In January, over 200 of you sent us video ‘selfies’ as part of ESA’s Wake Up Rosetta campaign, with the videos collectively receiving some 75 000 votes. It was a genuine pleasure for us to award some cool prizes to the top winners.
As the final step in the prize awards, we’re preparing to transmit the top 10 video selfies into space, using one of ESA’s tracking stations that regularly communicates with Rosetta, sending them on a light-speed journey far into deep space.
Here’s how it’s going to work
On 15 May, ESA’s 35m deep-space tracking station located at Cebreros, 77 kms west of Madrid, Spain, will transmit a 35MB archive file containing the Top 10 video selfies submitted during the Rosetta Wake Up campaign. (If you’d like, you can download the actual file that will be transmitted here.)
Cebreros is part of our Estrack network and is normally used to send telecommands to, and receive scientific data from, missions such as Mars Express, Venus Express, Rosetta and Gaia. In the future, it will be used for missions like BepiColombo, ExoMars and Juice, that are going to Mercury, Mars and Jupiter, respectively.
All Estrack stations are remote controlled from a specialised control room, the ECC (Estrack Control Centre), at ESOC. A team of station operators are on shift 365 days per year, ensuring receipt of precious data from spacecraft operated by ESA and numerous partner agencies.
Estrack network profile
For the purposes of this transmission into space, the station will be configured as follows:
- Pointing: Zenith – that is, directly up! The Estrack engineers call this the ‘Stow’ position. Well, in fact, it will be slightly off pointed from local vertical, at 89.99 degrees.
- Power: May Aimee Larsen, our Cebreros station engineer at ESOC, says Cebreros is equipped to transmit at up to 20 kW, but for our purposes we’ll use the 2 kW amplifier.
- Date/time: 15 May 2015. The transmission will start at about 14:40 CEST and last about 3 minutes.
- Bitrate: Normally, Cebreros transmits to different spacecraft at different rates, depending on the capabilities of the spacecraft, the radio frequencies being used, the range, etc. A typical maximum bit rate for transmission is 2 kbps (e.g. Rosetta) to 4 kbps (e.g. Gaia).
For 15 May, since Cebreros isn’t actually transmitting to a spacecraft, the bitrate can be set as high as possible for the station, to 250 kbps – this is just a fraction of the bitrate of a typical home DSL Internet connection (~ 5000-10000 kbps), but for space, it’s pretty darn fast!
Sequence of events
Since they’re located in Spain – and they were one of our Top 10 Wake Up Rosetta participants – we’ve invited a group of students from Colegio Público (Peñaluenga) De El Castillo De Las Guardas, near Seville, to make a bus trip to ESA’s ESAC Establishment, near Madrid, to help our Estrack engineers send the signal.
The students and their accompanying teachers, by the way, are totally excited and looking forward to the trip. The school has a very active science studies programme and focuses on STEM, so we are really pleased to be able to have them as guests. It’s not every day you get to send a transmission into the future!
Upon their arrival on the morning of 15 May, we’ve planned a guided tour of the Rosetta Science Operations facilities and the Villafranca 15m Estrack station. After lunch, at 14:00, the Cebreros station manager, Lionel Hernandez, will meet the students and provide a briefing on how we communicate with spacecraft in deep space and how Estrack stations help ESA gather scientific date from the Solar System.
At about 14:40, we’ll gather the students into one of the Villafranca station engineering rooms, and they’ll go on the voice loop with the Estrack Control Room at ESOC. After a short count-down, we’ll get the students to give the SEND command, and the ECC team will switch Cebreros transmit ON.
We’ll keep you updated here in the blog, via Twitter and Facebook and will post a full report in the main ESA website after the event on the 15th.
Where will the signal go?
It’s difficult to say with any certainty how far the signal will go, given the low-ish transmit power and the probability of being attenuated to undetectable levels in the future.
But here’s a quick listing of where the signal may go, put together by Markus Landgraf from ESA’s Mission Analysis team.
Below I have put together a table of times and objects that lie approximately along the path of the signal, assuming it is emitted from CEB on 15 May 2015 12:40 UTC.
|1 sec||Signal at distance of the Moon (but the Moon is on the other side of the Earth)|
|5 mins||Passing above the ecliptic plane close to Mercury – the target of ESA’s 2016 Bepi Colombo mission|
|21 mins||Passing the distance of the main part of the asteroid belt|
|30 mins||Same distance as Rosetta (which lies in a different direction)|
|4 hours||Now beyond Neptune, the outermost planet of our Solar System|
|14 hours||Travelling through the heliopause, which separates the realm of the solar wind from the local interstellar cloud|
|10 months||Passing through the Oort cloud of comets that surround the Sun|
|1 year||Leaving the local interstellar cloud that contains the Sun|
|200 years||Leaving the local bubble – an interstellar void carved out of the Orion spur by a supernova hundreds of million of years ago|
|300 years||Leaving behind the Orion spur – our branch of the Sagittarius spiral arm of our Milky Way galaxy|
|548 years||Passing close to Epsilon Persei – a bright star in the constellation of Perseus|
|1000 years||Passing by the California Nebula|
|5000 years||Leaving behind the neighbouring Perseus spiral arm of the Milky Way|
|20 000 years||Passing the outer fringes of the Milky Way galaxy|
|2 450 000 years||Same distance as the Andromeda galaxy, a neighbour to our Milky Way|
|10 000 000 years||Leaving the local group of 54 galaxies, of which the Milky Way and Andromeda are members|
|70 000 000 years||Leaving the Virgo Supercluster, in which the local group is contained|
|13 800 000 000 years||Reaching the edge of the observable Universe (observable from Earth as of today)|
OK – even if the signal doesn’t reach any where near the edge of the Universe, it’s pretty cool to think that it might!
About the station
Cebreros station (DSA 2) was inaugurated in 2005 and is the second in the Agency’s trio of 35-metre deep space stations; the other two are in New Norcia, Australia (DSA 1), and Malargüe, Argentina (DSA 3). The three are some of the world’s most sophisticated and technically advanced tracking stations used for satellite control, and are capable of communicating with missions orbiting as far away as Jupiter, i.e. up to about 3 to 4 AU.
They are part of ESA’s Estrack network, a worldwide system of ground stations providing links between satellites in orbit and our ESOC operations centre in Darmstadt. The core Estrack network comprises 10 stations in seven countries.
Watch Cebreros station in action via our dedicated webcam (offline for maintenance 8-9 May).
Here’s a low-qual (but very nice, IMHO) video I shot several years ago showing Cebreros station swinging into action for a pass with Mars Express:
And, better quality, a rather cool shaky hand-cam video of Cebrero’s sister station, new Norcia (Australia) in action: