Tag: science

Dog sits on editorial board of seven medical journals

4:16 pm

An Australian professor wondered if he could get his dog Ollie picked to be on the editorial board of a number of medical journals, and was astonished to discover seven who agreed without reservations.

Ollie’s owner is Mike Daube, Professor of Health Policy at Curtin University in Perth. Ollie likes to watch Mike working on his computer, and Mike gets a lot of emails from predatory journals. Wondering just how low these journals would go, he put together a curriculum vitae for his dog – detailing research interests such as “the benefits of abdominal massage for medium-sized canines” – and sent it off to a number of these journals, asking for a spot on their editorial boards.

Remarkably, the vast majority accepted Ollie without demur, and her name now adorns several journal websites. Ollie is a trailblazer, Professor Daube says, being the first dog ever to get on the editorial board of a journal.

“What makes it even more bizarre is that one of these journals has actually asked Ollie to review an article. It’s entitled “Malignant peripheral nerve sheath tumours and their management.” Some poor soul has actually written an article on this theme in good faith, and the journal has sent it to a dog to review.”

The article provides a nice look at the problems facing the modern peer review journal field.

12 comments

Brewing beer on the Moon

10:41 am

Capitalism in space: A student experiment to attempt to brew beer on the Moon, rejected by one Google Lunar X-Prize contestant, has been accepted by another.

The experiment involves a small canister that, once on the moon, will mix yeast with wort, the mixture of barley and other ingredients that give beer its flavor, to cause fermentation and carbonation. Besides proving that beer can be brewed remotely and in low gravity, the experiment demonstrates the potential for making other things involving yeast in low gravity, such as bread and certain medicines, which could be important if a lunar colony is ever established.

The canister, designed by the students at the Qualcomm Institute Prototyping Facility, will be aboard a spacecraft being built by Synergy Moon, one of the teams competing for the Google Lunar XPrize, a contest meant to inspire engineers and entrepreneurs to develop low-cost methods of robotic space exploration..

They have also been accepted to fly the experiment on several Synergy Moon orbital flights.

Leave a comment

Looking at Jupiter’s southern hemisphere

9:43 am

Jupiter's southern hemisphere

Cool image time! The image on the right, reduced to post here, shows Jupiter’s south pole and much of its southern hemisphere. It was taken during Juno’s last orbital fly-by of the gas giant’s cloud tops last week, and has been enhanced by Fevig-58, an ordinary citizen who downloaded the raw image and then uploaded his enhanced version to the Juno website.

It is definitely worthwhile taking a close look at the full resolution image. At the top its shows the horizontally banded Jupiter at equatorial- and mid-latitudes that has been that planet’s familiar face for centuries. In the middle is the transitional region from those horizontal bands to the chaotic polar regions. And at the bottom is the pole, where there the storms appear to follow no pattern and form a mish-mash.

One thing about Jupiter’s pole. It appears very different than Saturn’s. While I am certain they will find a vortex of some kind there, so far there is no indication of a coherent jet stream, as seen by Saturn’s hexagon. This once again demonstrates the one unbroken rule of planetary science that has been found with every planetary mission to every planetary body, whether they be pebbles, asteroids, dwarf planets, gas giants, or moons: Every single one of them is different and unique. They might fall into a single category, say gas giants, but each has its own unique features that make it different from every other member of that category.

5 comments

First science results from Juno

11:48 am

The Juno science team today released their first research results since the spacecraft entered orbit around Jupiter in July 2016.

“Although many of the observations have terrestrial analogs, it appears that different processes are at work creating the auroras,” said SwRI’s Dr. Phil Valek, JADE instrument lead. “With JADE we’ve observed plasmas upwelling from the upper atmosphere to help populate Jupiter’s magnetosphere. However, the energetic particles associated with Jovian auroras are very different from those that power the most intense auroral emissions at Earth.”

