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Space News Update — August 23, 2016 —

Contents

In the News

Story 1: NASA ‘hears’ from lost spacecraft after nearly two years

Story 2: Earth-like Exoplanet Orbiting Nearby Star?

Story 3: One of NASA’s cleanest spacecraft ever is ready to fly

Departments

The Night Sky

ISS Sighting Opportunities

Space Calendar

NASA-TV Highlights

Food for Thought

Space Image of the Week

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1. NASA ‘hears’ from lost spacecraft after nearly two years

NASA re-established contact with a wayward sun-watching science satellite Sunday nearly two years after the spacecraft suddenly dropped off line during a test, the agency said in a statement Monday.

NASA’s Deep Space Network, or DSN, “established a lock on the STEREO-B (spacecraft’s) downlink carrier at 6:27 p.m. EDT,” NASA said in a statement. “The downlink signal was monitored by the Mission Operations team over several hours to characterize the attitude of the spacecraft and then transmitter high voltage was powered down to save battery power.

“The STEREO Missions Operations team plans further recovery processes to assess observatory health, re-establish attitude control and evaluate all subsystems and instruments.”

Launched in 2006, the STEREO mission featured two spacecraft — STEREO-A and STEREO-B — designed to monitor solar activity from different locations, one “ahead” in its orbit and one “behind,” allowing scientists to see the entire star, not just the side facing Earth. The spacecraft were built and are managed by the Johns Hopkins University Applied Physics Laboratory in Laurel, Md.

Years beyond the original two-year mission duration, the spacecraft reached positions in their orbit relative to the sun and Earth where they would be on the far side of the star and out of direct contact with Earth for up to three months.

Both spacecraft featured a “command loss timer” designed to force the flight computer to reboot if it didn’t hear from Earth over a three-day period. On the far side of the sun, the command loss timer would trigger repeated computer resets during the three months the spacecraft were out of contact with Earth.

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To make sure the system was working properly, flight controllers tested both spacecraft by withholding commands and forcing the command loss time to trigger a reboot. The STEREO-A spacecraft responded normally. But STEREO-B had major problems.

Based on fragmentary data received before contact was lost, engineers concluded the timer triggered a restart as expected, but STEREO-B’s inertial measurement unit and star trackers, which tell the flight computer how the spacecraft is oriented and moving through space, suffered malfunctions.

“The bad IMU told STEREO-B that it was spinning, even though it was stationary,” Dan Ossing, the mission operations manager, said last December. “The spacecraft would have automatically taken steps to correct the supposed spin.”

But firing thrusters or adjusting spinning reaction wheels to counteract a non-existent spin would cause a stabilized spacecraft to do the opposite, imparting an unwanted spin. Engineers believe STEREO-B is doing just that, limiting the amount of sunlight that falls on its solar arrays.

That, in turn, probably prevents the on-board battery from fully charging and during multiple computer resets, the battery likely is exhausted before enough power is available for the spacecraft’s radio transmitter, NASA said on the mission website.

Using the DSN, flight controllers began sending commands “in the blind” last year, telling the spacecraft to turn off some of the systems that power up automatically after a reboot in a bid to improve battery charging. Additional commands were sent to turn on STEREO-B’s transmitter when enough power was available.

The work apparently paid off Sunday when the DSN picked up a “carrier” signal from STEREO-B.

Source: Spaceflight Now Return to Contents

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2. Earth-like Exoplanet Orbiting Nearby Star?

On Wednesday, Aug. 24, we could find out whether or not the recent rumors of an Earth-like exoplanet existing on our interstellar doorstep are real.

In a press notification on Monday, the European Southern Observatory (ESO) said only that they "will host a press conference at its Headquarters in Garching, near Munich, Germany" and that the ESO's Director General, Tim de Zeeuw, will open the event. The press conference will start at 1 p.m. Central European Time (CET) -- 7 a.m. EDT/4 a.m. PDT. There was no mention of the scientists who would be in attendance or what astronomical topic the event would focus on.

Though the announcement is vague, there's excitement surrounding the possibility of a potentially habitable extrasolar planet (or exoplanet) orbiting the sun's nearest neighbor, Proxima Centauri. The red dwarf star is located only 4.25 light-years away and, if confirmed, the world would be the closest confirmed exoplanet to our solar system.

Should this exoplanet have any Earth-like qualities, this historic astronomical discovery could transform our outlook of the galaxy.

But before we go getting too excited, the rumors of an "Earth-like" exoplanet are just that, rumors. And even the term "Earth-like" is quite misleading.

