“A Day in Space” – July 16, 2020 – National Space Society virtual event

An announcement from the National Space Society (NSS):

A Day in Space – NSS

Join us on July 16, 2020, for a remarkable event: A Day in Space, the first NSS live virtual speakers’ series!

This exciting, one-day virtual event will take you on a journey that begins with the Space Race, explores the solar system, examines the science and technology of human spaceflight, and looks at the future of space settlement. Exclusive bonus material will follow the premiere of A Day in Space. And best of all, it’s entirely FREE!

Guests include NSS leaders, Apollo astronauts and flight directors; engineers and scientists working on NASA’s planetary exploration programs; astrophysicists who search for habitable exoplanets; and educators, physicians, and investors focusing on the business and future of NewSpace and space settlement.

Besides the full-day premium event on July 16, those who sign up for A Day in Space will receive exclusive bonus content released in the following weeks—you can enter your email address at the A Day in Space website, https://adayinspace.nss.org/, to receive updates, bonus content, and a chance to win free books, meteorites and other cool space swag!

A Day in Space will be available across multiple platforms, including:

  • The NSS Facebook page
  • The NSS Youtube channel
  • The e360tv streaming TV network
  • e360tv’s Roku/AppleTV/Amazon Fire platforms
  • e360tv’s mobile streaming platforms
  • Space.com’s Youtube channel

More information can be found at the A Day in Space website, https://adayinspace.nss.org/. The presentation will be archived on the e360tv platform and the NSS Youtube page and website for future viewing.

We’ll see you at A Day in Space on July 16. For more information and to register for updates and prizes go to https://adayinspace.nss.org/



=== Space Art from C. Sergent Lindsey ===

Sweatshirt imprinted with “SpaceX Delivers the Goods” by C Sergent Lindsey.

Videos: “Space to Ground” ISS report – July.4.2020

Here is the latest episode in NASA’s Space to Ground weekly report on activities related to the International Space Station:

Other recent ISS related videos:

** Expedition 63 July 4th Message – July 3, 2020

Aboard the International Space Station, Expedition 63 Commander Chris Cassidy of NASA and NASA Flight Engineers Doug Hurley and Bob Behnken of NASA shared their thoughts about the 244th birthday of the United States in a downlink message received from the complex on June 19. Orbiting 260 miles above the Earth, the three American astronauts discussed the challenges facing the nation at this moment in history and the resolve of the nation in forging ahead with human exploration in the name of peaceful cooperation for the benefit of all humanity.

** Live Event with Astronaut Kate Rubins – July 1, 2020

On her first trip to the International Space Station, Kate Rubins became the first person to sequence DNA in space. Find out the plans for her next trip during a live event at 4 p.m. ET Wednesday, July 1. Rubins and two Russian crewmates will launch to the station in October.

** Expedition 63 InFlight event with Various Media – June 29, 2020

Aboard the International Space Station, Expedition 63 Commander Chris Cassidy of NASA and NASA Flight Engineer Robert Behnken discussed the progress of their mission during a series of in-flight interviews June 29 with the Washington Post, the Associated Press and NBC Nightly News’ “Kids Edition.” Cassidy is in the midst of a six-and-a-half month mission on the orbital outpost, while Behnken is completing a month on orbit after he and NASA crewmate Douglas Hurley launched May 30 on the SpaceX Falcon 9 rocket and the “Endeavour” Crew Dragon spacecraft in the first crewed mission in Commercial Crew Program history.

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Space transport roundup – June.30.2020

A sampling of recent articles, videos, and images dealing with space transport (find previous roundups here):

** SpaceX Falcon 9 successfully sends USAF GPS satellite into orbit. First stage booster on first flight lands safely on ocean platform. This was the first time SpaceX was allowed by the USAF to return and recover the booster when launching a military payload.

The fairings were recovered from the water:

See also:

Find more about other SpaceX activities below.

