MASS Meeting Notes for February 21, 2020
We had a good turn out after an 18 week hiatus. Dean, Beth, Chad, Harry, Dave, Keith and his friend, Hank and I. The background for my presentation had this interesting photo showing men on horseback riding up to check on the Soyuz capsule with one of the Russian helicopters in the shot. I thought it was such an interesting dichotomy of modern technology and ancient life styles.
The Soyuz landing was of Christina Koch and 2 other astronauts from the ISS. Christina is quite a record setter. Her rookie flight was 328 days, giving her the second longest single US mission in space. Second only to Scott Kelly’s 340 day one. With that single mission, she is also 54th on the total time in space list and 7th for the US. Peggy Whitson holds the US record for cumulative time in space with 666 days over 3 missions. Peggy is 9th on total time in space list with 8 Russians ahead of her. Gennady Padalka is first with 878 days over 5 missions. Of the top 20 experienced astronauts the US only has 3 on the list, Whitson, Jeff Williams with 534 days over 4 missions and Scott Kelly 520 days over 4 missions.
Total time of people in space as of Friday, February 21, 2020, has reached 151.45 person-years with Russia having 77.69 years and the US 58.23 years. There have been 569 people in space over 1284 flights. I should add 2 X-15 pilots to the list because they exceeded the 50 mile altitude that the US Air Force considers as the criterion for issuing “astronaut wings”. I want to be consistent in my database and in the last couple of years I’ve included 4 Virgin Galactic people in 2018 and 2019 in the list that only passed the 50 mile height. I’ve always include X-15 astronaut, Joe Walker, because 2 of his flights exceeded 62 miles (100 km) which is the International “Karmen Line”. It will take quite a bit of database maintenance to add the 2 X-15 pilots in the correct sequential order, so I might have to include them with just an asterisk.
The ISS will celebrate 20 years of continuous habitation on November 2 of this year 2020. With a typical crew of 6, the ISS has been the primary contributor to humanity’s experience in space.
Christina Koch is also record setting with being half of the first all female EVA back on October 18, 2019. She and her EVA-mate, Jessica Meir (still on ISS), went on to perform 2 more EVAs on January 15, 2020 and January 20, 2020 to replace nickel-hydrogen batteries with lithium-ion ones. Those EVAs and 2 more battery related ones in October 2019, made for a series of 5 EVAs needed for the battery work. Along with those EVAs, 4 EVAs were needed to repair the $2 billion AMS instrument on ISS. The AMS has recorded and analyzed 152 billion cosmic rays since its installation in 2011. The AMS EVAs (11/15/19, 11/22, 12/2 and 1/25/20) involved replacing the coolant components and required the development of 20 new tools to cut and splice 8 coolant tubes. They were the most complex EVAs since the Hubble Telescope upgrade. AMS work was lucky to have Italian astronaut, Luca Parmitano, in the mix. His height and arm reach was critical in being able to reach into the AMS and perform some of the tasks. Beth and Dean discussed the all female spacewalk in one of the Casual Space podcasts if you want more detail.
Our next topic was the dimming of the star Betelgeuse. Orion is one of my favorite constellations and I didn’t like any of its stars disappearing. I recently went out my back door on a clear night to confirm that the red star on the left shoulder of Orion (as we view it), was still there. Although dimmer, you can easily see it even in the light-polluted skies of suburban Chicago. But the star has dimmed a whole magnitude (a factor of 2.5 times difference in brightness) from .5 magnitude to 1.5. Magnitude is such an archaic measure with brighter objects having a smaller numeric magnitude and even going negative as objects get brighter. Betelgeuse is a red giant star 642 light years distance. If it was in the solar system, it would be as large as Jupiter’s orbit. Astronomers estimate that it is 8.5 million years old and 20 times the mass of the Sun. Its dimming is attributed to its puffing off its outer layers. The dust in these layers could be obscuring some of the light from the star. The star also has enormous convective cells on its surface which probably contributed to its historical variability. In any event, it is getting to the end of its life and could go supernova tomorrow or in 100,000 years. In that case, it would appear as bright as the full moon for several weeks and be the talk of the town for quite a while. This fact that it is only 8.5 million years old and starting to die, shows that large massive stars live life fast and die quickly. Betelguese has gone from the 11th brightest star in the sky to the 24th. Fraser Cain has a great 10 minute video summarizing our study of what is going on.
