Gravitational waves are caused by calamitous events in the Universe. Neutron stars that finally merge after circling each other for a long time can create them, and so can two black holes that collide with each other. But sometimes there’s a burst of gravitational waves that doesn’t have a clear cause.Continue reading “A Mysterious Burst of Gravitational Waves Came From a Region Near Betelgeuse. But There’s Probably No Connection”
When it comes to the future of space exploration, a number of systems will come into play. In addition to the Space Launch System (SLS) that will send astronauts beyond Low Earth Orbit (LEO), there is also the Orion capsule. This is the vehicle that will take astronauts to the Moon again as part of Project Artemis (which is currently slated for 2024) and facilitate missions to Mars by the 2030s.
In preparation, the Orion capsule is being put through its paces to show that it’s up to the challenge. This past Tuesday, July 2nd, NASA successfully conducted the Ascent Abort-2 (AA-2) test, bringing the Orion one step closer to completion. The launch took place during the early morning hours and involved the capsule being launched from NASA’s Space Launch Complex 46 at Cape Canaveral aboard a modified Peacekeeper missile.Continue reading “Orion Capsule Passes Key Launch Abort Test. Next Stop: The Moon!”
The Orion Nebula is one of the most observed and photographed objects in the night sky. At a distance of 1350 light years away, it’s the closest active star-forming region to Earth.
This diffuse nebula is also known as M42, and has been studied intensely by astronomers for many years. From it, astronomers have learned a lot about star formation, planetary system formation, and other bedrock topics in astronomy and astrophysics. Now a new discovery has been made which goes against the grain of established theory: stellar winds from newly-formed massive stars may prevent other stars from forming in their vicinity. They also play a much larger role in star formation, and in galaxy evolution, than previously thought.Continue reading “Newborn Stars in the Orion Nebula Prevent Other Stars from Forming”
In recent years, NASA has been busy developing the technology and components that will allow astronauts to return to the Moon and conduct the first crewed mission to Mars. These include the Space Launch System (SLS), which will be the most powerful rocket since the Saturn V (which brought the Apollo astronauts to the Moon), and the Orion Multi-Purpose Crew Vehicle (MPCV).
When it comes time for NASA to send astronauts back to the Moon and on to Mars, a number of new spacecraft systems will come into play. These include the Space Launch System (SLS), the most powerful rocket ever built, and the Orion Multi-Purpose Crew Vehicle (MPCV) – a next-generation spacecraft that will carry crews beyond Low Earth Orbit (LEO).
Naturally, before either of these systems can conduct missions, extensive testing needs to be conducted to ensure they are safe and will perform well. In this spirit, NASA Advanced Supercomputing (NAS) research scientists are currently conducting highly-detailed simulations and visualizations to ensure that the Orion spacecraft’s Launch Abort Vehicle (LAV) will keep crews safe, should an emergency occur during takeoff.
Basically, the LAV is the combined configuration of the Orion Launch Abort System (LAS) and crew module, and is designed to get the crew to safety if an emergency occurs on the launch pad or during the first two minutes of flight. These simulation and visualization techniques, which were conducted with the Pleiades supercomputer at the NASA Ames Research Center, predict how vibrations will affect the Orion spacecraft’s launch abort vehicle during takeoff.
Not only are these tests assisting with the design efforts of the Orion LAV motor (a collaborative effort between NASA and Orion prime contractor Lockheed Martin), they are also rather unprecedented as far as spacecraft development goes. As Francois Cadieux, a research scientist in the NAS Computational Aerosciences Branch, explained:
“This is one of the first times where large eddy simulation (LES) techniques have been used in full-scale spacecraft analysis and design at NASA. I’m excited to play a part in the agency’s next big human space exploration project—this work brings LES to a point where it can provide accurate predictions within a short enough turnaround time to guide Orion’s design.”
Previously, the use of such high-fidelity tools has been largely restricted to academic research, and not something private industry contractors could take advantage of. Together with Michael Barad – an aerospace engineer at the Ames Research Center – Cadieux produced a variety of turbulence-resolving computational fluid dynamics (CFD) simulations using the NAS-developed Launch Ascent and Vehicle Aerodynamics (LAVA) software.