Also surprising, Jupiter’s signature bands disappear near its poles. JunoCam images show a chaotic scene of swirling storms up to the size of Mars towering above a bluish backdrop. Since the first observations of these belts and zones many decades ago, scientists have wondered how far beneath the gas giant’s swirling façade these features persist. Juno’s microwave sounding instrument reveals that topical weather phenomena extend deep below the cloudtops, to pressures of 100 bars, 100 times Earth’s air pressure at sea level.

“However, there’s a north-south asymmetry. The depths of the bands are distributed unequally,” Bolton said. “We’ve observed a narrow ammonia-rich plume at the equator. It resembles a deeper, wider version of the air currents that rise from Earth’s equator and generate the trade winds.”

Juno is mapping Jupiter’s gravitational and magnetic fields to better understand the planet’s interior structure and measure the mass of the core. Scientists think a dynamo — a rotating, convecting, electrically conducting fluid in a planet’s outer core — is the mechanism for generating the planetary magnetic fields. “Juno’s gravity field measurements differ significantly from what we expected, which has implications for the distribution of heavy elements in the interior, including the existence and mass of Jupiter’s core,” Bolton said. The magnitude of the observed magnetic field was 7.766 Gauss, significantly stronger than expected. But the real surprise was the dramatic spatial variation in the field, which was significantly higher than expected in some locations, and markedly lower in others. “We characterized the field to estimate the depth of the dynamo region, suggesting that it may occur in a molecular hydrogen layer above the pressure-induced transition to the metallic state.”

What I want to see is a depth map showing where Jupiter’s atmosphere ends and its solid core begins. I expect Juno will eventually be able to give us a first glimpse.

One comment

Star becomes black hole without supernova explosion

10:20 am

The uncertainty of science: Astronomers think they have identified a star that, rather than die and become a black hole in a supernova explosion, merely fizzled into a black hole.

Starting in 2009, one particular star in the Fireworks Galaxy, named N6946-BH1, began to brighten weakly. By 2015, it appeared to have winked out of existence. The astronomers aimed the Hubble Space Telescope at the star’s location to see if it was still there but merely dimmed. They also used the Spitzer Space Telescope to search for any infrared radiation emanating from the spot. That would have been a sign that the star was still present, but perhaps just hidden behind a dust cloud.

All the tests came up negative. The star was no longer there. By a careful process of elimination, the researchers eventually concluded that the star must have become a black hole.

There are a lot of uncertainties here. Nonetheless, astronomers have theorized that some stars could collapse into black holes with any explosions, and it appears they might have found their first example of that.

6 comments

After 7 years Cassini reaches Saturn’s solstice

3:55 pm

In 2010 NASA extended the Cassini mission orbiting Saturn for seven years to the planet’s next solstice, so that the spacecraft could observe Saturn, its moons, and its rings, for one full season of its 28 year orbit.

Today, Cassini reached that target.

NASA’s Cassini spacecraft still has a few months to go before it completes its mission in September, but the veteran Saturn explorer reaches a new milestone today. Saturn’s solstice — that is, the longest day of summer in the northern hemisphere and the shortest day of winter in the southern hemisphere — arrives today for the planet and its moons. The Saturnian solstice occurs about every 15 Earth years as the planet and its entourage slowly orbit the sun, with the north and south hemispheres alternating their roles as the summer and winter poles.

The article provides a detailed review of all the changes that have occurred during this long time period.

Leave a comment

The face of Ceres

9:35 am

The face of Ceres

Cool image time! The image on the right, reduced in resolution to show here, was taken by Dawn on April 29, 2017, when the spacecraft had been positioned between the Sun and the dwarf planet at a moment when its entire surface was lit. They have enhanced the colors to bring out the contrasts.

Images combining these different color filter perspectives reveal fine details of Ceres’ surface. For example, they emphasize the distinct compositions and textures of the material ejected from craters. The brightest region on Ceres, called Cerealia Facula, is highlighted in Occator Crater in the center of this image. Vinalia Faculae, the set of secondary bright spots in the same crater, are located to the right of Cerealia Facula.

One of the darkest regions on Ceres is next to Occator, and represents ejected material from the impact that formed the crater. The ejected material forms a large arc that extends over several hundred kilometers, below the center of Ceres in this image. That material’s distribution is partly determined by Ceres’ rotation.

