Tag: engineering

New data says going to Mars involves significant radiation exposure

9:18 am

New data from Trace Gas Orbiter, part of Europe’s ExoMars project, says a journey to Mars will expose humans to significant radiation.

The results imply that on a six-month journey to the Red Planet, and assuming six-months back again, an astronaut could be exposed to at least 60% of the total radiation dose limit recommended for their entire career.

The ExoMars data, which is in good agreement with data from Mars Science Laboratory’s cruise to Mars in 2011–2012 and with other particle detectors currently in space – taking into account the different solar conditions – will be used to verify radiation environment models and assessments of the radiation risk to the crewmembers of future exploration missions.

This data was gathered during the spacecraft’s journey to Mars during a time of falling solar activity. Thus, the radiation exposure came more from cosmic rays than from solar activity.

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A Martian shoreline?

11:52 am

Collapsing cliff in Tempe Fossae

Cool image time! The image on the right, reduced and cropped to post here, was part of the August 31 image release from the high resolution camera of Mars Reconnaissance Orbiter (MRO). (Click on the image to see the full image.) It shows a slowly separating cliff feature in a region dubbed Tempe Fossae

As part of that monthly mass release, no caption was provided for this image. However, we can gain some understanding by looking at the larger context.

Tempe Fossae is located at the margins between the low flat northern plains and the high southern highlands. The location is also part of the vast drainage region to the east of Mars’ gigantic volcanoes. This is obvious from the overview image below and on the right. The location of this image is indicated by the white cross.

Mars overview

In this area of that drainage the canyons appear to follow southwest to northeast trending fault lines. Tempe Fossae is one of the smaller of these canyon complexes. All however appear to drain out into the northern plains.

Most of the MRO images of features in this area focus on the canyon cliffs. This image however focused on this one isolated small cliff in the middle of the canyon. To my eye it appears that these features document the slow drying of that vast intermittent ocean in Mars’s northern plains. The cliff is actually two steps, with the higher one appearing to mark an older shoreline. The lower cliff is abutted by a low flat area where it appears as if there had once been ponded water, now dried.

close-up of cracked area

The cracks in the cliff itself suggest it is slowly breaking apart and falling down towards that low flat area. In fact, the entire feature reminds me of the sand cliffs that are sometimes found along shorelines. The sand is not very strong structurally, and with time sections will separate and then fall down. The image to the right zooms in on this cracked region. The presence of sand dunes reinforces my impression.

I imagine that as the water drained down from the glaciers on the sides of the volcanoes and filled that intermittent sea, the shoreline regions would have had the most water. At Tempe Fossae the canyons might have been partly filled. As the water level drained out and lowered, first the upper cliff edge was exposed, then the lower. The draining water probably helped created these cracks as it flowed down through them.

Finally, the last remaining pits of water ponded at the base of the cliff, eventually drying out. With time, the weakly structured sand cliffs, already carved partly by the flowing water, began to slump apart and fall downward, producing the cracks we now see. I expect that some time in the near future, on geological time scales, there will be a landslide and the outer section will collapse downward.

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Vulcan found?

9:51 am

Scientists have found a super-earth orbiting 40 Eridani-A, a star located sixteen light years away and proposed by Gene Roddenberry in 1991 as the home star for his race of logical Vulcans.

It turns out the letter authors’ prediction was right — a world really does orbit the primary star of the three-star 40 Eridani system. (Whether it’s home to a logic-based alien society, though, is anyone’s guess!)

The world is a super-Earth, the most common type of planet in the galaxy (though a type that’s missing from our solar system). At twice Earth’s radius and eight to nine times its mass, 40 Eridani b sits on the line that divides rocky super-Earths from gaseous ones. The planet orbits its star every 42 days, putting just inside the system’s habitable zone — in other words, where it’s nice and hot. At 16 light-years away, it’s the closest super-Earth known and therefore a good potential target for followup observations.

The discovery was made by a survey taking place using a relatively small telescope right here in the Tucson area, on top of Mount Lemmon. Most cool!

