Category: Points of Information

Very brief descriptions, with appropriate links, of current or recent news items.

SpaceX offers to buy all nearby property to Boca Chica launchsite

9:46 am

SpaceX has made a purchase offer to all the remaining property owners living in close proximity to its Boca Chica launchsite.

The company has sent a letter to all the owners, stating that the company is

…committed to a fair and equitable process for acquiring this real estate” and, to that end, the company hired an independent firm to appraise each property. … SpaceX is offering you three times the independently appraised fair market value of your property. The offer is good through two weeks from the date of this letter.”

It appears from the article at the link that a number of landowners are unwilling to accept this offer. It appears they to want more money, and also do not like the hard-nosed language of SpaceX’s offer.

Since there are not very many landowners, I would not be surprised if they team-up and get their own negotiating team.

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Scientists propose mission to interstellar comet Borisov

9:31 am

In a paper published on the Cornell arXIiv site for preprint science papers, scientists have posted a paper proposing sending an unmanned probe to the newly discovered interstellar Comet Borisov, arriving in 2045.

You can download the paper here. [pdf]

Their analysis found that we just missed the ideal and most efficient launch date using the Falcon Heavy. If it had launched in July 2018 a two-ton spacecraft could have reached Comet Borisov by next month.

The best alternative option is a launch in January 2030, flying past Jupiter, then the Sun, and arriving in 2045. Because of the mission’s close approach to the Sun to gain speed, the mission would require the type of shielding developed for the Parker Solar Probe. If the Space Launch System was used for launch, a six-ton spacecraft could be sent. With other available rockets the largest possible payload would be 3 kilograms (about 6 pounds), making the probe a cubesat. As they note,

Despite this very low mass, a CubeSat-scale spacecraft could be sent to the interstellar object. Existing interplanetary CubeSats (Mars Cube One) show that there is no principle obstacle against using such a small spacecraft to deep space.

In fact, having a decade and a half before launch guarantees that a cubesat will be able to do this job, because by 2030 the technology for using smallsats for this kind of planetary mission should be fully developed.

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The never-ending snowstorm circling Saturn

10:21 am

New data suggests that the water being spewed out of Enceladus’s tiger stripes is depositing so much snow and ice on Saturn’s three inner moons, Mimas, Enceladus and Tethys, that these moons, as well as Enceladus, are about twice as bright in radar than previously thought.

Dr Le Gall and a team of researchers from France and the US have analysed 60 radar observations of Saturn’s inner moons, drawing from the full database of observations taken by the Cassini mission between 2004 and 2017. They found that previous reporting on these observations had underestimated the radar brightness by a factor of two.

Unprotected by any atmospheres, Saturn’s inner moons are bombarded by grains of various origins which alter their surface composition and texture. Cassini radar observations can help assess these effects by giving insights into the purity of the satellites’ water ice.

The extreme radar brightness is most likely related to the geysers that pump water from Enceladus’s internal ocean into the region in which the three moons orbit. Ultra-clean water ice particles fall back onto Enceladus itself and precipitate as snow on the other moons’ surfaces.

Dr Le Gall, of LATMOS-UVSQ, Paris, explained: “The super-bright radar signals that we observe require a snow cover that is at least a few tens of centimetres thick. However, the composition alone cannot explain the extremely bright levels recorded. Radar waves can penetrate transparent ice down to few meters and therefore have more opportunities to bounce off buried structures. The sub-surfaces of Saturn’s inner moons must contain highly efficient retro-reflectors that preferentially backscatter radar waves towards their source.”

While the new results suggest that the surfaces of these moons are much brighter that expected, I find the circumstances they describe far more fascinating: a never-ending snow storm in the orbits around Saturn and landing continually on these moons.

My, isn’t the universe wonderful?

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Io volcano erupts like Ol’ Faithful

10:09 am

Having determined that Io’s largest volcano appears to erupt on a regularly schedule, scientists have predicted that a new eruption should occur sometime in the next week or so.

The volcano Loki is expected to erupt in mid-September, 2019, according to a poster by Planetary Science Institute Senior Scientist Julie Rathbun presented today.

“Loki is the largest and most powerful volcano on Io, so bright in the infrared that we can detect it using telescopes on the Earth,” Rathbun said. Based on more than 20 years of observations, Loki undergoes periodic brightenings when it erupts on a relatively regular schedule. In the 1990s, that schedule was approximately every 540 days. It currently appears to be approximately every 475 days. Rathbun discovered the 540-day periodicity, described in her 2002 paper “L. Loki, Io: A periodic volcano” that appeared in Geophysical Research Letters.

These same scientists successfully predicted Loki’s last eruption based on this data, but also warn that there is no guarantee the volcano will do what they say. As stock brokers are required to say, past performance is no guarantee of future results.

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New data cuts neutrino mass in half

9:54 am

The uncertainty of science: New data now suggests that the highest mass possible for the neutrino is about half the previous estimates.