I next launched into two attempts to explain facts that I had learned from “Daniel & Jorge Explain the Universe” podcasts. The first podcast answers “what is the densest object in the universe?” Here is the full podcast from 6/25/2019. I asked the group what their opinion was. Most said neutron stars and at least one person said black holes. Well, both could be right. It depends on whether you believe in quantum mechanics (Erwin Schrodinger) or general relativity (Albert Einstein).
I went through a list of object with increasing densities. Empty space between galaxies has only about 1 proton in a teaspoon (tsp) of space (about 5 cubic centimeters). Its density is 10^-27 kg (a kilogram (kg) is 1000 grams and 28.33 grams (g) equals an ounce (oz)). Water is 1g/cm^3 or 5g/tsp. The sun is 7g/tsp on average, the earth 30g/tsp on average, the heaviest element, osmium (element 76), is 110 g/tsp. A neutron star, which is a ball of only neutrons because the electrons have been crushed into the protons forming neutrons, is the density of the atomic nucleus of atoms and is 5 x 10^11 kg/tsp. The gravity of a neutron star is so intense that if you dropped a marshmallow from waist height it would hit the surface with the energy of an atomic bomb. Neutron stars have been observed. One of the famous ones lies in the center of the Crab Nebula, which is the remnant of a star that went supernova in the year 1054 AD. When neutron stars emit pulses of radiation they are called pulsars. Pulsars can rotate so fast the the polar emitting region points towards us in a period of only a few milliseconds. Sometimes this rapid rotation generates enormous magnetic fields. Those neutron stars are called magnetars.
Back to our density discussion, even larger stars collapse to form black holes. Around a black hole there is a surface called the event horizon where gravity is so strong that even light cannot escape. What goes on inside the event horizon is a bit of conjecture because nothing can be observed beyond the event horizon. Some physicists believe the mass of a black hole collapses into a singularity with infinite density (general relativity) but quantum mechanics says that matter cannot occupy that same small space. If we compute the black hole density by using its event horizon for the volume, things get interesting. An object with the mass of the sun would have an event horizon defined by its Schwarzschild radius of 3 km. That black hole would have a density similar to a neutron star. But more massive black holes are actually less dense. The event horizon radius increases linearly with the mass but volume is dependent on the cube of the radius (volume of a sphere = 4/3 x pi x r^3). Density is mass / volume. So, a 2x the mass of the sun black hole has an event horizon twice as large (6 km) but a volume 8 times as much (2^3) and therefore a density of only 1/4 as much (twice the mass in 8 times the volume). A black hole with the mass of 6.5 billion times the mass of the sun (like the one imaged by the Event Horizon Telescope last April 2019 in the center of M87 galaxy) has an event horizon density calculation yielding less than the density of water.
The smallest black hole ever observed is 4 times the mass of the sun, so its event horizon density would be 16 times less than the density of a one solar mass black hole and therefore 1/16th the density of a neutron star.
So if you believe in quantum mechanics, a neutron star is the densest object. If you believe in only general relativity, the unobserved infinite density of a black hole singularity is the densest object.
My second Daniel & Jorge fact, is more concise. Here is the full Multi-verse podcast. It concerns the fact that the size of the Big Bang was larger than a singularity. The initial space that expanded into the universe we know, was not just a single infinitely dense point. The original Big Bang volume of expansion could have been any size. Objects 1 meter apart in this original volume are now separated by 10 billion light years. Since scientists feel our universe currently is 46 billion light years in radius, that means that two objects 9 meters apart might have separated into the expanse of our current observable universe. If something was more distant than that, it would be part of an adjacent un-observable universe from our perspective. This could be the source of the multi-verse where an almost infinite number of universes were created. Each would have its own laws of physics. And each would be separated from knowing the others exist. We are lucky that we live in the universe that has the constants suitable for life, the birth of stars and galaxies and all the good things we know and love. It’s comforting to conjecture that all these bubble universes are all around us.
On the downside, I found out that 97% of the galaxies we observe can not be reached even if we had a rocket traveling at the speed of light. Galaxies at this distance are outside the “cosmic event horizon” which is calculated to be 16 billion light-years distant. Galaxies with a redshift of z=1, have the space expanding between us and them at .6 the speed of light and galaxies with a z=2 are racing away from us a .8 the speed of light. We’ll just never catch them. Bummer. We’ve got to invent warp drive soon or most of our universe is going to get away from us.