Be sure to take a close look at the full image. It isn’t super high resolution, but it reveals a lot of interesting details

Leave a comment

Moon discovered around Kuiper belt dwarf planet

11:28 am

Astronomers have discovered a moon orbiting 2007 OR10, one of the Kuiper Belt’s larger objects.

With this discovery, most of the known dwarf planets in the Kuiper Belt larger than 600 miles across have companions. These bodies provide insight into how moons formed in the young solar system. “The discovery of satellites around all of the known large dwarf planets — except for Sedna — means that at the time these bodies formed billions of years ago, collisions must have been more frequent, and that’s a constraint on the formation models,” said Csaba Kiss of the Konkoly Observatory in Budapest, Hungary. He is the lead author of the science paper announcing the moon’s discovery. “If there were frequent collisions, then it was quite easy to form these satellites.”

Leave a comment

Mars rover update: May 15, 2017

12:31 pm

This update could also be entitled, “Up and down into Martian gullies,” as that is what both rovers, Curiosity and Opportunity, are presently focused on doing.

Curiosity

Curiosity's position, Sol 1696 (May 12, 2017)

For the overall context of Curiosity’s travels, see Pinpointing Curiosity’s location in Gale Crater.

In the past month, since my previous April 21, 2017 update, Curiosity has been working its way up the dry wash, frequently stopping to inspect the rocky surface terrain within. As they note,

As we climb up Mount Sharp, recently over slopes of 4-6 degrees, we have seen more varied outcrop structures and chemistries than the rest of the Murray formation, and such changes catch the collective eye of the team.

Only in the last week have they shifted to the east, as planned. Their near term goal is the lighter, yellowish layer of rock, dubbed the Hematite Unit, that sits higher up the slope of Mount Sharp. As they have been traveling on the Murray Formation now for more than a year, since March, 2016, I am certain the science team is even more eager to get to this different layer of geology to find out what it is made of and why it is there.

You can get an overall view of the geology Curiosity is traversing from this October 3, 2016 press release. Below is a version of the traverse map shown at that site that I posted as part of my October 6, 2016 rover update, updated to show Curiosity’s present location. It is apparent that Curiosity is finally moving out of the foothills below Mount Sharp and beginning its climb up the mountain’s actual slopes.
» Read more

5 comments

Propellers by the dozens

12:52 pm

Propellers

Cool image time! The latest image releases from Cassini, taken during its recent close fly-by campaign of the rings of Saturn, focus on the propeller features produced in the rings by larger ring objects. The image on the right, reduced to show here, reveals dozens of propellers of all shapes and sizes.

The original discovery of propellers in this region in Saturn’s rings … was made using several images taken from very close to the rings during Cassini’s 2004 arrival at Saturn. Those discovery images were of low resolution and were difficult to interpret, and there were few clues as to how the small propellers seen in those images were related to the larger propellers Cassini observed later in the mission….

This image, for the first time, shows swarms of propellers of a wide range of sizes, putting the ones Cassini observed in its Saturn arrival images in context. Scientists will use this information to derive a “particle size distribution” for propeller moons, which is an important clue to their origins.

The parallel pattern of rings in the center of the image is a series of density waves in the ring structure, caused by an interaction with one of Saturn’s larger nearby moons.

They have also released the best view we can now expect of a propeller by Cassini.

This is the third and final propeller to be targeted for a close flyby observation during Cassini’s ring-grazing orbits (the period from Nov. 2016 to April 2017 when Cassini’s orbit passed just outside the main rings). …Because propellers are seen in the outermost parts of the main rings, the ring-grazing orbits provided Cassini’s best opportunity to see them up close.

Cassini is now diving between the rings and the planet, so the propellers are farther away.

Leave a comment

Irreplaceable plant specimens destroyed by Australian customs.

10:29 am

Do the paperwork! Because the proper paperwork was not completed, and then mailed to the wrong address, Australian customs officials destroyed six daisy specimens, some collected in the 1700s.

