XMM System Verification Test 3
9 November 1999Thursday 14th October, day four of SVT-3. The object of the third and final XMM Systems Verification Test before launch is to command the spacecraft at a distance, as if it were in orbit, and particularly to control the reception of information from its science payload. It is the first time that the six cameras and radiation monitor installed on the spacecraft provide their data to the XMM Science Operations Centre (SOC).
On one side of the Atlantic the spacecraft preparation campaign is in full swing in Kourou. For the duration of SVT-3, XMM standing in a corner of the Ariane 5 Final Assembly Building is connected to locally installed work consoles.
The spacecraft is being controlled from ESOC, some 8000 km away in Darmstadt, Germany. The SVT-3 test had first begun by sending commands and receiving data from each camera separately. This was initiated in ESOC's impressive Main Control Room, where stickers on a glass door are a reminder of past missions. Amongst them is the EXOSAT mission.
"RGS-1 to spacecraft, we would like to run the next test". "Copy that" replies, on the speakers of the control room, a voice from Kourou.
The atmosphere is relatively calm in the Mission Operations Centre (MOC) as each member scrutinises his screen, occasionally checking with his colleagues. It's a laborious process; the procedures they are running through are detailed in a document several centimetres thick!
XMM Science Operations Centre
There is considerably more movement and excitement in the Science Operations Centre, located in a nearby building. The numerous workstations are constantly beeping as each packet of data arrives. Occasionally a warning signal interrupts the lively conversations of the small groups. It is the first time that science data is being received at a distance from XMM's science instruments. The teams (those of the MOS, EPIC, RGS, OM cameras and of the Radiation Monitor) are clearly delighted as the SOC software transforms the arid hexadecimal bytes on their screens into coloured graphs and curves visualising the data from the cameras.
Representatives from the science institutes are not the only people present in this very large SOC work area. There are also the XMM science support teams, responsible for the management of the very large quantity of data that XMM will be sending back to Earth; the software developer teams from Logica UK, DataSpazio, Rome, and GMV, Spain are beavering away, fine tuning the different components of the SOC software; and several men are also packing computers and monitors. Because immediately SVT-3 is finished all the computers are moving to the XMM Science Operations Centre's definitive location at Villafranca, near Madrid.
Since the start of SVT-3, all of XMM's science instruments have been put through their paces, running for instance their self-diagnosis tests, individually and then activated in pairs in various combinations.
But day four is to see the big crunch! All seven instruments are to be switched on to send back data simultaneously. With the MOC and SOC on full load, how will the software cope?
Early afternoon. Faces light up in the SOC as it is confirmed that the data from three cameras is flowing through. Then, as the minutes pass, it is four, five, six and finally seven instruments that are all simultaneously sending their data - all the way from Kourou. And the SOC software is holding well. As the XMM Science Control System Technical Officer Mario Merri explains, there may be a few bugs to iron out and improvements made to the software, but for a first run, it is a considerable achievement.