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  ESA's Rosetta comet probe: Questions, comments (Page 1)

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Author Topic:   ESA's Rosetta comet probe: Questions, comments
Robert Pearlman
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posted 01-21-2014 06:34 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
ESA's Rosetta to Comet 67P: questions, comments

This thread is intended for comments and questions regarding the updates under: ESA's Rosetta probe and lander to Comet 67P.

Rosetta is the first mission designed to orbit and land on a comet. It consists of an orbiter, carrying 11 science experiments, and a lander — called 'Philae' — carrying ten additional instruments, for the most detailed study of a comet ever attempted.

moorouge
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posted 01-21-2014 06:38 PM     Click Here to See the Profile for moorouge   Click Here to Email moorouge     Edit/Delete Message   Reply w/Quote
Here is the latest on Rosetta, via ESA's Rosetta Blog -
  • After yesterday's (Jan. 20) spectacular receipt of first signal at 19:18 CET, ending 31 months of hibernation, the team have re-established full control over Rosetta.

  • All basic parameters have been checked out, and it looks like Rosetta came through hibernation fine.

  • For example, the propellant tank temperatures are running now at 7-9 deg C, slightly colder than the 10-15 deg C expected but well within predictions

  • Power levels (i.e. electricity available from the huge solar panels) are fine and substantially similar to the levels prior to hibernation.

  • The solar arrays appear not to have suffered very much degradation if any during 31 months.

  • Team working today to start configuring the solid-state mass memory for use.

  • Next big step will be warming up the reaction wheels and then spinning them up for verification; this will take several days.

  • Acquisition of signal (AOS) yesterday came 18 minutes later than hoped for, but also well within expectations.

  • The slight AOS delay was due to the on-board computer automatically rebooting itself at the beginning of the hibernation exit sequence; the team are looking into this (but Andrea stresses this is not problematic).

  • The team has switched the spacecraft's transmitter to X-band; this means we can now get a decent download rate of about 9 kbps.

  • Tracking has been provided via NASA's Canberra and ESA's New Norcia stations; NASA Goldstone was on call for backup; from now DSN stations will swap roles (Canberra will be on call for back-up).

Blackarrow
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posted 07-31-2014 05:18 PM     Click Here to See the Profile for Blackarrow     Edit/Delete Message   Reply w/Quote
The nucleus of Rosetta's target comet seen from a distance of 1,212 miles (1,950 km) on July 29, 2014.
Good luck mapping the gravity of such an irregular object! Sounds like a job for Buzz "Dr Rendezvous" Aldrin.

Robert Pearlman
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posted 08-06-2014 05:33 AM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
After a decade-long journey chasing its target, ESA's Rosetta has today become the first spacecraft to rendezvous with a comet, opening a new chapter in Solar System exploration.
Congratulations to the European Space Agency and the Rosetta team!

A question though: is Rosetta really the first probe to rendezvous with a comet?

Rosetta is on track to become the first to orbit a comet, and the first to land a probe on a comet's surface, but what of ICE (ISEE-3), Giotto, Stardust and Deep Impact? Did they not also rendezvous during their planned and successful flybys?

cspg
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posted 08-06-2014 09:36 AM     Click Here to See the Profile for cspg   Click Here to Email cspg     Edit/Delete Message   Reply w/Quote
My understanding is that Rosetta is the first to orbit a comet (and land a probe on the surface), not the first to rendezvous/fly-by. It's also the first probe to get so close to a comet (current altitude of the orbit: 100 kilometers).

Hats off to the team for this extraordinary achievement!

cspg
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posted 08-06-2014 10:06 AM     Click Here to See the Profile for cspg   Click Here to Email cspg     Edit/Delete Message   Reply w/Quote
The new released images are quite stunning. I wonder if the comet will end up breaking up in two due to its shape. Also on one photo, it seems that there is a huge crater on one edge of the comet.

Robert Pearlman
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posted 08-06-2014 10:16 AM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
A tattoo ten years in the making... (Photo courtesy ESA/S. Bierwald)

Robert Pearlman
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posted 08-06-2014 11:02 AM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
Neat size comparison from ESA:

Blackarrow
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posted 08-06-2014 12:57 PM     Click Here to See the Profile for Blackarrow     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by cspg:
The new released images are quite stunning.
That's one weird-looking piece of real estate. At last a part of my taxes has contributed to a headline space achievement (or at least I hope it has!)

cspg
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posted 08-06-2014 01:55 PM     Click Here to See the Profile for cspg   Click Here to Email cspg     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by Robert Pearlman:
A tattoo ten years in the making...
As I have been watching "Miami Ink" and "LA Ink" shows these days, it never occurred to me that someone would have tattooed a spacecraft!