They were assisted by NAS visualization experts, who helped the researchers identify different types of vortices that can caused noise and vibrations. Using this simulation data, the visualization experts created a series of high-quality images and movies that illustrated what kind of flow dynamics the Orion LAS would experience during a launch abort. As Cadieux explained:
“From these visualizations, we were able to identify areas of high vibrational loads on the vehicle, and their sources. What we learned is that noise coming from the turbulence of the plume is substantially higher than any noise generated from its interaction with attached shockwaves.”
The video below shows the simulation of an ascent abort scenario, where the LAS has detached from the SLS and is traveling at close to the speed of sound. The abort process initiates with the ignition of the LAS motor and then slows down as the pressure and airflow conditions become particularly harsh.
The colored plumes indicate high pressure (red) and low pressure (blue), with pixels changing from blue to red (and vice versa) in relation to pressure waves that cause vibrations on the vehicle (white). The regions where the color changes abruptly, but remains generally blue or red over time, indicates the presence of shock waves. In the end, these simulations are directly impacting the spacecraft’s design and will help ensure astronaut safety and spacecraft performance.
“We’re still asking lots of questions,” said Cadieux. “Like, how do the loads on the LAV surface change at higher angles of attack? How do we best use data from wind tunnel tests to predict loads for actual flight conditions where the vehicle is accelerating?”
The answers to these questions will will be used to design the next series of ground tests, crew mockup tests, and critical flight tests, which will will prepare the Orion spacecraft for its first crewed mission – Exploration Mission 2 (EM-2). This mission, which is scheduled for launch by 2023, will consist of four crew members conducting a lunar flyby and delivering the first components for the Deep Space Gateway.
Be sure to check out the simulation video as well, courtesy of the NASA Ames Research Center:
On October 11th, 2010, Congress signed the bipartisan NASA Authorization Act, which allocated the necessary funding for the space agency to commence preparations for its “Journey to Mars“. For the sake of mounting the first crewed missions to the Red Planet, several components were designated as being crucial. These included the Space Launch System (SLS) and the Orion Multi-Purpose Crew Vehicle.
Despite a recent announcement that NASA would be prioritizing a return to the Moon in the coming years, both the SLS and Orion are on track with the eventual goal of mounting crewed missions to Mars. In recent weeks, NASA conducted critical assessments of both components and their proposed launch schedules, and determined that they will be launched together in 2020 for the sake of conducting Exploration Mission-1 (EM-1).
This test flight, which will be uncrewed, will test both systems and lay the foundations for the first crewed mission of the SLS and Orion. Known as Exploration Mission- 2 (EM-2), which was originally scheduled for 2021, this flight is now expected to take place in 2023. EM-1 will also serve to establish a regular cadence of mission launches that will take astronauts back to the Moon and eventually on to Mars.
The recent review came on the heels of an earlier assessment where NASA evaluated the cost, risk and technical factors of adding crew to the mission. This review was initiated as a result of the crew study and the challenges related to building the core stage of the SLS. Foremost among these was the recent tornado damage caused to the Michoud Assembly Facility in New Orleans, where the SLS is currently being built.
On top of that, there are also the challenges related to the manufacture and supply of the first Orion Service Module. This module, which is being developed by the European Space Agency (ESA), serves as the Orion’s primary power and propulsion component, until it is discarded at the end of each mission. During the summer of 2016, the design of the Service Module was also the subject of a critical design review, and passed.
After conducting their review, NASA reaffirmed the original plan to fly the EM-1 uncrewed. As acting NASA Administrator Robert Lightfoot announced in a recent NASA press release:
“While the review of the possible manufacturing and production schedule risks indicate a launch date of June 2020, the agency is managing to December 2019. Since several of the key risks identified have not been actually realized, we are able to put in place mitigation strategies for those risks to protect the December 2019 date.”
In addition, NASA has established new production performance milestones to address a key issue identified by the review, which was scheduling risks. Based on lesson learned from first-time builds, NASA and its contractors have adopted new measures to optimize building plans which will ensure flexibility – specifically if contractors are unable to deliver on schedule.