For a bit of nostalgia, I played the video showing SpaceX’s initial Falcon Heavy rocket launch where the payload was a red Tesla electric car. I still get a little verklempt when I watch it accompanied by the David Bowie song. February 6, 2020 was the 2 year anniversary of the first launch. There have been 3 Falcon Heavy launches and Beth and Chad were fortunate to attend the last one down in Florida where LightSail2, a satellite created by the Planetary Society, was one of the payloads. LightSail2 demonstrated the ability of a satellite to change its orbit using only the push from the Sun’s light. Carl Sagan originally explained the process to Johnny Carson in 1976 on the Tonight Show. There is one Falcon Heavy launch planned for 2020. The rocket currently can place more mass in orbit, 64,000 kg (64 metric tons) or 141,000 lbs, than any other operational rocket. It is also extremely inexpensive with a $90 million price tag when used in completely expendable mode.
The SLS under development by NASA will be able to lift more, 70 metric tons, when it first flies in 2021. But with a price tag possibly as high as $2 billion per launch, NASA is considering using the Falcon Heavy whenever possible to save money.
Although SpaceX has recovered 49 of their Falcon 9 rockets and Falcon Heavy side boosters, they never have recovered a center core from a Falcon Heavy yet. They did land the center core from the second Falcon Heavy launch on the barge but since SpaceX didn’t have the equipment to secure it to the deck, it fell over in heavy seas and broke apart.
My last factoid is something that I learned from a Lawrence Krauss lecture on YouTube. Tycho Brahe was a Danish astronomer who lived in the late 1500s before the invention of the telescope. He was amazingly accurate with his observations beating the accuracy of other observers by a factor of 10. But he was a man of over indulgence in both food and drink. Another oddity of Brahe was he had two pets which he kept on chains. One was a pet reindeer and one was a pet human midget. We’ve come a long way in political correctness since that time. Toward the end of Brahe’s life, a very prim and proper religious astronomer named, Johannes Kepler, came to be his understudy. I don’t think Kepler shed too many tears when Brahe died from a ruptured bladder. But he really appreciated those years of accurate observations that let him formulate his 3 laws of motion.
Lawrence Krauss went on to discuss how serendipitous scientific discovery can be. The LIGO gravity wave detectors in Washington and Louisiana were upgraded for additional accuracy and after a couple of days they were powered up for an engineering run. The grad students were told to not record the data but they didn’t listen to the scientists and kept the data. In the first hour after LIGO was turned on, they detected the gravity waves from the merger of two black holes 1.3 billion light years distant. The signal only lasted .2 seconds. Imagine those gravity waves traveled for 1.3 billion years and we only caught them an hour before they would have passed by the Earth because some students ignored their instructions. Now that’s karma!
The last example of the “fickle finger of fate”, is a South American amateur astronomer who discovered a supernova just hours after it exploded while testing a new telescope and camera he had just purchased. All the large ground based observatories on earth and all the satellites in space had not yet seen it, but this guy had the luck to catch it and report it. What are the odds?
Keith’s suggested an interesting site that shows how crowded Earth orbit is. You can search for certain satellites like “starlink” and display only those 300 recently launched SpaceX objects. You can up the speed of display by changing the speed parameter to “100”. It was cool to see the streams of Starlink satellites pass by in their orbital planes.
Harry also brought a site discussing a potential rocket launch site in northeast Michigan. I guess if you have an abandon air force base and a large body of water like Lake Huron anything is possible. The site would air launch rockets from an air plane.
The last object explored by the New Horizons mission received a new name. The project had temporarily called our “snow man in space”, Ultima Thule. But that name had some Nazi connotations. But now it has received an official name, Arrokoth, which means “sky” to the Powhatan people. Arrokoth is a contact binary object in the Kuiper Belt and 4.1 billion miles from Earth. It is coated with frozen methanol and other complex organic molecules. It is 22 miles long and 12 mile wide. It is classified as a planetesimal and coalesced 4.5 billion years ago as a key intermediate size step on the way to building planets. It’s two bodies merged very gently. Previously explored asteroids were badly battered by impactors and cooked by approaching too close to the sun. Arrokoth escaped that fate by staying way out in the Kuiper Belt. No water was found on it. New Horizons is now 316 million miles beyond it and is looking for another object to observe.