SkyMan1958
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posted 09-11-2014 10:45 AM     Click Here to See the Profile for SkyMan1958   Click Here to Email SkyMan1958     Edit/Delete Message   Reply w/Quote
Rosetta took a "selfie" of itself on September 7. Here's a BBC article that includes the image.

cspg
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posted 09-11-2014 03:06 PM     Click Here to See the Profile for cspg   Click Here to Email cspg     Edit/Delete Message   Reply w/Quote
It's a stunning picture, taken by the landing craft Philae of itself and its target. Image from ESA is here.

lspooz
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posted 10-24-2014 12:37 PM     Click Here to See the Profile for lspooz   Click Here to Email lspooz     Edit/Delete Message   Reply w/Quote
ESA recently released a short science fiction film about the Rosetta probe, notable both for the mission goals and a reminder of the dreams and goals that underlie space exploration (yeah, and a Game Of Thrones actor...).

Robert Pearlman
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posted 11-07-2014 06:13 AM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
European Space Agency (ESA) video release
Demonstrating Rosetta's Philae lander on the Space Station

ESA astronaut Alexander Gerst performs a demonstration of how ESA’s Rosetta mission will attempt to put a lander, called ‘Philae’ on the surface of comet 67P/Churyumov–Gerasimenko.

Alexander narrates the story of the Rosetta mission and performs a demonstration that visualises the difficulties of landing on an object that has little gravitational pull. Using the weightless environment of the Space Station, Alexander attempts to land ‘Philae’ (an ear plug) onto the surface of the ‘comet’ (an inactive SPHERES robot) with increasing levels of difficulty: a rotating comet that is not moving to one that is both rotating and moving.

This video is one of the six experiments and demonstrations in the Flying Classroom, Alexander will use small items to demonstrate several principles of physics in microgravity to students aged 10–17 years.

The Rosetta mission’s lander, Philae, will be deployed on 12 November at 08:35 GMT/09:35 CET from a distance of 22.5 km from the centre of the comet. It will land about seven hours later, with confirmation expected to arrive at Earth at around 16:00 GMT/17:00 CET.

Robert Pearlman
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posted 11-11-2014 02:25 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
You can watch Philae attempt to land on Comet 67P/Churyumov Gerasimenko:

Schedule of some key milestones on Nov. 12:

  • 12:35 a.m. CST (0635 GMT): Earliest Go/No Go - final decision for landing
  • 01:35 a.m. CST (0735 GMT): Latest Go/No Go - final decision for landing
  • 04:03 a.m. CST (0903 GMT): Philae separation (Forecast; 94-sec window)
  • 11:02 a.m. CST (1702 GMT): Expected landing and receipt of signal (Forecast; 40 minute variability)
For a more detailed timeline, see the European Space Agency's website here.

moorouge
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posted 11-12-2014 10:29 AM     Click Here to See the Profile for moorouge   Click Here to Email moorouge     Edit/Delete Message   Reply w/Quote
Well done ESA on the successful completion of a ground breaking mission. Looking forward to the first pictures from the surface of the comet.

Robert Pearlman
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posted 11-12-2014 10:50 AM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
Despite what was initially stated, ESA has now reported that Philae's harpoons did not fire and so the status of the probe on the surface is not clear.

The mission's controllers are weighing whether to try firing the harpoons again.

Headshot
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posted 11-12-2014 11:36 AM     Click Here to See the Profile for Headshot   Click Here to Email Headshot     Edit/Delete Message   Reply w/Quote
Has there been any confirmation that the lander is resting in an upright position?

Robert Pearlman
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posted 11-12-2014 09:12 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
There has been no explicit statement that they are upright, but earlier today, the head of the landing team said that they were still receiving data (both housekeeping and science), which presumably would not be the case if Philae was flipped upside down.

There is word tonight though, that it seems Philae made at least three touchdowns over a two hour period, which begs the question if the probe can actually be said to have "landed" when the cheers went up in control rooms.

Jurg Bolli
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posted 11-12-2014 09:17 PM     Click Here to See the Profile for Jurg Bolli   Click Here to Email Jurg Bolli     Edit/Delete Message   Reply w/Quote
Groundbreaking and breathtaking, Congratulations to ESA!

