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After two launches scrubbed this week, Musk says SpaceX needs to improve

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Scrubbed launches are a fact of life in the rocket industry. But Elon Musk is determined to minimize them for SpaceX, following the events of this week in which two SpaceX launches had to be aborted.

The first launch should have occurred on Thursday, October 1, when a Falcon 9 rocket was set to launch carrying the latest batch of Starlink satellites for the company’s project to provide global satellite broadband internet. However, the launch had to be aborted due to an “out of family ground system sensor reading” which was detected during the countdown. The Falcon rocket and its satellites were said to be in good health, but the ground problem forced the delay of the launch.

The second launch was slated for Friday, October 2, with a Falcon 9 carrying a GPS satellite for the U.S. Space Force. This launch was scrubbed at just two seconds before liftoff. No reason was given for the scrub, but SpaceX said on its website that, “The team is evaluating the next earliest launch opportunity and we will provide an update as soon as a date is confirmed.”

The biggest factor in scrubbed launches is the weather, as it can be dangerous to launch a rocket when there is lightning in the region or too much of certain types of clouds. There’s nothing to be done about that, but other scrubbed launches like the two SpaceX experienced this week can be due to issues on the ground. This is the area SpaceX is looking to improve, as every scrubbed launch represents a significant cost as the rocket has to be wheeled away and a valuable new launch slot obtained.

“We will need to make a lot of improvements to have a chance of completing 48 launches next year!” Musk said on Twitter, referring to the company’s ambitious launch goals. When asked what the biggest problem was with launches: “Mechanical issues? Susceptibility to weather? Range constraints?,” Musk replied, “All of that and more.”

Musk also said the company was undertaking a review this weekend of its launch operations including launch site, propulsion, structures, avionics, and range and regulatory constraints, trying to improve on its launch capabilities. In addition, Musk said he would be visiting Cape Canaveral himself in the coming week to oversee the hardware review.

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SpaceX Starship Passes Static Fire Test With Three Raptor Engines, Finally Gets Nose Cone! – Universe Today

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It’s beginning to look like SpaceX will attempt to make the 15 km (9.3 mi) hop test before Christmas! After two successful 150 m (~500 ft) hops with the SN5 and SN6 prototypes, engineers at SpaceX’s Boca Chica launch facility in South Texas rolled out the SN8 – the first Starship prototype to have three Raptor engines. But before the SN8 can conduct a high-altitude test flight, the engineers needed to run a static fire test.

This test is crucial to ensuring that the Starship‘s interior plumbing can handle its cryogenic propellants, and is the last milestone before the Starship can conduct a high-altitude flight. On the evening of Tuesday, October 20th, that’s exactly what they did! At 3:13 AM local time (01:13 AM PDT; 04:13 AM EDT), the SN8 fired up its three Raptor engines and kept firing them for several seconds straight.

Although SpaceX has not yet released a statement about the test, footage captured near the launch facility by NASA Spaceflight’s Mary McConnaughey (aka. @BocaChicaGal) would suggest that it was a success. The video of the event (posted below) shows the engine being ignited at 2h27m12s after several minutes of venting and remaining lit for several seconds.

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With this milestone achieved, the company appears ready to conduct the historic 15 km (9.3 mi) hop test. At this point, that seems likely to happen before the end of October or in early November. While the SN8 was receiving its three Raptor engines and preparing to test fire them, another team was busy assembling the nose cone in another part of the facility.

Not since the Starhopper test vehicle was in active service has a Starship prototype come with a nose cone. However, this segment was removed shortly after the Starhopper blew over in high winds in January of 2019. What remained, the single-engine lower section, went on to conduct a tethered hop test, followed by a first free-flight hop test to 20 meters (~65 ft).

In August of 2019, these tests culminated in a 150 meter (~500 ft) hop test, a feat that would not be accomplished again until a year later with the SN5 and SN7 prototype. Since then, the development of the SN8 has proceeded apace, which began with the core undergoing a series of proof tests (from Oct. 6th to Oct. 8th) to validate its stainless steel propellant tanks in preparation for its static fire test.

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What followed was the addition of the large maneuvering flaps to the core section and nose cone. The nose cone was then attached by crane to the SN8 fuselage on Thursday (Oct. 22nd), an event that was witnessed by multiple observers who took pictures and footage. Above is a time-lapse video of the stacking operation recorded by @LabPadre, which was made using their 24-hour live-coverage of the Boca Chica launch facility.

With the nose cone and flaps installed, the vehicle now looks like the finalized Starship design for the first time. With its three engines, nose cone, and maneuvering flaps integrated, the SN8 is about ready to attempt its 15 km (9.3 mi) hop test, which will include a “belly-flop” maneuver that will test its ability to glide back to its landing site using its maneuvering surfaces alone.

