Tag: spaceflight

New research on ISS shows weightlessness causes significant harm to mice babies and their descendents

12:59 pm

A recent 42-day experiment on ISS, where mice were allowed to reproduce in weightlessness and produce offspring, has found that the weightlessness environment not only causes significant harm to mice conceived and born under these conditions, it appears to carry that harm down to at least the next generation.

From the abstract, which labels the first generation offspring as F1 and the next generation F2:

In the NASA Rodent Research 20 mission, we examined the impact of a 42-d spaceflight on the female reproductive axis including ovulatory capacity, implantation rate, and fecundity as well as behavioral, metabolic, and functional outcomes in F1 and F2 offspring. Females bred 5 d after return to Earth became pregnant but only exhibited a slight decline in fecundity compared to ground controls.

In contrast, F1 offspring from spaceflight dams exhibited marked growth, functional, and behavioral differences compared to F1 offspring from control dams. Moreover, F1 female offspring from spaceflight dams exhibited decreased ovarian reserves as evidenced by reduced anti-Mullerian hormone levels early in life (21 d of age) and premature ovarian failure or an early loss in fertility, as indicated by reduced numbers of litters and total number of pups born to females over a 9-mo period.

Strikingly, transgenerational metabolic and reproductive disturbances were also observed in F2 pups of spaceflight granddams, including persistent reductions in ovarian reserve, suggesting germline-level effects.

In other words, mice babies conceived and born in space exhibited serious issues that were also carried over into the next generation.

Though a number of similar studies have been done previously on ISS, the research is generally limited and inconclusive. Experiments on Earth duplicating lower or zero gravity suggest it has no effect on reproduction. This study however tested actual weightlessness, and found it decidedly harmful for newborn mice and later generations.

The results strongly argue that no woman should allow herself to become pregnant while in space. This conclusion might change given time, but I have my doubts. This result is what most people assume about the consequences of conception in weightlessness.

It also argues strongly for the need of some form of artificial gravity on future long term interplanetary space vessels. Without it, space travel will be significantly limited.

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The present state of NASA’s Artemis program

12:00 pm

Artemis logo

The aggressive effort by NASA administrator Jared Isaacman to rationalize and speed up the agency’s Artemis program to get back to the Moon and build a base there has resulted in a plethora of new missions, almost all of which are being built by the private sector.

Today Isaacman and his Moon Base program manager, Carlos García-Galán, held a press conference where they announced four more missions.

  • Astrobotic won a $297.9 million contract to build and fly two more of its smaller Peregrine lunar landers. This lander attempted a landing in 2024, but a fuel leak right after launch made that impossible.
  • Firefly won a $144.2 million contract to build and fly another Blue Ghost lander, the only commercial lander to successfully achieve a lunar soft landing, in 2025.
  • Intuitive Machines won a $148.3 million contract to build and fly another Nova-C lander. This lander attempted two landings, and in both cases it tipped over just after launch. The Nova-D design, under development, has a lower center of gravity, but for reasons not well explained by García-Galán NASA chose to go with the Nova-C design.

All are considered part of the first phase of the Artemis program and thus are targeting a launch by 2028.

In addition, NASA is considering using back-up equipment developed to build the Curiosity and Perseverance Mars rovers to create quickly and relatively inexpensively a lunar rover that they have dubbed “Promise.”

In order to make some sense of this program and these many misssions, I have created below a chronological list of confirmed missions, with their present status indicated (including uncertainties), as well as some unconfirmed missions based on my own speculations. All dates are tentative at this point, even if NASA has provided us a specific target date.

Several things to note as you review this list. While there are handful of missions going elsewhere, Isaacman is attempting to focus the program toward landing at the planned lunar base near the south pole, and to do so as fast as possible in the most effective way. The cargo missions and rovers are to get there ahead of the manned missions, in order to provide the astronauts supplies and surface transportation once they arrive. Those same missions will also do some preliminary scouting, and likely carry power and excavation equpiment needed to build the base.

It is also important to note that this plan is still in its very early stages of development. Many of the rockets and spacecraft and landers needed for these missions are not yet operational. Many have not yet demonstrated the capability to do what is requested. Thus, the program will certainly not follow the plan as presently outlined by the agency. Moreover, there will be failures along the way.

The program however is designed to accelerate development, to accept those failures within the program’s larger scope. If one mission fails, others are on the table to fly quickly to overcome the loss. And since the program is relying on the entire aerospace industry, the agency will have great redundancy from many companies.

