Tag: astronomy

Hubble gyro problem appears fixed

8:18 am

Engineers have apparently pinpointed and fixed the issue that was causing the Hubble Space Telescope’s last back up gyroscope to operate incorrectly, making it likely that the telescope will return to full normal operations shortly.

In an attempt to correct the erroneously high rates produced by the backup gyro, the Hubble operations team executed a running restart of the gyro on Oct. 16. This procedure turned the gyro off for one second, and then restarted it before the wheel spun down. The intention was to clear any faults that may have occurred during startup on Oct. 6, after the gyro had been off for more than 7.5 years. However, the resulting data showed no improvement in the gyro’s performance.

On Oct. 18, the Hubble operations team commanded a series of spacecraft maneuvers, or turns, in opposite directions to attempt to clear any blockage that may have caused the float to be off-center and produce the exceedingly high rates. During each maneuver, the gyro was switched from high mode to low mode to dislodge any blockage that may have accumulated around the float.

Following the Oct. 18 maneuvers, the team noticed a significant reduction in the high rates, allowing rates to be measured in low mode for brief periods of time. On Oct. 19, the operations team commanded Hubble to perform additional maneuvers and gyro mode switches, which appear to have cleared the issue. Gyro rates now look normal in both high and low mode.

This is wonderful news, in that it means the telescope will once again be able to point accurately enough to continue to take sharp images across the entire sky. It also highlights how close we are now to the telescope’s demise, since it no longer has a back-up gyroscope. With the next failure, which will occur eventually, Hubble will descend into one gyroscope operations, holding off its second working gyro as a backup.

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Giant planets around young star defy model predictions

8:21 am

The uncertainty of science: The recent discovery of four Saturn/Jupiter-sized planets orbiting a star only about two million years old throws a wrench into all existing solar system formation theories.

The star, CI Tau, is located about 500 light years away in a highly-productive stellar ‘nursery’ region of the galaxy. Its four planets differ greatly in their orbits: the closest (the hot Jupiter) is within the equivalent of the orbit of Mercury, while the farthest orbits at a distance more than three times greater than that of Neptune. The two outer planets are about the mass of Saturn, while the two inner planets are respectively around one and 10 times the mass of Jupiter.

The discovery raises many questions for astronomers. Around 1% of stars host hot Jupiters, but most of the known hot Jupiters are hundreds of times older than CI Tau. “It is currently impossible to say whether the extreme planetary architecture seen in CI Tau is common in hot Jupiter systems because the way that these sibling planets were detected – through their effect on the protoplanetary disc – would not work in older systems which no longer have a protoplanetary disc,” said Professor Cathie Clarke from Cambridge’s Institute of Astronomy, the study’s first author.

According to the researchers, it is also unclear whether the sibling planets played a role in driving the innermost planet into its ultra-close orbit, and whether this is a mechanism that works in making hot Jupiters in general. And a further mystery is how the outer two planets formed at all.

“Planet formation models tend to focus on being able to make the types of planets that have been observed already, so new discoveries don’t necessarily fit the models,” said Clarke. “Saturn mass planets are supposed to form by first accumulating a solid core and then pulling in a layer of gas on top, but these processes are supposed to be very slow at large distances from the star. Most models will struggle to make planets of this mass at this distance.” [emphasis mine]

In other words, the present models are absurdly premature. We simply don’t know enough to formulate any theory that can be taken seriously.

This is not to say that models shouldn’t be formulated, only to emphasize that no one should consider them predictive of any part of reality. They give astronomers some guidance on what to look for, but if they take them too seriously they might not look in the right places.

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Chandra goes into safe mode

11:43 pm

When it rains it pours: The Chandra X-ray Observatory went into into safe mode on October 10 for reasons that are either not yet understood or have not yet been revealed.

Chandra, Spitzer, and Hubble are the three remaining of the original four great observatories proposed in the late 1980s, with the Compton Gamma-Ray Observatory the fourth. Compton was de-orbited in 2000. Spitzer’s infrared observational capabilities became limited when its cryogenic cooling gas became exhaused in 2009.

Hubble and now Chandra are both in safe mode, leaving astronomy badly crippled.

This situation is actually the fault of the astronomical community, which in the early 2000s put all its money behind the James Webb Space Telescope, leaving little for the construction of replacement space telescopes for either Hubble or Chandra. In addition, the astronomical community has continued to put is money behind similar big, expensive, and giant projects like Webb, pushing for WFIRST with its 2011 decadal survey. Like Webb, WFIRST will cost billions and take almost a decade to build and launch, assuming there are no delays.

Meanwhile, the workhorses in orbit are failing one by one.