According to past statements by Musk, SpaceX hopes to conduct a suborbital hop test to an altitude of 200 km (~125 mi) sometime next year. For this final test, the Starship will be equipped with six Raptor engines – three optimized sea-level thrust and three optimized for the vacuum of space. The company is also busy working on the Super Heavy element of the launch system, which will have no less than 28 Raptor engines.

Further Reading: ArsTechnica

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First Habitable-Zone, Earth-Sized Exoplanet Discovered With Planet-Hunter TESS – SciTechDaily

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TOI 700, a planetary system 100 light-years away in the constellation Dorado, is home to TOI 700 d, the first Earth-size habitable-zone planet discovered by NASA’s Transiting Exoplanet Survey Satellite. Credit: NASA’s Goddard Space Flight Center

TESS, the Transiting Exoplanet Survey Satellite, was launched in 2018 with the goal of discovering small planets around the Sun’s nearest neighbors, stars bright enough to allow for follow-up characterizations of their planets’ masses and atmospheres. TESS has so far discovered seventeen small planets around eleven nearby stars that are M dwarfs — stars that are smaller than the Sun (less than about 60% of the Sun’s mass) and cooler (surface temperatures less than about 3900 kelvin). In a series of three papers that appeared together this month, astronomers report that one of these planets, TOI-700d, is Earth-sized and also located in its star’s habitable zone; they also discuss its possible climate.

CfA astronomers Joseph Rodriguez, Laura Kreidberg, Karen Collins, Samuel Quinn, Dave Latham, Ryan Cloutier, Jennifer Winters, Jason Eastman, and David Charbonneau were on the teams that studied TOI-700d, one of three small planets orbiting one M dwarf star (its mass is 0.415 solar masses) located one hundred and two light-years from Earth. The TESS data analysis found the tentative sizes of the planets as being approximately Earth-sized, 1.04, 2.65 and 1.14 Earth-radii, respectively, and their orbital periods as 9.98, 16.05, and 37.42 days, respectively.

TOI 700 d Illustration

This illustration of TOI 700 d is based on several simulated environments for an ocean-covered version of the planet. Credit: NASA’s Goddard Space Flight Center

In our solar system, Mercury orbits the Sun in about 88 days; it is so close to the Sun that its temperature can reach over 400 Celsius. But because this M-dwarf star is comparatively cool the orbit of its third planet, even though much closer to the star than Mercury is to the Sun, places it in the habitable zone – the region within which the temperatures allow surface water (if any) to remain liquid when there is also an atmosphere. That makes this Earth-sized planet TOI-700d particularly interesting as a potential host for life.

The TESS detections were exciting but uncertain: the signals were faint and a small possibility remained that the TOI-700d detection was spurious. Because of the potential importance of finding a nearby Earth-sized planet in a habitable zone, the TESS scientists turned to the IRAC camera on the Spitzer Space Observatory for confirmation. Before being turned off by NASA in February 2020, the IRAC camera was by far the most sensitive near infrared camera in space.

TOI-700 Schematic

A schematic of the planets around the nearby M dwarf star TOI-700, discovered by TESS. The third (the farthest planet from the star), TOI-700d, lies within the star’s habitable zone (shown in green). Using the IRAC camera on Spitzer, the team refined the planet’s mass as 2.1 Earth-masses and 1.14 Earth-radii. (The scale shows 0.2 astronomical units; AU being the average Earth-Sun distance.) Credit: Rodriguez et al 2020

The TESS team observed TOI-700 with IRAC in October of 2019 and January of 2020, acquiring clear detections of the planets with about twice the signal-to-noise of TESS, enough to give a 61% improvement in the planet’s orbit and to significantly refine our knowledge of its other characteristics, refining the radius as above and finding the mass to be 2.1 Earth-masses. The results, especially when compared with other planets’ properties, suggest that this planet may be rocky and likely to be “tidally locked” with one side of the planet always facing the star.

If there were liquid water on the surface of TOI-700d, the astronomers argue, there would also be water-bearing clouds in the atmosphere, and the team uses climate system models to estimate its possible properties and what more sensitive measurements might find. They conclude, however, that pending space missions, including JWST, will probably lack the sensitivity to detect atmospheric features by a factor of ten or more. Their detailed climate studies will nevertheless help astronomers constrain the kinds of telescopes and instruments that will be needed to investigate this exciting new neighbor.

