Rosetta safe mode 5 km from comet

Over the weekend, Rosetta experienced a ‘safe mode’ event 5 km from the surface of Comet 67P/Churyumov-Gerasimenko. Contact with the spacecraft has since been recovered and the mission teams are working to resume normal operations.

“We lost contact with the spacecraft on Saturday evening for nearly 24 hours,” says Patrick Martin, ESA’s Rosetta mission manager. “Preliminary analysis by our flight dynamics team suggests that the star trackers locked on to a false star – that is, they were confused by comet dust close to the comet, as has been experienced before in the mission.”

Credits: ESA-C.Carreau

This led to spacecraft pointing errors, which triggered the safe mode. Unfortunately the star trackers then got hung in a particular sub mode requiring specific action from Earth to recover the spacecraft.

“It was an extremely dramatic weekend,” says Sylvain Lodiot, ESA’s Rosetta spacecraft operations manager.

“After we lost contact, we sent commands ‘in the blind’, which successfully tackled the hung star tracker issue and brought the spacecraft back into three-axis stabilised safe mode, and we now have contact with the spacecraft again. However, we are still trying to confirm the spacecraft’s exact position along its orbit around the comet – we only received images for navigation this morning, the first since Saturday.”

As is normal during an event like this, extra ground tracking station time was requested to provide additional support for recovering the spacecraft. The regularly scheduled Rosetta tracking slot using ESA's New Norcia deep space station in Australia on Sunday was extended, with time reallocated from Mars Express operations. The blind commanding was done from New Norcia, and later, ESA's Cebreros deep space station in Spain was also used to support the recovery.

Rosetta's star trackers are marked here in red (above Philae in this pre-seperation artist impression). Part of the high gain antenna can be seen in the background. Image credit: ESA/ATG medialab.

Star tracker recap
The spacecraft’s star trackers are used to navigate, and help control the attitude of the spacecraft. By using an autonomous star pattern recognition function, they provide input to the onboard Attitude and Orbit Control and Measurement Subsystem used to maintain the spacecraft’s orientation with respect to the stars. This allows the spacecraft to know its orientation with respect to the Sun and Earth. In turn, this ensures the spacecraft can correctly orient its high gain antenna, used to send and receive signals to and from ground stations on Earth.

Correct attitude is maintained when the star trackers are properly tracking stars. If this is interrupted, the spacecraft’s antenna can drift away from Earth and communication with the spacecraft potentially lost. When the star trackers are not tracking, the attitude is propagated on gyro measurements. But the attitude can drift, especially if the spacecraft is slewing a lot.

Operating close to the comet means that the spacecraft is surrounded by a lot of dust. Even though the comet’s activity has diminished significantly since passing through its closest point to the Sun along its orbit last August, the environment is still dusty enough that the star trackers can occasionally mistake comet debris in its field of view for stars.

OSIRIS narrow-angle camera image taken in the morning of 28 May 2016 (many hours before the safe mode) when Rosetta was 7.05 km from the centre of Comet 67P/Churyumov–Gerasimenko. The scale is 0.13 m/pixel. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

What happens next?
As usual with a safe mode, the science instruments are automatically switched off, allowing the spacecraft operators to take the necessary steps to fully recover the spacecraft before resuming science operations. Prior to the safe mode, the plan for this week was to move into 30 km orbits around the comet on Wednesday 1 June. The team still hopes to meet this target and be able to resume normal operations by then.

The dramatic events of the weekend are a stark reminder of the dangers associated with flying close to the comet, and highlights the risks the spacecraft will face during the final few weeks of the mission as it descends even closer to the comet.

“The last six weeks of the mission will be far more challenging for flight dynamics than deploying Philae to the surface was in November 2014, and it is always possible that we could get another safe mode when flying close to the comet like this,” says Sylvain.

“Although we will take more risks nearer to the end of the mission, we’ll always put the spacecraft safety first.

“However,  the very final sequence where Rosetta makes a controlled impact on the surface of the comet should not be affected by such star tracker issues as we plan to take them out of the attitude and orbit control system loop.”

The team will also consider taking the star trackers out of the loop when required in the last weeks of the mission.

Details of Rosetta’s final descent will be provided soon. The provisional plan is to target the small lobe close to Philae’s original planned landing site at Agilkia, most likely on 30 September.

from Rosetta – ESA's comet chaser http://ift.tt/1sne9K1
via IFTTT

NASA to Televise Expansion Operations for Bigelow Expandable Activity Module

NASA and Bigelow Aerospace will make a second attempt at 9 a.m. EDT Saturday, May 28, to expand the Bigelow Expandable Activity Module (BEAM), currently attached to the International Space Station. NASA Television coverage will begin at 8:45 a.m.

from NASA Breaking News http://ift.tt/20LXBGH
via IFTTT

Rosetta’s comet contains ingredients for life

This story is mirrored from the ESA Web Portal

Ingredients regarded as crucial for the origin of life on Earth have been discovered at the comet that ESA’s Rosetta spacecraft has been probing for almost two years.