According to the German weekly magazine Der Spiegel on Aug. 12, the discovery was made by the ESO's La Silla Observatory in the Atacama Desert in Chile. La Silla is home to several telescopes, including instruments that are designed to seek out planets orbiting other stars.

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For example, La Silla's High Accuracy Radial velocity Planet Searcher, or HARPS, has been studying the light from stars in the hope of detecting the very slight spectroscopic "wobble" caused by exoplanets gravitationally tugging at them as they orbit. This high-precision technique of exoplanet hunting is known as the "radial velocity" method. If there's a planet orbiting Proxima Centauri, though a Earth-sized planet would have a minuscule effect on its parent star, perhaps HARPS has been able to detect the slight wobble as Proxima Centauri is so near.

As exciting as this potential discovery is, "Earth-like" carries a lot of caveats. The term is often bandied around to describe an exoplanet, of approximately Earth dimensions orbiting within a given star's habitable zone. The habitable zone is the distance from a star where it's not too hot and not too cold for water on a hypothetical rocky world to remain in a liquid state. On Earth, where there's liquid water, there's life, so finding an alien world in any star's habitable zone is exciting for the possibilities of extraterrestrial biology.

But there's a lot more to Earth than simply being in the right place around the sun that makes it habitable. Earth is also rocky, has a thick atmosphere, has a protective magnetosphere etc., all ingredients for a bona fide life-giving world. The only planet we know that is Earth-like isEarth.

Should there really be a world that approximates Earth mass/size at a distance that could allow water to exist in a liquid state on its hypothetically rocky surface, that's all we'll know. We won't know whether it has an atmosphere or a magnetosphere. We won't know if it possesses water.

And as Proxima is a red dwarf star, which is cooler than our sun, a habitable zone planet would need to orbit very close to the star, which presents the problem of tidal locking -- a very un-Earth-like quality!

So if there has been an exoplanetary discovery at Proxima, we'll need to wait for more powerful observatories before we'll know just how Earth-like it is, but it will be perfectly placed for us to astronomically study. It's not such a stretch to think that when NASA's James Webb Space Telescope is launched in 2018 that such a world would be high on the list of targets.

We could decipher if the Proxima exoplanet possesses an atmosphere, if this atmosphere contains water and ifit contains any traces of molecules that would hint at some kind of extraterrestrial biology.

For now, this is all speculation, but Wednesday could be the historic day when we start pondering an exiting new world a mere galactic stone's throw from Earth.

Source: Seeker Return to Contents

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3. One of NASA’s cleanest spacecraft ever is ready to fly

Five years after winning $1 billion from NASA to mount the first U.S. asteroid sample return mission, scientists and engineers will get their last look at the OSIRIS-REx spacecraft this week as it is closed up inside the nose cone of an Atlas 5 rocket for launch in September.

The probe’s encapsulation inside the Atlas 5’s payload fairing marks the end of a multi-year campaign to ensure every piece of the spacecraft meets stringent cleanliness standards. During construction, engineers tracked contaminants wherever OSIRIS-REx went on Earth, all the way down to concentrations measured in parts per billion.

Experts were especially concerned with organic residue left behind by humans and certain materials, like nylon and adhesives, normally used in the assembly of satellites.

OSIRIS-REx will bring back specimens for researchers to interrogate inside high-tech labs around the world, seeking clues about the origin of life, water and the planets themselves. The results could be skewed by an unexpected microbe or spore from planet Earth.

Small clumps of matter formed from a cloud of dust and gas at the dawn of the solar system. These proto-worlds grew into larger objects — and some became full-fledged planets — as they collided with one another, accreting more and more material along the way. Scientists believe asteroids brought the ingredients of life to Earth.

Analysts will look for amino acids — the building blocks of proteins — simple and complex organic compounds, and other markers from asteroid Bennu, an object orbiting the sun relatively close to Earth that managers selected as OSIRIS-REx’s target.

“The core of OSIRIS-REx is to return a sample to the Earth to understand the origin of the solar system, and the origin of life perhaps, and to do that we need a pristine sample,” said Jason Dworkin, OSIRIS-REx project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

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For scientists and engineers working on OSIRIS-REx, this week is a turning point. It’s the last time they will see the spacecraft — the product of 12 years of research and development — but it also means their long-held worries about contaminating the probe are nearly over.

“It’s incredibly emotional,” Dworkin said.

“It’s hard not to tear up around the spacecraft, but I don’t want to contaminate it,” he joked.