At this juncture, NASA is on track to develop the new deep space exploration systems that will take astronauts back to the Moon and beyond. Cost assessments for EM-1, which include the SLS and ground systems, are currently within their original targets. By June 2020, NASA estimates that cost overruns will remain within a 15% limit for the SLS and just slightly above for the ground systems.
As part of the review, NASA also considered when the test of the Orion’s launch abort system (which needs to happen ahead of EM-1) would take place – which they chose to move up to April 2019. Known as Ascent-Abort 2, this test will validate the launch abort system’s ability to land the crew safely during descent, and ensure that the agency can remain on track for a crewed flight in 2023.
To build the SLS and Orion, NASA is relying on several new and advanced manufacturing techniques. These include additive manufacturing (3-D printing), which is being used to fashion more than 100 parts for the Orion spacecraft. NASA is also using a technique known as self-reaction friction stir welding to join the two largest core stages of the rocket, which are the thickest structures ever joined using this technique.
Integration of the first service module is well under way in Bremen, Germany, with work already starting on the second. This is taking place at the Airbus integration room, where crews on eight-hour shifts are busy installing more than 11 km (6.8 mi) of cables that will connect the module’s central computers to everything from solar planes and fuel systems to the module’s engines and air and water systems.
These crews also finished installing the Orion’s 24 orientation thrusters recently, which complement the eight larger engines that will back up the main engine. The complex design of the module’s propulsion system requires that some 1100 welds be completed, and only 173 remain. At present, the ESA crews are aiming to finish work on the Orion and ship it to the USA by the summer of 2018.
As far as the assembly of the SLS is concerned, NASA has completed welding on all the major structures to the rocket stages is on track to assemble them together. Once that is complete, they will be able to complete an engine test that will fire up the four RS-25 engines on the core stage simultaneously – the EM-1 “green run”. When EM-1 takes place, the launch will be supported by ground systems and crews at NASA’s Kennedy Space Center in Florida.
The agency is also developing a Deep Space Gateway (DSG) concept with Roscosmos and industry partners like Boeing and Lockheed Martin. This space station, which will be placed in orbit around the Moon, will facilitate missions to the lunar surface, Mars, and other locations deeper into the Solar System. Other components currently under consideration include the Deep Space Transport, and the Martian Basecamp and Lander.
These latter two components are what will allow for missions beyond the Earth-Moon system. Whereas the combination of the SLS, Orion and the DSG will allow for renewed lunar missions (which have not taken place since the Apollo Era) the creation of a Deep Space Transport and Martian Basecamp are intrinsic to NASA’s plans to mount a crewed mission to the Red Planet by the 2030s.
But in the meantime, NASA is focused on the first test flight of the Orion and the SLS, which will pave the way towards a crewed mission in a few years’ time. As William Gerstenmaier, the associate administrator for NASA’s Human Exploration and Operations Mission Directorate, indicated:
“Hardware progress continues every day for the early flights of SLS and Orion. EM-1 will mark a significant achievement for NASA, and our nation’s future of human deep space exploration. Our investments in SLS and Orion will take us to the Moon and beyond, advancing American leadership in space.”
For almost forty years, no crewed spaceflights have been conducted beyond Low-Earth Orbit. And with the retiring of the Space Shuttle Program in 2011, NASA has lost the ability to conduct domestic launches. For these reasons, the past three presidential administrations have indicated their commitment to develop the necessary tools to return to the Moon and send astronauts to Mars.
Not only will this restore the United State’s leadership in space exploration, it also will open up new venues for human exploration and create new opportunities for collaboration between nations and between federal agencies and industry partners. And be sure to check out this video showcases NASA’s plans for Deep Space Exploration:
An angry monster lurks in the shoulder of the Hunter. We’re talking about the red giant star Betelgeuse, also known as Alpha Orionis in the constellation Orion. Recently, the Atacama Large Millimeter Array (ALMA) gave us an amazing view of Betelgeuse, one of the very few stars that is large enough to be resolved as anything more than a point of light.