They include the amino acid glycine, which is commonly found in proteins, and phosphorus, a key component of DNA and cell membranes.

Scientists have long debated the important possibility that water and organic molecules were brought by asteroids and comets to the young Earth after it cooled following its formation, providing some of the key building blocks for the emergence of life.

While some comets and asteroids are already known to have water with a composition like that of Earth’s oceans, Rosetta found a significant difference at its comet – fuelling the debate on their role in the origin of Earth’s water.

But new results reveal that comets nevertheless had the potential to deliver ingredients critical to establish life as we know it.

Amino acids are biologically important organic compounds containing carbon, oxygen, hydrogen and nitrogen, and form the basis of proteins.

Hints of the simplest amino acid, glycine, were found in samples returned to Earth in 2006 from Comet Wild-2 by NASA’s Stardust mission. However, possible terrestrial contamination of the dust samples made the analysis extremely difficult.

Now, Rosetta has made direct, repeated detections of glycine in the fuzzy atmosphere or ‘coma’ of its comet.

“This is the first unambiguous detection of glycine at a comet,” says Kathrin Altwegg, principal investigator of the ROSINA instrument that made the measurements, and lead author of the paper published in Science Advances today.

“At the same time, we also detected certain other organic molecules that can be precursors to glycine, hinting at the possible ways in which it may have formed.”

The measurements were made before the comet reached its closest point to the Sun – perihelion – in August 2015 in its 6.5 year orbit.

The first detection was made in October 2014 while Rosetta was just 10 km from the comet. The next occasion was during a flyby in March 2015, when it was 30–15 km from the nucleus.

Glycine was also seen on other occasions associated with outbursts from the comet in the month leading up to perihelion, when Rosetta was more than 200 km from the nucleus but surrounded by a lot of dust.

“We see a strong link between glycine and dust, suggesting that it is probably released perhaps with other volatiles from the icy mantles of the dust grains once they have warmed up in the coma,” says Kathrin.

Glycine turns into gas only when it reaches temperatures just below 150°C, meaning that usually little is released from the comet’s surface or subsurface because of the low temperatures. This accounts for the fact that Rosetta does not always detect it.

 

“Glycine is the only amino acid that is known to be able to form without liquid water, and the fact we see it with the precursor molecules and dust suggests it is formed within interstellar icy dust grains or by the ultraviolet irradiation of ice, before becoming bound up and conserved in the comet for billions of years,” adds Kathrin.

Another exciting detection made by Rosetta and described in the paper is of phosphorus, a key element in all known living organisms. For example, it is found in the structural framework of DNA and in cell membranes, and it is used in transporting chemical energy within cells for metabolism.

“There is still a lot of uncertainty regarding the chemistry on early Earth and there is of course a huge evolutionary gap to fill between the delivery of these ingredients via cometary impacts and life taking hold,” says co-author Hervé Cottin.

“But the important point is that comets have not really changed in 4.5 billion years: they grant us direct access to some of the ingredients that likely ended up in the prebiotic soup that eventually resulted in the origin of life on Earth.”

“The multitude of organic molecules already identified by Rosetta, now joined by the exciting confirmation of fundamental ingredients like glycine and phosphorous, confirms our idea that comets have the potential to deliver key molecules for prebiotic chemistry,” says Matt Taylor, ESA’s Rosetta project scientist.

“Demonstrating that comets are reservoirs of primitive material in the Solar System and vessels that could have transported these vital ingredients to Earth, is one of the key goals of the Rosetta mission, and we are delighted with this result.”

 

“Prebiotic chemicals – amino acid and phosphorus – in the coma of comet 67P/Churyumov–Gerasimenko”, by K. Altwegg et al is published in the journal Science Advances.

from Rosetta – ESA's comet chaser http://ift.tt/1X19smk
via IFTTT

NASA Updates Time for Today’s Media Briefing on Status of Bigelow Expandable Activity Module

NASA has rescheduled today’s media teleconference, originally scheduled for noon EDT, to 2 p.m. for a discussion on the status of the Bigelow Expandable Activity Module (BEAM) installed on the International Space Station. The teleconference will stream live on the agency’s website.

from NASA Breaking News http://ift.tt/1UavE6D
via IFTTT

CometWatch 19 May

This week's CometWatch entry is an image of Comet 67P/Churyumov-Gerasimenko taken with Rosetta's NAVCAM on 19 May 2016, when the spacecraft was 7.6 km from the centre of the comet nucleus and about 5.6 km from the surface.