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NASA’s Transiting Exoplanet Survey Satellite (TESS) has discovered its first Earth-size planet in its star’s habitable zone, the range of distances where conditions may be just right to allow the presence of liquid water on the surface. Scientists confirmed the find, called TOI 700 d, using NASA’s Spitzer Space Telescope and have modeled the planet’s potential environments to help inform future observations. Credit: NASA’s Goddard Space Flight Center

References:

“The First Habitable-zone Earth-sized Planet from TESS. I. Validation of the TOI-700 System” by Emily A. Gilbert, Thomas Barclay, Joshua E. Schlieder, Elisa V. Quintana, Benjamin J. Hord, Veselin B. Kostov, Eric D. Lopez, Jason F. Rowe, Kelsey Hoffman, Lucianne M. Walkowicz, Michele L. Silverstein, Joseph E. Rodriguez, Andrew Vanderburg, Gabrielle Suissa, Vladimir S. Airapetian, Matthew S. Clement, Sean N. Raymond, Andrew W. Mann, Ethan Kruse … Benjamin J. Shappee, Mackennae Le Wood and Jennifer G. Winters, 14 August 2020, The Astronomical Journal.
DOI: 10.3847/1538-3881/aba4b2

“The First Habitable-zone Earth-sized Planet from TESS. II. Spitzer Confirms TOI-700 d” by Joseph E. Rodriguez, Andrew Vanderburg, Sebastian Zieba, Laura Kreidberg, Caroline V. Morley, Jason D. Eastman, Stephen R. Kane, Alton Spencer, Samuel N. Quinn, Ryan Cloutier, Chelsea X. Huang, Karen A. Collins, Andrew W. Mann, Emily Gilbert, Joshua E. Schlieder, Elisa V. Quintana, Thomas Barclay, Gabrielle Suissa, Ravi kumar Kopparapu … Philip S. Muirhead, Elisabeth Newton, Mark E. Rose, Joseph D. Twicken and Jesus Noel Villaseñor, 14 August 2020, The Astronomical Journal.
DOI: 10.3847/1538-3881/aba4b3

“The First Habitable-zone Earth-sized Planet from TESS. III. Climate States and Characterization Prospects for TOI-700 d” by Gabrielle Suissa, Eric T. Wolf, Ravi kumar Kopparapu, Geronimo L. Villanueva, Thomas Fauchez, Avi M. Mandell, Giada Arney, Emily A. Gilbert, Joshua E. Schlieder, Thomas Barclay, Elisa V. Quintana, Eric Lopez, Joseph E. Rodriguez and Andrew Vanderburg, 14 August 2020, The Astronomical Journal.
DOI: 10.3847/1538-3881/aba4b4

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Scientists Peer Inside an Asteroid – Is Bennu in the Process of Spinning Itself Into Pieces? – SciTechDaily

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OSIRIS REx Arrives at Asteroid Bennu

This series of images taken by the OSIRIS-REx spacecraft shows Bennu in one full rotation from a distance of around 50 miles (80 km). The spacecraft’s PolyCam camera obtained the thirty-six 2.2-millisecond frames over a period of four hours and 18 minutes. Credit: NASA’s Goddard Space Flight Center/University of Arizona

New findings from NASA’s OSIRIS-REx mission suggest that the interior of the asteroid Bennu could be weaker and less dense than its outer layers—like a crème-filled chocolate egg flying though space.

The results appear in a study published in the journal Science Advances and led by the University of Colorado Boulder’s OSIRIS-REx team, including professors Daniel Scheeres and Jay McMahon. The findings could give scientists new insights into the evolution of the solar system’s asteroids—how bodies like Bennu transform over millions of years or more.  

OSIRIS-REx rendezvoused with Bennu, an asteroid orbiting the sun more than 200 million miles from Earth, in late 2018. Since then, the spacecraft, built by Colorado-based Lockheed Martin, has studied the object in more detail than any other asteroid in the history of space exploration.

So far, however, one question has remained elusive: What’s Bennu like on the inside?

Bennu Orbit Diagram

Diagram of the orbit of Bennu in relation to Earth and other planets. Credit: NASA/Goddard/University of Arizona/Lockheed Martin

Scheeres, McMahon and their colleagues on the mission’s radio science team now think that they have an answer—or at least part of one. Using OSIRIS-REx’s own navigational instruments and other tools, the group spent nearly two years mapping out the ebbs and flows of Bennu’s gravity field. Think of it like taking an X-ray of a chunk of space debris with an average width about the height of the Empire State Building.

“If you can measure the gravity field with enough precision, that places hard constraints on where the mass is located, even if you can’t see it directly,” said Andrew French, a coauthor of the new study and a former graduate student at CU Boulder, now at NASA’s Jet Propulsion Laboratory (JPL).

What the team has found may also spell trouble for Bennu. The asteroid’s core appears to be weaker than its exterior, a fact that could put its survival at risk in the not-too-distant future.

“You could imagine maybe in a million years or less the whole thing flying apart,” said Scheeres, a distinguished professor in the Ann and H.J. Smead Department of Aerospace Engineering Sciences.

Evolution of asteroids

Of course, that’s part of the fun of studying asteroids. Scheeres explained that Bennu belongs to a class of smaller bodies that scientists call “rubble pile” asteroids—which, as their name suggests, resemble loosely held-together mounds of debris. 