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Instrument on GRACE-FO fails

9:45 am

The U.S/German science two-satellite constellation, launched in May, has not gathered any science data since July because one instrument on one satellite has shut down.

It appears the problem is related to an electrical problem. The article provides little information, though they say they will switch to a back up system later this month. I wonder why this has taken so long.

The article at the link calls this “a glitch.” That is a lie and bad journalism. Any failure that shuts down a spacecraft for months and requires the use of a back up is a major failure, not a mere “glitch.” I wish news organizations would stop using that word, as it only exists to help minimize the seriousness of a problem.

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Curiosity fails again to drill into Vera Rubin Ridge

9:13 am

For the third time Curiosity has failed to drill into the rock on top of Vera Rubin Ridge.

Last night we learned that our drill attempt on “Inverness” was not successful, reaching only 4 mm into the rock.

The only successful drill attempt on the ridge occurred when they moved down off the top of the ridge to a slightly lower geological layer.

They are moving Curiosity to another candidate drill site on the ridge, where they will try again. While they imply in their reports that it is solely the hardness of the ground that is stopping them, I still wonder if the improvised drill technique, using the robot arm to push down rather than the drill’s jammed feed mechanism, is partly to blame. I would think that they have placed limits on how hard the arm can push to protect it.

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SpaceX’s first BFR passenger is Yusaku Maezawa, owner of Japanese fashion company

7:28 pm

Yusaku Maezawa

Capitalsm in space: SpaceX’s first BFR passenger will be Yusaku Maezawa, the owner of Japanese fashion company, shown on the right.

Maezawa began his statement by echoing John Kennedy with these words, “I choose to go to the Moon.” He purchased the entire first flight, and will invite six to eight artists to join him on the flight and ask them to create art afterward inspired by the flight. They are aiming for a launch in 2023.

BFR

Musk began the presentation tonight with an overview of the status of BFR, noting that they plan unmanned test launches before putting humans on the rocket. The image an the right shows the habitable upper stage.

During the question and answer session after the announcement Musk was asked questions about the present stage of BFR design, and whether it has been finalized. He said they plan “a lot of test flights” and are aiming for first orbital flights in 2 to 3 years, “if things go really well.”

Musk made it clear that Maezawa chose SpaceX for the flight, rather than the other way around. Musk also said that Maezawa was paying them a lot of money for the flight, though they were not going to reveal the amount. Musk did note that the price was not trivial, and that Maezawa has already made a significant deposit. Maezawa had first approached them for a Dragon/Falcon Heavy flight, but because of the limitations of of those spacecraft, they decided it better to go with the bigger rocket.

Musk noted that the first test hops of the upper stage to test its landing capabilities will take place at Boca Chica in Texas. The launch site for the orbital missions is not yet decided.

Musk estimated that the cost for developing BFR is going to probably be around $5 billion, which he also noted rightly is quite small for this kind of project. He also said that right now they are only devoting 5% of SpaceX’s resources to this mission. As they complete the crew Dragon project, they will then begin to shift resources to BFR. He estimated that will happen sometime late next year.

Overall, it strikes me that they really do not have all the details yet worked out, with the rocket or their flight schedule. As Musk openly admitted when asked if they are sure about the schedule, “We are definitely not sure.” This is not necessarily a bad thing, since it is often better to keep an open-mind in planning something this ambitious. At the same time it tells us not to expect any of this to happen, as described.

One final point: Musk at one point said he wants a base on the Moon. “It’s 2018, why don’t we have a base on the Moon?” To me, this was an almost direct dig at NASA’s Gateway/FLOP-G project, which isn’t a base but locks us in lunar orbit. Musk was being very careful to avoid criticizing NASA, his biggest customer, but anyone who knows what is going on will quickly recognize that BFR is in direct competition with SLS/Orion/Gateway.

Based on SpaceX’s history, going from first orbit flight to flying the world’s largest rocket in only ten years, I am very confident that this company could get that first base on the Moon, long before NASA even gets Gateway launched.

