoft, where workers were more accustomed to longer development schedules than Musk’s famously short deadlines. Another senior manager that left SpaceX was Kim Schulze, who was previously a development manager at Microsoft, one of the people said. Schulze did not respond to a request for comment.
“Rajeev wanted three more iterations of test satellites,” one of the sources said. “Elon thinks we can do the job with cheaper and simpler satellites, sooner.”
A billionaire and Chief Executive Officer of Tesla Inc, Musk is known for ambitious projects ranging from auto electrification and rocket-building to high-speed transit tunnels.
Musk’s desire for speed here actually makes very good economic sense. There are other companies developing similar internet satellite constellations, and if SpaceX’s launches late they will likely lose a significant market share.
His concern about the slow pace seems to me also justified. This technology, while cutting edge, shouldn’t require as much testing and prototype work as it appears the fired managers wanted. Better to get something working and launched and making money, introducing upgrades as you go, as SpaceX has done so successfully with its Falcon 9 rocket.
NASA decides to continue to ping Opportunity
NASA has decided to continue through January its effort to both listen and send signals to Opportunity in the hope of bringing it to life.
The 45-day deadline passed late last week. But NASA will continue active listening — a strategy that involves both sending commands to Opportunity and listening for any peeps the six-wheeled robot may make — for several more months at least, agency officials announced yesterday. “After a review of the progress of the listening campaign, NASA will continue its current strategy for attempting to make contact with the Opportunity rover for the foreseeable future,” NASA officials wrote in a mission update yesterday. “Winds could increase in the next few months at Opportunity’s location on Mars, resulting in dust being blown off the rover’s solar panels,” they added. “The agency will reassess the situation in the January 2019 time frame.”
This is exactly what the planetary scientists wanted. Their hope is that, with the beginning of dust devil season in November, the chances will then increase for removing the dust that likely covers the rover’s solar panels. It is thought that the rover has a better shot at coming back to life during this time period.
Hawaii Supreme Court rules in favor of TMT
Hawaii’s Supreme Court today upheld by a 4-1 vote the construction permits of the consortium building the Thirty Meter Telescope (TMT) on Mauna Kea.
In its own press release, the TMT consortium said that it “will move forward with fulfilling the numerous conditions and requirements of [the state’s permit] prior to the start of any construction.”
The comments by one of the the telescope’s opponents at the first link are revealing.
Kealoha Pisciotta, one of the main leaders against the telescope, said she’s doesn’t know what their next steps will be, but she’s not hopeful that more legal wrangling will help. “The court is the last bastion in democracy,” she said. “The only other option is to take to the streets. If we lose the integrity of the court, then you’re losing normal law and order, and the only other option is people have to rise up.” [emphasis mine]
Let me translate: We didn’t get our way, so we’re now going to throw another tantrum! Expect more protests and attempts to block construction. Expect the Hawaiian government, dominated almost entirely by Democrats, to fold to those protests. Expect more delays. For example, do you really think the permit process was really done?
State Department of Land and Natural Resources Chairwoman Suzanne Case said the next steps involve telescope builders submitting construction plans. The department will review the plans before issuing permission to proceed.
This was all done almost a decade earlier, and was exactly what the Supreme Court ruled on. To bring it up now suggests the state government is still quietly looking for loopholes to stop the construction, even though the public supports construction and the protesters are a decided minority.
Samuel Taylor Coleridge – Kubla Khan
An evening pause: Read by Tom O’Bedlam. Listen close, and you will understand why this poem came after a dream induced by taking opium. Most fitting, the day before Halloween.
Hat tip Jim Mallamace.
NASA officially retires Kepler
NASA today officially retired Kepler after nine years of operations.
After nine years in deep space collecting data that indicate our sky to be filled with billions of hidden planets – more planets even than stars – NASA’s Kepler space telescope has run out of fuel needed for further science operations. NASA has decided to retire the spacecraft within its current, safe orbit, away from Earth. Kepler leaves a legacy of more than 2,600 planet discoveries from outside our solar system, many of which could be promising places for life.
Exoplanet hunting however does not end here. Unlike Hubble, astronomers and NASA planned ahead for Kepler’s demise, and this year launched TESS to continue its work, in an even more sophisticated manner.
The steep slumping wall of a Martian volcano caldera
Cool image time. The Mars Reconnaissance Orbiter science team today released a nice captioned image of the steep wall of the caldera of Ascraeus Mons, the northernmost of the three giant volcanoes that lie to the east of Olympus Mons, the biggest volcano of all. The image on the right, reduced and cropped, shows that steep wall, with full image available by clicking on it. The caption from the release focuses on the fluted upper parts of the wall.
We can see chutes carved into the soft dust that has built up on the slope, with some similarities to gully landforms elsewhere on the planet.
More revealing to me is how this image reveals the slumping that is slowing eroding the caldera’s walls while also making that caldera larger. First, the plateau above the cliff shows multiple small cliffs and pit chains, all more or less parallel to the wall. This suggests that the plateau is over time breaking apart and falling into that caldera. Think of it as an avalanche in slow motion, with the upper plateau separating into chunks as sections slowly tilt down toward eventual collapse. As these chunks separate, they cause cracks to form in that plateau, and hence the parallel cliffs and strings of pits.
On the floor of the caldera we can see evidence of past chunks that did fall, piled up in a series terraces at the base of the wall. These are covered with the soft dust that dominates Martian geology. That soft dust also apparently comprises much of the wall’s materials, and almost acts like a liquid as it periodically flows down the wall, producing the chutes at the top of the wall.
The weak Martian gravity here is an important factor that we on Earth have difficulty understanding. It allows for a much steeper terrain, that also allows structurally weaker materials to hold together that would be impossible on Earth.This image gives a taste of this alien geology, on a large scale.