The schedule calls for the 4,651-pound (2,110-kilogram) spacecraft, already filled with hydrazine fuel for delicate in-space maneuvers, to be lifted on to an attach fitting this week inside the Payload Hazardous Servicing Facility at NASA’s Kennedy Space Center, then enclosed within the Atlas 5’s 13-foot diameter (4-meter) nose fairing.

“We have a completely fueled spacecraft that’s ready to go,” said Rich Kuhns, OSIRIS-REx program manager at Lockheed Martin, which built the spacecraft. “Over the next few days, what’re going to do is we’re actually going to lift the spacecraft onto the mechanism that will separate it from the top of the Centaur stage. Then we’re going to. .. close it up inside of the fairing, which will then get shipped over to the launch pad and stacked on top of the overall rocket.”

Ground crews will position the OSIRIS-REx spacecraft between two halves of the fairing, which will peel away in flight like a clamshell, then seal the probe inside.

“This is the last chance really for anybody on Earth to see that hardware until the sample is back in 2023, and only the return capsule is coming back,” said Dante Lauretta, OSIRIS-REx principal investigator from the University of Arizona.

On Aug. 29, technicians will transport the spacecraft inside the fairing to the Vertical Integration Facility at Cape Canaveral’s Complex 41 launch pad, where a crane will hoist the payload atop the Atlas 5.

Engineers plan to pluck the final “remove before flight” covers from OSIRIS-REx’s instruments and sensors before encapsulation. The last time anyone will put hands on the spacecraft before launch will come in the predawn hours of Sept. 6, when a technician will crawl through a special access door cut into the Atlas 5 fairing to activate OSIRIS-REx’s battery system.

A United Launch Alliance Atlas 5 rocket will kick off the probe’s seven-year journey Sept. 8. The two-hour launch window opens at 7:05 p.m. EDT (2305 GMT), and the mission has until Oct. 12 to depart Earth or else wait a year for the next opportunity.

OSIRIS-REx will return to the vicinity of Earth in September 2017 for a gravity assist, slingshotting the probe toward asteroid Bennu, a miniature world about 1,600 feet (500 meters) across. Bennu is a rare kind of object — scientists know it as a “B-type” asteroid — and is likely loaded with lots of carbon, the backbone of organic molecules.

In August 2018, the solar-powered voyager will begin its final approach to the asteroid, and eventually slip into orbit.

After a thorough survey of Bennu with OSIRIS-REx’s spectrometers, cameras and laser altimeter, scientists will decide where to snag a sample.

The payload package will look for organics and collect detailed temperature measurements all across Bennu, which has regions colder than an icebox and others hot enough to boil water.

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The asteroid has a surface area of about 200 acres — 0.78 square kilometers — and some of OSIRIS-REx’s instruments will capture data with centimeter-scale resolution, or better. The observations will add context to the sample OSIRIS-REx will return to Earth, and identify resources that might be valuable for astronauts in the future.

During the next phase of the mission, in late 2019, mission scientists will narrow down targets for OSIRIS-REx to go down and snatch up a piece of Bennu. A final decision by top NASA management will pick the sampling site based on several factors, primarily to avoid damaging the spacecraft and to maximise the likelihood of capturing primitive, pre-biotic material, the mission’s scientific payoff.

There are limitations, however, on where OSIRIS-REx can go. The mechanism aboard the probe to gather the asteroid specimens can only handle rocks up to three-quarters of an inch — about 2 centimeters — in diameter, so officials prefer a site with fine dust grains or a gravelly outer layer.

“We don’t need a big rock,” Nakamura-Messenger said. “We just need the signature of those organics.”

When NASA gives the green light to send OSIRIS-REx to the sampling site, a device called the TAGSAM will swing into action. Mounted on the end of of an articulating 11.1-foot (3.4-meter) robot arm, TAGSAM is about the size of a dinner plate, resembling an air filter affixed to an antique automobile.

TAGSAM is short for the Touch and Go Sample Acquisition Mechanism.

Starting from a point a few thousand feet — less than a kilometer — from Bennu, the spacecraft will fire thrusters to leave orbit, then adjust its speed to match the asteroid’s rotation, allowing OSIRIS-REx to hover over the sampling target as it goes in for the prize, a sporty approach currently scheduled some time around July 4, 2020.

Once the sample is captured, controllers will send commands for the TAGSAM arm to place the collection canister inside OSIRIS-REx’s landing capsule. Explosive bolts will sever the TAGSAM head from the craft’s robotic arm, and the capsule’s lid will close over the device for the trip home.