MCroft04
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posted 11-12-2014 09:21 PM     Click Here to See the Profile for MCroft04   Click Here to Email MCroft04     Edit/Delete Message   Reply w/Quote
How can a spacecraft "land" when there is no (very little) gravity? Wouldn't it bounce off (unless something grasped the comet surface)?

Robert Pearlman
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posted 11-12-2014 09:27 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
Had everything gone as planned, then Philae would have fired an upward facing thruster to push its landing legs into the ground of the comet while ice screws at the base of each foot drilled in. The probe would have also deployed two harpoons to anchor itself in place.

The thruster never fired because the active descent system couldn't be activated. The harpoons didn't fire for reasons not yet known. The ice screws may or may not have worked, but given the bounces, maybe not (leading to speculation that the ground where they landed may be very soft).

Brian Bayley
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posted 11-13-2014 04:55 AM     Click Here to See the Profile for Brian Bayley     Edit/Delete Message   Reply w/Quote
This may be a stupid question and forgive me if it has already been asked, but are these photos colour or black and white?

Robert Pearlman
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posted 11-13-2014 06:36 AM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
The photos returned from Philae's Comet nucleus Infrared and Visible Analyzer (CIVA) — the six cameras mounted on the sides of the lander 60 degrees apart — are black and white. Rosetta is equipped with a color camera (ROLIS).

Robert Pearlman
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posted 11-13-2014 06:38 AM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
According to Philae's official Twitter account, the data now shows the lander bounced three times ("performed three landings").
Yesterday was exhausting! I actually performed three landings,15:33, 17:26 and 17:33 UTC.

gliderpilotuk
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posted 11-13-2014 10:24 AM     Click Here to See the Profile for gliderpilotuk   Click Here to Email gliderpilotuk     Edit/Delete Message   Reply w/Quote
For once the (UK) media is giving this project the praise, coverage and historical context it richly deserves. Elsewhere the focus seems to be on the "failure" of the probe to attach itself securely rather than the amazing feat of traveling millions of miles for a spot landing on a fast-moving comet. Technically a lot harder than landing on a planet.

SkyMan1958
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posted 11-13-2014 10:40 AM     Click Here to See the Profile for SkyMan1958   Click Here to Email SkyMan1958     Edit/Delete Message   Reply w/Quote
I'd like to congratulate the ESA, and our European members, for a difficult job well done. Nice going folks!

It should be interesting to see what comes out in the scientific literature in a year or two.

Robert Pearlman
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posted 11-13-2014 11:15 AM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by gliderpilotuk:
Elsewhere the focus seems to be on the "failure" of the probe to attach itself securely rather than the amazing feat of traveling millions of miles for a spot landing on a fast-moving comet.
To be fair though, it is Rosetta, not Philae, that deserves (and has gotten) the credit for the 10-year journey to the comet. Philae did not make a spot landing, or arguably, a landing at all. Rather it did what Deep Impact did, just at a much slower velocity, colliding with a comet.

It is a tremendous feat regardless, but the lack of any of Philae's controlled landing mechanisms working defines the type of success.

onesmallstep
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posted 11-13-2014 11:44 AM     Click Here to See the Profile for onesmallstep   Click Here to Email onesmallstep     Edit/Delete Message   Reply w/Quote
Without splitting hairs whether the lander touched down or 'collided' (certainly better than what happened to the Ranger probes to the moon), it is an amazing achievement, with ESA now going two for two in comet exploration (first rendezvous and photos of Halley's Comet, and now Rosetta and its comet lander and surface photos).

As often happens in space exploration, the actual results often yield surprises to change theories or models of planets or environments. Not much was known of the composition of the lunar surface before Apollo 11; hence Surveyor was launched to exactly determine the conditions a Lunar Module would face in a landing. There were even theories that the surface was composed of deep, thick dust and any LM or astronaut boot would sink like in a bog! So rack one up for a bumpy but successful landing by Philae.

gliderpilotuk
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posted 11-14-2014 11:54 AM     Click Here to See the Profile for gliderpilotuk   Click Here to Email gliderpilotuk     Edit/Delete Message   Reply w/Quote
The (scientific) success will be defined by the output not by the quality of the landing!

It was nevertheless a remarkable technological/engineering achievement. So much so that even Buzz Aldrin appeared on BBC Newsnight last night to praise the achievement (and market his "Get your mule to Mars" t-shirt ).

Blackarrow
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posted 11-14-2014 12:48 PM     Click Here to See the Profile for Blackarrow     Edit/Delete Message   Reply w/Quote
Could someone direct me to a website where I can see all of the individual images taken by Philae on the surface of the comet? So far I can only find them presented in a single panorama.

