Closest approach is scheduled for 08:45 CET, 13 November, but mission operators will perform a number of critical actions before and after the swingby to ensure that Rosetta is on the right trajectory.

View "Full story" for critical event timeline. -- Amruta

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Keep your notebooks and pens ready! In the next couple of hours, we'll provide a listing of the most critical swingby activities together with a timeline. -- Amruta

Just got a note from Flight Dynamics - the number crunching experts here at ESOC - on their calculations for Thursday's trajectory correction manoeuvre (TCM).

They’ve started their calculations for the manoeuvre design. They’re now waiting to receive the latest DSN tracking data from NASA. Next step: they’ll spend time today to optimise and finalise the manoeuvre calculations.

After that, the team will begin generation of the commands that need to be uploaded to Rosetta for the TCM. Once the commands are in, we will be able to tell you the precise start and end times of Thursday's TCM burn.

As of now, the preliminary estimate (change possible) is a thruster burn of 6 secs.

Rosetta Spacecraft Operations Manager (SOM) Andrea Accomazzo confirms that the manoeuvre will make use of the 4 axial thrusters located at each corner of the Rosetta main body. These point directly along the central axis of the spacecraft.

Each of Rosetta's 24 thrusters can generate a force of 10 Newtons, about the same as you would experience if you were holding a large bag of apples on Earth. At launch in 2004, over half the spacecraft's mass comprised propellant (approx. 1670 kg)!

Click on 'Full story' to view a short YouTube clip on Rosetta ESB3. -- Daniel

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A quick note on times that we mention while reporting on Earth swingby No. 3 (ESB3)!

Times will be given in UTC (Coordinated Universal Time), usually as the spacecraft event time - i.e. the time that something happens on board Rosetta. The time on Earth will be more or less the same, except for the one-way signal travel time. This delay, obviously, becomes negligible as Rosetta gets nearer to Earth and then increases again as she recedes. For most purposes, UTC can be taken as identical to GMT (Greenwich Mean Time).

We will also try to give the local CET time (Central European Time), which is actually Central European Summer Time (CEST, or daylight savings time) until Sunday, 25 October 2009.

In summary

Until 25 Oct:: CEST = UTC/GMT + 2 hours
After 25 Oct::  CET = UTC/GMT + 1 hours

A quick snapshot taken this morning as the Rosetta Flight Control Team were in a meeting to prepare for today's important simulation training.

I thought this sign, recently posted near the entrance to the interplanetary missions combined dedicated control room area here at ESOC, was pretty neat, in a futuristic, minimalist way.

Today's simulation will be a ‘dress rehearsal’ for one of the upcoming trajectory correction manoeuvres (TCM); there are a total of four slots for TCMs during this swingby.

The main and most important one is scheduled to begin at 12:30 UT (14:30 CEST) on Thursday, 22 October (the day after tomorrow!). The TCM is intended to place Rosetta on the correct approach trajectory for Earth swingby #3 (ESB3).

Afterwards, the number-crunchers, ESA’s Flight Dynamics team, will analyse the results to determine the exact orbit, which will help judge whether any additional TCMs will be necessary (there are slots for three more TCMs: at 1 week, 1 day and 6 hours before closest approach).

Thursday's TCM will take place while Rosetta is in communication with mission controllers via ESA's New Norcia Deep Space Antenna (DSA 1), in Australia, which is part of the Agency's ESTRACK network.

Rosetta Spacecraft Operations Engineer Sylvain Lodiot, who is acting as Spacecraft Operations Manager (SOM) for the B-half of the Flight Control Team during ESB3 activities, told me this morning to drop by around 16:00 CEST today to get an update on the simulation. -- Daniel

On Friday, 13 November, 2009, at 07:46 UT, ESA's Rosetta satellite will make her third (and final) swing-by of Earth, picking up a gravity assist from our bulky home planet and altering trajectory as she enters the next stages of the 10-year journey to Comet 67 P/Churyumov-Gerasimenko.

The ESA Flight Dynamics team have predicted Rosetta's altitude at the point of closest approach (perigee height) on 13 November to be 2481 km, slightly higher than her first swing-by in March 2005 (1954 km) and lower than her second swing-by on 13 November 2007 (5295 km). We'll update this figure as we get closer to the swing-by date itself...

The geographical point of closest approach (the point on the Earth's surface over which she'll make closest approach) is 109°E and 8°S - just off the coast of the Indonesian island of Java.

109°E, 8°S

Rosetta Earth Swing-by 13.11.2009 07:46 UT - Point of closest approach @ 2481 km altitude

As of 18:00 UTC (19:00 CET) Friday, 16 October, Rosetta was 0.1558 AU (astronomical unit - equal to the Earth-Sun distance, or 149 598 000 kms) from the Earth, a distance which is, of course, quickly decreasing.

In fact, at that time, she will be approaching Earth at 10.79 km/second. In comparison, a modern passenger jet aircraft travels about 14 km/minute, so Rosetta is travelling over 46 times faster!

Welcome back to the Rosetta Blog! The web team here are looking forward to bringing you regular updates on Rosetta's third and last Earth swing-by, due for 13 November. In the next few weeks, we will provide updates on her progress, including the planned trajectory correction manoeuvres, the flight dynamics calculations, the scientific observations and flight control team activities from the Rosetta control room at ESA's European Space Operations Centre, Darmstadt (click on Full story for a quick summary of Rosetta mission highlights to date).
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