Tag: science

Astronomers detect the first comet whose nucleus’ reversed its rotation

11:28 am

Astronomers using data collected by the orbiting Gehrels Swift and Hubble space telescopes now think the nucleus of a small comet reversed its rotation sometime in 2017, caused by the force of the material sublimated off its surface.

From the abstract of their paper [pdf]:

The rotations of cometary nuclei are known to change in response to outgassing torques. The nucleus of the Jupiter-family comet 41P/Tuttle–Giacobini–Kresak exhibited particularly dramatic rotational changes when near perihelion in 2017 April. Here, we use archival Hubble Space Telescope observations from 2017 December to study the postperihelion lightcurve of the nucleus and to assess the nucleus size.

From both Hubble photometry and nongravitational acceleration measurements, we find a diminutive nucleus with effective radius 500 ± 100 meters. Systematic optical variations are consistent with a two-peaked (i.e., rotationally symmetric) lightcurve with period 0.60 ± 0.01 days, substantially different from periods measured earlier in 2017. The spin of the nucleus likely reversed between perihelion in 2017 April and December as a result of the outgassing torque.

In plain English: the thrust of the material being thrown from the surface as the comet made its close approach to the Sun was sufficient to slow and then reverse the nucleus’s rotation. This process was helped by the relatively small size of the nucleus compared to the material being sublimated from it.

The data also suggests the nucleus was once much larger, and has been whittled down to its present small size as it made its multiple close fly-bys of the Sun during the past 1,500 years. Rather than break-up, as most comets do at some point as their nucleus gets smaller, this comet’s nucleus simply kept shrinking, to the point that the thrust of that material could change its rotation.

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Webb and Hubble take a look at Saturn

9:37 am

Saturn seen by Webb and Hubble

Astronomers using both the Hubble Space Telescope and the Webb Space Telescope have produced new complementary views of the ringed planet Saturn.

Those photographs are shown above, with Webb’s false-color infrared image to the left and Hubble’s optical image to the right. From the press release:

In the Webb image, a long-lived jet stream known as the “ribbon wave” meanders across the northern mid-latitudes, influenced by otherwise undetectable atmospheric waves. Just below that, a small spot represents a lingering remnant from the “Great Springtime Storm” of 2010 to 2012. Several other storms dotting the southern hemisphere of Saturn are visible in Webb’s image, as well. All these features are shaped by powerful winds and waves beneath the visible cloud deck, making Saturn a natural laboratory for studying fluid dynamics under extreme conditions.

…In Webb’s infrared image, the rings are extremely bright because they are made of highly reflective water ice. In both images, we’re seeing the sunlit face of the rings, a little less so in the Hubble image, hence the shadows visible underneath on the planet.

There are also subtle ring features such as spokes and structure in the B ring (the thick central region of the rings) that appear differently between the two observatories. The F ring, the outermost ring, looks thin and crisp in the Webb image, while it only slightly glows in the Hubble image.

The press release says little about the Hubble image, mostly because it shows little new by itself. It however is part of an on-going decade-long survey using Hubble to track Saturn’s changing weather patterns.

While both images are valuable, they also highlight our present limits in observing Saturn. Views from Earth can only see so much. It is like trying to watch a football game from ten miles away, with binoculars. And sadly, no mission is presently planned to return to Saturn.

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Triton: Neptune’s largest moon

11:19 am

The southern mid-latitudes of Neptune's moon Trident
Click for original image.

Triton

Today’s cool image begins a new tour I plan on doing over the next week or so of the few close-up photographs we have of Neptune and its moons, sent back by Voyager-2 when it did its close fly-by of this distant planet on August 25, 1989. That fly-by was almost 37 years ago, and it remains our only close look. While at the time it shined a quick flashlight of new knowledge on Neptune, its moons, and its ring system, we remain generally in the dark about what’s there, despite some good imagery produced in subsequent years by Hubble and some ground-based telescopes.

The image above, cropped and enhanced to post here, shows a portion of the southern mid-latitudes of Triton, Neptune’s largest moon, as Voyager-2 made its closest pass at a distance of about 25,000 miles. The photo to the right, cropped and reduced, shows a more global view to provide some context, with the box indicating the approximate area covered by the upper image. It was taken when Voyager-2 was on approach, at a distance of about 330,000 miles. The top picture captures several dozen black plumes that appear to vent material from below. From the caption:

The plumes originate at very dark spots generally a few miles in diameter and some are more than 100 miles long. The spots which clearly mark the source of the dark material may be vents where gas has erupted from beneath the surface and carried dark particles into Triton’s nitrogen atmosphere. Southwesterly winds then transported the erupted particles, which formed gradually thinning deposits to the northeast of most vents.