Earlier this week, many botanists learned about the destruction of six type specimens of daisies—some collected during a French expedition to Australia from 1791 to 1793—which the National Museum of Natural History (NMNH) in Paris had mailed along with 99 other specimens to the Queensland Herbarium in Brisbane, Australia.

After the package arrived in Brisbane in early January, the specimens were held up at customs because the paperwork was incomplete. Biosecurity officers asked the Queensland Herbarium for a list of the specimens and how they were preserved, but the herbarium sent its responses to the wrong email address, delaying the response by many weeks. In March, the officers requested clarification, but then incinerated the samples. “It’s like taking a painting from the Louvre and burning it,” says James Solomon, herbarium curator at the Missouri Botanical Garden in St. Louis.

According to Australia’s Department of Agriculture and Water Resources, which enforces biosecurity rules, part of the problem was that the samples had a declared value of $2—and its agents routinely destroy low-value items that have been kept longer than 30 days. Michel Guiraud, director of collections at NMNH, says his museum’s policy is to put minimal values on shipments. “If it is irreplaceable, there is no way to put an insurance value on it,” he says.

It appears that the fault here is not entirely limited to Australian customs. Both the Paris and Brisbane museums appear to have been very sloppy in this matter.

The result, for now, is that some research organizations are now ceasing all shipments to Australia.

Leave a comment

Two Dragon Mars missions in 2020?

7:06 pm

It appears that SpaceX is considering flying two test Dragon capsules to Mars in 2020.

NASA’s manager of science missions, Jim Green, said on Tuesday that the 2020 launch window when Earth and Mars are in favorable alignment for relatively short transits is getting crowded. Speaking Tuesday at the Humans to Mars conference in Washington, DC, Green said, “Every 26 months, the highway to Mars opens up, and that highway is going to be packed. We start out at the top of that opportunity with a SpaceX launch of Red Dragon. That will be followed at the end of that opportunity with another Red Dragon. Those have been announced by SpaceX.” NASA plans to launch a Mars lander in 2020 as well.

Two Red Dragon missions in 2020 have not yet formally been announced by SpaceX. Company spokesman John Taylor told Ars he would have to look into the question of sending two Dragons to Mars in 2020. However, other industry sources told Ars this is definitely under consideration by SpaceX, although no final decisions have been made.

That would mean two Falcon Heavy launches that year, just for this. And it would happen long before NASA manages its first launch of a complete SLS rocket.

10 comments

New multi-wavelength image of Crab Nebula

12:00 pm

Crab Nebula

Cool image time! The image on the right, reduced and cropped to show here, was created in November 2012 using a number of different telescopes, both on the ground and in space, to image the Crab Nebula in as much of the entire electromagnetic spectrum as possible.

This image combines data from five different telescopes: The VLA (radio) in red; Spitzer Space Telescope (infrared) in yellow; Hubble Space Telescope (visible) in green; XMM-Newton (ultraviolet) in blue; and Chandra X-Ray Observatory (X-ray) in purple.

Be sure to check out the full image at the Hubble website. It is packed with fascinating details you need to zoom in to to see.

2 comments

Sunspot update for April 2017

3:53 pm

Today NOAA posted its monthly update of the solar cycle, covering sunspot activity for April. It is posted below, with annotations, as I have done now every month since 2010.

April 2017 Solar Cycle graph

The graph above has been modified to show the predictions of the solar science community. The green curves show the community’s two original predictions from April 2007, with half the scientists predicting a very strong maximum and half predicting a weak one. The red curve is their revised May 2009 prediction.

April showed an uptick in sunspot activity, enough to move the numbers back up above the 2007 low prediction. Nonetheless, activity as the cycle has been ramping down has consistently and generally remained below expectation, and does seem heading to an early arrival of solar minimum, sometime in late 2019 or early 2020, about a year early.

I don’t want to sound like a broken record, as I have written this practically every month since I started these updates in 2010, but this short and weak solar maximum suggests the possibility that we might be facing a grand minimum, where there are no significant sunspots for decades. Some solar scientists think this is coming. Others are much more doubtful. Regardless, we can only wait and watch, while also recognizing that weak solar maximums and grand minimums have in the past consistently coincided with global cool weather. The reasons why this has happened are not yet known, but it has happened nonetheless.

