Fig. 1 -
An animated sequence of Rc images of WT1190F, taken the night of
Nov 7, 2015 at the 1.52m "Cassini" telescope of the Loiano Observatory.
The telescope, in differential-tracking mode, was equipped with the BFOSC imager.
The reported field is 3 arcmin across, with an exposure time of 7 minutes on the single frames.
North is up, East to the left. Pixel size is 0.58 arcsec across.
The puzzling nature of object WT1190F, that will fall on Earth next Friday, Nov 13,
has been tackled at the Bologna Observatory, taking advantage of the observing
facility of the INAF telescopes at Loiano.
Along the nights of Nov 7 and Nov 9, 2015, Alberto Buzzoni
and Giuseppe Altavilla
, with the invaluable
technical help of Ivan Bruni
have been carried out two extended observing sessions, by imaging
the mysterious target with the 1.52m "Cassini" telescope, equipped with the
Fig. 2 -
Giuseppe Altavilla, Alberto Buzzoni and Roberto Gualandi (from left to right), taking a break
during the observations, to welcome the enthusiastic nightly visit of the OABo Director,
Andrea Comastri (to the right).
Deep-space data have been collected in the standard B,V, and Rc
Johnson/Cousins photometric system, reaching a limit magnitude of Rc
WT1190F has been successfully detected 550,000 km (that is about one a half
the Moon distance) away from Earth. The target appeared as a very faint
= 20.4 mag) "star", moving fast (i.e. about 300 arcsec/hr)
across the sky in the Orion constellation.
The accurate detection has been possible thanks to the "refurbished" capabilities
of the Loiano telescope, which allow us to track fast-moving
objects across the sky (like comets, NEO asteroids, and artificial satellites)
and magnify their apparent luminosity by concentrating photons on the same pixels
of the CCD detector in the BFOSC imager.
The observations also provided us with a valuable astrometric data set, in
collaboration with the SSA NEO Coordination Centre, of ESA at Frascati, with the special
contribution of Marco Micheli
The new astrometric data are being collected by ESA to further constrain the object
trajectory and refine its orbital parameters in view of its impact on Earth of Nov 13.
The preliminary results of our observations indicate that
WT1190F displays a lightcurve with moderate variablility on timescales of roughly
2.5 hours, a feature that leads to suggest a drum-shaped
(instead of a much more rapid and unstable pencil-shaped) geometrical structure
of the object;
by scaling with the recent observations of the space probe
at 1.5 million km from Earth in the Lagrangian L2 point, a size of the order
of 3.5 meters can be derived for WT1190F;
with this size, the accepted Area-to-Mass ratio A/M = 0.011 m2/kg,
as derived in the literature from the orbit perturbation, leads to a
preliminar estimate for the WT1190F total mass of the order of
Fig. 3 -
The WT1190F observed colors in the B-V versus V-R plane, according to the two
observing sessions of Nov 7 and Nov 9, 2015. To better assess the target properties,
a comparison is made in the plot with the observed colors of two outstanding
man-made probes, namely the satellites Planck and Gaia (as labelled in the plot).
Also, the colors of the Sun, as well as of the dwarf and giant stars of our own Galaxy
(with varying their temperature according to the labelled spectral type) are reported, as
a guideline. The exceedingly "red" colors of WT1190F
clearly point to a non-natural nature of this object.
The observed B-V and V-R colors, along the observing nights (shown to be too "red"
and "blue depleted" with respect to asteroids and comets), clearly
point to an artificial nature of WT1190F, as a lightly-coloured
(silver or white?)
main body with the possible photometric signature of the on-board presence of
some gold-coloured material, like multi-layer insulation (MLI) blankets, which
are a typical ingredient of human spacecraft.
Although no direct evidence can be obtained from the images of such a distant
(and small) object, overall, the inferred features make the WT1190F target
consistent with a man-made probe very like to the Apollo Lunar Module LEM.
The outstanding candidate, in this interpretative framework, is of course
the Apollo 10 "Snoopy" module which, in May 1969,
simulated the Moon landing procedure
two months before the historical event of Apollo 11. After a successful
completion of the landing maneuver (aborted 15 km above the Lunar surface),
the LEM descending module was abandoned, while the ascent module of Snoopy
was eventually jettisoned by firing its engines for over 4 minutes, such as to enroute
the spacecraft in a solar (roughly Earth co-rotating) orbit.
This may have led the spacecraft to eventually re-approach our planet 44 years later,
in year 2013, turning back again as a terrestrial artificial satellite.
The end of this long journey is now appointed for next Friday, November 13 2015,
with a fiery re-entry of WT1190F in the Earth atmosphere above the Indian
Ocean, about 100 km south of Sri Lanka.