Loaded with celestial goodies, OSIRIS-REx’s 100-pound (60-kilogram) sample return canister will blaze into Earth’s atmosphere at around 9 a.m. Mountain time on Sunday, Sept. 24, 2023. A recovery team will await the capsule at a landing site in Utah, then ship the carrier to NASA’s Johnson Space Center in Houston, where scientists will first open the canister.

Source: Spaceflight Now Return to Contents

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The Night Sky

Tuesday, August 23

• Saturn, Mars, and Antares finally line up. They make a nearly straight, nearly vertical line in the south-southwest as the stars come out, as shown above. Tomorrow the line will be nearly as straight, but with Mars now on the other side of the Saturn-Antares line (at the time of twilight for the Americas).

Wednesday, August 24

• Last chance to catch Saturn, Mars, and Antares in their evening lineup. Think photo opportunity!

• Last-quarter Moon tonight (exact at 11:41 p.m. EDT). The Moon, in Taurus, rises around midnight. By early dawn Thursday morning they're high in the south with Aldebaran to the Moon's left. They're drawing closer hour by hour: see the next entry.

Thursday, August 25

• During the middle of the day today, the last-quarter Moon occults Aldebaran for much of the central and western U.S. Using a telescope under a clean, haze-free blue sky, you may be able to see the orange star wink out on the Moon's bright edge, then reappear from behind the Moon's invisible dark edge up to an hour or more later.

When these events happen depends on where you are. Some times: at Kansas City, the star's disappearance is at 12:56 p.m., and its reappearance is at 1:11 p.m. CDT; at Denver, disappearance 11:43 a.m., reappearance 12:14 p.m. MDT; Los Angeles, disappearance 10:21, reappearance 11:26 a.m. PDT; Berkeley, disappearance 10:17, reappearance 11:15 a.m. PDT; Honolulu, disappearance 5:52, reappearance 7:17 a.m. HAST.

• August is prime Milky Way time. After dark, the Milky Way runs from Sagittarius in the south, up and left across Aquila and through the Summer Triangle very high in the east, and on down through Cassiopeia to Perseus rising low in the north-northeast.

Friday, August 26

• Venus and Jupiter have closed to only 1° apart, very low in the west after sunset. That's less than a finger-width at arm's length. See tomorrow below.

Source: Sky & Telescope Return to Contents

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ISS Sighting Opportunities

For Denver: No sightings for Denver. Sighting information for other cities can be found at NASA’s Satellite Sighting Information

NASA-TV Highlights (all times Eastern Daylight Time)

2 p.m., Wednesday, August 24 - ISS Expedition 48 U.S. Spacewalk #37 Preview Briefing (all channels) 5:30 a.m., Friday, August 26 - Coverage of the Release of the SpaceX/Dragon CRS-9 Cargo Ship from the ISS (Release scheduled at 6:10 a.m. ET) (starts at 5:45 a.m.) (NTV-1 (Public), NTV-3 (Media)) 1 p.m., Friday, August 26 - ISS Expedition 48 In-Flight Event with ISS Commander Jeff Williams and Flight Engineer Kate Rubins of NASA (starts at 1:25 p.m.) (NTV-1 (Public), NTV-3 (Media))

Watch NASA TV on the Net by going to the NASA website. Return to Contents

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Space Calendar

• Aug 23 - [Aug 18] 50th Anniversary (1966), 1st Photo of Earth from Moon (Lunar Orbiter 1) • Aug 23 - Comet 18D/Perrine-Mrkos Closest Approach To Earth (1.563 AU) • Aug 23 - Comet P/2015 F1 (PANSTARRS) Closest Approach To Earth (2.602 AU)