One comment

Saturn’s north pole hexagon jet stream

8:52 am

Saturn's north polar hexagon jet stream

Cool image time! The image on the right, reduced and cropped to show here, was taken by Cassini in January as it was preparing to head into its final 22 orbital dives between Saturn and its rings. The image shows the gas giant’s north polar, with all its magnificent features. As the press release notes, the north pole was in shadow for the first part of Cassini’s mission, and only in recent years has finally moved into sunlight so that the spaceship can see and image it.

Although the sunlight falling on the north pole of Saturn is enough to allow us to image and study the region, it does not provide much warmth. In addition to being low in the sky (just like summer at Earth’s poles), the sun is nearly ten times as distant from Saturn as from Earth. This results in the sunlight being only about 1 percent as intense as at our planet.

This view looks toward Saturn from about 31 degrees above the ring plane. The image was taken with the Cassini spacecraft wide-angle camera on Jan. 22, 2017 using a spectral filter which preferentially admits wavelengths of near-infrared light centered at 939 nanometers.

Be sure to look at the full image.

3 comments

Trump administration removes members of EPA science advisory board

8:34 am

In a move related to Trump’s effort to change policy at the EPA, the administration yesterday is reported to have forced out as many as a dozen members of EPA’s 18-person Board of Scientific Counselors.

At an April meeting, the Board of Scientific Counselors discussed the importance of climate change research at EPA and “the growing need for information on, and understanding of, climate change and responses to its impacts,” according to an agenda. They also talked about the importance of considering climate change as a stressor in areas of non-climate research.

The Trump administration has already sent signals that it does not value some areas of federal research, in particular climate science and work that could lead to further regulation of the fossil fuel and chemical industries. The board had 18 members, including Richardson, who said he knew of at least one other member fired. Departures could reach a dozen, he said.

There is going to be a lot of pigs squealing about this. The big question will be whether the Trump administration will have the courage to stand up to those squeals.

8 comments

Cassini science team releases movie of images from first ring dive

5:25 pm

The Cassini science team has released a movie compiled from images taken during the spacecraft’s first dive between Saturn and its rings.

I have embedded the movie below the fold. It cuts off before the spacecraft’s closest approach because they took a very conservative approach to this fly-by, turning the vehicle so that its antenna dish protected it. This prevented the taking of the best images. The second dive, that occurred yesterday, will have better images.
» Read more

One comment

The soft avalanches of Mars

9:23 am

Krupac Crater gullies

Cool image time! The image on the right, reduced in resolution to show here, shows the gullies flowing down Krupac Crater on Mars. Be sure to check out the original, released today by the Mars Reconnaissance Orbiter science team, since they have enhanced the colors to bring out the sandy flows, noting as well that while most of these gullies are found in higher latitudes, this crater at 7.8 latitude has them as well.

Although large gullies (ravines) are concentrated at higher latitudes, there are gullies on steep slopes in equatorial regions. An enhanced-color closeup shows part of the rim and inner slope of Krupac Crater located just 7.8 degrees south of the equator.

The colors of the gully deposits match the colors of the eroded source materials. Krupac is a relatively young impact crater, but exposes ancient bedrock. Krupac Crater also hosts some of the most impressive recurring slope lineae (RSL) on equatorial Mars outside of Valles Marineris.

Below I have cropped out a small section showing, at full resolution, the termination point of one of these flows, indicating where this section is on the larger image to the right. This avalanche is clearly not liquid, though it has a very sandy and soft nature, suggesting — as some scientists have theorized — that liquid from below the surface might have played a part in its flow.

It is important in looking at these images to repeatedly remind yourself that the gravity here is about one third that of Earth, and thus the angle of repose will be different, and that avalanches will behave very differently in this environment. Moreover, Mars’s far colder climate will also effect things. The avalanche we are looking at could not happen in this way on Earth.

close-up of flow

10 comments

NASA looks to private companies for lunar missions

8:53 am

Capitalism in space: NASA has issued a request for information on possible private commercial missions capable of carrying NASA payloads to the Moon.

