Year: 2018

Globular clusters not as old as universe?

9:04 am

The uncertainty of science: A new computer model, based on binary star systems found in globular clusters, now estimates that those clusters are far younger than previously believed.

Comprised of hundreds of thousands of stars densely packed into a tight ball, globular clusters had been thought to be almost as old as the Universe itself – but thanks to newly developed research models it has been shown that they could be as young as 9 billion years old rather than 13 billion. The discovery brings into question current theories on how galaxies, including the Milky Way, were formed – with between 150-180 clusters thought to exist in the Milky Way alone – as globular clusters had previously been thought to be almost as old as the Universe itself.

Designed to reconsider the evolution of stars, the new Binary Population and Spectral Synthesis (BPASS) models take the details of binary star evolution within the globular cluster into account and are used to explore the colours of light from old binary star populations – as well as the traces of chemical elements seen in their spectra. The evolutionary process sees two stars interacting in a binary system, where one star expands into a giant whilst the gravitational force of the smaller star strips away the atmosphere, comprising hydrogen and helium amongst other elements, of the giant. These stars are thought to be formed as the same time as the globular cluster itself.

Through using the BPASS models and calculating the age of the binary star systems the researchers were able to demonstrate that the globular cluster of which they are part was not as ancient as other models had suggested.

All this study really does is demonstrate again that we really don’t know enough to make a very accurate estimate of the ages of globular clusters. They are very old, but determining precisely how old will require a lot more knowledge.

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Boulder-sized asteroid discovered just before it hit Earth

8:59 am

The Catalina Sky Survey, designed to find asteroid with the potential of hitting the Earth, discovered a boulder-sized such asteroid this past weekend just hours before it burned up in the atmosphere.

Although there was not enough tracking data to make precise predictions ahead of time, a swath of possible locations was calculated stretching from Southern Africa, across the Indian Ocean, and onto New Guinea. Reports of a bright fireball above Botswana, Africa, early Saturday evening match up with the predicted trajectory for the asteroid. The asteroid entered Earth’s atmosphere at the high speed of 10 miles per second (38,000 mph, or 17 kilometers per second) at about 16:44 UTC (9:44 a.m. PDT, 12:44 p.m. EDT,6:44 p.m. local Botswana time) and disintegrated several miles above the surface, creating a bright fireball that lit up the evening sky. The event was witnessed by a number of observers and was caught on webcam video.

When it was first detected, the asteroid was nearly as far away as the Moon’s orbit, although that was not initially known. The asteroid appeared as a streak in the series of time-exposure images taken by the Catalina telescope . As is the case for all asteroid-hunting projects, the data were quickly sent to the Minor Planet Center in Cambridge, Massachusetts, which calculated a preliminary trajectory indicating the possibility of an Earth impact. The data were in turn sent to the Center for Near-Earth Object Studies (CNEOS) at NASA’s Jet Propulsion Laboratory in Pasadena, California, where the automated Scout system also found a high probability that the asteroid was on an impact trajectory. Automated alerts were sent out to the community of asteroid observers to obtain further observations, and to the Planetary Defense Coordination Office at NASA Headquarters in Washington. However, since the asteroid was determined to be so small and therefore harmless, no further impact alerts were issued by NASA.

The video at the link makes it appear that the asteroid has hit the ground, but that is not what happened.

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SpaceX successfully launches commercial satellite

10:17 pm

Capitalism in space: SpaceX has successfully launched a commercial satellite using a previously flown first stage.

They did not attempt to recover the used first stage as it was one of their older stages, which they are clearing out as they move to the final Block 5 version of the Falcon 9.

The top leaders in the 2018 launch race:

16 China
11 SpaceX
5 Russia
5 ULA

In the national standings the U.S. has moved back ahead of China, 17-16.

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Stratolaunch still lacks a launch vehicle

10:51 am

In a news interview today about their plans for the next year or so, the CEO of Stratolaunch danced around the lack of a committed and appropriate rocket to act as a second stage for the giant airplane.

At the first flight event, we are going to talk a little bit about what is our suite of product offerings in terms of launch vehicles. We haven’t really talked much about that up until this point, but once we get the plane flying, we want to reveal to everyone exactly what we’re talking about. We have talked about the Pegasus system [from Orbital ATK] and we are going to launch the Pegasus on our first launch. It’s a very small rocket, but it’s a very good rocket, very reliable, which is one of the reasons we want to launch that first.

But it’s a 50,000 pound rocket. This plane can carry 550,000 pounds, so it’s an undersized rocket for the capabilities we’re talking about.

They hope this first launch will occur by summer of this year.

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Reuseability lowers SpaceX launch price to $50 million

10:46 am

Capitalism in space: Reuseability lowers SpaceX launch price to $50 million.

The article is mostly about tonight’s commercial launch of an SES communications satellite. In it however it notes this comment by Musk:

SpaceX is in the process of flying and discarding older, less advanced Block 4 first stages to clear inventory – the company will likely fly just one more before moving its entire manifest to the Block 5 iteration, which CEO Elon Musk says can fly up to 10 times with minimal refurbishment between missions. Beyond that, the boosters could launch up to 100 times with moderate inspections and changes.