Located 650 light years distant, Betelgeuse is destined to live fast, and die young. The star is only eight million years old – young as stars go. Consider, for instance, our own Sun, which has been shining as a Main Sequence star for more than 500 times longer at 4.6 billion years – and already, the star is destined to go supernova at anytime in the next few thousand years or so, again, in a cosmic blink of an eye.
An estimated 12 times as massive as Sol, Betelgeuse is perhaps a staggering 6 AU or half a billion miles in diameter; plop it down in the center of our solar system, and the star might extend out past the orbit of Jupiter.
As with many astronomical images, the wow factor comes from knowing just what you’re seeing. The orange blob in the image is the hot roiling chromosphere of Betelgeuse, as viewed via ALMA at sub-millimeter wavelengths. Though massive, the star only appears 50 milliarcseconds across as seen from the Earth. To give you some idea just how small a milliarcsecond is, there’s a thousand of them in an arc second, and 60 arc seconds in an arc minute. The average Full Moon is 30 arc minutes across, or 1.8 million milliarcseconds in apparent diameter. Betelgeuse has one of the largest apparent diameters of any star in our night sky, exceeded only by R Doradus at 57 milliarcseconds.
The apparent diameter of Betelgeuse was first measured by Albert Michelson using the Mount Wilson 100-inch in 1920, who obtained an initial value of 240 million miles in diameter, about half the present accepted value, not a bad first attempt.
You can see hints of an asymmetrical bubble roiling across the surface of Betelgeuse in the ALMA image. Betelgeuse rotates once every 8.4 years. What’s going on under that uneasy surface? Infrared surveys show that the star is enveloped in an enormous bow-shock, a powder-keg of a star that will one day provide the Earth with an amazing light show.
Thankfully, Betelgeuse is well out of the supernova “kill zone” of 25 to 100 light years (depending on the study). Along with Spica at 250 light years distant in the constellation Virgo, both are prime nearby supernovae candidates that will on day give astronomers a chance to study the anatomy of a supernova explosion up close. Riding high to the south in the northern hemisphere nighttime sky in the wintertime, +0.5 magnitude Betelgeuse would most likely flare up to negative magnitudes and would easily be visible in the daytime if it popped off in the Spring or Fall. This time of year in June would be the worst, as Alpha Orionis only lies 15 degrees from the Sun!
Of course, this cosmic spectacle could kick off tomorrow… or thousands of years from now. Maybe, the light of Betelgeuse gone supernova is already on its way now, traversing the 650 light years of open space. Ironically, the last naked eye supernova in our galaxy – Kepler’s Star in the constellation Ophiuchus in 1604 – kicked off just before Galileo first turned his crude telescope towards the heavens in 1610.
You could say we’re due.
KENNEDY SPACE CENTER VISITOR COMPLEX, FL – Following up last week’s announcement of NASA’s proposed Fiscal Year 2018 top line budget of $19.1 Billion by the Trump Administration, Universe Today spoke to NASA’ s Kennedy Space Center (KSC) Director Robert Cabana to get his perspective on the new budget and what it means for NASA and KSC; “Stay on the path!” – with SLS, Orion, ISS and Commercial Crew was his message in a nutshell.
The highlights of NASA’s $19.1 Billion FY 2018 budget request were outlined last week by NASA Acting Administrator Robert Lightfoot during a ‘State of NASA’ speech to agency employees held at NASA HQ, Washington, D.C. and broadcast to the public live on NASA TV on May 23.
In order to get a better idea of the implications of the 2018 NASA budget proposal for KSC, I spoke one-on-one with Robert Cabana – one of NASA’s top officials, who currently serves as Director of the Kennedy Space Center (KSC) as well as being a former astronaut and Space Shuttle Commander. Cabana is a veteran of four space shuttle missions.
How did NASA and KSC fare with the newly announced 2018 Budget?
“We at KSC and NASA as a whole did very well with the 2018 budget,” KSC Director Robert Cabana explained during an interview with Universe Today by the Rocket Garden at the Kennedy Space Center Visitor Complex (KSCVC) in Florida.
“I think it really solidifies that the President has confidence in us, on the path that we are on,” Cabana noted while attending a student robotics competition at KSCVC sponsored by NASA.
“With only a 1 percent cut – when you look at what other agency’s got cut – this budget allows us to stay on the path that we are on.”