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Update on Hubble: no real news

2:15 pm

NASA today released an update on the effort to bring the Hubble Space Telescope out of safe mode and back to full operation.

The only new information they really provide is what they will do, depending on whether they can fix the back up gyroscope or not.

If the team is successful in solving the problem, Hubble will return to normal, three-gyro operations. If it is not, the spacecraft will be configured for one-gyro operations, which will still provide excellent science well into the 2020s, enabling it to work alongside the James Webb Space Telescope and continue groundbreaking science.

In other words, if they cannot find a way to get this third gyro functioning properly, they will shut down one of the two remaining working gyros so that it can operate as a backup, and operate the telescope on one gyroscope.

I find the last section of the quote above very amusing, in a dark sort of way. Not only does NASA rationalize the sad loss of Hubble’s ability to take sharp images, it tries to rationalize the decade-long delays it has experienced building the James Webb Space Telescope. Webb was supposed to have been launched in 2011. It should have been up there already, working alongside Hubble for the past seven years.

Now, the best we can hope for is that Webb will finally reach space while Hubble is still functioning, in a crippled condition. I would not be surprised however if Webb is further delayed, and Hubble is gone before it gets into space.

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Astronomers double the number of known fast radio bursts

9:31 am

Using a radio telescope in Australia astronomers have now doubled the number of known fast radio bursts.

Fast radio bursts come from all over the sky and last for just milliseconds. Scientists don’t know what causes them but it must involve incredible energy—equivalent to the amount released by the Sun in 80 years.

“We’ve found 20 fast radio bursts in a year, almost doubling the number detected worldwide since they were discovered in 2007,” said lead author Dr Ryan Shannon, from Swinburne University of Technology and the OzGrav ARC Centre of Excellence.

In other words, only forty bursts total have ever been detected. The data here however suggests that the bursts are coming from very far away and from the early universe, information which will help scientists figure out what is causing them.

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Hubble in safe mode, down to two gyroscopes

8:52 am

The end might be near: The Hubble Space Telescope went into safe mode this weekend when one of its three working gyroscopes failed.

Hubble has six gyroscopes, all of which were replaced by spacewalking astronauts during a servicing mission in May 2009. The telescope needs three working gyroscopes to “ensure optimal efficiency,” mission team members have written, and the failure brings that number down to two (if the “problematic” one that had been off can’t be brought back online).

But that doesn’t mean it’s time to panic. Hubble can do good science with two gyroscopes, or even one, astrophysicist Grant Tremblay, of the Harvard-Smithsonian Center for Astrophysics, said via Twitter Sunday.

While it is true that Hubble can do science on one or two gyroscopes, in that mode it will no longer be able to take the sharp spectacular pictures that represent its great glory.

Hubble was launched in 1990, fixed in 1993, and has been the most successful science robot ever launched. Scientists had hoped, when they made the James Webb Space Telescope their priority in the very early 2000s that both would be in space and operating to provide top notch science data, with Hubble working in visible wavelengths and Webb in the infrared. Webb’s endless delays and cost overruns has now probably made that impossible.

Worse, there are no plans to build a replacement for Hubble. For the first time since 1993, the human race will no longer be able to see, with our own eyes, the universe sharply.

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Data from Voyager 2 suggests it is entering interstellar space

7:50 pm

New data since August from Voyager 2 now suggests it is finally leaving the heliosphere of the solar system and entering interstellar space.

Since late August, the Cosmic Ray Subsystem instrument on Voyager 2 has measured about a 5 percent increase in the rate of cosmic rays hitting the spacecraft compared to early August. The probe’s Low-Energy Charged Particle instrument has detected a similar increase in higher-energy cosmic rays.

Cosmic rays are fast-moving particles that originate outside the solar system. Some of these cosmic rays are blocked by the heliosphere, so mission planners expect that Voyager 2 will measure an increase in the rate of cosmic rays as it approaches and crosses the boundary of the heliosphere.

In May 2012, Voyager 1 experienced an increase in the rate of cosmic rays similar to what Voyager 2 is now detecting. That was about three months before Voyager 1 crossed the heliopause and entered interstellar space.

The scientists warn that there is great uncertainty here, and that the actual transition into interstellar space might take longer than with Voyager 1 since Voyager 2 is traveling in a different direction and is leaving during a different time in the solar cycle.

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The first exomoon found?

11:29 am

Worlds without end: Scientists using data from the Hubble Space Telescope and Kepler have detected evidence that suggests the discovery of the first moon outside our solar system.

The data indicate an exomoon the size of Neptune, in a stellar system 8000 light-years from Earth. The new results are presented in the journal Science Advances.