I welcome comments and suggested changes or corrections. I fully intend to publish this list repeatedly over the coming years as the Artemis program evolves. And as the private sector begins flying its own missions to the Moon, independent of NASA, I intend to include those as well.
» Read more

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Study: Seventeen days in space does little to change brain power

10:31 am

According to a new study testing the vital brain signs of two astronauts before and after the seventeen day Axiom tourist mission to ISS in 2022, weightlessness and the space environment resulted in no sign of cognitive decline or changes in brain function.

You can read the paper here. From the abstract:

This study is a methodological demonstration of comparing cognitive performance and electroencephalography (EEG) brain vital signs in 2 astronauts before, shortly after, and 5 months following a 17-d mission to the International Space Station. Cognitive task performance remained consistent between pre- and post-spaceflight measures. Similarly, EEG brain vital signs revealed minimal change in the time-frequency domain. These findings suggest that short-duration spaceflight, combined with sufficient Earth adaptation time, showed no major decrements in cognitive and neurophysiological function.

Though it has been evident now since the 1960s that two- to three-week missions cause no lasting impact on the body or brain, this study documents a baseline technique for measuring the changes that might occur on longer flights.

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NASA’s IG: Boeing must foot the bill to get Starliner certified for manned flights

10:02 am

Starliner docked to ISS
Starliner docked to ISS.

The inspector general (IG) for NASA today released a new audit report [pdf] of the agency’s management of its manned commercial crew program, specifically looking at Boeing’s Starliner capsule and its failures. Though the IG made six recommendations, mostly about management procedures to better run the program, the first was the most important:

As the [Boeing] contract allows, defer payments, including partial or advanced payments, to Boeing for any Starliner-3 milestones until the human-rating certification of Starliner is complete.

In other words, the IG doesn’t want NASA to pay Boeing anything more. Boeing’s contract for Starliner was fixed price. It is Boeing’s responsibility to deliver the product, and until it does so NASA should lay out no more cash.

More significantly, NASA’s management immediately concurred with this recommendation.

This IG report now explains much of what happened in the past few months. » Read more

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New Horizons confirms: the solar wind slows as you travel outward

9:25 am

Figure 6 from the paper.
Figure 6 from the paper. Click for full resolution.

The science team for the New Horizons spacecraft, presently zipping outward towards the edge of the solar system, has confirmed earlier data from the Voyager spacecraft that the solar winds speed slows gradually as you move outward from the Sun.

You can read the paper here [pdf]. The distances are measured using astronomical units (AU), each equivalent to the distance from the Sun to the Earth, about 93 million miles.

Previously, New Horizons and Voyager 2 measurements between 30 and 43 AU indicated the solar wind was 5 to 10% slower than at 1 AU near Earth. Now, New Horizons researchers found at 58 AU that the solar wind is 13 to 15% slower than the wind at 1 AU. This gradual slowdown aligns with previous models of how interstellar material enters the heliosphere and affects the solar wind. It also demonstrates how the Sun’s influence decreases over long distances.

The scientists postulate that the slowing is caused by interaction with “interstellar neutral gas particles” that have managed to slip into the solar system. Their interaction with solar wind particles acts to slow the particles down.

New Horizons has not yet reached the termination shock that delineates the edge of the solar system. When it does, entering interstellar space, the wind speed will plummet significantly more, based on data from both Voyagers.

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The rise and fall of two Australian spaceports

8:53 am

Australian commercial spaceports
Australia’s commercial spaceports as of 2024. Click for original map.

Two stories today about the success of one Australian commercial spaceport and the failure of another illustrate perfectly the normal ups and downs one can expect from freedom and capitalism.

The ports in question are Southern Launch and Equatorial Launch Australia. In the first story, Southern Launch announced today that it has raised $25 million in private investment capital.

Adelaide-based spaceport operator Southern Launch has raised $25 million in a funding round led by national security investor Brindabella & Company, with the National Reconstruction Fund Corporation (NRFC) committing $10 million in direct equity to help scale Australia’s sovereign launch infrastructure.

The capital will fund expansion of Southern Launch’s two facilities – the Koonibba Test Range on the far west coast of South Australia and the Whalers Way Orbital Launch Complex near Port Lincoln – as the company works to meet growing demand from domestic and international launch customers.

Though the spaceport has obtained several tentative launch contacts, this success is mostly the result of its multiple contracts by capsule companies to use Koonibba as a landing site. There is a boom in this recoverable capsule industry at this time — with lots of investment money and multiple companies flying or building capsules. Koonibba at this moment has become the go-to place for such landings.