Trump cut NASA’s 2018 budget request by $0.5 Billion compared to the recently enacted FY 2017 budget of $19.6 Billion approved by the US Congress and signed by the President.
Other Federal science agency’s also critically vital to the health of US scientific research such as the NIH, the NSF, the EPA, DOE and NIST suffered terrible double digit slashes of 10 to 20% or more.
KSC is the focal point for NASA’s human spaceflight programs currently under intense development by NASA – namely the Space Launch System (SLS) Mars megarocket, the Orion deep space crew capsule to be launched beyond Earth orbit (BEO) atop SLS, and the duo of Commercial Crew Program (CCP) space taxis being manufactured by Boeing and SpaceX that will ferry our astronauts to low Earth orbit (LEO) and the International Space Station (ISS).
Numerous NASA science missions also launch from the Florida Space Coast.
“At KSC the budget keeps us on a path that continues to provide a commercial crew vehicle to fly crews to the ISS in 2018,” Cabana stated.
“The budget also keeps us on track to launch SLS and Orion in 2019.”
“I think that’s really important – along with all the other stuff we are doing here at KSC.”
“From our point of view it’s a good budget. We need to press ahead and continue on with what we promised.”
What’s ahead for commercial crew at KSC?
“We are moving forward with commercial crew,” Cabana told me.
“Within the next calendar year  we are moving ahead with flying the first certification flight with crew to the ISS. So that’s test flights and by the end of the year an actual crewed flight to the ISS. I want to see that happen.”
Industry partners Boeing and SpaceX are building the private CST-100 Starliner and Crew Dragon spaceships respectively, as part of NASA’s commercial crew initiative aimed at restoring America’s human spaceflight capability to launch our astronauts aboard American spaceships on American rockets from American soil.
Commercial Crew is a public/private partnership initiative with commercial contracts valued at $4.2 Billion and signed by Boeing and SpaceX with NASA in September 2014 under the Obama Administration.
The goal of commercial crew is to end our sole reliance on the Russian Soyuz capsule for astronaut flights to the space station since the retirement of the space shuttles back in 2011 – by manufacturing indigenous rockets and human rated spaceships.
However the CCP program suffered severe budget reductions by the US Congress for several years which forced significant work stretch-outs and delays in the maiden crew launches by both companies from 2015 to 2018 – and thus forced additional payments to the Russians for Soyuz seat purchases.
Both the Boeing Starliner and SpaceX Dragon crew vehicles can carry 4 or more astronauts to the ISS. This will enable NASA to add another crew member and thereby enlarge the ISS crew from 6 to 7 permanent residents after they become operational.
Meanwhile NASA is focusing on developing the SLS heavy lift rocket and Orion crew capsule with prime contractors Boeing and Lockheed Martin in an agency wide effort to send humans on a ‘Journey to Mars’ in the 2030s.
The European Space Agency(ESA) is also partnered with NASA and providing the service module for Orion.
What’s the status of the delivery of the European Space Agency’s service module?
“The service module will be here sometime next year,” Cabana said.
He noted that the details and exact timing are yet to be determined.
The first integrated launch of SLS and Orion on the unpiloted Exploration Mission-1 (EM-1) is now slated for sometime in 2019 after NASA recently slipped the date to the right from Fall 2018.
At the request of the Trump Administration, NASA also just completed a detailed study to ascertain the feasibility of adding a crew of two NASA astronauts to the EM-1 flight and launch it by the end of 2019.
In the end, NASA officials decided to stick with the baselined plan of no crew on EM-1 for a variety of technical and safety reasons, as well as cost – as I reported here.
I asked Cabana for his insight and opinion on NASA not adding crew to Orion on the EM-1 flight.
“No we are not launching crew on the first flight [EM-1],” Cabana stated.
“With the budget that we have and what we need to do, this is the answer we got to at the end.”
“You know the crew study was still very important. It allowed us to find some things that we should still do on [EM-1], even though we are not going to launch crew on that flight.
“So we will make some further modifications that will reduce the risk even further when we do fly crew [on the next flight of EM-2].”