…In 2017 NASA’s Kepler Space Telescope detected hints of an exomoon orbiting the planet Kepler-1625b. Now, two scientists from Columbia University in New York (USA) have used the incomparable capabilities of the NASA/ESA Hubble Space Telescope to study the star Kepler-1625, 8000 light-years away, and its planet in more detail. The new observations made with Hubble show compelling evidence for a large exomoon orbiting the only known planet of Kepler-1625. If confirmed, this would be the first discovery of a moon outside our Solar System.

The candidate moon, with the designation Kepler-1625b-i, is unusual because of its large size; it is comparable in diameter to the planet Neptune. Such gargantuan moons are unknown in our own Solar System. “This may yield new insights into the development of planetary systems and may cause astronomers to revisit theories of how moons form,” Alex Teachey, a graduate student who led the study, explained excitedly.

Like its moon, Kepler-1625b is also bigger than its counterparts in the Solar System. The exoplanet is a gas giant, several times more massive than Jupiter. It orbits its parent star at a distance similar to the distance between the Sun and Earth, which puts it — and its candidate moon — at the inner edge of the habitable zone of the star system.

The alien nature of this solar system should not surprise us. If anything, it is only a hint at the wild and exotic solar systems we have yet to discover.

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Astronomers discover very distant object orbiting the Sun

9:32 am

Astronomers have discovered a very distant object in a solar orbit ranging from 6 billion to 213 billion miles from the Sun.

Designated 2015 TG387 and nicknamed “The Goblin” by its discoverers, this object resides in the inner Oort Cloud, a region beyond the Kuiper Belt that until now harbored only two other known bodies: the dwarf planet Sedna and the less well-known 2012 VP113.

The scientists estimate its size to be about 200 miles in diameter. Based on the existence of the three known objects in this region of space, the scientists estimate there could be as many as 2 million objects there bigger than 25 miles in diameter. There is a lot of uncertainty in that number.

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More intergalactic stars discovered

9:22 am

Worlds without end: Using the data from Gaia’s second data release astronomers have identified twenty stars that are moving too fast to be permanent members of the Milky Way galaxy.

More significantly, most appeared to be approaching the galaxy, not flying away from it, suggesting they are visitors from other galaxies.

It is possible that these intergalactic interlopers come from the Large Magellanic Cloud, a relatively small galaxy orbiting the Milky Way, or they may originate from a galaxy even further afield. If that is the case, they carry the imprint of their site of origin, and studying them at much closer distances than their parent galaxy could provide unprecedented information on the nature of stars in another galaxy – similar in a way to studying Martian material brought to our planet by meteorites.

…An alternative explanation is that the newly identified sprinting stars could be native to our Galaxy’s halo, accelerated and pushed inwards through interactions with one of the dwarf galaxies that fell towards the Milky Way during its build-up history. Additional information about the age and composition of the stars could help the astronomers clarify their origin.

At least two more data releases shall come from Gaia, launched by Europe to precisely track the location and motions of a billion stars. So far, they have complete 3D velocity information for about seven million stars. After these additional data releases they expect to have complete 3D velocity information for 150 million stars, and should identify a lot more intergalactic stars at that time.

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Breakthrough Listen adds southern hemisphere telescope to extraterrestrial listening campaign

8:51 am

Breakthrough Listen has added the MeerKAT telescope in South Africa to its extraterrestrial listening campaign, thereby expanding the campaign to cover almost the entire sky.

Breakthrough Listen’s MeerKAT survey will examine a million individual stars – 1,000 times the number of targets in any previous search – in the quietest part of the radio spectrum, monitoring for signs of extraterrestrial technology. With the addition of MeerKAT’s observations to its existing surveys, Listen will operate 24 hours a day, seven days a week, in parallel with other surveys. “Collaborating with MeerKAT will significantly enhance the capabilities of Breakthrough Listen”, said Yuri Milner, founder of the Breakthrough Initiatives. “This is now a truly global project.”

Built and operated by the South African Radio Astronomy Observatory (SARAO), and inaugurated in July 2018, MeerKAT is a powerful array of 64 radio antennas in the remote Karoo Desert of South Africa. By partnering with SARAO, Breakthrough Listen gains access to one of the world’s premier observing facilities at radio wavelengths. Signals from the 64 dishes (each 13.5 meters in diameter) are combined electronically to yield an impressive combination of sensitivity, resolution and field of view on the sky. MeerKAT also serves as a precursor for the Square Kilometre Array, which will expand and enhance the current facility in the coming decades, eventually spanning a million square meters across South Africa and Australia to create by far the world’s largest radio telescope.

They have also widened their approach. They are not simply looking for intelligent radio communications, they are looking for any signs of technology.

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