In the second story, we learn the sad fate of Equatorial Launch Australia (ELA). » Read more

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Rocket Lab buys Iridium

3:39 pm

In a blockbuster deal today, Rocket Lab acquired the satellite company Iridium and all its satellite constellation assets.

Rocket Lab will acquire all the outstanding shares of Iridium common stock for $54 per share in a cash and stock transaction. This represents an enterprise value for Iridium of approximately $8.0 billion.

The acquisition … merges Rocket Lab’s leading launch capabilities and satellite manufacturing with Iridium’s global satellite communications network, spectrum, and 500-plus strong partner ecosystem to create a competitive, vertically-integrated space company that designs, builds, launches, and operates its own constellations, delivering critical communications capability to millions of users worldwide.

The transaction will give Rocket Lab an immediate foothold in space-based applications, including both proprietary and standards-based satellite Internet of Things (IoT) and direct-to-device (D2D), PNT (GPS-capability), and critical safety-of-life services, creating a formidable challenger in the global telecom market.

This deal continues Rocket Lab’s aggressive effort in the last few years to diversify its capabilities beyond simply launching rockets. It has successfully demonstrated its ability to build satellites and even interplanetary probes. This merger immediately gives the company the spectrum and communications constellation that already has 2.5 million subscribers, with the ability to enhance and expand that constellation using its launch and satellite capabilities. With the introduction of its larger Neutron rocket next year, Rocket Lab will be well positioned to compete directly with all the other communications constellations, and to do it at a lower cost.

The deal also strengthens the company’s vertical integration. As the press release notes, it “creates an end-to-end space company spanning launch, spacecraft, spectrum, and on-orbit communications services through a proprietary network. Expected to eliminate third-party launch costs for constellation deployment and replenishment and captures launch margin internally while guaranteeing orbital access as launch capacity tightens, ensuring continuity of service to customers.”

Not surprisingly, the value of Rocket Lab’s stock today has leaped upward, rising from a closing price on Friday of around $85 to over $100 today (late Monday).

The industry trend across the board now is vertical integration, begun by SpaceX. It just pays to have the rocket company own the satellite constellation. Such a partnership lowers cost, and gives the company great flexibility and control. Expect more satellite constellations to team up with other rocket companies, especially the startups like Stoke Space and Relativity that are building reusable rockets.

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Hayabusa-2 to fly past asteroid July 5, 2026

9:13 am

Ryugu's northern hemisphere
Ryugu as seen by Hayabusa-2 shortly before it grabbed
samples from the surface in 2019. Arrow indicates planned touchdown
site.

Despite having only one working ion engine, Japan’s Hayabusa-2 asteroid probe will do a fast and extremely close fly-by of the asteroid Torifune on July 5, 2026.

The flyby will see Hayabusa2 get within 1 to 10 kilometers (0.62 to 6.2 miles) of Torifune, using its instrument suite to study the roughly 450-meter-wide (1,476 feet) asteroid as it whizzes past at 5.3 kilometers per second (3.3 miles per second).

Not much is known about Torifune, so a fly-by this close carries risk. In addition, three of Hayabusa’s four ion engines no longer work, and the fourth is starting to degrade.

If successful, however, the fly-by will not only tell us something more about Torifune, it will increase the chances Hayabusa-2 can reach asteroid 1998 KY26 in 2031. That asteroid is small, only about 35 feet across. The plan would be for Hayabusa- to fly in formation for a period, and even attempt a touch down.

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NASA asks industry for proposals for building lunar base infrastructure

8:57 am

NASA today issued a request for feedback from the private sector for building its Moon Base, including the infrastructure for providing “surface power, in-situ resource utilization, [and] advanced manufacturing.”

The solicitation focuses on five technologies that NASA considers necessary but insufficiently developed at this point, some of which it also considers necessary for exploring and colonizing the entire solar system.

  • Solar power generation, including power management and distribution, and energy storage.
  • Radioisotope power, for use by operating spacecraft systems in the solar system’s “darkest, dustiest, and most remote places”.
  • In-situ resource utilization, including using lunar materials to produce fuel, water, and oxygen.
  • In-space advanced manufacturing for producing “essential tools and materials” on the Moon and Mars.
  • Innovative nanomaterials, for use in spacecraft and instruments in order to reduce their weight and size at launch.

The announcement notes that NASA is requesting input from industry, hoping it can “identify any areas of ambiguity, or concerns.” The agency will then revise accordingly.