It is possible that the eruptions have been driven by seasonal heating of very shallow subsurface deposits of volatiles, and the winds transporting particles similarly may be seasonal winds. The polar terrain, upon which the dark streaks have been deposited, is a region of bright materials mottled with irregular, somewhat dark patches. The pattern of irregular patches suggests that they may correspond to lag deposits of moderately dark material that cap the bright ice over the polar terrain.

As we only have a few images of this planet, and those provided views of only about 40% of its surface, any theory that tries to explain the weird geology here is certain to be wrong to some degree.

More to come in the next few days. As much as we think we know, these pictures are going instead highlight how sparse that knowledge really is.

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Intuitive Machines wins $180.4 million new NASA lunar lander contract

8:46 am

Intuitive Machines' Nova-D lunar lander
Click for original.

The lunar lander startup Intuitive Machines announced yesterday that it has won its fifth contract from NASA, a $180.4 million deal to place its larger upgraded Nova-D lander near the Moon’s south pole.

The IM-5 mission will target Mons Malapert, a ridge near the Lunar South Pole that offers continuous Earth visibility, stable illumination conditions, and access to permanently shadowed regions. These characteristics make the site a compelling location for future communications, navigation, and surface infrastructure.

The artist’s rendering to the right shows this Nova-D lander. What stands out immediately is its low-slung appearance. Intuitive Machines’ smaller Nova-C lander was tall (see this image), with a high center of gravity. In its only two landing attempts on the Moon it tipped over both times after touchdown. It appears the company has finally recognized the issue and reworked this new lander to make it more stable after touchdown.

This contract award appears to be part of the accelerated program by NASA administrator Jared Isaacman to land 30 unmanned rovers on the moon in three years, beginning in 2027. Mons Malapert is a plateau that Intuitive Machines second lander tipped over on. It is also the landing site for Astrobotics’ Griffin lander, as well as a candidate landing site for the first Artemis manned missions.

Note the small rover on the right in the graphic. While the mission will carry seven NASA science instrument payloads, it will also carry this commercial rover, built by Honeybee Robotics, a subsidiary of Blue Origin. As the company states above, the lander on this mission also has additional available payload capacity for more commercial customers.

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Juno data suggests lightning on Jupiter is a hundred to a million times more powerful than lightning on Earth

11:08 am

The uncertainty of science: Using data from the orbiter Juno as it passed multiple times above a storm on Jupiter, scientists now believe lightning bolts on Jupiter could be a hundred to a million times more powerful than lightning bolts on Earth.

Juno made 12 passes over isolated storms during that period, and was close enough on four of them to measure microwave static from lightning. The flashes averaged three per second during these passes; on one flyover, Juno detected 206 separate pulses of microwave radiation. Of a total of 613 pulses measured, Wong calculated that the power ranged from about that of a lightning bolt on Earth to 100 or more times the power of an Earth bolt. Because he compared Earth lightning emissions at one radio wavelength to Jupiter lightning emissions at a different wavelength, there’s some uncertainty in the comparison, Wong cautioned. Based on one study of lightning radio emissions on Earth, Jupiter’s bolts could have been a million times more powerful than those on Earth.

Lots of uncertainty and assumptions in these conclusions, but they are not only not surprising, they fit earlier data collected before Juno.

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Changes to the Crab Nebula after a quarter century

9:44 am

The Crab Nebula, changes after a quarter century
For original images go here and here.

Using the Hubble Space Telescope, astronomers have obtained a new high resolution image of the Crab Nebula, and by comparing it with earlier Hubble images taken in 1999/2000 have been able to track the continuing expansion and evolution of this supernova remnant over a period now covering almost a quarter century.

The supernova itself became visible on Earth in 1054, though it actually erupted about 6,500 years earlier, as the Crab Nebula is 6,500 light years away. In the 25 years Hubble has been tracking the remnant’s expansion astronomers estimate it is expanding at about 3.4 million miles per hour.

[William Blair of Johns Hopkins University] noted that filaments around the periphery of the nebula appear to have moved more compared to those in the center, and that rather than stretching out over time, they appear to have simply moved outward. This is due to the nature of the Crab as a pulsar wind nebula powered by synchrotron radiation, which is created by the interaction between the pulsar’s magnetic field and the nebula’s material. In other well-known supernova remnants, the expansion is instead driven by shockwaves from the initial explosion, eroding surrounding shells of gas that the dying star previously cast off.

The new, higher-resolution Hubble observations are also providing additional insights into the 3D structure of the Crab Nebula, which can be difficult to determine from a 2D image, Blair said. Shadows of some of the filaments can be seen cast onto the haze of synchrotron radiation in the nebula’s interior. Counterintuitively, some of the brighter filaments in the latest Hubble images show no shadows, indicating they must be located on the far side of the nebula.