• Aug 24 - [Aug 18] 50th Anniversary (1966), Luna 11 Launch (USSR Moon Orbiter) • Aug 24 - [Aug 21] Intelsat 33e/ Intelsat 36 Ariane 5 Launch • Aug 24 - Comet P/1998 VS24 (LINEAR) Closest Approach To Earth (3.066 AU) • Aug 24 - Aten Asteroid 326290 Akhenaten Closest Approach To Earth (0.494 AU) • Aug 24 - Asteroid 44597 Thoreau Closest Approach To Earth (1.354 AU) • Aug 24 - Asteroid 4337 Arecibo Closest Approach To Earth (2.341 AU) • Aug 24 - 10th Anniversary (2006), Pluto Demoted As A Planet • Aug 25 - Moon Occults Aldebaran • Aug 25 - Mars Passes 4.4 Degrees from Saturn • Aug 25 - Northern Iota Aquarids Meteor Shower Peak • Aug 25 - Comet 73P-AJ/Schwassmann-Wachmann Closest Approach To Earth (0.479 AU) • Aug 25 - Comet 176P/LINEAR At Opposition (1.725 AU) • Aug 25 - Asteroid 4 Vesta Occults TYC 1343-01188-1 (9.5 Magnitude Star) • Aug 25 - Apollo Asteroid 2016 PS26 Near-Earth Flyby (0.036 AU) • Aug 25 - Apollo Asteroid 2005 QQ87 Near-Earth Flyby (0.085 AU) • Aug 25 - Asteroid 3313 Mendel Closest Approach To Earth (1.567 AU) • Aug 25 - Asteroid 242516 Lindseystirling Closest Approach To Earth (1.745 AU) • Aug 25 - Asteroid 2919 Dali Closest Approach To Earth (1.797 AU) • Aug 25 - Kuiper Belt Object 2004 NT33 At Opposition (38.053 AU) • Aug 26 - Amor Asteroid 433 Eros Closest Approach To Earth (0.725 AU) • Aug 26 - Asteroid 2281 Biela Closest Approach To Earth (0.877 AU) • Aug 26 - Atira Asteroid 2007 EB26 Closest Approach To Earth (0.882 AU) • Aug 26 - Asteroid 149 Medusa Closest Approach To Earth (1.128 AU) • Aug 26 - Asteroid 19019 Sunflower Closest Approach To Earth (1.223 AU) • Aug 26 - Asteroid 2451 Dollfus Closest Approach To Earth (1.376 AU) • Aug 26 - Asteroid 7554 Johnspencer Closest Approach To Earth (2.950 AU) • Aug 26 - Kuiper Belt Object 225088 (2007 OR10) At Opposition (86.592 AU) • Aug 26 - 35th Anniversary (1981), Voyager 2, Saturn Flyby

Source: JPL Space Calendar Return to Contents

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Food for Thought

A new Goldilocks for habitable planets

The search for habitable, alien worlds needs to make room for a second "Goldilocks," according to a Yale University researcher. For decades, it has been thought that the key factor in determining whether a planet can support life was its distance from its sun. In our solar system, for instance, Venus is too close to the sun and Mars is too far, but Earth is just right. That distance is what scientists refer to as the "habitable zone," or the "Goldilocks zone."

It also was thought that planets were able to self-regulate their internal temperature via mantle convection—the underground shifting of rocks caused by internal heating and cooling. A planet might start out too cold or too hot, but it would

eventually settle into the right temperature.

A new study, appearing in the journal Science Advances on Aug. 19, suggests that simply being in the habitable zone isn't sufficient to support life. A planet also must start with an internal temperature that is just right.

"If you assemble all kinds of scientific data on how Earth has evolved in the past few billion years and try to make sense out of them, you eventually realize that mantle convection is rather indifferent to the internal temperature," said Jun Korenaga, author of the study and professor of geology and geophysics at Yale. Korenaga presents a general theoretical framework that explains the degree of self-regulation expected for mantle convection and suggests that self-regulation is unlikely for Earth-like planets.

"The lack of the self-regulating mechanism has enormous implications for planetary habitability," Korenaga said. "Studies on planetary formation suggest that planets like Earth form by multiple giant impacts, and the outcome of this highly random process is known to be very diverse."

Such diversity of size and internal temperature would not hamper planetary evolution if there was self-regulating mantle convection, Korenaga said. "What we take for granted on this planet, such as oceans and continents, would not exist if the internal temperature of Earth had not been in a certain range, and this means that the beginning of Earth's history cannot be too hot or too cold."

The NASA Astrobiology Institute supported the research. Korenaga is a co-investigator of the NASA "Alternative Earths" team, which is organized around the principle of understanding how the Earth has maintained a persistent biosphere through most of its history, how the biosphere manifests in "biosignatures" on a planetary scale, and how reconstructing this history can inform the search for life within and beyond the solar system.

Explore further: Life on other planets could be far more widespread, study finds

Source: Phys.org Return to Contents

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Space Image of the Week

First Earthrise Image Taken 50 Years Ago Today

50 Years ago today, on 23 August 1966, Lunar Orbiter 1 snapped the first photo of Earth as seen from lunar orbit. While a remarkable image at the time, the full resolution of the image was never retrieved from the data stored from the mission.

In 2008, this earthrise image was restored by the Lunar Orbiter Image Recovery Project at NASA Ames Research Center. The project obtained the original data tapes from the mission (the last surviving set) and restored original FR-900 tape drives to operational condition using both 60s era parts and modern electronics.

Source: SpaceRef.com Return to Contents