** Virgin Galactic‘s SpaceShipTwo VSS Unity glides back to Spaceport America for second time, setting the stage for the first powered flights from the New Mexico facility. Virgin Galactic’s SpaceShipTwo Completes Second Flight from Spaceport America – Virgin Galactic

AS CRUCES, N.M. June 25, 2020 -Virgin Galactic Holdings, Inc. (NYSE: SPCE) (“Virgin Galactic” or “the Company”) today announced the successful completion of the second SpaceShipTwo test flight from Spaceport America. This flight follows the completion of the first test flight from the Company’s commercial headquarters in New Mexico on May 1, 2020, and marks another important milestone as the team progresses toward the launch of Virgin Galactic’s commercial service.

On SpaceShipTwo Unity’s flight deck were Mark ‘Forger’ Stucky and Michael ‘Sooch’ Masucci. Both pilots are commercial astronauts, having each previously flown Unity into space on different flights. Piloting the Company’s carrier aircraft, VMS Eve, were Nicola Pecile and CJ Sturckow.

This glide flight, flown at higher speeds, allowed the team to continue to evaluate systems and vehicle performance in advance of future rocket-powered space flights from the Company’s new operating base in New Mexico. Flying VSS Unity in glide configuration at higher speeds enables certain vehicle systems to operate close to the environment seen during phases of rocket boost on a spaceflight. The spaceship achieved a glide speed of Mach 0.85 after being released from the mothership VMS Eve at an altitude of 51,000 ft. Unity completed multiple test-points before touching back down smoothly for a runway landing at Spaceport America.

Forger and Sooch performed a series of maneuvers with Unity designed to gather data about performance and handling qualities while flying at higher speeds. This data will be verified against similar maneuvers that were performed in the previous glide flight to enhance aerodynamic modelling.

Pending the completion of an extensive data review of this flight, the team will start preparing for the next stage of our flight test program – powered spaceflights from Spaceport America. In addition to the data review, we have several steps to complete, including final modifications to the spaceship customer cabin and detailed inspections of the vehicle and systems.

See also: Virgin Galactic completes second successful glide test at Spaceport America – Spaceport America

** Virgin Galactic may fly NASA astronauts in addition to space tourists: Virgin Galactic is ‘excited’ about the opportunity to fly NASA astronauts – CNBC

Virgin Galactic is steadily moving closer to flying customers to the edge of space for the first time but the space tourism company is looking forward to the growing opportunity to fly NASA personnel as well. 

“I’m really excited about this one because for a long time NASA has been thinking about using suborbital vehicles, the ones that we’ve got, to train their astronauts and other NASA employees like researchers to go into space,” Virgin Galactic CEO George Whitesides told CNBC’s Morgan Brennan on “Squawk Alley.”

FAA approval for commercial suborbital spaceflights could be coming soon:: Virgin Galactic expects to receive key FAA license within next two spaceflights – CNBC

** Boeing tests parachutes for Starliner crew vehicle:Boeing: Starliner Parachutes Perform Under Pressure – Boeing

This latest balloon drop, conducted high above White Sands Space Harbor in New Mexico, demonstrates Starliner’s parachutes continue to perform well even under dynamic abort conditions and a simulated failure. Boeing and NASA jointly developed the conditions for this test as part of a comprehensive test campaign to demonstrate Starliner parachute performance across the range of deployment conditions.

Teams wanted to be sure that if an abort were to occur early into launch, certain parachutes in Starliner’s landing sequence would inflate correctly despite needing to deploy in significantly different flight conditions than those seen with normal landings.

“Parachutes like clean air flow,” said Jim Harder, Boeing’s flight conductor. “They inflate predictably under a wide range of conditions, but in certain ascent aborts, you are deploying these parachutes into more unsteady air where proper inflation becomes less predictable. We wanted to test the inflation characteristics at low dynamic pressure so we can be completely confident in the system we developed.”

See also Boeing gives Starliner crew capsule’s parachutes a workout in drop test – Space.com.

**** Blue Origin delivers a BE-4 engine to ULA. BE-4 engines will power the first stage booster on the company’s new Vulcan rocket. This is a “pathfinder”, which means it will be used for ground testing but not for flight. Blue Origin delivers the first BE-4 engine to United Launch Alliance – SpaceNews.com

** A problem with Atlas V launcher causes delay in launch of Perseverance Mars rover. Current “no-earlier-than” date for liftoff is July 30th. The window for launching to Mars closes around mid-August. So the margin for further delay is decreasing. If the rover is not launched by mid-August, it will have to wait over two years before the next opportunity to takeoff for the Red Planet.