At the 2019 Topics in Astroparticle and Underground Physics conference in Toyama, Japan, leaders from the KATRIN experiment reported Sept. 13 that the estimated range for the rest mass of the neutrino is no larger than about 1 electron volt, or eV. These inaugural results obtained earlier this year by the Karlsruhe Tritium Neutrino experiment — or KATRIN — cut the mass range for the neutrino by more than half by lowering the upper limit of the neutrino’s mass from 2 eV to about 1 eV. The lower limit for the neutrino mass, 0.02 eV, was set by previous experiments by other groups.

This lower limit does not tell us what the neutrino actually weighs, only reduces the uncertainty of the range of possible masses.

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New theory says evaporating exomoon explains Tabby’s Star

9:47 am

Astronomers have proposed a new theory for the random and inexplicable light variations that Tabby’s Star undergoes, a melting and evaporating exomoon.

The Columbia team suggests that Tabby’s Star abducted an exomoon from a now long-gone, nearby planet and pulled it into orbit around itself, where it has been getting torn apart by stronger stellar radiation than existed in its former orbit. Chunks of the exomoon’s dusty outer layers of ice, gas, and carbonaceous rock have been able to withstand the radiation blow-out pressure that ejects smaller-grain dust clouds, and the volatile, large-grain material has inherited the exomoon’s new orbit around Tabby’s Star, where it forms a disk that persistently blocks the star’s light. The opaqueness of the disk can change slowly, as smaller-grain clouds pass through and larger particles stuck in orbit move from the disk toward Tabby’s Star, eventually getting so hot that they melt and fall onto the star’s surface.

Ultimately, after millions of years, the exomoon orbiting Tabby’s Star will completely evaporate, the researchers suggest.

The article does not explain why the theory requires this exoplanet to have once been a moon to another exoplanet, now gone. It seems to me that this is adding unnecessary complexity to the solution, but I have not read the paper itself, so their might be reasons.

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Stony-iron asteroid caused flash on Jupiter in August

11:26 am

According to an analysis of the data obtained from the light flash that occurred when an object hit Jupiter on August 7, scientists have estimated its probably make-up, mass, and size.

They estimate from the energy released by the flash that the impactor could have been an object around 12-16 metres in diameter and with a mass of about 450 tons that disintegrated in the upper atmosphere at an altitude of about 80 kilometres above Jupiter’s clouds. Sankar and Palotai’s models of the light-curve for the flash suggest the impactor had a density typical of stony-iron meteors, indicating that it was a small asteroid rather than a comet.

Their conclusions are strengthened because they were able to compare this flash with five other similar but not as bright flashes, all detected since 2010.

These recent detections, all by amateurs, are because of the higher quality equipment now available to ordinary people, including the use of computers and remote operation. This technology is making it possible for amateurs to discover things that once only professionals could find.

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Hayabusa-2 dropping orbiting target marker

8:54 am

In preparation for the release and landing of Hayabusa-2’s second MINERVA-II2 tiny rover/bouncer, the spacecraft today began a close-approach to the asteroid Ryugu, where it will release two target markers.

Once released, Hayabusa-2 will back off to observe these markers as they spiral down into Ryugu, landing sometime around September 23.

This operation is a rehearsal for the release and landing of MINERVA-II2, which like the first two bouncers back in September 2018 will bounce along the asteroid’s surface, taking pictures and gathering data.

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Update on effort to save heat probe on InSight

8:38 am

Link here. The article, written in late August by one of the German scientists in charge of the heat probe on the Mars lander InSight, gives a detailed look at the effort to figure out what is blocking the Mole, the digging tool designed to pound the heat probe as much as 15 feet into the ground.

They had discovered previously is that the ground had collapsed around the drill shaft, creating a very wide hole. The Mole however needed the friction caused by the surrounding dirt to push downward, and thus didn’t have it.

They have since used InSight’s scoop at the end of the robot arm to push at the ground around the hole in an effort to fill the hole. As of mid-August this has managed to fill the hole about half way.

This report was written on August 27, just before contact with Mars was lost for two weeks because the Sun had moved between the Earth and Mars. Communications have now resumed, so I expect they will also resume their efforts to fill the hole enough that they might then try to resume the digging effort.

Hat tip to Doug Messier of Parabolic Arc, who by the way is right now running his annual fund-raising drive for the website. Please consider donating.

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UAE’s first manned flight launches this week on Soyuz

8:51 am

This article provides a nice detailed Arab perspective on the upcoming September 25 launch of the United Arab Emirates’ (UAE) first manned mission, sending one of their jet fighter pilots on a Soyuz to ISS for about a week.

The article not only also reviews the entire history of past Arab astronaut missions in space, the first on an American shuttle in 1985 and the second on a Soyuz in 1987, it summarizes the present-day space-related efforts throughout the Arab world, not just in the UAE. Good information in advance of this week’s upcoming launch.

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