To rapidly introduce several topics, I used a Marcus House YouTube video of 17 minutes. It included the recently launched Solar Probe to study the poles of the Sun, SpaceX topics of the launch of Starlink satellites, progress on developing their new fully reusable rocket Starship, the hiring of Bill Gerstenmaier, and the status of the Commercial Crew DM-2 mission. Plus Boeing’s troubles with the Starliner test and the new fiscal year 2021 Presidential Budget Report. By blasting all the topics out quickly, I hoped it would let us cover a lot of ground expeditiously. It seemed to work and then we circled back to cover the topics in more detail depending on interest.
The Solar Orbiter probe is an ESA craft launched by NASA. It will use numerous gravitational assists from Venus and the Earth to get to an orbit, (Fraser Cain 10 minute video with more detail), that will be able to observe the poles of the Sun. There have been previous solar polar satellites but none had cameras. The group discussed how a hexagon shaped cloud pattern was found on one of Saturn’s poles and the amazing polar hurricane features at the poles of Jupiter. Who knows what the poles of the Sun will look like? It will take quite a few years for the probe to reach its final orbit, I hope we’ll see many pictures before that final gravity assist in Sep of 2030.
In other Sun observing news, the largest Earth based Solar Telescope has just begun to image the Sun and produced some amazing pictures of the granulation of convective cells on the Sun’s surface (short video). It is misleading how large these cells are. Many are the size of Texas. The telescope is named the Daniel K. Inouye Solar Telescope (DKIST) and it is a 4 meter aperture instrument on the mountain peak, Haleakala, on Maui. Many of the scientific instruments are still not installed. Construction began in 2012 and full operation is planned for July 2020. It is meant to operate for 44 years so that it can span 2 entire solar cycles. This project has been able to weather the protests by native Hawaiians better than the 30 meter telescope project that is still in the courts. We appear to be heading into a “Golden Age” of study of the Sun with the Parker Probe and its record breaking close approaches, Solar Orbiter obtaining information on the poles and DKIST.
SpaceX Starlink communication satellites number 300 in orbit after the 5th launch. The are going up 60 at a time on Falcon 9 rockets. SpaceX thinks they can start providing Internet from space in the US by mid 2020. Tentatively there will be a Starlink launch every 2 weeks in 2020. SpaceX has gotten the OK from the FCC for 12,000 satellites and they may request permission for another 30,000. The thought of 42,000 additional low-earth-orbiting satellites has astronomers up in arms that ground based observations will be ruined. When you see a stream of the satellites just after launch, it is a little alarming. But I think as the satellites reach their final higher orbit, they will not appear as bright. Remember the satellites will usually only be visible around sunset and sunrise when the sky is relatively dark and the satellite is in direct sunlight. SpaceX is experimenting with darker coatings to minimize brightness. Cost of the service has not been announced but statements say you will get 5-10 times your current provider’s speed (gigabit speed with low 25 ms latency) for less money than you are paying now. Customers will have a pizza box sized receiver and a Starlink terminal. The US government is testing with the US Air Force Research Laboratory using Starlink communication to get 610 Mbps with an in-flight C-12 turboprop aircraft. SpaceX will be getting competition from a European company, OneWeb, which wants to build their own constellation of 650 satellites. OneWeb uses Soyuz rockets and puts up 34 satellites at a time. They currently have 40 satellites in orbit after 2 launches (6 then 34). The Soyuz rockets launch from Baikanour and French Guiana and 21 more launches are planned.
SpaceX continues to make progress on its new totally reusable rocket, Starship. It is a unique situation that the construction is out in the open down in Boca Chica, Texas and at the Kennedy Space Center in Florida. The initial build labeled, Mk1 (Mark 1), was pressure tested to failure and made for a pretty awesome video of the cryogenic propellants cascading down. Newer versions of the rocket are already being built and the improvement in construction techniques are readily visible on the rocket’s frame. The model under construction called SN01 (Serial # 1, formerly Mk3) will be a 3 Raptor engine prototype that will fly to a 20 km height as early as March 2020. The current full design has the Starship as a 6 engine craft on top of an enormous booster, called Super Heavy, with 35 engines. A Japanese billionaire, Yusaku Maezawa, is supporting the development of Starship and he will circle the moon on a 6-day mission called StarShip Moon with a crew of about 6-8 artists, painters, poets etc. It is tentatively scheduled for 2023. He recently posted that he was looking for a girl friend to join him on the trip. He received about 27,000 offers but he apparently dropped the request. Elon Musk says Starship will cost about $2 million to build and launch which is 1/1000 of NASA’s SLS rocket. With refueling in orbit, Starship will be able to bring 100 metric tons to the surface of the moon or Mars.