A technical issue with the United Launch Alliance Atlas 5 rocket that will send NASA’s $2.4 billion Perseverance rover toward Mars has pushed the mission’s launch date back to no earlier than July 30, nearly two weeks into a month-long window for the rover to head to the Red Planet, or else face a two-year delay.

NASA confirmed the launch delay to no sooner than July 30 in a statement Tuesday.

“Due to launch vehicle processing delays in preparation for spacecraft mate operations, NASA and United Launch Alliance have moved the first launch attempt of the Mars 2020 mission to no earlier than July 30,” NASA said. “A liquid oxygen sensor line presented off-nominal data during the Wet Dress Rehearsal, and additional time is needed for the team to inspect and evaluate.”

** Sierra Nevada begins bonding thermal protection tiles to the Dream Chaser spaceplane.

TPS tiles protect the vehicle from re-entry heat. Around 2,000 of these tiles will protect Dream Chaser from temperatures that could reach upwards of 3,000°F on entry, while keeping the vehicle itself at only 350°F. The white tiles reject more heat from the sun while on-orbit, which helps to keep the components within Dream Chaser cooler. In comparison, more than 24,000 tiles were used on NASA’s space shuttles orbiters. Dream Chaser is about 30 feet long, or about ¼ the total length of the space shuttles.

In order to keep the tiles on Dream Chaser, our engineers are using room temperature vulcanizing (RTV) silicone. RTV silicone is able to withstand high temperatures, making it perfect for bonding the tiles. Each tile is tested by using a mechanism that pulls on them, which ensures the bond is sufficient.

SNC engineers have been able to update our TPS tiles from what was used during NASA’s shuttle program with more innovation, better technology and utilizing lessons learned.   We use more modern manufacturing techniques to increase strength and reduce cost. Another difference between the tiles is Dream Chaser tiles are about 10 inches by 10 inches, while those on the shuttle were six inches by six inches.  Dream Chaser is also smaller in size, which also means less tiles to replace in general.

Dream Chaser tiles are stronger and lighter weight than those used during the shuttle program and meet all Micro-Meteroid Orbital Debris (MMOD) requirements to ensure safe entry, descent and runway landings for crewed or cargo missions.

** An air-breathing rocket engine is in development at Mountain Aerospace Research Solutions. The project is described in: The rocket motor of the future “breathes” air like a jet engine | Ars Technica

A rocket normally carries all the oxidizer needed to burn its fuel. So the rocket engine(s) must accelerate the mass of both the rocket’s structure, engines, payload, etc and also the fuel + oxidizer. This results in getting only a few percent of the total mass at liftoff into orbit.  If during the ascent through the atmosphere the rocket could use external oxygen from the air instead of from onboard tanks, this could allow for putting far more payload mass into orbit.

Reaction Engines has been developing the SABRESynergetic Air Breathing Rocket Engine” for over two decades to do just this. The SABRE propulsion system uses an elaborate precooler to cool down the air that is heated up as the vehicle flies faster and faster through the atmosphere. The precooler “Rapidly cools the incoming air (1,000 °C to ambient) enabling SABRE to operate at higher speeds than existing engines”. During takeoff and once the SABRE is out of the atmosphere, the SABRE operates with onboard liquid oxygen like a conventional rocket. The company believes the SABRE will enable a single-stage-to-orbit (SSTO) fully reusable vehicle.

Mountain Aerospace, a small startup company based in Montana, claims the FenriS engine is a new and unique design for an air-breathing rocket. The details of the design have not been revealed but the company has given a general description and released a video of the first static test firing. It appears that as fuel is pumped into the combustion volume, air is sucked in and the two are ignited. For the first test, the plume was  a big mess but they say it demonstrated the basic functions of the design.  It’s certainly an accomplishment if one’s first prototype rocket engine doesn’t blow up. Presumably, further tuning and design refinements can produce a more impressive plume.