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Cryo-volcanism had less influence on shaping Ceres than predicted

10:23 am

The uncertainty of science: A careful analysis of the Dawn data has found that though cryo-volcanism has occurred repeatedly on Ceres, it had less influence on the dwarf planet’s surface than previous models had predicted.

At the same time, the data also suggests that Ceres has been more active throughout its history than predicted. They found about 22 domes that are apparently past cryo-volcanoes that have flattened out.

“Given how small Ceres is, and how quickly it cooled off after its formation, it would be exciting to identify only one or two possible cryovolcanoes on the surface. To identify a large population of features that may be cryovolcanoes would suggest a long history of volcanism extending up to nearly the present day, which is tremendously exciting,” said Sizemore. “Ceres is a little world that ought to be ‘dead,’ but these new results suggest it might not be. Seeing so much potential evidence for cryovolcanism on Ceres also lends more weight to discussions of cryovolcanic processes on larger icy moons in the outer solar system, where it’s likely more vigorous.”

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SpaceX announcement of first passenger for Lunar BFR

9:43 am

Capitalism in space: SpaceX will have a webcast today at 6 pm (Pacific) to announce the name of the first passenger to fly on a lunar mission using their Big Falcon Rocket (BFR).

The embed of that webcast is below, so if you wish you can watch right here.

Note that my initial post mistaken said this was happening at 6 pm Eastern time. That was an error.

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Multiple launches today

4:13 pm

Two launches today:

  • ULA’s last Delta 2 rocket launches ICESat-2 icecap tracking satellite for NASA
  • Indian’s PSLV rocket launches two British satellites

More details about ICESat-2 can be found here.

The PSLV launch raises India’s 2018 launch total to 4, tying Japan. The leaders in the 2018 launch standings:

24 China
16 SpaceX
8 Russia
7 ULA
5 Europe (Arianespace)

The U.S. and China are once again tied at 24 each.

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Russians considering spacewalk as part of airleak investigation

4:03 pm

The Russians are now considering having their astronauts on ISS do a spacewalk to inspect the outside of the Soyuz capsule for evidence of sealant work at the location of the drill hole that caused the airleak.

If the spacewalk is attempted, the cosmonauts would have to get to the Habitation Module, peel off soft thermal layers blanketing the spacecraft and then cut through the meteoroid shielding bordering this section of the spacecraft at a distance of around 1.5 centimeters from its pressurized hull.

To access the area of the hole on the exterior of the Soyuz, Russian officials are developing a spacewalk scenario relying on the available Strela boom, GStM. The telescopic device can be used to carry a cosmonaut secured to a special anchor at the end of the boom to a location aboard the station otherwise inaccessible to spacewalkers due to lack of railings.

The spacewalk would take place sometime in November or December. The goal is to help confirm that the sealant work was done on the ground, as well as help pinpoint when.

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Soyuz capsule was drilled after it was fully assembled

1:48 pm

The investigation into the drillhole leak in the Soyuz capsule docked to ISS has revealed that it had to have been done after the capsule was fully assembled.

“During the analysis of those images, traces of drilling were found on the anti-meteorite shield,” the source said, adding that “the top of the drill came through the pressure hull and hit the non-gastight outer shell.”

According to another industry source, the non-gastight anti-meteorite protection is installed right before the spacecraft is taken to the final assembly workshop. “When Soyuz MS-09 has just arrived to the final assembly workshop, it was photographed in details. No hole and no signs of drilling… were found. The spacecraft was drilled later, when it was fully assembled,” the source said. He added that the anti-meteorite shield was also photographed before being installed, and no traces on it were found as well.

The source suggested that the spacecraft could be damaged either during the very last stage of works or during its 90-day stay in the checkout stand, adding that it was highly unlikely that the damage occurred during the transportation to the Baikonur space center in Kazakhstan or at the launch facility.

This narrowing of the time frame for the drilling will increase the chances that the Russians will be able to identify who did.