From the announcement:

NASA has identified a variety of exploration, science, and technology demonstration objectives that could be addressed by sending instruments, experiments, or other payloads to the lunar surface. To address these objectives as cost-effectively as possible, NASA may procure payloads and related commercial payload delivery services to the Moon

In other words, NASA has money to spend on lunar science missions, and rather than plan those missions itself, as it has done since the 1960s, it is now offering to buy and launch proposals from private companies.

2 comments

ISRO requests Indian proposals for Venus probe

8:39 am

India’s space agency ISRO has issued a request for proposals from Indian scientists for the scientific instruments to be installed on a future probe to Venus.

The announcement included the following information about the proposed Venus orbiter itself:

The payload capability of the proposed satellite is likely to be 175 kg with 500W of power. However these values are to be tuned based on the final configuration. The proposed orbit is expected to be around 500 x 60,000 km around Venus. This orbit is likely to be reduced gradually, over several months to a lower apoapsis.

All told it appears that India is moving forward with this project, and probably intends to build it much like they build Mangalyaan, their successful Mars orbiter, quickly, efficiently, and for relatively low cost.

One comment

Astronomers find that Epsilon Eridani solar system resembles our own system

1:28 pm

New data of the Epsilon Eridani solar system 10.5 light years away confirms that its debris disk has a structure somewhat resembling our own solar system.

The data has found that the debris disk has two narrow belts, one located at about the same distance from the star as our asteroid belt, and the other orbiting at about where Uranus is located. In addition, the system appears to have a Jupiter-sized planet orbiting the same distance from the star as does Jupiter.

8 comments

Cassini finds gap in Saturn’s rings surprisingly empty

6:50 pm

The uncertainty of science: The data from Cassini’s first dive through the gap between Saturn and its innermost ring suggests that the space there has much less material than predicted.

Cassini’s Radio and Plasma Wave Science (RPWS) instrument was one of two science instruments with sensors that poke out from the protective shield of the antenna (the other being Cassini’s magnetometer). RPWS detected the hits of hundreds of ring particles per second when it crossed the ring plane just outside of Saturn’s main rings, but only detected a few pings on April 26. When RPWS data are converted to an audio format, dust particles hitting the instrument’s antennas sound like pops and cracks, covering up the usual whistles and squeaks of waves in the charged particle environment that the instrument is designed to detect. The RPWS team expected to hear a lot of pops and cracks on crossing the ring plane inside the gap, but instead, the whistles and squeaks came through surprisingly clearly on April 26.

“It was a bit disorienting — we weren’t hearing what we expected to hear,” said William Kurth, RPWS team lead at the University of Iowa, Iowa City. “I’ve listened to our data from the first dive several times and I can probably count on my hands the number of dust particle impacts I hear.” The team’s analysis suggests Cassini only encountered a few particles as it crossed the gap — none larger than those in smoke (about 1 micron across).

The second dive through the rings will occur tomorrow, with data sent down the next day. Because the gap is emptier than expected, they will not have to protect the spacecraft so thoroughly, and will thus have more instruments gathering data during the fly through.

One comment

Hibernation research for long space flights

12:19 pm

Scientists are doing new research at using some form of hibernation for humans traveling on interplanetary missions lasting months or years.

Bradford’s engineering and medical team used the first of those NIAC grants, issued in 2013, to design a compact zero-gravity, rigid-structure habitat based on the International Space Station crew module designs. The habitat featured closed-loop oxygen and water production systems, direct access to the Mars ascent and descent vehicles, and support for a crew of six, all of whom would be kept in torpor for the entire six- to nine-month Mars journey.

The proposed medical treatment relies on using techniques similar to the ones surgeons perfected to induce hypothermia. For example, cooling nitrogen gas could be fed to astronauts via nasal cannula, lowering brain and body temperatures to between 89 and 96 degrees—close enough to normal to maintain torpor without overcooling the heart or increasing the risk of other complications. Cooling tends to decrease the body’s ability to clot, Tisherman says. He has also noted that patients who are cooled to mild levels of hypothermia—93 degrees—for 48 hours or more have more infections than uncooled people.

