ESA's Space Situational Awareness programme supports Europe's independent utilisation of, and access to, space through the provision of timely and accurate information, data and services regarding the space environment, and particularly regarding hazards to infrastructure in orbit and on the ground. More via Credit: ESA - CC BY-SA IGO 3.0

ESA’s Space Situational Awareness programme supports Europe’s independent utilisation of, and access to, space. More via Credit: ESA – CC BY-SA IGO 3.0

Reentry data will help improve prediction models

ESA website, 23 Oct 2015: A rare reentry of a suspected rocket body from a very high orbit next month offers an excellent opportunity to gather data to improve our knowledge of how objects interact with Earth’s atmosphere. The expected 13 November reentry of what is likely to be a rocket body poses very little risk to anyone but could help scientists improve our understanding of how any object – man-made or natural – interacts with Earth’s atmosphere (full report).


Editor’s note: We asked Ettore Perozzi, manager of ESA’s NEO Coordination Centre, ESRIN, Italy, to provide some background on how WT1190F got its name. Yes, like anyone else who has spent anything more than about five minutes on the Internet in the past decade, we, too, noticed that the asteroid’s designation contains a popular sequence of three English letters that is used colloquially – and often! – to express consternation. And we, too, smiled.

So, we thought we’d explain how the designation came about, and try to determine if there’s any actual meaning in christening a suspected rocket body ‘WT1190F’.

The fact is that when you use a state-of-the-art telescope for surveying the sky, in particular if equipped with wide-field, highly sensitive sensors, you are likely to find in each image many moving objects. Most of the detections will turn out to be already known objects (e.g. asteroids, comets, space debris) that need to be carefully checked before an actual discovery can be announced.

This is a non-trivial task, so, for internal reference, every observing programme or organisation (e.g. like ESA’s own partner, the TOTAS survey in Spain, or any one of hundreds of amateur star-gazing groups worldwide) assigns an arbitrary sequence of letters and numbers to every object spotted in the sky during any observing run. This object (with its ‘observer-defined temporary designation’) then gets reported to the Minor Planet Center, USA, the International Astronomical Union (IAU)’s official international body for such observations; any further observations are then temporarily labelled with this designation purely for identification purposes.

In general, this internally assigned name sticks to the object only until it is recognized to be either a known celestial body or a new discovery. In the latter case, the naming procedure follows different paths depending on the nature of the object.

In the case of WT1190F, its provisional designation was assigned by the Catalina Sky Survey (see an update from CSS Principal Investigator Eric Christensen here).

Natural objects

If it is an asteroid, then, by IAU rules, it is assigned a ‘provisional designation’, which is a code composed by the year of the discovery followed by letters indicating the time of the year when it was spotted, followed by a progressive number.

A simpler sequential number is then assigned once the orbit is known well enough, and from that time the discoverer has 10 years to propose the final, actual name.

Artificial objects

If it is a man-made object, then its trajectory is analysed in order to determine to which space mission it originally belonged; the designation will then be assigned based on that mission’s name.

WT1190F, however, is a rare case. It is still in the ‘limbo’ of heavenly bodies: even if there are strong indications that it is a man-made object, this is not yet fully certain and the final confirmation must still be provided by on-going observations.

Yet naming (permanently) WT1190F won’t be easy even if it is recognized to be space debris generated by an earlier mission.

We know that its peculiar and very elongated orbit has brought it close enough to the Moon to be ‘perturbed’ (shaken by the Moon’s gravitational pull) in such a way that it is no longer possible to extrapolate backwards along its past orbital evolution to determine which mission it came from with any degree of accuracy.

So, not knowing which mission it belongs to, WT1190F is very likely fated to go down in history known only by its provisional name.

But then not all names have a root meaning, do they?