So for 2017 what are the major milestone you hope to complete here at KSC for SLS and Orion?
“So for me here at the Kennedy Space Center, my goal for the end of this calendar year 2017 we will have completed all of the construction of all of the [ground systems] hardware and facilities that are necessary to process and launch the Space Launch System (SLS) and Orion,” Cabana elaborated.
‘We will still have a lot of work to do with the software for the spacecraft command and control systems and the ground systems.”
“But my goal is to have the hardware for the ground systems complete by the end of this year.”
What are those KSC facilities?
“Those facilities include the VAB [Vehicle Assembly Building] which will be complete to accept the mobile launcher in September and pad 39B will be complete in August,” Cabana said.
“The RPSF is already complete. The NPFF is already complete and we are doing testing in there. The LASF [Launch Abort System Facility] is complete – where they put the abort rocket on.”
“The Mobile Launcher will be complete from a structural point of view, with all the systems installed by the end of the year [including the umbilical’s and while room].”
Watch for Ken’s onsite CRS-11 mission reports direct from the Kennedy Space Center and Cape Canaveral Air Force Station, Florida.
Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.
Learn more about the SpaceX Dragon CRS-11 resupply launch to ISS, NASA missions and more at Ken’s upcoming outreach events at Kennedy Space Center Quality Inn, Titusville, FL:
May 30/31: “SpaceX CRS-11 and CRS-10 resupply launches to the ISS, Inmarsat 5 and NRO Spysat, EchoStar 23, SLS, Orion, Commercial crew capsules from Boeing and SpaceX , Heroes and Legends at KSCVC, ULA Atlas/John Glenn Cygnus launch to ISS, SBIRS GEO 3 launch, GOES-R weather satellite launch, OSIRIS-Rex, Juno at Jupiter, InSight Mars lander, SpaceX and Orbital ATK cargo missions to the ISS, ULA Delta 4 Heavy spy satellite, Curiosity explores Mars, Pluto and more,” Kennedy Space Center Quality Inn, Titusville, FL, evenings
KENNEDY SPACE CENTER, FL – After conducting a thorough review examining the feasibility of adding a two person crew to the first integrated launch of America’s new Space Launch System (SLS) megarocket and Orion capsule on a mission that would propel two astronauts to the Moon and back by late 2019, NASA nixed the proposal during a media briefing held Friday.
The announcement to forgo adding crew to the flight dubbed Exploration Mission-1 (EM-1) was made by NASA acting Administrator Robert Lightfoot during a briefing with reporters on May 13.
“We appreciate the opportunity to evaluate the possibility of this crewed flight,” said NASA acting Administrator Robert Lightfoot during the briefing.
“The bi-partisan support of Congress and the President for our efforts to send astronauts deeper into the solar system than we have ever gone before is valued and does not go unnoticed. Presidential support for space has been strong.”
Although the outcome of the study determined that NASA could be “technically capable of launching crew on EM-1,” top agency leaders decided that there was too much additional cost and technical risk to accommodate and retire in the limited time span allowed.
Lightfoot said it would cost in the range of $600 to $900 million to add the life support systems, display panels and other gear required to Orion and SLS in order to enable adding astronauts to EM-1.
“It would be difficult to accommodate changes needed to add crew at this point in mission planning.”
Thus NASA will continue implementing the current baseline plan for EM-1 that will eventually lead to deep space human exploration missions starting with the follow on EM-2 mission which will be crewed.
At the request of the new Trump Administration in February, NASA initiated a comprehensive two month long study to determine the feasibility of converting the first integrated SLS/Orion flight from its baselined uncrewed mission to cislunar space into a crewed mission looping around the Moon.
Had the crewed lunar SLS/Orion flight been approved it would have roughly coincided with the 50th anniversary the first human lunar landing by NASA astronauts Neil Armstrong and Buzz Aldrin during the Apollo 11 mission in July 1969.
Instead NASA will keep to the agencies current flight plan.
The first SLS/Orion crewed flight is slated for Exploration Mission-2 (EM-2) launching no earlier than 2021.
If crew had been added to EM-1 it would have essentially adopted the mission profile currently planned for Orion EM-2.