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SpaceX to name on Monday its first customer for BFR flight around Moon

11:15 pm

Capitalism in space: In a tweet SpaceX announced that it will name on Monday its first customer for flight around Moon, using its Big Falcon Rocket rather than the Falcon Heavy as previously announced.

There will be a lot of speculation over the next few days, but we must remember that the BFR is years away from launch, so nothing here is either set in concrete, nor even likely to happen.

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Cassini’s last view of Titan

11:25 am

The Cassini science team today released a mosaic of the last images Cassini took of Titan before it crashed into Saturn’s atmosphere four days layer.

The mosaic shows Titan’s north polar region, and shows seas, lakes, and spotty clouds. The lack of clouds is a puzzle to scientists, as they had expected the north polar region to be cloud-covered at this time as summer arrived there, as had been seen at the south pole.

During Titan’s southern summer, Cassini observed cloud activity over the south pole.

However, typical of observations taken during northern spring and summer, the view here reveals only a few small clouds. They appear as bright features just below the center of the mosaic, including a few above Ligeia Mare. “We expected more symmetry between the southern and northern summer,” said Elizabeth (“Zibi”) Turtle of the Johns Hopkins Applied Physics Lab and the Cassini Imaging Science Subsystem (ISS) team that captured the image. “In fact, atmospheric models predicted summer clouds over the northern latitudes several years ago. So, the fact that they still hadn’t appeared before the end of the mission is telling us something interesting about Titan’s methane cycle and weather.”

The truth is we haven’t the slightest idea whether the clouds over the south pole during its previous summer were normal or an aberration. We have barely seen a full year of seasons at Saturn and Titan. To confidently extrapolate any pattern from this slim data is silly.

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Oblique view of lunar crater

9:51 am

Wallach Crater

Cool image time! The Lunar Reconnaissance Orbiter (LRO) science team this week released an image showing Wallach Crater as seen from the side. The image on the right is a section of that image and has been reduced to show here. The full image of 3.5-mile-wide crater and its surrounding terrain can be explored at the link. From the link:

Wallach crater (4.89°N, 32.27°E) formed within a thin layer of black basaltic lava flows that overlie much brighter anorthositic material. Think of a white cake with chocolate icing. When the asteroid (or comet) impacted this “iced cake”, ejecta from deeper portions (white cake, or rather brighter anorthosite) was thrown out onto the icing (darker basalt) resulting in intermediate tones where the two materials mixed.

The dark streaks seen inside the crater are blocks of the icing (basalt) breaking off and creeping down slope. The fact that the deepest material lands on top of the shallowest material (known as inverted stratigraphy) was first described by Gene Shoemaker from his pioneering observations at Meteor Crater, Arizona. This effect simplifies sampling the local geology in three dimensions. As an astronaut traverses towards the rim of a crater, the rocks underfoot come from deeper and deeper within the crater. The rocks at the rim are from the deepest portions of the crater!

It is especially interesting to use the viewer at the link to see the surrounding terrain, which includes two other craters that are far less distinct.

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More suborbital private rockets in the news

9:36 am

Two news stories today about two different suborbital rockets built by private companies:

The first story outlines the results from the August 25 test flight of SARGE.

The rocket reached an altitude of approximately 28 km. Launch and recovery took place at Spaceport America on August 25th, 2018. The rocket carried nine payloads. The flight demonstrated the SARGE system’s reusability when the vehicle was recovered with damage only to sacrificial components. The test also demonstrated the capability of the autonomous control system and validated the preflight vehicle integration process.

They have designed SARGE to fly up to 200 times, and then plan to sell it to the military which will use it as a target in its own tests.

The second story describes a suborbital launch yesterday at Spaceport America. This suborbital rocket carried three NASA experiments, the most interesting of which was the first test of a heat shield designed to open like an umbrella.

Made out of thickly woven and highly heat-resistant carbon fibers, supported by semi-rigid ribs, the ADEPT system fits into existing vehicle launch systems, but expands when separated from the rocket into a configuration that allows it to perform its mission.