While a ground test is a good start, they still must overcome a number of fundamental hurdles to development of an orbital capable system. For one, the system must deal with the problem that the SABRE’s precooler solves – the super hot incoming air.  Combustion is more efficient if the air mixes with fuel at low temp. Another major challenge for airbreathing space vehicles designs is handling the heat build-up on the structure. The vehicle must spend more time in the atmosphere than a conventional rocket, which gets out of the thick atmosphere as soon as possible, while gaining speed. The friction with the air raises the temperature on the skin of the vehicle. Thermal protection adds weight and undermines at least some of the gains from using atmospheric oxygen.

These two videos show the static test and give some information about the company and the Fenris design.

** The Planetary Society’s LightSail-2 remains in orbit, using sunlight pressure to fight drag from the very thin but non-negligible atmosphere that it flies through:  LightSail 2: Celebrating One Year in Space – Planetary Society

Join Bill Nye and members of the LightSail 2 mission team as they mark the end of the primary mission and the beginning of extended operations after one year in orbit. Panelists include:
-Bill Nye, Chief Executive Officer of The Planetary Society
-Jennifer Vaughn, Chief Operating Officer of The Planetary Society
-Bruce Betts, LightSail Program Manager and Chief Scientist of The Planetary Society
-Dave Spencer, LightSail 2 Project Manager and NASA/JPL Mission System Manager for Mars Sample Return

** Firefly aiming for first launch of orbital Alpha rocket in mid-October: Firefly Aerospace is connecting the dots to fly above smallsat launch challenges – Connectivity Business

Jason Rainbow: A test stand fire in January set Firefly back a bit and then, of course, COVID-19 started taking its toll. Where are you with plans to launch the first Alpha rocket?

Tom Markusic: The plan is now mid-October this year, which does represent a couple of months slip from earlier. The fire we had didn’t put us back very far, actually, there was no damage to the test stand, and we’d gotten most of the test data we wanted out of this stage anyway. It was perhaps a month and we had another month/month and a half related to COVID. Overall, I think we’ve been very fortunate in both incidents that we weren’t set back for a longer duration.


As a tribute to Max Polyakov, who rescued  Firefly from liquidation, the company lit up birthday cake candles in the best way rocketeers know how to do:  Firefly Aerospace uses rocket engine to light birthday candles in epic cake video – Space.com

Let’s light that candle! The folks at Firefly Aerospace took a brief break from rocket development recently to fire up an engine in honor of co-founder Max Polyakov, who turned 43 years old Tuesday (June 30).

The Lightning upper stage engine, in true celebratory form, was used to light candles on a large birthday cake as high-speed cameras rolled, according to a new video. (The other planned use for the engine will be to help launch small satellites to orbit cheaply, using Firefly’s Alpha rocket.)

** Briefs:


Check out the
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The latest issue:
Riding a Dragon, Rockets Rising, Space Resource Policy
Vol. 15, No. 4, June 14, 2020

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** SpaceX:

**** The Starlink 9 mission set to launch  last week with 57 Starlink satellites and 2 Blacksky imaging satellites was postponed due to an undisclosed technical issue. (There were rumors of a small pressure drop in a propellant line to one of the booster engines.) The launch of the GPS satellite described above became the top priority. The current target launch date for Starlink 9 is July 8th. SpaceX postpones Starlink launch – Spaceflight Now.

Meanwhile, work continues on development of a ground system for the Starlink Internet system that would be affordable for consumers: One of SpaceX’s most ambitious projects remains on the ground, for now – CNBC

Starlink’s major terrestrial hurdle, Musk acknowledges, is the antenna that will get users online — the internet analog of the TV parabolic dish. Starlink’s low-flying satellites zoom across the sky in about five minutes, and antennas will need to keep up. SpaceX’s design has to balance technological sophistication with mass-market affordability.

The company plans to use “phased array antennas,” which can direct the machine’s focus electronically rather than physically spinning it around. The technique simplifies the device mechanically, but comes at a high price. Farrar estimates that the gadget could cost more than $1,000, although Musk is targeting a price tag of under $300. In March, the FCC authorized SpaceX to distribute one million antennas, and SpaceX board members recently tested the devices (which reportedly resemble “UFOs on a stick”), but the company has not yet announced the retail version. 