A movie showing the changes between these two images can be seen here. It is worth your while to take a look. These optical images will be further enhanced as the Webb Space Telescope gathers infrared data.

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Growing damage to the wheels of the Curiosity Mars rover

9:19 am

Close-up of the wheel in the worst condition
Images cropped and reduced to post here. For the original images go here and here.

Survey of wheels

Every few months or so the Curiosity science team uses one of the rover’s cameras to do a survey of the rover’s wheels to track their condition. Since early in the mission they had found the wheels were not holding up as well as expected as they rolled over the rough terrain in Gale Crater and on Mount Sharp, and so they take great care in how they move the rover as well as review the wheels regularly.

A year ago it had appeared that the damage to one particular wheel had increased, to a point where its outer section might even break off.

Yesterday the science team did another survey, as shown in the picture to the right.

The two photos above (found here and here) focus on one particular wheel of that survey, which I suspect is the same wheel that was the focus of last year’s post. After taking the first image on the left the team moved Curiosity so that the other side of the wheel could be photographed. As you can see, the damage is extensive, so much so that it is possible the wheel could collapse entirely in the not-to-distant future.

It also looks like another wheel is beginning to see similar damage (see here and here), though not yet as extreme.

The good news is that Curiosity has six wheels, and that it can continue to travel even with the loss of one or maybe two wheels. It also appears that future terrain might not be so rocky.

The bad news is that this wheel damage is likely the one problem that will likely end the mission, possibly sooner than anyone would like. And from these photographs, that end might be sooner rather than later.

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Canada cancels small lunar rover that was to fly on Firefly’s Blue Ghost lander in ’29

2:13 pm

Even as Canada has increased its government space spending in Europe and in Canada — mostly it appears to prop up bureaucracies or failing businesses — its space agency has at the same time cancelled its first lunar rover project, scheduled to brought to the south pole of the Moon by a Firefly Blue Ghost lander in 2029.

As part of its 2026-2027 departmental plan, the Canadian Space Agency (CSA) has cancelled its ambitious lunar rover mission. The lunar rover was announced in 2022. It would have been Canada’s first rover, built by Canadensys, and hitching a ride to the moon on a commercial launch vehicle built by a private U.S. company, Firefly Aerospace.

…The principal investigator of the mission, Gordon Osinski, a planetary geologist from Western University, said that he found out about a month ago, and that he was “devastated” by the news.

Note that this rover was hardly “ambitious.” It was a small unmanned rover comparable to similar rovers deployed by India, Japan, and others, mostly aimed at testing the engineering for later larger rovers.

The real issue however is how this decision illustrates Canada’s leftist government misplaced priorities. Increasingly it appears it is canceling actual space research or planetary missions and shifting the money to other uses, either European projects or bureaucracies in Canada or failing Canadian businesses.

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Private mission to Apophis gets another customer, two student-built landers

1:43 pm

Apophis' path past the Earth in 2029
A cartoon (not to scale) showing Apophis’s
path in 2029.

The orbital tug startup Exlabs has signed up a second payload customer to fly on its private ApophisExL mission to rendezvous with the potentially dangerous asteroid Apophis when it makes its April 13, 2029 close fly-by of the Earth.

ExLabs has announced its partnership with Japan’s Chiba Institute of Technology (ChibaTech) and its Planetary Exploration Research Center (PERC) to send university-led payloads to the surface of asteroid Apophis during its rare near-Earth flyby in 2029. ApophisExL is the world’s first commercial deep-space rideshare and is supported by mission design and operations collaboration with NASA’s Jet Propulsion Laboratory (JPL) operated by Caltech.

Under the leadership of planetary scientist and PERC Director, Dr. Tomoko Arai, ChibaTech students and researchers are developing two landing payloads to be deployed on the asteroid’s surface.

An Australian satellite startup, Fleet Space Technologies, had already signed on to fly a mapping instrument on ApophisExL.

Though the press release at the link calls this private mission “a new model,” using private enterprise rather than relying on the government for doing planetary missions, it actually harks back to the way things were done in the U.S. before World War II, when the private sector did most of this pure research. In fact, as late as the 1960s there was at least one company, American Science and Engineering, doing the first X-ray astronomical observations flying suborbital rockets. It later won contracts from NASA and other agencies to help build several later orbiting X-ray telescopes.

Over time the government space agencies became dominant, so that most of this design work was either done by them or by universities, with private companies relegated to the roles of minor subcontractors.

This new model is simply an extension of the capitalism model that is taking over the entire space industry, shifting power and ownership from big, expensive, and inefficient government programs to small, cheap, and economical private missions. Those space agencies can still do missions, but they do it by buying payload space on these private missions.

Below is a list of the missions going to Apophis in 2029:
» Read more

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Uranus: one glimpse and that was forty years ago

12:27 pm

Uranus as seen by Voyager-2, natural colors on left, false color on right
Uranus as seen by Voyager-2, natural colors on left, false color on right. Click for original.