The next-generation vehicles feature improved reusability, upgraded thrust, retractable black landing legs that can reduce time between launches, a new black interstage and a slightly larger payload fairing, to name a few. It will also help SpaceX reduce costs from $60 million to about $50 million per launch, Musk said in May. [emphasis mine]

This price is about a third less than what both Arianespace and ULA have estimated they will charge for their new rockets, Ariane 6 and Vulcan respectively. This is also about half the price that the Russians had been charging for their Proton, which used to be the lowest price in town.

I’ll make a prediction: The drop in prices has only just begun.

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The upcoming Falcon Heavy schedule

10:31 pm

Link here. After the estimated October launch of an Air Force technology demonstration satellite, the next launch is a communications satellite for Saudi Arabia set for the December/January time frame.

After that there are no scheduled Falcon Heavy launches, though three companies, Intelsat, Viasat, and Inmarsat, have options for launches.

In related SpaceX news, the company came within 200 feet of catching one half of the fairing from last week’s launch. The picture of the fairing coming down by parachute is very cool, and indicates that SpaceX is very close to recovering them.

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Certain microbes survive in clean rooms by eating the cleaning fluids

10:51 pm

Researchers have found that the reason certain microbes seem to survive in all spacecraft clean rooms is that those microbes actually live off the very cleaning fluids used to scrub the rooms.

Despite extensive cleaning procedures, however, molecular genetic analyses show that the clean rooms harbor a diverse collection of microorganisms, or a spacecraft microbiome, that includes bacteria, archaea and fungi, explained Mogul. The Acinetobacter, a genus of bacteria, are among the dominant members of the spacecraft microbiome.

To figure out how the spacecraft microbiome survives in the cleanroom facilities, the research team analyzed several Acinetobacter strains that were originally isolated from the Mars Odyssey and Phoenix spacecraft facilities.

They found that under very nutrient-restricted conditions, most of the tested strains grew on and biodegraded the cleaning agents used during spacecraft assembly. The work showed that cultures grew on ethyl alcohol as a sole carbon source while displaying reasonable tolerances towards oxidative stress. This is important since oxidative stress is associated with desiccating and high radiation environments similar to Mars.

The tested strains were also able to biodegrade isopropyl alcohol and Kleenol 30, two other cleaning agents commonly used, with these products potentially serving as energy sources for the microbiome.

With this information, the space engineering community will be able to refine their clean room operations to eliminate these microbes so as to better sterilize spacecraft heading on life-seeking missions.

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Cubesats heading to Mars complete first course correction

10:46 pm

The two cubesats, MarCO-A and MarCO-B, that were launched with NASA’s InSight Mars lander, have both completed their first course corrections, the first ever done in interplanetary space by cubesats.

While MarCO-A corrected its course to Mars relatively smoothly, MarCO-B faced some unexpected challenges. Its maneuver was smaller due to a leaky thruster valve that engineers have been monitoring for the past several weeks. The leak creates small trajectory changes on its own. Engineers have factored in these nudges so that MarCO-B can still perform a trajectory correction maneuver. It will take several more weeks of tracking to refine these nudges so that MarCO-B can follow InSight on its cruise through space.

“We’re cautiously optimistic that MarCO-B can follow MarCO-A,” said Joel Krajewski of JPL, MarCO’s project manager. “But we wanted to take more time to understand the underlying issues before attempting the next course-correction maneuver.”

Once the MarCO team has analyzed data, they’ll know the size of follow-on maneuvers. Several more course corrections will be needed to reach the Red Planet.

Since these two cubesats are an engineering test, even MarCo-B’s fuel leak issue provides valuable information that will make future interplanetary missions more likely and viable.

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The surface properties of 122 asteroids revealed

1:12 pm

Using archive data produced by the Wide-field Infrared Explorer telescope (WISE, renamed NEOWISE) astronomers have been able to estimate the surface properties of 122 small asteroids located in the asteroid belt.

“Using archived data from the NEOWISE mission and our previously derived shape models, we were able to create highly detailed thermophysical models of 122 main belt asteroids,” said Hanuš, lead author of the paper. “We now have a better idea of the properties of the surface regolith and show that small asteroids, as well as fast rotating asteroids, have little, if any, dust covering their surfaces.” (Regolith is the term for the broken rocks and dust on the surface.)

It could be difficult for fast-rotating asteroids to retain very fine regolith grains because their low gravity and high spin rates tend to fling small particles off their surfaces and into space. Also, it could be that fast-rotating asteroids do not experience large temperature changes because the sun’s rays are more rapidly distributed across their surfaces. That would reduce or prevent the thermal cracking of an asteroid’s surface material that could cause the generation of fine grains of regolith. [emphasis mine]

If this conclusion holds, it means that mining these asteroids might be much easier. Dust can be a big problem, as it can clog up equipment and interfere with operations. It also acts to hide the underlying material, making it harder to find the good stuff.

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