**** Despite the Starlink 9 delay, SpaceX launch rate is on a tear despite lockdowns, etc : Even amid a pandemic, SpaceX is launching more than ever | Ars Technica

“The successful GPS III SV03 launch and recovery serves as another step in our journey with industry partners to create innovative, flexible, and affordable services to meet NSSL mission objectives and propel US dominance in space,” said Col. Robert Bongiovi, Launch Enterprise director.

Tuesday afternoon’s launch puts the company on pace for 22 missions in this calendar year, which would break the company’s previous record of 21 launches set in 2018. What seems more remarkable about this pace is that it has occurred amid a global pandemic that has slowed operations in many other countries.

For example, SpaceX’s 11 launches match the total so far this year by Russia, Europe, and Japan combined. Globally, the company ranks second only to China’s state enterprise, which has attempted 15 orbital launches in 2020, two of which have been failures.

**** The Crew Dragon docked to the ISS is performing well. After nearly a month in space, NASA seems really happy with Crew Dragon | Ars Technica

Before this flight of Dragonship Endeavour, one of the biggest questions from engineers at NASA and SpaceX concerned the durability of the spacecraft. The first Crew Dragon spacecraft launched on an uncrewed test flight in 2019 and spent less than a week attached to the space station. NASA hoped this Dragon could last a few months in space.

In particular, the engineers were not sure how quickly Endeavour’s solar panels would degrade and accordingly produce less power. Therefore, since the spacecraft docked to the station, it has been powered up once a week to test power output from the solar panels.

So far, said the manager of NASA’s Commercial Crew Program, Steve Stich, the panels are producing more power than expected. “The vehicle is doing extremely well as we put it through its paces,” Stich said Wednesday during a news conference. NASA had hoped Endeavour could stay docked to the space station for as long as 114 days, and Dragon should easily be able to meet that threshold.

**** Reuse of 1st stage boosters now required for sustaining SpaceX operations: For SpaceX, Falcon 9 reuse is now essential | Ars Technica

To complete all of these missions will require the company to continue to successfully return its first stages, push beyond five flights per booster, and possibly further reduce the turnaround time between missions. So far, the company’s record for the time required to check and re-certify a Falcon 9 first stage for flight is 63 days.

The bottom line is that today’s launch of a Falcon 9 rocket is an essential mission for the US Air Force. But for SpaceX, getting the new core back on the Just Read the Instructions droneship will be just as important to flying out a lengthy manifest in 2020. Reuse is no longer experimental; it’s on the critical path.

See also:

****  SpaceX’s Abandoned Plans – Final Episode (for now!)Scott Manley

The final batch of projects which SpaceX announced development of but later abandoned in favour of other goals. As technology was developed some plans were realised to be beyond what was possible in the timescale, or more cost effective solutions were discovered, or the benefits weren’t going to deliver an advantage to the overall business.

**** Starship

****** Starship prototype SN5 takes center stage at Boca Chica. The test vehicle was rolled to the pad area and mounted on the launch structure last week. On Tuesday evening through Wednesday morning, cryogenic pressure tests with liquid nitrogen appeared to go well: Starship SN5 completes successful cryogenic proof, commencing test campaign – NASASpaceFlight.com

****** Elon hints he will continue his series of annual updates on the Starship program with a presentation this September: SpaceX Starship event expected this September, says Elon Musk – Teslarati

****** Latest animated illustration of the launch pad facility at Boca Chica: SpaceX Starship Launch Pad Update / June 24th, 2020Alex Rex

This short video shows a virtual flight over the Starship Facility in Boca Chica, TX on June 24th, 2020. It is kept as simple as possible with major focus on BUILDINGS, JIGS and STARSHIP-Parts. For other design projects, please visit my webpage: http://www.alexrex.de/

****** June 26: SpaceX Boca Chica – New downcomer arrives, thrust section spotted, and SN5 testing preps – NASASpaceflight – YouTube

A new downcomer and thrust section were spotted today for a future Starship prototype. Meanwhile, work at the pad continues to prepare Starship SN5 for testing. Video and Pictures from Mary (@bocachicagal). Edited by Jack Beyer (@thejackbeyer).