This solicitation is another example of NASA administrator Jared Isaacman’s push to rationalize the entire Artemis program, to take seriously the real requirements for building a Moon base. Previously NASA made noises along these lines, but management did not do the proper due diligence to figure out what needs to get built in order to actually make a Moon base happen.

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SpaceX launches Sirius radio geosynchronous satellite

11:55 pm

SpaceX tonight successfully launched a SiriusXM radio geosynchronous satellite, its Falcon 9 rocket lifting off from Cape Canaveral Space Force station in Florida.

The first stage (B1085) completed its 17th flight (31 days after its previous mission), landing on a drone ship in the Atlantic. The two fairings completed their 6th and 30th flights respectively.

This was SpaceX’s second launch today. The leaders in the 2026 launch race:

78 SpaceX
41 China
10 Rocket Lab (plus two suborbital HASTE launches)
8 Russia

For the third straight year SpaceX leads the entire world combined in total launches, 78 to 71.

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SpaceX launches 24 more Starlink satellites

9:16 am

SpaceX this morning successfully launched another 24 Starlink satellites, its Falcon 9 rocket lifting off from Vandenberg Space Force Base in California.

The first stage (B1088) completed its 17th flight (25 days after its previous flight), landing on a drone ship in the Pacific.

The leaders in the 2026 launch race:

77 SpaceX
41 China
10 Rocket Lab (plus two suborbital HASTE launches)
8 Russia

For the third straight year SpaceX leads the entire world combined in total launches, 77 to 71.

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First unmanned test of India’s manned Gaganyaan capsule possibly delayed until late ’27

9:11 am

Artist rendering of India's Gaganyaan capsule
Artist rendering of India’s Gaganyaan capsule

In a presentation yesterday, the head of India’s space agency ISRO V Narayanan indicated that the first unmanned test flight of its manned Gaganyaan capsule might be delayed until the third quarter of 2027.

That test flight was originally targeting a March 2026 launch — part of a series of three unmanned test flights before the manned flight in early 2027 — but March came and went and nothing happened, nor did ISRO explain the lack of any action.

In indicating the possible delay, Narayanan also noted that the agency was looking at a launch before the end of this year. A delay until late ’27 — more than a year — however would suggest a significant issue. It would also mean the manned flight could not occur until 2028, at the earliest.

When Gaganyaan was first proposed in 2018, the goal was to have the first orbital flight in 2022. Since then the program has experienced endless delays and postponements. This new announcement, with no explanation, fits ISRO’s recent pattern of secrecy. No specific reasons for this year’s delays have ever been offered. Meanwhile, the agency has refused to outline for more than two years the specific causes of the two PSLV rocket failures of its third stage, both of which occurred at almost the exact same time in launch.

The secrecy suggests a cultural problem at ISRO, even more serious than a technical one. It implies an unwillingness to deal with error, thus resulting in repeated failures.

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Rocket Lab launches another radar satellite for Japanese company Synspective

10:55 am

Rocket Lab early today successfully completed its tenth launch (out of a 27-launch contract) for the Japanese radar satellite company Synspective, its Electron rocket lifting off from one of its two launchpads in New Zealand.

The leaders in the 2026 launch race:

76 SpaceX
41 China
10 Rocket Lab (plus two suborbital HASTE launches)
8 Russia

For the third straight year SpaceX leads the entire world combined in total launches, 76 to 71.

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Tiny polygon ridges on Mars

9:19 am

Tiny polygon ridges on Mars
Click for original image.

Cool image time! The picture to the right, cropped and reduced slightly to post here, was taken on June 21, 2026 by the high resolution camera on the Mars rover Curiosity. It looks down to provide a close-up of the ground the rover is presently parked over, a surface covered with thousands of these tiny polygon ridges, all of which appear less than three inches across.

For a wider view and the overall context, see my post from June 24, 2026. While from a distance the ground at this point looked smoother than anything the rover has seen in more than five years since it entered the foothills of Mount Sharp, once it got close it discovered the ground was completely covered with these small polygons.

The picture to the right is part of a close-up mosaic of these polygons the science team is gathering using the high resolution camera.

The geology here is certainly puzzling. Polygon cracks are not unusual on both Earth and Mars, in places where the ground was once wet and then dried. In drying the material shrinks, producing polygon-configured cracks. On Earth those cracks often fill later with material that is more resistant, such as lava, which remains to form ridges when the surrounding dirt erodes away. Whether this was the process here on Mars however is not known. For one thing, why are these polygons so small? And why so uniform in size?