Enhanced NAVCAM image of Comet 67P/C-G taken on 19 May 2016, 7.6 km from the nucleus centre. The average scale is 0.65 m/pixel and the image measures about 660 m across. The faint vertical striping effect, especially visible in the lower part of this view, is an image artifact. Credits: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0

This close-up view shows a portion of the comet's southern hemisphere, on the large lobe, around the Bes region. The image reveals the diverse appearance of the surface on this portion of the nucleus, with rugged and smooth patches, several cross-cutting fracture lines and a multitude of boulders of various sizes.

Also released this week was an impressive view captured by Rosetta's OSIRIS wide-angle camera of the nearby Imhotep region, also on the large comet lobe. The image, taken only 7 km from the nucleus centre (about 5 km from the surface) on 25 May, is dominated by boulders.

OSIRIS wide-angle camera image taken on 25 May 2016, when Rosetta was 7.0 km from the centre of Comet 67P/C-G. The scale is 0.69 m/pixel. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

Two large boulders can be seen in the top right, embedded in the smooth environment of Imhotep where surface changes have been observed since mid-2015 (see our earlier post: "Comet surface changes before Rosetta’s eyes"). Many more boulders of different sizes are also visible towards the lower left part of the image.

Meanwhile, the National Astronomical Observatory of Japan recently released a ground-based image of Comet 67P/C-G, taken with the Hyper Suprime-Cam on the Subaru Telescope on 8 March 2016.

Image taken with the Hyper Suprime-Cam on the Subaru Telescope on 8 March 2016 (top right). The image is centered on the compact group of galaxies HCG 59, while Comet 67P/Churyumov-Gerasimenko is visible in the bottom right. Zoomed-in views of HCG 59 and of the comet are shown, respectively, on the upper left and at the bottom. Credit: Subaru Telescope, National Astronomical Observatory of Japan (NAOJ)

While the comet was not the main goal of this observation, which was aimed at the Hickson Compact Group 59 (or HCG 59), a group of galaxies about 190 million light-years away from us, the very large field of view of this camera enabled 67P/C-G to be captured in full glory, with its coma, long tails, and a faint but clearly visible dust trail. Read more about it on the Subaru Telescope webpage.

The original NAVCAM image is provided below.

from Rosetta – ESA's comet chaser http://ift.tt/1RwW40M
via IFTTT

Mark Zuckerberg to Connect with Space Station Astronauts via Facebook Live

Mark Zuckerberg, Facebook founder and chief executive officer, will speak with three astronauts currently living and working aboard the International Space Station at 12:55 p.m. EDT Wednesday, June 1. The Earth-to-space call will be seen live on NASA’s Facebook page.

from NASA Breaking News http://ift.tt/1TJjAMB
via IFTTT

NASA to Brief Media on Status of Bigelow Expandable Activity Module

NASA will host a media teleconference at noon EDT Friday, May 27 to provide an update on the expansion operations for the Bigelow Expandable Activity Module (BEAM) installed on the International Space Station. The teleconference will stream live on the agency’s website.

from NASA Breaking News http://ift.tt/1Z42wSI
via IFTTT

NASA Selects Contractor for Safety, Mission Assurance Services

NASA has selected Honeywell Technology Solutions, Inc. of Columbia, Maryland, to provide safety and mission assurance, audits and assessments support services for the agency’s Safety Center in Cleveland.

from NASA Breaking News http://ift.tt/20HDqK3
via IFTTT

NASA Awards Financial and Business Management Services Contract

NASA has selected Logical Innovations, Inc., of Houston to provide financial and business management services for the Office of the Chief Financial Officer, Office of Procurement and other entities at the agency's Johnson Space Center in Houston.

from NASA Breaking News http://ift.tt/25muccO
via IFTTT

NASA Astronaut Kate Rubins Available for Interviews Before Space Station Launch

NASA astronaut Kate Rubins will be available for live satellite interviews from Moscow on Wednesday, June 1, before her launch to the International Space Station. She will answer questions about her upcoming mission aboard the world’s only orbiting laboratory from 9-10 a.m. EDT, airing live on NASA Television and streaming on the agency’s website.

from NASA Breaking News http://ift.tt/1qHDRrp
via IFTTT

NASA Telescopes Find Clues For How Giant Black Holes Formed So Quickly

Using data from NASA’s Great Observatories, astronomers have found the best evidence yet for cosmic seeds in the early universe that should grow into supermassive black holes.

from NASA Breaking News http://ift.tt/1XunWcW
via IFTTT