****** June 29:  SpaceX Boca Chica – Super Heavy and Future Starships line up ahead of SN5 test preps – NASASpaceflight – YouTube

Another epic sunrise marked the start of another day of work on SN5, future Starships and the Super Heavy launch site. SN5 is set for proof testing as early as Tuesday. Video and Pictures from Mary (@BocaChicaGal). Edited by Brady Kenniston (@TheFavoritist).

****** Julye 2: SpaceX Boca Chica – Starship SN5 Preps for Raptor and Tracking Station Action – NASASpaceflight – YouTube

The Thrust Simulator is removed from the launch mount as SN5 is readied to receive a Raptor Engine and progress to the next phase in testing. A new nosecone is moved outside and the tracking station tracks Falcon 9 Stage 2 and GPSIII-3 shortly after launch. Video and Pictures from Mary (@BocaChicaGal). Edited by Jack Beyer (@TheJackBeyer)

** Webcast rocket reports:

**** Starship updates with SN7 explosion & SN5 news, Starlink test terminals, Mars Perseverance RoverMarcus House

Another action-packed week of space news. Starship updates with the SN7 explosion being a key topic of the week. SN5 updates continue with it rolling to the launch site. We’ve finally seen some Starlink test terminals (hopefully we’ll have access to these more broadly soon to trail the service). Rounding out all of that space goodness, NASA remains confident that the Mars Perseverance rover mission will launch on schedule, so we are eagerly awaiting that launch, now less than a month away.

**** SpaceX Starship Updates – Countdown To Mars: Perseverance’s Last Days On EarthWhat about it!?

In this Episode, we will take another good look at the new SpaceX Super Heavy & Starship launch pad under construction in Boca Chica right now. We wil also take a look at a new Launch Control building, Starship SN7’s test to destruction, SN5’s roll out to the SpaceX Launch facility in Boca Chica and the Boston Dynamics Spot called Zeus, checking for hazards. Last but not least, we will take a look at the ongoing preparations for NASA’s and ULA’s launch of the Mars 2020 rover Perseverance towards the red planet.


=== The Art of C. Sergent Lindsey ===

Grainger Tomato” by C. Sergent Lindsey printed on a throw pillow. Available at Fine Art America.

Night sky highlights – July 2020

[ Update:  What’s Up: Skywatching Tips from NASA – NASA Solar System Exploration

What are some skywatching highlights you can see in July 2020? Enjoy the giant planets Jupiter and Saturn with their moons, stay up late to spot Mars rising. Plus: what would you see stargazing on the Red Planet? Additional information about topics covered in this episode of What’s Up, along with still images from the video, and the video transcript, are available at https://solarsystem.nasa.gov/whats-up….


** Tonight’s Sky: JulySpace Telescope Science Institute

In July, find the Scorpius constellation to identify the reddish supergiant Antares, which will lead you to discover a trio of globular star clusters. Keep watching for space-based views of these densely packed, spherical collections of ancient stars, as well as three nebulas: the Swan Nebula, the Lagoon Nebula, and the Trifid Nebula.

** What’s in the Night Sky July 2020 #WITNS | Lunar Eclipse | Milky Way | NLCs – Alyn Wallace

** What to see in the night sky: July 2020BBC Sky at Night Magazine

What can you see in the night sky this month? Astronomers Pete Lawrence and Paul Abel reveal their stargazing tips for July 2020.

** July 2020: Rare Astronomical Events (Best Month for Stargazers) –

July is the best month for Stargazers! Watch the video to know why. Music: Stratosphere by Adam Vitovsky

** Skywatch: What’s happening in the heavens in July – The Washington Post

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ESO: Massive star vanishes from view

The latest report from the European Southern Observatory (ESO):

A Cosmic Mystery:
ESO Telescope Captures the Disappearance of a Massive Star

This illustration shows what the luminous blue variable star in the Kinman Dwarf galaxy could have looked like before its mysterious disappearance. Credits: ESO

Using the European Southern Observatory’s Very Large Telescope (VLT), astronomers have discovered the absence of an unstable massive star in a dwarf galaxy. Scientists think this could indicate that the star became less bright and partially obscured by dust. An alternative explanation is that the star collapsed into a black hole without producing a supernova.