“If the agency decides to put crew on the first flight, the mission profile for Exploration Mission-2 would likely replace it, which is an approximately eight-day mission with a multi-translunar injection with a free return trajectory,” said NASA earlier. It would be similar to Apollo 8 and Apollo 13.
Orion is designed to send astronauts deeper into space than ever before, including missions to the Moon, asteroids and the Red Planet.
NASA is developing SLS and Orion for sending humans initially to cislunar space and eventually on a ‘Journey to Mars’ in the 2030s.
They are but the first hardware elements required to carry out such an ambitious initiative.
Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.
Two Million Stars on the Move
Gaze into Gaia’s crystal ball and you will see the future. This video shows the motion of 2,057,050 stars in the coming 5 million years from the Tycho-Gaia Astrometric Solution sample, part of the first data release of European Space Agency’s Gaia mission.
Gaia is a space observatory parked at the L2 Lagrange Point, a stable place in space a million miles behind Earth as viewed from the Sun. Its mission is astrometry: measuring the precise positions, distances and motion of 1 billion astronomical objects (primarily stars) to create a three-dimensional map of the Milky Way galaxy. Gaia’s radial velocity measurements — the motion of stars toward or away from us — will provide astronomers with a stereoscopic and moving-parts picture of about 1% of the galaxy’s stars.
Think about how slowly stars move from the human perspective. Generations of people have lived and died since the days of ancient Greece and yet the constellations outlines and naked eye stars appear nearly identical today as they did then. Only a few stars — Arcturus, Sirius, Aldebaran — have moved enough for a sharp-eyed observer of yore to perceive their motion.
We know that stars are constantly on the move around the galactic center. The Sun and stars in its vicinity orbit the core at some half-million miles an hour, but nearly all are so far away that their apparent motion has barely moved the needle over the time span of civilization as we know it.
This video shows more than 2 million stars from the TGAS sample, with the addition of 24,320 bright stars from the Hipparcos Catalogue that weren’t included in Gaia’s first data release back in September 2016. The video starts from the positions of stars as measured by Gaia between 2014 and 2015, and shows how these positions are expected to evolve in the future, based on the stars’ proper motions or direction of travel across space.
Watching the show
The frames in the video are separated by 750 years, and the overall sequence covers 5 million years. The dark stripes visible in the early frames reflect the way Gaia scans the sky (in strips) and the early, less complete database. The artifacts are gradually washed out as stars move across the sky.
Using the map above to get oriented, it’s fun to watch Orion change across the millennia. Betelgeuse departs the constellation heading north fairly quickly, but Orion’s Belt hangs in there for nearly 2 million years even if it soon develops sag! The Pleiades drift together to the left and off frame and then reappear at right.
Stars seem to move with a wide range of velocities in the video, with stars in the galactic plane moving quite slow and faster ones speeding across the view. This is a perspective effect: most of the stars we see in the plane are much farther from us, and thus seem to be moving slower than the nearby stars, which are visible across the entire sky.
Some of the stars that appear to zip in and out of view quickly are passing close to the Sun. But motion of those that trace arcs from one side of the sky to the other while passing close to the galactic poles (top and bottom of the frame) as they speed up and slow down, is spurious. These stars move with a constant velocity through space.
Stars located in the Milky Way’s halo, a roughly spherical structure centered on the galaxy’s spiral disk, also appear to move quite fast because they slice through the galactic plane with respect to the Sun. In reality, halo stars move very slowly with respect to the center of the galaxy.
Early in the the visualization, we see clouds of interstellar gas and dust that occupy vast spaces within the galaxy and block the view of more distant suns. That these dark clouds seem to disappear over time is also a spurious effect.
After a few million years, the plane of the Milky Way appears to have shifted towards the right as a consequence of the motion of the Sun with respect to that of nearby stars in the Milky Way. Regions that are depleted of stars in the video will not appear that way to future stargazers but will instead be replenished by stars not currently sampled by Gaia. So yes, there are a few things to keep in mind while watching these positional data converted into stellar motions, but the overall picture is an accurate one.
I find the video as mesmerizing as watching fireflies on a June night. The stars seem alive. Enjoy your ride in the time machine!