The ADEPT model tested Wednesday spread to 30 inches in diameter after separation. Venkatapathy said a diameter of 75 to 80 feet would be required to deliver a crew of seven or so human explorers safely onto the surface of Mars, which has a lower gravity pull than Earth.

He said a thicker carbon weave and different dimensions would be needed to deliver scientific equipment to the surface of Venus, a planet with a gravity pull nearly as great as Earth’s, making approaches hotter and faster.

Even if neither of these companies ever scale up to orbital rockets, they signal the change in how NASA does things. In the past NASA built its own suborbital rockets. Now, they are using privately-built rockets, which allows for competition and more innovation.

This is basically the same transition NASA is undergoing in its commercial manned program, going from being the sole builder and designer of spacecraft, enforced by a government-imposed monopoly, to merely a customer buying spacecraft from many private builders. It is a transition that can only generate good results in the future.

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Dress rehearsal of Hayabusa-2’s landing scrapped

9:22 am

The dress rehearsal of Hayabusa-2’s eventual landing on the asteroid Ryugu was cut short yesterday when the spacecraft found it could not get a reliable distance reading of the surface once it descended to 600 meters.

The problem was apparently due to the pitch black surface of the carbon-rich asteroid that made laser distance measurements difficult. JAXA says the Hayabusa 2 is in good condition, and the agency is considering changing landing procedures such as adjusting the configuration of measuring devices.

Despite the suspension, the altitude of 600 meters the explorer has descended to the asteroid is the closest ever recorded. JAXA had planned to bring down the probe to 30 meters and make detailed observations of a landing spot.

Just to clarify, this was a height record for Hayabusa-2 only.

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HP to mass produce large 3D metal printers

9:18 am

The replicators are coming! HP has announced that it plans to mass produce a large 3D metal printer that can be used by large industrial manufacturers.

Each Metal Jet production machine will cost less than US$400,000, and will give you a maximum build volume of 430 x 320 x 200 mm (16.9 x 12.6 x 7.9 inches).

HP is timetabling the Metal Jet roadmap in stages. Right now, it’s already operational in two pilot programs. Metal injection molding specialist Parmatech is using it to produce medical equipment like surgical scissors and endoscopic surgical jaws, and GKN Powder Metallurgy is producing parts for automotive and industrial giants like Volkswagen and Wilo.

In 2019, HP will start up a production service, which will allow manufacturers to upload 3D design files and have them printed out in industrial quantities by Parmatech and GKN. The printers themselves will begin shipping in 2020, with “broad availability in 2021.” Desktop Metal, for its part, has pushed back availability of its production machines from this year to 2019.

HP is not the first to do this, but this appears to be the largest-scale production attempt.

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Astronomers use radio emissions from distant galaxy to observe asteroid

9:03 am

The wonders of science: Astronomers have successfully used the faint radio emissions from very distant galaxy to roughly determine the shape and size of a nearby asteroid.

In an unusual observation, astronomers used the National Science Foundation’s Very Long Baseline Array (VLBA) to study the effects on radio waves coming from a distant radio galaxy when an asteroid in our Solar System passed in front of the galaxy. The observation allowed them to measure the size of the asteroid, gain new information about its shape, and greatly improve the accuracy with which its orbital path can be calculated.

When the asteroid passed in front of the galaxy, radio waves coming from the galaxy were slightly bent around the asteroid’s edge, in a process called diffraction. As these waves interacted with each other, they produced a circular pattern of stronger and weaker waves, similar to the patterns of bright and dark circles produced in terrestrial laboratory experiments with light waves. “By analyzing the patterns of the diffracted radio waves during this event, we were able to learn much about the asteroid, including its size and precise position, and to get some valuable clues about its shape,” said Jorma Harju, of the University of Helsinki in Finland.

The amount of information is not great, and there is an enormous amount of uncertainty in the data. Nonetheless, this is an amazing and fascinating observation.

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