“If true,” says team leader and PhD student Andrew Allan of Trinity College Dublin, Ireland, “this would be the first direct detection of such a monster star ending its life in this manner.”

Between 2001 and 2011, various teams of astronomers studied the mysterious massive star, located in the Kinman Dwarf galaxy, and their observations indicated it was in a late stage of its evolution. Allan and his collaborators in Ireland, Chile and the US wanted to find out more about how very massive stars end their lives, and the object in the Kinman Dwarf seemed like the perfect target. But when they pointed ESO’s VLT to the distant galaxy in 2019, they could no longer find the telltale signatures of the star.

Instead, we were surprised to find out that the star had disappeared!” says Allan, who led a study of the star published today in Monthly Notices of the Royal Astronomical Society.

Located some 75 million light-years away in the constellation of Aquarius, the Kinman Dwarf galaxy is too far away for astronomers to see its individual stars, but they can detect the signatures of some of them. From 2001 to 2011, the light from the galaxy consistently showed evidence that it hosted a ‘luminous blue variable’ star some 2.5 million times brighter than the Sun. Stars of this type are unstable, showing occasional dramatic shifts in their spectra and brightness. Even with those shifts, luminous blue variables leave specific traces scientists can identify, but they were absent from the data the team collected in 2019, leaving them to wonder what had happened to the star.

“It would be highly unusual for such a massive star to disappear without producing a bright supernova explosion,” says Allan.

Image of the Kinman Dwarf galaxy, also known as PHL 293B, taken with the NASA/ESA Hubble Space Telescope’s Wide Field Camera 3 in 2011, before the disappearance of the massive star. Located some 75 million light-years away, the galaxy is too far away for astronomers to clearly resolve its individual stars, but in observations done between 2001 and 2011, they detected the signatures of the massive star. These signatures were not present in more recent data. Credits: ESO

The group first turned the ESPRESSO instrument toward the star in August 2019, using the VLT’s four 8-metre telescopes simultaneously. But they were unable to find the signs that previously pointed to the presence of the luminous star. A few months later, the group tried the X-shooter instrument, also on ESO’s VLT, and again found no traces of the star.

“We may have detected one of the most massive stars of the local Universe going gently into the night,” says team-member Jose Groh, also of Trinity College Dublin. “Our discovery would not have been made without using the powerful ESO 8-metre telescopes, their unique instrumentation, and the prompt access to those capabilities following the recent agreement of Ireland to join ESO.” Ireland became an ESO member state in September 2018.

The team then turned to older data collected using X-shooter and the UVES instrument on ESO’s VLT, located in the Chilean Atacama Desert, and telescopes elsewhere.

“The ESO Science Archive Facility enabled us to find and use data of the same object obtained in 2002 and 2009,” says Andrea Mehner, a staff astronomer at ESO in Chile who participated in the study. “The comparison of the 2002 high-resolution UVES spectra with our observations obtained in 2019 with ESO’s newest high-resolution spectrograph ESPRESSO was especially revealing, from both an astronomical and an instrumentation point of view.”

The old data indicated that the star in the Kinman Dwarf could have been undergoing a strong outburst period that likely ended sometime after 2011. Luminous blue variable stars such as this one are prone to experiencing giant outbursts over the course of their life, causing the stars’ rate of mass loss to spike and their luminosity to increase dramatically.

Based on their observations and models, the astronomers have suggested two explanations for the star’s disappearance and lack of a supernova, related to this possible outburst. The outburst may have resulted in the luminous blue variable being transformed into a less luminous star, which could also be partly hidden by dust. Alternatively, the team says the star may have collapsed into a black hole, without producing a supernova explosion. This would be a rare event: our current understanding of how massive stars die points to most of them ending their lives in a supernova.

Future studies are needed to confirm what fate befell this star. Planned to begin operations in 2025, ESO’s Extremely Large Telescope (ELT) will be capable of resolving stars in distant galaxies such as the Kinman Dwarf, helping to solve cosmic mysteries such as this one.


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