OSIRIS-REx

Die Prozedur zur Verstauung des Probenbehälters hat begonnen:

OSIRIS-REx in the Midst of Stow

Anscheinend ist der Behälter mit den Bodenproben bereits in der aufgeklappten Rückkehrkapsel angekommen und eingerastet. Danach muss noch der Arm mit den Treibgasflaschen abgetrennt werden.

stow_for-release.jpg

Credit: NASA/Goddard/University of Arizona/Lockheed Martin
 
:y: :y: :y: - Tolle Sache. Hoffen wir mal dass das alles so klappt und noch genug Material in dem Probensammler verblieben ist. Es bleibt also noch ein bisschen spannend.

CS
Jörg
 
Inzwischen konnte die Operation erfolgreich abgeschlossen werden:

OSIRIS-REx Successfully Stows Sample of Asteroid Bennu

The mission team spent two days working around the clock to carry out the stowage procedure, with preparations for the stowage event beginning last weekend. For the spacecraft to proceed with each step in the stowage sequence, the team had to assess images and telemetry from the previous step to confirm the operation was successful and the spacecraft was ready to continue. Given that OSIRIS-REx is currently more than 330 million km from Earth, this required the team to also work with a greater than 18.5-minute time delay for signals traveling in each direction.

Throughout the process, the OSIRIS-REx team continually assessed the Touch-And-Go Sample Acquisition Mechanism’s (TAGSAM) wrist alignment to ensure the collector head was being placed properly into the SRC. Additionally, the team inspected images to observe any material escaping from the collector head to confirm that no particles would hinder the stowage process. StowCam images of the stowage sequence show that a few particles escaped during the stowage procedure, but the team is confident that a plentiful amount of material remains inside of the head.

By the evening of Oct. 27, the spacecraft’s TAGSAM arm had placed the collector head into the SRC. The following morning, the OSIRIS-REx team verified that the collector head was thoroughly fastened into the capsule by performing a “backout check.” This sequence commanded the TAGSAM arm to attempt to back out of the capsule – which tugged on the collector head and ensured the latches are well secured.

On the afternoon of Oct. 28, following the backout check, the mission team sent commands to disconnect the two mechanical parts on the TAGSAM arm that connect the sampler head to the arm. The spacecraft first cut the tube that carried the nitrogen gas that stirred up the sample through the TAGSAM head during sample collection, and then separated the collector head from the TAGSAM arm itself.

That evening, the spacecraft completed the final step of the sample stowage process – closing the SRC. To secure the capsule, the spacecraft closed the lid and then fastened two internal latches. As of late Oct. 28, the sample of Bennu is safely stored and ready for its journey to Earth.

The OSIRIS-REx team will now focus on preparing the spacecraft for the next phase of the mission – Earth Return Cruise. The departure window opens in March 2021 for OSIRIS-REx to begin its voyage home, and the spacecraft is targeting delivery of the SRC to Earth on Sep. 24, 2023.

StowCam_SRC-Close.jpg

Captured on Oct. 28, this image shows NASA’s OSIRIS-REx spacecraft completing the final step of the sample stowage process: closing its SRC. To seal the SRC, the spacecraft closes the lid and then secures two internal latches. The sample of Bennu is now safely stored and ready for its journey to Earth.
Credit: NASA/Goddard/University of Arizona/Lockheed Martin
 
Am 10. Mai soll OSIRIS-REx die Rückreise vom Asteroiden Bennu antreten. Vorher sollen noch mal Aufnahmen der Landestelle gemacht werden, um mit vorher/nachher-Vergleichen die Auswirkungen vom Touchdown zu dokumentieren.

OSIRIS-REx mission plans for May asteroid departure

Die Landung der Kapsel mit den Bodenproben ist weiterhin für den 24. September 2023 vorgesehen.

Eventuell wird das Mutterschiff dann ähnlich Hayabusa in einer 'extended mission' noch andere Ziele verfolgen.
 
OSIRIS-REx completes final tour of asteroid Bennu

OSIRIS-REx completed its last flyover of Bennu around 6 a.m. EDT April 7 and is now slowly drifting away from the asteroid; however, the mission team will have to wait a few more days to find out how the spacecraft changed the surface of Bennu when it grabbed a sample of the asteroid.

The OSIRIS-REx team added this flyby to document surface changes resulting from the Touch and Go (TAG) sample collection maneuver Oct. 20, 2020.

It will take until at least April 13 for OSIRIS-REx to downlink all of the data and new pictures of Bennu's surface recorded during the flyby. It shares the Deep Space Network antennas with other missions like Mars Perseverance, and typically gets 4–6 hours of downlink time per day.

Once the mission team receives the images and other instrument data, they will study how OSIRIS-REx jumbled up Bennu's surface.