Bill Gerstenmaier signs on as a consultant with SpaceX. He led NASA’s human space flight for 14 years until ousted by the Artemis reshuffle. He had a 42 year career at NASA. Engineering Today 11 minute video of Gerstenmaier’s transition. Douglas Loverro is the new head of human space flight and exploration at NASA and is responsible for almost half of NASA’s $25 billion budget. He has had decades of experience in national security space (Department of Defense and National Reconnaissance Office).
Commercial Crew – SpaceX mission (DM2) with a crewed Dragon capsule listed as launching May 7, 2020. SpaceX is making steady progress to launching astronauts. On Jan 19, 2020, they performed an in-flight abort test. This is where a Dragon capsule demonstrates that it can pull away from the rocket blasting it into space at the moment where the capsule is experiencing maximum pressure from its acceleration thru the atmosphere. It was very impressive with the Falcon 9 rocket creating a fireball from a safe distance behind the capsule. The 2 SpaceX DM2 astronauts , Bob Behnken and Doug Herley will ride out to the Falcon 9 rocket and Dragon capsule in white gull-winged Model X Teslas. Now that our MASS Prize contest is so close to completion and Sophia is the certain winner, Beth suggested that we make one more round of guesses as to when American astronauts launched from American soil, dock with the ISS and retrieve the flag left by the last Space Shuttle mission. We should have the guesses by mid-March and I’ll post the results on the website as MASS Prize 3.
Boeing’s is having a little trouble with their entry in Commercial Crew, the Starliner capsule. They had a pad abort test in New Mexico on Nov 4, 2019. The engines fired successfully but the capsule came down on 2 rather than the intended 3 parachutes. Apparently someone inserted the parachute pin improperly and one of the chutes was ripped away from the capsule. Then on December 20, 2019 they launched an uncrewed Starliner on the Orbital Flight Test (OFT) to the ISS. The Starliner capsule had a clock that was 11 hours off from the correct time. The capsule made too made attitude corrections, used up too much fuel and couldn’t complete the necessary engine firing to dock to the ISS as intended. The capsule orbited for a couple of days accomplishing as many of the tests it could and then landed on parachutes (3 of them) and air bags in New Mexico. The capsule looked amazingly well. No signs of charring on its surface. But later it was found out that errors in its software would have made the capsule contact its service module when the two separated just before dropping out of orbit. That error would have not been detected and corrected if checks hadn’t been made due to the “11 hour off clock” issue. Many people feel this is too many errors and Boeing should be required to perform another uncrewed Starliner test to the ISS before a crewed mission is allowed. This would be about a $410 million hit to Boeing but they also received $1.5 billion more than SpaceX to develop their capsule. The extra money was justified by Boeing being the more mature aerospace company and they would probably do a better job of staying on schedule than the newcomer SpaceX. It seems like they didn’t use that extra money to thoroughly test their software.
NASA’s 2021 Presidential Budget Request – We just got the 2020 budget through Congress with NASA getting $22.629 billion through Sept 30, 2020 when the request for 2021 came in of $25.246 billion. A 12% increase overall. The current administration is very generous with funding the Artemis Program to get us back to the moon by 2024. Big bucks for the SLS rocket and Orion but gutting or completely killing some important line items. Totally unfunded is the WFIRST infrared space telescope that will follow the James Webb Telescope. WFIRST was identified as the most important project by scientists in the latest decadal survey. Also zeroed was the STEM outreach of NASA to schools. The Planetary Society put out a good chart comparing the 2 years of budget. Another short editorial was by Sky & Telescope magazine. My concern is that we are throwing money at short term goals and not doing a more regimented, thought out, sustainable effort to return to the moon for the long term and then use what we learn there to advance to deeper space goals like Mars. The current budget defers development of a more powerful second stage for the SLS rocket that would help make it more justified as the premium rocket for manned moon missions. There are foundational science cuts in Earth science, the search for Near Earth Objects that threaten us and many other areas. It’s just not worth cutting all these other areas for some arbitrary short moon effort. At least the PBR will have to clear the House and Senate before it is enacted. I am concerned that when a new Administration comes in, NASA’s plans are re-written and a lot of waste occurs. But with the current Administration, it seems a completely new plan comes out every year and the waste of dropping the old plan occurs on a yearly basis.