As is usual in these modern fascist times, bureaucracy and the fear of radical protesters are preventing this research from moving forward. NASA is forbidden to fund any research that uses live animal subjects, such as pigs, even though they are ideal subjects and, as noted in the article, “The number of pigs involved in this kind of study wouldn’t amount to one’s week’s breakfast for the average American.” Private funds have also not raised because no one wants to deal with the public relations nightmare of PETA protests.

The article is long and detailed, and gives an excellent overview of the state of the field as well as the research questions it faces. Above all, it does indicate that the idea of using hibernation in space, born in science fiction, is not so much of a fantasy after all.

10 comments

Cassini successfully completes first dive between Saturn and its rings

8:14 am

The Cassini spacecraft has successfully survived its close flyby of Saturn, diving between the rings and the top of the planet’s cloud tops.

As it dove through the gap, Cassini came within about 1,900 miles (3,000 kilometers) of Saturn’s cloud tops (where the air pressure is 1 bar — comparable to the atmospheric pressure of Earth at sea level) and within about 200 miles (300 kilometers) of the innermost visible edge of the rings.

Cassini is beaming down its images and data now, with the images to be available later today.

Leave a comment

Third reaction wheel on Dawn fails

7:33 pm

The third of four reaction wheels on Dawn failed on April 23, forcing the spacecraft to use its conventional thrusters to orient itself.

The team discovered the situation during a scheduled communications session on April 24, diagnosed the problem, and returned the spacecraft to its standard flight configuration, still with hydrazine control, on April 25. The failure occurred after Dawn completed its five-hour segment of ion thrusting on April 22 to adjust its orbit, but before the shorter maneuver scheduled for April 23-24. The orbit will still allow Dawn to perform its opposition measurements. The reaction wheel’s malfunctioning will not significantly impact the rest of the extended mission at Ceres.

This might shorten Dawn’s remaining mission, but since it is in its final days anyway, the loss will not be severe.

Leave a comment

Cassini about to make first dive into Saturn’s rings

8:27 am

Cassini will make its first dive through a gap in Saturn’s ring today, and this link provides details.

Because that gap is a region no spacecraft has ever explored, Cassini will use its dish-shaped high-gain antenna (13 feet or 4 meters across) as a protective shield while passing through the ring plane. No particles larger than smoke particles are expected, but the precautionary measure is being taken on the first dive. The Cassini team will use data collected by one of the spacecraft’s science instruments (the Radio and Plasma Wave Subsystem, or RPWS) to ascertain the size and density of ring particles in the gap in advance of future dives. As a result of its antenna-forward orientation, the spacecraft will be out of contact with Earth during the dive.

The first images are not expected until mid-day tomorrow.

Leave a comment

Latch blamed for Webb vibration test issue

6:03 pm

A latch that hadn’t closed properly has been identified as the cause of the anomaly that halted vibration testing of the James Webb Space Telescope in December.

At the committee meeting, Smith said the problem was tracked down to a latch designed to hold in place one of the wings of JWST’s primary mirror, which consists of 18 hexagonal segments. Those wings are folded into place to fit within the payload fairing of the Ariane 5 that will launch JWST, then deployed into place once in space. The latch, he said, consists of two plates with serrated teeth a few millimeters in size. “The thought is that the teeth, when they closed it, they didn’t quite seat,” he said. “So during the vibe [test], the teeth clapped together on the order of a millimeter or two, and that was what made the noise.”

Engineers were able to replicate the noise by placing the plates slightly out of alignment in the lab and subjecting them to similar vibrations, giving them confidence that was the cause of the anomaly.

I love how the Webb program manager also says that Webb is “on budget and on schedule.” That claim could only be true if you make believe that the budget was always $9 billion and the launch date was always supposed to be 2018 instead of the original $1 billion and 2011 launch date.

4 comments
1 … 139 140 141 142 143 … 275