Breaking News Philae rises from the Ashes

[John Murrell]

ESA and the BBC have just announced the Philae lander has woken up and contacted Rosetta – not Earth as the BBC have stated.

 

Have a look at the news for more information

 

Regards

 

John

 

[John Murrell]

The Sky at Night tonight is scheduled to be an update on Rosetta – I wonder if there is a bit of hurried re-writing & editing going on to reflect the latest news.

 

The latest I have seen is that 300 frames of data were downloaded and are being analysed but there are around 8k in Philae’s memory waiting for another contact opportunity.  Hopefully the radio Doppler shift should help in locating Philae as well though the calculations will be quite challenging.

 

Regards

 

John Murrell

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[Roy Easto]

Current distance from Sun 1.43 AU, closest approach 1.29 AU so just 20 percent off peak solar brightness, quite lucky it woke up when it did.

I wonder if there is anything left to do to try to make it bounce up?

Telemetry download rates from Rosetta to Earth is slow, around 45 kbps decreasing slowly so images take a long time to send to Earth.

Roy

[john chandler honnor]

Hi All,

Was it the approach to the sun – increasing sun’s brightness – and a possible shift in the comet’s angle to the sun that woke up Philae?

John Chandler

On 14/06/2015 21:16, "Roy Easto" <roy....@btinternet.com> wrote:

[Sean McAree]

Fantastic news what is the ideal operating temperature for Philae and how many watts does it need to operate at its maximum capacity?

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[John Murrell]

There is a video cast by Chris Lintott on the Sky at Night site where he talks about the news on Philae waking up. See http://www.bbc.co.uk/programmes/p02tq22d , I think it is on there where it was stated ’24 watts is plenty of power’

 

In addition to the Sun’s power of course the Rosetta orbiter needs to be visible to Philae for data to be sent so there are orbit geometry considerations as well. Apparently the 8k frames of data have been gathered over several days prior to contact so Philae has been awake but only managed to contact Rosetta on Saturday night.

 

More data was expected on Sunday night – I have not seen any confirmation yet – keep looking at the Rosetta Blog on http://blogs.esa.int/rosetta/ or the various twitter accounts for Philae and Rosetta.

 

Best Wishes

 

John

[Sean McAree]

Cheers John! 

[John Murrell]

Prof. Carole Mundell was on BBC Breakfast this morning talking about Philae waking up and the results to date. Wind the clock back to 7:40 on BBC player if you want to see it.

 

Two of the major results are that the water on Earth did not come from Comets like 76P due to the different isotropic ratios.

 

The second is that Philae’s bounces enabled them to determine the comet has no significant magnetic field so the material did not aggregate due to magnetic fields.

 

There should be more on these on the Sky @ Night yesterday but I have not looked at it yet – I was expecting S@N to be on at 22:00 as recent episodes so I they put it on at 20:00 instead ! As a result I decided not to view my recording but finish the test of the MOOC before I forgot the lectures !

 

Regards

[Roy Easto]

I remember the upload link from Philae to Rosetta is very fast but the connection to Earth is the slow link.

Roy

[Tony Roberts]

Interesting fact that Sky at Night gave was that if Philae had landed in full sunlight as planned it would by now have over heated (batteries over charging as the sunlight increased was the mechanism given).

By landing in unplanned deep shadow it has accidentally extended its life through perihelion, so the current and future downloads contain information from a part of the comets life they originally had not planned to observe.

This is one mission which has exceeded its concept repeatedly, and also shows that what initially looks like a disaster can actually work to ones advantage.

Tony 

Sent from my iPhone

[John Murrell]

Hi Roy,

 

Hope you are Ok.

 

One of the recent Rosetta blogs quoted ‘On the evening of 13 June, a weak but solid radio link between Rosetta and the lander was finally established for 85 seconds. More than 300 ‘packets’ – 663 kbits – of lander housekeeping telemetry were received.’

 

So 7,800 bits per second or  975 (8 Bit) bytes. I think Rosetta was around 200km away from another post.

 

Regards

[John Murrell]

It appears they got unexpected information from Philae’s bounce in November as well – this confirmed the Comet has no magnetic field. Presumably the bounce allowed them to factor out the spacecraft magnetic field.

 

Sunday communication was quite poor so they are trying to work out why. They need to try to charge the battery so Philae can working when the Sun is not up – a lot depends on how much Sunlight they get. Rather worrying is the Sunday results showed the lander temperature rising from -35 C to -5 C . That rate of rise cannot be sustained for long if true.