I close today our week-long tour of Voyager-2’s fly-by of Uranus in January 1986 with three cool images, the two images of the planet itself above and a close-up of its rings. All three illustrate that though Voyager-2 gave us our first very good first close-up view of this distant world, it also gave us only a tiny glimpse, very superficial and lacking in any larger context.

The two images above were taken on January 17, 1986 when Voyager 2 was till 5.7 million miles away, on approach.

The picture at left has been processed to show Uranus as human eyes would see it from the vantage point of the spacecraft. The picture is a composite of images taken through blue, green and orange filters. The darker shadings at the upper right of the disk correspond to the day-night boundary on the planet. Beyond this boundary lies the hidden northern hemisphere of Uranus, which currently remains in total darkness as the planet rotates. The blue-green color results from the absorption of red light by methane gas in Uranus’ deep, cold and remarkably clear atmosphere.

The picture at right uses false color and extreme contrast enhancement to bring out subtle details in the polar region of Uranus. Images obtained through ultraviolet, violet and orange filters were respectively converted to the same blue, green and red colors used to produce the picture at left. The very slight contrasts visible in true color are greatly exaggerated here. In this false-color picture, Uranus reveals a dark polar hood surrounded by a series of progressively lighter concentric bands. One possible explanation is that a brownish haze or smog, concentrated over the pole, is arranged into bands by zonal motions of the upper atmosphere. The bright orange and yellow strip at the lower edge of the planet’s limb is an artifact of the image enhancement. In fact, the limb is dark and uniform in color around the planet.

The third cool image below of Uranus’s rings was taken just after the closest approach, when Voyager-2 was in Uranus’s shadow and looking back at its rings from a distance of 142,000 miles.
» Read more

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SLS/Orion have begun 12-hour trip from VAB to launchpad

8:59 am

Artemis-2 mission flight path
The Artemis-2 flight path. Click for full animation.

NASA engineers today began the long and slow 12-hour trip of the SLS rocket from the Vehicle Assembly Building (VAB) to the launchpad in preparation for a targeted April 1, 2026 launch date of this Artemis-2 mission around the Moon.

NASA’s Artemis II SLS (Space Launch System) rocket and Orion spacecraft slated to send four astronauts around the Moon began rolling to Launch Pad 39B at 12:20 a.m. EDT on Friday, March 20. Rollout operations at the agency’s Kennedy Space Center in Florida were delayed earlier in the day due to high winds in the area.

The trek to the pad is expected to take up to 12 hours, as NASA’s crawler-transporter 2 carefully carries the rocket on top of the mobile launcher approximately 4 miles along the crawlerway.

The launch will send four astronauts on a ten-day mission swinging around the Moon and back to Earth, using a questionable heat shield and a life support system not yet been tested in space. On the first unmanned Artemis-1 mission around the Moon in 2022, the shield experienced far more damage than predicted, with large chunks breaking off. NASA engineers think they understand why this happened, and have decided that they can mitigate the problem by using a less stressful flight path upon return into Earth’s atmosphere.

They don’t really know if this is so, but they hope so. As for the life support system, the plan is to remain in a high Earth orbit for the mission’s first day to test it. If it has problems then, the crew will be able to return to Earth somewhat quickly. If it has problems after heading to the Moon, however, that won’t be possible.

If a private company tried to convince NASA to do this mission with these issues, the agency would say “Hell no!” It is proceeding because, like the Challenger and Columbia failures, it is a NASA-built project and politics and schedule have superseded safety and good engineering procedures

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Engineers regain contact with Proba-3’s Coronagraph probe

8:36 am

The Proba-3 mission
The Proba-3 mission. Click for original.

A month after all contact was lost with the Coronagraph probe of Europe’s two-spacecraft Proba-3 solar observatory, engineers have regained contact with it this week, and have been able to place it in safe mode in preparation for re-establishing science operations.

After more than a month of silence, ESA’s ground station in Villafranca, Spain, received telemetry from the Coronagraph spacecraft. Telemetry is a package of data sent by a spacecraft including information on its temperature, voltages, and health of onboard systems.

The Coronagraph is now in safe mode and stable, and the mission team and operators are running health checks on the spacecraft to understand if any parts of it have been damaged.

The spacecraft’s solar panel is facing the Sun, powering the essential electronics on board, and charging the battery with the remaining power.

Before it can resume observations engineers need to get the spacecraft back up to operating temperature after a month without power.

As shown in the graphic to the right, the Coronograph satellite is the heart of this mission. It records the data, available because the Occulter blocks the Sun from view so that the corona, the Sun’s atmosphere, can be seen. It is almost a miracle that it has survived that month, and can soon resume observations.

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