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SpaceX’s proposed cloud constellation of a million satellites named “Starmind”

8:54 am

Elon Musk has confirmed that SpaceX has named its proposed constellation of a million data computing satellites will be dubbed “Starmind”, following its pattern in recent years of naming every new project in a similar manner.

After Starship, Musk has named every project a variation thereof. We have had Starlink, Starshield, Starbase, Starfactory, Starfall, and now Starmind. It is also building natural gas pipeline to supply methane to Boca Chica that it has dubbed Starpipe.

The company hopes to launch the first Starmind satellites on Starship early in 2027.

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Firefly buys the AI navigation technology used on its Blue Ghost lunar landing

8:45 am

Blue Ghost's shadow on the Moon, with the Earth in the background
Blue Ghost’s shadow on the Moon, with the Earth in the background,
after its 2025 touchdown.

Firefly has now acquired Space-ng, the company that makes the AI navigation technology and software that Firefly used on its successful Blue Ghost lunar landing in 2025.

Space-ng’s vision navigation software was utilized during Firefly’s historic Blue Ghost Mission 1 to determine position and attitude, detect hazardous lunar terrain, and autonomously redirect Blue Ghost in real-time, enabling a safe, precise touchdown within the Moon’s Mare Crisium.

…In addition to vision navigation software, Space-ng brings high-resolution spacecraft cameras and AI compute hardware to enable advanced space domain awareness, onboard optical navigation, rendezvous and proximity operations, and docking without requiring GPS or GNSS. Firefly plans to integrate Space-ng’s technologies across its fleet of lunar landers and orbital vehicles to support its growing mission manifest, including three additional lunar missions under NASA’s Commercial Lunar Payload Services initiative, another lunar mission supporting NASA MoonFall, and a space domain awareness mission for the Defense Innovation Unit.

Of all the recent attempts by commercial companies to land on the Moon, Firefly is the only one to have a complete success. While Space-ng’s technology worked perfectly to guide Blue Ghost to a safe touch down, the guidance technology used by Intuitive Machines (twice), Ispace (twice), Beresheet, and the first Vikram lander for India all failed close to landing. No wonder Firefly decided to buy it.

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Musk’s employee stock options made them millions; Bezos’s employee options were worthless

8:31 am

According to a very intriguing article at Business Insider today, the stock options offered to employees at SpaceX and Blue Origin were starkly different, with SpaceX’s options making millions for its workers while Blue Origin’s were essentially worthless.

Three ex-employees of Jeff Bezos’ rocket maker Blue Origin told Business Insider that the company’s unusual approach to equity left them with stock options that are essentially worthless.

Meanwhile, they’ve watched SpaceX’s dizzying rise to a $2 trillion-plus valuation provide a massive windfall for early hires — from engineers to welders to cafeteria workers — who received stock options during their time at Elon Musk’s company.

Blue Origin’s options were written so that they only could be cashed in if the company went public within ten years. As Bezos has shown zero interest in going public — which would take away his full ownership and control of the company — those options have been steadily expiring as they reach their ten year due date.

At SpaceX however the employee stock options could always be cashed in, even before the company went public. Employees, both current and former, were allowed to sell their stock back to SpaceX or to its investors in private liquidity events that usually occurred twice each year. After the IPO they could now sell the stock on the open market, at the going rate.

The difference is possibly one additional reason the accomplishments of the two companies have been so starkly dissimilar/ SpaceX made sure its employees got a pay off for the long hours it demanded. Blue Origin did not.

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Astronomers: We might be experiencing a shower of comets from the distant Oort cloud due to a close pass of another star 2.5 million years ago

1:18 pm

The uncertainty of science: Using computer models and the somewhat sparse data about the distant Oort cloud on the outer fringes of our solar system (from 2,000 to 200,000 astronomical units [au] away) and combining that with the data from the Gaia space telescope that mapped precisely the motions and distances of billions of Milky Way stars, astronomers now posit that the close pass of another star about 2.5 million years ago perturbed the Oort cloud and thus produced the shower of comets that humanity has been experiencing for the last few thousand years.

HD 7977 is a still nearby Sun-like star in the constellation Cassiopeia whose close passage was discovered by the Gaia mission. Approximately 2.5 million years ago, the orbits of the Sun and HD 7977 brought the two stars close together, but exactly how close is still an open question. Gaia data suggest they passed within 4000-25000 astronomical units of one another. Now, Kaib and Raymond have shown that the orbits of long-period comets suggest HD 7977 came within 6000-10000 AU of our Sun, setting off a major shower of new comets into the inner solar system.