OSIRIS-REx, with its pristine and precious asteroid cargo, will remain in the vicinity of Bennu until May 10 when it will fire its thrusters and begin its two-year cruise home. The mission will deliver the asteroid sample to Earth Sept. 24, 2023.
 
Seit bald einem Jahr befindet sich OSIRIS REx nun schon auf dem Rückflug zur Erde und es wird noch gut ein weiteres Jahr dauern, bis die Kapsel am 24.09.2024 mit den bei Bennu eingesammelten Bodenproben am Fallschirm in Utah landen soll. Derweil fliegt das Mutterschiff an der Erde vorbei, aber wohin, das war bislang noch nicht klar.

Jetzt hat die NASA sich festgelegt und ein besonders interessantes Ziel ausgewählt, eben jenen ominösen Asteroiden Apophis, welcher am 13. April 2029 ganz knapp innerhalb der Bahn von geostationären Satelliten vorbeischrammen wird. Wenige Tage später soll die Sonde unter der neuen Bezeichnung OSIRIS APEX ein Rendezvous mit dem Asteroiden eingehen und diesen ähnlich wie seinerzeit bei Bennu für 18 Monate begleiten und dabei natürlich eingehend untersuchen:

On 25 April 2022, NASA confirmed that the mission would be extended. After dropping off its sample to Earth in 2023, the mission will become OSIRIS-APEX ('APophis EXplorer'). As its new name suggests, its next target will the near-Earth asteroid (and potentially hazardous object) 99942 Apophis. Apophis will make an extremely close pass to the Earth on 13 April 2029. Observations of Apophis will commence on 8 April 2029, and a few days later, on 21 April, OSIRIS-APEX is planned to rendezvous with the asteroid. OSIRIS-APEX will orbit Apophis for around 18 months in a regime similar to that at Bennu. The spacecraft will perform a maneuver, similar to sample collection at Bennu, by using its thrusters to disturb Apophis's surface, in order to expose and spectrally study the subsurface and the material beneath it.

New Target for Asteroid Probe: "Potentially Hazardous" Apophis

Das verspricht ein ziemliches Spektakel mit maximalem Interesse der Medien und der Öffentlichkeit zu werden!
 
Zuletzt bearbeitet:
Bevor OSIRIS-REx den Asteroiden Bennu untersuchen konnte, hatte man eigentlich eine mit feinkörnigem Regolith bedeckte Oberfläche erwartet, so ähnlich wie man das vom Mond oder größeren Asteroiden wie Eros kennt. Umso größer war die Überraschung angesichts der zerklüfteten Erscheinungsform von Bennu. Dafür gibt es jetzt eine plausible Erklärung:

Fine-grained regolith loss on sub-km asteroids

Bennu hat mit einer geschätzten Masse von 7,33 x 10^10 kg und einem mittleren Radius von 245 m nur eine geringe Fluchtgeschwindigkeit von ca. 0,2 m/s. Das hat zur Folge, dass feinkörniges Material, welches durch Sonneneinstrahlung elektrostatisch aufgeladen wird und dann so ähnlich wie Popcorn in der Pfanne nach oben schießt, wegen der geringen Schwerkraft tatsächlich verloren geht.

Hopping space dust makes asteroids look rougher

OSIRIS-REx_landing.jpg

Image Credit: NASA/Goddard/University of Arizona
 
Science

Science Advances

Hinterher ist man immer schlauer, das hätte auch schiefgehen können:

Asteroid Bennu almost swallowed spacecraft whole

New analysis shows that NASA's OSIRIS-REX probe punched right through the surface of rubble-pile asteroid 101955 Bennu while on its way to collect a sample. If the probe hadn’t been programmed to lift itself back into orbit a few seconds after landing, the half-kilometer asteroid could have swallowed it whole.

The asteroid is so loosely bound that the brief jet of gas that was supposed to blow surface material into the collection hopper instead blasted out 6,000 kilograms of dust and rock.

The plan was then for the TAGSAM head to touch the surface and stay there for five seconds while a jet blew nitrogen gas into surface material, swirling it up for collection by the head. The spacecraft would then slowly lift off the asteroid with the sample and return to orbit.

However, TAGSAM didn't stop when it touched the surface. It kept on going, pushing another half-meter down before the spacecraft reversed course, lifting the mechanism upward through the blasted-out dust and particles ...
 
Erosion durch Sonneneinstrahlung:

Alignment of fractures on Bennu’s boulders indicative of rapid asteroid surface evolution

On asteroids, fractures develop due to stresses driven by diurnal temperature variations at spatial scales ranging from sub-millimetres to metres. However, the timescales of such rock fracturing by thermal fatigue are poorly constrained by observations.