I also listed some events coming in 2020. The “shooting star” satellite was launched on Dec 6, 2019 by Tokyo based ALE entertainment on the 10th RocketLabs launch from New Zealand. The Sky Canvas satellite will go into a 400 km circular sun sychronous orbit beneath the ISS. It will have 400 pellets that will make artificial shooting stars that will be visible in a 200 km diameter area anywhere on the Earth. Here is a 2 minute promo video. The 2020 Tokyo Olympics might be their first customer. Typically a customer would purchase 20 pellets. A 2 cm pellet costs $8000 to make and comes in 9 different colors. A shower would last 3 to 10 seconds.
Yerkes Observatory might re-open. No date is set but at least efforts are being made.
The landing site for the Osiris-Rex probe orbiting Bennu has been selected and it is named Nightingale. The probe will attempt to gather a sample of the asteroid’s surface during the Summer of 2020 and return it to earth on Sep 24, 2023 by landing in Utah. Scott Manley did a nice 11 minute video describing the 4 landing sites (named for water birds) and the challenges from the unexpected rough textured surface. We’ve got to understand what these asteroids are made of if we want to deflect them from impacting the earth in the future. The Japanese probe Hayabusa 2 is already heading back with a sample from the asteroid Ryugu and is expected to land in Dec 2020 in Australia.
NASA’s Mars 2020 rover will launch between July 17 and August 5, 2020 and land on my birthday Feb 18, 2021 with the same 7 minutes of terror Skycrane procedure that the Curiosity rover used on August 6, 2012. The name for the new rover has been narrowed down to 9 finalists and NASA will announce the name soon. The rover is very similar to the design of Curiosity but includes new instruments that will allow it to drill and store samples of Mars rocks for a future mission to pick up and send back to earth. It also has a helicopter that will scout Mars for interesting places to rove to.
NASA is scheduled to perform their “green run” test on the first stage of the SLS rocket down at Stennis in July or August of 2020. The booster will fire all 4 of its RS-25 shuttle engines for 8 minutes to simulate the thrust required to send the Orion capsule on its mission around the moon. Lucky the engines run on cryogenic hydrogen and oxygen creating only steam as a by product in the exhaust. Beth was down there to see the booster and listen to the NASA Administrator describe the test. Boeing builds the first stage and is about 4 years late with its construction. A successful test should set up the Artemis 1 mission for a launch date which has recently slipped to no earlier than April 18, 2021. All of the other SLS hardware, 5 segment solid rocket boosters, ICPS second stage, Orion capsule and European Service Module, are ready to go. Everything needs to be shipped to Florida and assembled into the first SLS rocket. NASA has contracted with Boeing to build 10 more SLS first stages. At $2 billion a rocket, I hope we find good usage for them.
The Cosmos “Possible Worlds” series with Neil DeGrasse Tyson is coming back for another 13 part season. It is set to premiere on March 9, 2020 on National Geographic Channel and play on Fox during the Summer. I just love science based programming.
China might attempt a lunar sample return mission in December 2020. Their mission with a rover on the farside of the moon keeps going and going. I think China’s efforts are fueling some of the US’s fervor of returning quickly to the moon.
The James Webb Space Telescope has only a 12% chance of making its March 2021 launch date according to the GAO. NASA usually uses a 70% chance criterion to set a launch date. The new probable date is July 2021. There is a problem that the Ariane 5 rocket that the Europeans will use to launch the telescope is being phased out. Hopefully, the shelf life of the rocket to be used won’t be expired by the time it lifts off. The project cost is up to $9.7 billion with all the delays. The latest problems are with bolt strength, failing straps and actuator reliability. None of those seem like rocket science. Let’s get this thing up and deployed so we can relax and let the science come on down.
The last topic is on the mass of the Milky Way Galaxy. I am always a little heartened when the size of our galaxy increases, but when the galaxy is listed as 890 billion times the mass of the sun but 830 billion of those masses are dark matter, I get a little annoyed. Only 60 billion times the mass of the sun remains to create stars, planets, gas and dust. C’mon, let’s find out what this dark matter is made of!! Machos, neutralinos, axions, I would accept just about anything.