Asteroids also change over time more than people think. 

“None of them have sat out there unchanging since the dawn of the solar system,” Scheeres said. “They’re being changed by things like sunlight affecting how they spin and collisions with other asteroids.”

To study how Bennu and other similar asteroids may change, however, he and his colleagues needed to take a peek inside.

Asteroid Bennu Particles

OSIRIS-REx observed small bits of material leaping off the surface of the asteroid Bennu on January 19, 2019. Credit: NASA/Goddard/University of Arizona/Lockheed Martin

This is where the team got lucky. When OSIRIS-REx first arrived at Bennu, the spacecraft spotted something unusual: Over and over again, tiny bits of material, some just the size of marbles, seemed to pop off the asteroid and into space. In many cases, those particles circled Bennu before falling back down to the surface. Members of the mission’s radio science team at JPL were able to witness how the body’s gravity worked first-hand—a bit like the apocryphal story of Isaac Newton inferring the existence of gravity after observing an apple falling on his head. 

“It was a little like someone was on the surface of the asteroid and throwing these marbles up so they could be tracked,” Scheeres said. “Our colleagues could infer the gravity field in the trajectories those particles took.”

Squishy center

In the new study, Scheeres and his colleagues combined those records of Bennu’s gravity at work with data from OSIRIS-REx itself—precise measurements of how the asteroid tugged on the spacecraft over a period of months. They discovered something surprising: Before the mission began, many scientists had assumed that Bennu would have a homogenous interior. As Scheeres put it, “a pile of rocks is a pile of rocks.” 

But the gravity field measurements suggested something different. To explain those patterns, certain chunks of Bennu’s interior would likely need to be more tightly packed together than others. And some of the least dense spots in the asteroid seemed to lie around the distinct bulge at its equator and at its very core.

“It’s as if there is a void at its center, within which you could fit a couple of football fields,” Scheeres said.

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Now, thanks to laser altimetry data and high-resolution imagery from OSIRIS-REx, we can take a tour of Bennu’s remarkable terrain. Credit: NASA’s Goddard Space Flight Center

The asteroid’s spin may be responsible for that void. Scientists know that the asteroid is spinning faster and faster over time. That building momentum could, Scheeres said, be slowly pushing material away from the asteroid’s center and toward its surface.  Bennu, in other words, may be in the process of spinning itself into pieces.

“If its core has a low density, it’s going to be easier to pull the entire asteroid apart,” Scheeres said.

For the scientist, the new findings are bittersweet: After measuring Bennu’s gravity field, Scheeres and his team have mostly wrapped up their work on the OSIRIS-REx mission. 

Their results have contributed to the mission’s sample analysis plan—currently in development. The returned sample will be analyzed to determine the cohesion between grains—a key physical property that affects the mass distribution observed in their study.

“We were hoping to find out what happened to this asteroid over time, which can give us better insight into how all of these small asteroids are changing over millions, hundreds of millions or even billions of years,” Scheeres said. “Our findings exceeded our expectations.”

Read Asteroid Bennu Secrets Unlocked by NASA’s OSIRIS-REx Ahead of Historic Heist for more on this and related research.

“Heterogeneous mass distribution of the rubble-pile asteroid (101955) Bennu” by D. J. Scheeres, A. S. French, P. Tricarico, S. R. Chesley, Y. Takahashi, D. Farnocchia, J. W. McMahon, D. N. Brack, A. B. Davis, R.-L. Ballouz, E. R. Jawin, B. Rozitis, J. P. Emery, A. J. Ryan, R. S. Park, B. P. Rush, N. Mastrodemos, B. M. Kennedy, J. Bellerose, D. P. Lubey, D. Velez, A. T. Vaughan, J. M. Leonard, J. Geeraert, B. Page, P. Antreasian, E. Mazarico, K. Getzandanner, D. Rowlands, M. C. Moreau, J. Small, D. E. Highsmith, S. Goossens, E. E. Palmer, J. R. Weirich, R. W. Gaskell, O. S. Barnouin, M. G. Daly, J. A. Seabrook, M. M. Al Asad, L. C. Philpott, C. L. Johnson, C. M. Hartzell, V. E. Hamilton, P. Michel, K. J. Walsh, M. C. Nolan and D. S. Lauretta, 8 October 2020, Science Advances.
DOI: 10.1126/sciadv.abc3350

The University of Arizona leads science operations for OSIRIS-REx. NASA’s Goddard Space Flight Center in Maryland manages the overall mission.

Other coauthors on the new study include researchers at the Jet Propulsion Laboratory, Smithsonian Institution, The Open University, Northern Arizona University, KinetX Aerospace, Inc., NASA Goddard Space Flight Center, University of Maryland, Johns Hopkins University, York University, University of British Columbia, Southwest Research Institute, Université Côte d’Azur and University of Arizona.

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