Some asteroids 'aged early' by sun, NASA finds

Scientists from NASA's OSIRIS-REx mission recently learned that surface regeneration happens a lot quicker on asteroids than on Earth. By analyzing rock fractures on asteroid Bennu from high-resolution images taken by the OSIRIS-REx spacecraft, the team discovered that the Sun's heat fractures rocks on Bennu in just 10,000 to 100,000 years.

Rapid temperature changes on Bennu create internal stress that fractures and breaks down rocks, similar to how a cold glass breaks under hot water. The Sun rises every 4.3 hours on Bennu. At the equator, daytime highs can reach almost 127 C, and nighttime lows plummet to nearly minus 23 C.
 
Zitat von P_E_T_E_R:
Bis zur geplanten Landung der Kapsel mit den Bodenproben in knapp einem Jahr am 24. September werden noch weitere Bahnjustierungen folgen.
Klicke in dieses Feld, um es in vollständiger Größe anzuzeigen.
Und das passierte gestern am 26.07.2023:

OSIRIS-REx Spacecraft Adjusts Course to Get Closer to Earth

On July 26, NASA’s OSIRIS-REx spacecraft fired its engines for about 63 seconds to slightly thrust itself onto a course closer to Earth.

Preliminary tracking data indicates OSIRIS-REx changed its velocity, which includes speed and direction, by 1.3 miles, or 2 kilometers, per hour. It’s a tiny but critical shift; without course adjustments like this one the spacecraft would not get close enough to Earth on Sept. 24 to drop off its sample of asteroid Bennu.

The spacecraft is currently 24 million miles, or 38.6 million kilometers, away, traveling at about 22,000 miles, or about 35,000 kilometers, per hour toward Earth.

Gruß, Peter
 
Am kommenden Sonntag Nachmittag deutscher Zeit, also am 24. September, soll die Kapsel mit den Bodenproben von Bennu am Fallschirm in Utah runterkommen!

Wikipedia

NASA Mitteilung

Wie oben in Post #70 bereits berichtet, wird das Mutterschiff die Erde passieren und dann den berüchtigten Asteroiden Apophis ansteuern:

On 25 April 2022, NASA confirmed that the mission would be extended. After dropping off its sample to Earth in 2023, the mission will become OSIRIS-APEX ('APophis EXplorer'). As its new name suggests, its next target will be the near-Earth asteroid (and potentially hazardous object) 99942 Apophis. Apophis will make an extremely close pass to the Earth on 13 April 2029. Observations of Apophis will commence on 8 April 2029, and a few days later, on 21 April, OSIRIS-APEX is planned to rendezvous with the asteroid. OSIRIS-APEX will orbit Apophis for around 18 months in a regime similar to that at Bennu. The spacecraft will perform a maneuver, similar to sample collection at Bennu, by using its thrusters to disturb Apophis's surface, in order to expose and spectrally study the subsurface and the material beneath it.

New Target for Asteroid Probe: "Potentially Hazardous" Apophis

Gruß, Peter
 
Erwarter Touchdown morgen Sonntag in Utah um 14:55 GMT = 16:55 MESZ, mit Live-Übertragung ab 16:00 MESZ:

OSIRIS-REx Landing Schedule

10:55 a.m. EDT (8:55 a.m. MDT, 1455 GMT)Touchdown on Earth of the OSIRIS-REx asteroid sample return capsule, carrying material from the surface of Bennu.

NASA’s live coverage of the OSIRIS-REx sample capsule landing starts at 10 a.m. EDT (8 a.m. MDT) and will air on X, Facebook, YouTube, Twitch, NASA TV, the NASA app, and the agency’s website.

Gruß, Peter
 
Was mich an der Sache am meisten wundert - wie kriegt man das auf die große Strecke von Bennu bis zur Erde hin, dass das Ding auf die Minute genau am Ziel ankommt. Mit anderen Worten, welche Stellschrauben hat man da an der Anflugtrajektorie, um das so genau zu justieren?

Gruß, Peter
 
Zitat von P_E_T_E_R:
Was mich an der Sache am meisten wundert - wie kriegt man das auf die große Strecke von Bennu bis zur Erde hin, dass das Ding auf die Minute genau am Ziel ankommt. Mit anderen Worten, welche Stellschrauben hat man da an der an der Anflugtrajektorie, um das so genau zu justieren?
Klicke in dieses Feld, um es in vollständiger Größe anzuzeigen.
Gute Frage.
Ab wann war der Landezeitpunkt denn überhaupt so genau bekannt?
Vielleicht hat man ja ein halbes Jahr vorher oder so geschaut, in derundder Minute wird das Ding landen, und erst dann die genaue Zeit veröffentlicht?

Gruss
Thorsten
 
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