You can read the preprint paper here [pdf].

These results are filled with many uncertainties of course. For one, the actual distance for HD 7977’s close pass is not well constrained. The margin of error is large, so that the star might have not done anything at all. Second, our map of the Oort cloud is very uncertain. In fact, it exists at this time only in theory, as it has never been directly observed. Astronomers hypothesize its existence based on the orbits of the long period comets that they have documented for the past few centuries, all coming from that distant region. So while it appears to exist, that existence remains unproven.

These uncertainties thus make the conclusions of this paper interesting but unconfirmed. Nonetheless, they are fascinating, because they are strongly suggestive, and hint at the impact of the galaxy and its stars on the evolution of our solar system itself. That impact is real, though tracing its history is difficult because of the vast time scales and distances. It appears the Gaia data and computers are giving us a first glimpse into that past history.

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South Korea’s space agency wants to accelerate its launch capabilities

10:53 am

The head of South Korea’s space agency KASA, Oh Tae-seok, yesterday outlined plans to to accelerate the launch cadence of its government-built Nuri rocket, while also beginning research into building a second spaceport along with a specific launchpad for private companies.

Oh Tae-seok, head of KASA, held a press briefing at the agency in Sacheon, South Gyeongsang Province, on Thursday. “This week, the assembly of the first, second, and third stages of the fifth Nuri rocket will be completed,” he said. “From next week, we will begin full assembly of the entire rocket, and after the Launch Management Committee in early August, a September launch is expected.”

Oh also stressed the need to build a repeated launch system after the fifth launch to advance toward an era of “commercial launch services.” “To ensure the economic viability of Nuri, changes are needed in standardization and specification, as well as contracting methods and launch site operations, in addition to the advancement project,” he said. “We are preparing for four launches from 2029 to 2032.”

In addition, the agency plans to accelerate construction of the second spaceport. KASA began accepting candidate site applications for the second spaceport on the 22nd of this month. “We will select the final candidate site in October this year and aim to begin the project in 2028,” the agency said Thursday.

This second news report quoted Oh as also saying this:

“In the 2030s, rather than the current R&D approach, we should consider converting to a system where we commission launch services through purchasing, as NASA does.” This is a model similar to how NASA purchases launch services from private companies such as SpaceX.

In other words, even as he accelerates the use of Nuri, Oh wants to replace it with private rockets. Whether he can do both is questionable, because they act to cancel each other. A cheaper and viable government rocket will make it difficult for private startups to compete.

At the moment South Korea has one truly viable rocket startup, Innospace, which has one launch failure and hopes to try again before the end of the year. That it does not launch in South Korea but in Brazil suggests KASA has not been as cooperative with the commercial sector as Oh wants. His statements about building a launchpad for the private sector suggest he is aware of this.

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Astronomers discover two exoplanets as dense as cotton candy

9:40 am

The observed transits of TOI-791 c.
The observed transits of TOI-791 c by different telescopes
during its 232 day orbit. Figure 9 from the paper.

Using a combination of ground- and space-based telescopes, astronomers have now discovered two exoplanets in the same solar system that have a deas dense as cotton candy.

You can read their paper here. From the NASA press release:

Data from NASA’s TESS (Transiting Exoplanet Survey Satellite) mission has revealed two new “super-puff” planets, giant worlds so light that their density is comparable to cotton candy. Scientists calculate that these Jupiter-sized planets—named TOI-791 b and TOI-791 c—are the “puffiest” worlds ever found.

The planets orbit a Sun-like star named TOI-791 that is approximately 1,113 light years away from Earth. The TESS mission first detected the planets by watching for repeated dips in TOI-791’s brightness, a telltale sign that a planet is transiting, or passing in front of, a star. Further study revealed two large planets with unusual features.

TOI-791 b is nearly the same size as Jupiter but contains just 3.0 percent of Jupiter’s mass. TOI-791 c is even larger than Jupiter but contains just 5.9 percent of Jupiter’s mass.

The data for determining both planet’s density came from follow-up observations using a telescope based in Antarctica. Both planets have long orbits, 139 and 232 days respectively, so these observations took place over a period of eight years, in order to capture multiple orbital transits.

One interesting tidbit: Though the data suggests both planets are spherical, this is not confirmed with certainty. Overall, the nature of such puffy planets is not really understood at this time.

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