ESA sponsors WT1190F observations

Editor’s note: We received word late this afternoon that ESA’s Space Situational Awareness (SSA) Programme office will sponsor a European team to join an airborne observation campaign to track and observe the reentry of WT1190F, an unidentified object thought to be a discarded rocket body. It is forecast to enter Earth’s atmosphere high above the Indian Ocean on 13 November. Here is a short update from Dr Stefan Löhle, lead scientist on the University of Stuttgart team that will conduct the observations.

Two researchers from the High Enthalpy Flow Diagnostics Group (HEFDiG), Institute of Space Systems, University of Stuttgart, Germany, will participate in an airborne observation campaign to track and record the reentry of the unknown object dubbed WTF1190F, expected to reenter over the Indian Ocean at 06:19 GMT (11:49 local; 07:19 CET) on 13 November 2015.

Dr Stefan Löhle and Dr Fabian Zander, both experienced researchers in optical diagnostics of aero-thermodynamic phenomena, will deploy their instruments on board an aircraft that will observe WTF1190F reentry. ESA is sponsoring this mission, which will complement other space- and ground-based observation efforts and is expected to provide valuable data on reentry physics.

WT1190F seen from ground. The object was observed by B. Bolin, R. Jedicke and M. Micheli from the University of Arizona in their Catalina Sky
Survey Program.

Object WTF1190F was observed by B. Bolin, R. Jedicke and M. Micheli via the University of Arizona’s Catalina Sky Survey Program (red arrow in the image).

It is not yet known what the object is, exactly. From its behaviour, it can be surmised that, due to its low density, it is possibly hollow and thus probably a man-made piece of space junk. The size is approximately 2 m. From analysis performed so far, it is thought that object will enter (i.e. re-enter) the Earth’s atmosphere on 13 November 2015, around mid-day, with an entry velocity of about 11 km/s.

Thus, a very steep, high-speed entry is expected, so that most probably the object will be destroyed in the upper atmospheric layers.

The interest in observing such objects is, on the one hand, that this could serve as a ‘test case’ for future asteroid entries, and, on the other hand, the data collected can be used to improve our understanding of space debris behavior.

In the past, the University of Stuttgart’s HEFDiG group has participated in the airborne observations of Hayabusa (2010) and ESA’s ATV-1 (2008). Most recently, Stefan was the science team lead in the mission to observe the re-entry of the last ATV, Georges Lemaître, which was cancelled due to technical issues and which was a joint ESA-NASA activity.

The Gulfstream 450 business jet to be deployed for the observation. Image courtesy M. Shawkat Odeh

The WT1190F observation mission will be conducted from a Gulfstream 450 business jet, sponsored by United Arab Emirates and coordinated by Mohammad Shawkat Odeh from the International Astronomical Center, Abu Dhabi. There are only five windows available to observe the object. The observation teams comprise:

• Peter Jenniskens, Mike Koop, Jim Albers (SETI Institute): High dynamic range imaging, exact timing, flight path optimisation
• Ron Dantowitz (Clay Center Observatory, Dexter Southfield), Forrest Gasdia (Embry-Riddle Aeronautical University): High resolution imaging, spectral imaging
• Stefan Löhle, Fabian Zander (HEFDiG): high-dispersion visible spectroscopy
• Mohammad Shawkat Odeh (IAC): Imaging cameras
• United Arab Emirates Space Agency: Imaging cameras

The goal of the observations is to acquire video sufficiently resolved to provide data for modelling this reentry, which will then be used to improve our understanding of the reentry physics of space debris.

At the Institute of Space Systems in Stuttgart, HEFDiG routinely simulates these processes in ground-testing facilities, and so getting live data would be very helpful for improving these efforts.

Experimental set up of HEFDiG in the laboratory in Stuttgart. L: Dr S. Loehle, R: Dr F. Zander. Image courtesy S. Loehle

The system we have foreseen (the laboratory installation is seen above) is a combination of video imaging and high-resolution spectroscopy in visible wavelengths using a fibre-fed Echelle spectrograph. It will be a very challenging endeavour, because the reentry will last, perhaps, not much longer than 8 seconds.