Robert Pearlman
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posted 11-14-2014 02:10 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
ESA, to my knowledge, has not yet released the individual frames. They have said the images still need to be further processed.

Robert Pearlman
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posted 11-14-2014 02:14 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
You knew it was only a matter of time.
"Comet 67P is NOT a comet," the letter continues. "Some 20 years ago NASA began detecting radio bursts from an unknown origin out in space. It would later be known that these had likely come from the direction of the now named comet 67P. It does show signs on its outside of machine like parts and unnatural terrain."

Ending on an ominous note, it adds: "Whatever this object is, it did not ask to be found or scrutinised."

Headshot
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posted 11-14-2014 02:52 PM     Click Here to See the Profile for Headshot   Click Here to Email Headshot     Edit/Delete Message   Reply w/Quote
The funny thing is that Comet 67P was not Rosetta's original target. It was supposed to explore and land on 46P, Comet Wirtanen. In 2003 a problem with an Ariane 5 rocket forced the launch of Rosetta to be delayed enough (until 2004) so that 46P was no longer a viable target and the back-up, 67P, affectionately knick-named Cherry-Gerry was chosen.

Of course if you prefer the alien artifact story ... be my guest.

cspg
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posted 11-14-2014 02:53 PM     Click Here to See the Profile for cspg   Click Here to Email cspg     Edit/Delete Message   Reply w/Quote
From Swiss cartoonist Chappatte: Europe's Space Odyssey.

moorouge
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posted 11-14-2014 03:02 PM     Click Here to See the Profile for moorouge   Click Here to Email moorouge     Edit/Delete Message   Reply w/Quote
If one goes to the Rosetta website one can hear 67P sing.

Robert Pearlman
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posted 11-14-2014 07:20 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
European Space Agency (ESA) release
Our lander's asleep

With its batteries depleted and not enough sunlight available to recharge, Philae has fallen into 'idle mode' -- a possibly long silence. In this mode, all instruments and most systems on board are shut down.

"Prior to falling silent, the lander was able to transmit all science data gathered during the First Science Sequence," says DLR's Stephan Ulamec, Lander manager, who was in the main control room at ESOC tonight.

"This machine performed magnificently under tough conditions, and we can be fully proud of the incredible scientific success Philae has delivered."

Contact was lost at 00:36 UTC [6:36 p.m. CST], not long before the scheduled communication loss that would have happened anyway as Rosetta orbited below the horizon.

From now on, no contact would be possible unless sufficient sunlight falls on the solar panels to generate enough power to wake it up. The possibility that this may happen was boosted this evening when mission controllers sent commands to rotate the lander's main body, to which the solar panels are fixed. This may have exposed more panel area to sunlight.

The next possible communication slot begins on Nov. 15 at about 10:00 UTC [4:00 a.m. CST]. The orbiter will listen for a signal, and will continue doing so when its orbit enables communication visibility.

The hugely successful Rosetta mission will continue, as the spacecraft tracks comet 67P/C-G on its journey to the Sun. Rosetta is the first spacecraft to rendezvous with and orbit a comet and has already returned incredible scientific data.

Blackarrow
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posted 11-15-2014 10:54 AM     Click Here to See the Profile for Blackarrow     Edit/Delete Message   Reply w/Quote
Prior to falling silent, the lander was able to transmit all science data gathered during the First Science Sequence," says DLR's Stephan Ulamec, Lander manager, who was in the main control room at ESOC tonight
I find this confusing. Surely the "First Science Sequence" was conducted shortly after Philae made its final landing. What I want to hear is whether all of the data from the FINAL Science Sequence was successfully and completely transmitted.

Robert Pearlman
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posted 11-15-2014 11:01 AM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
Philae was equipped with 10 science instruments, and it was the full sequence of using all 10 that Ulamec is referring to. That first sequence took up the full 50 to 60 hours of battery life Philae had upon landing.

Additional sequences would have followed had Philae landed (and stayed) where planned and its solar panels could recharge its batteries.

John C UK
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posted 11-15-2014 11:38 AM     Click Here to See the Profile for John C UK   Click Here to Email John C UK     Edit/Delete Message   Reply w/Quote
My little homage to Rosetta and Philae is complete.

The paper model can be found on the ESA Rosetta outreach website

I have added some behind the scenes photos from the assembly of the spacecraft on my STEM Ambassador blog too...


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