249 research outputs found
The dust coma environment of the short period comets 32P/Comas Sola, 56P/Slaughter-Burnham and 78P/Gehrels 2 from ground-based observations
No full textAims. The aim of this paper is to contribute to the characterisation of the general properties, differences, and commonalities of the short period comet family and, more in particular, to characterise the dust environment of three poorly studied members of the family: 32P/Comas Solá, 56P/Slaughter-Burnham, and 78P/Gehrels 2.
Methods. Multicolour broad-band photometry of the comets observed around their perihelion in October 2004 from the Loiano telescope has been used to characterise their dust coma morphology and properties and to model the dust production rate
Results. 32P/Comas Solá shows no remarkable dust coma features, while both 56P/Slaughter-Burnham and 78P/Gehrels 2 show departures from regular brightness distribution, with a north/south asymmetry and axysimmetric lobes, respectively, probably indicating emission features on the nucleus surface. For comet 78P, it has been possible to compute a 1-D surface brightness profile with slope m = −1.54 ± 0.05. In an aperture of radius ρ = 7.2 × 103 km, the measured Afρ is 127 ± 10 cm, 102 ± 8 cm (weighted average between two observing nights) and 846 ± 55 cm for comets 32P, 56P and 78P, respectively. All comets have a redder dust coma than the Sun. Comets 32P (dust production rate Qd from 2 to 46 kg/s) and 56P (Qd from 1 to 24 kg/s) are quite standard dust emitters among the short-period comet family, while comet 78P (Qd from 14 to 345 kg/s) is more active than the average at that heliocentric distance
Sample Return Missions from Minor Bodies: Achievements, Future Plan and Observational Support
No full textWe are entering in a new era of space exploration signed by sample return missions. Since the Apollo and Luna Program, the study of extraterrestrial samples in laboratory is gathering an increased interest of the scientific community so that nowadays exploration program of the Solar System is characterized by swelling sample return missions. Beside lunar samples, the NASA Stardust mission was the first successful space mission that on 15 January 2006 brought to Earth solid extraterrestrial samples collected from comet 81P/Wild 2 coma. Grains were collected during cometary fly-by into aerogel and once on Earth have been extracted for laboratory analyses. In the coming two decades many space missions on going or under study will harvest samples from minor bodies. Measurements required for detailed analysis that cannot be performed from a robotic spacecraft, will be carried out on Earth laboratories with the highest analytical accuracy attainable so far. An intriguing objective for the next sample return missions is to understand the nature of organic compounds. Organic compounds found in Stardust grains even if processed to large extend during aerogel capturing are here reported. Major objectives of Marco Polo mission are reported. Various ground-based observational programs within the framework of general characterizations of families and classes, cometary-asteroid transition objects and NEOs with cometary albedo are discussed and linked to sample return mission
523676 (2013 UL10): The first active red centaur
No full textAims. We present observations of 523676 (2013 UL10), a centaur orbiting between Jupiter and Uranus that is dynamically similar to the few tens of active centaurs that are currently known. Methods. We analysed visible BVR images of the centaur obtained at the Telescopio Nazionale Galileo (La Palma, Canary Islands, Spain) to investigate the weak comet-like activity and to derive information on the nucleus surface colours and size. Results. Centaur 523676 (2013 UL10) is the only centaur known so far that has both comet-like activity and red surface colours: its nucleus has a colour index [BR] = 1.88 0.11. The nucleus R magnitude (R = 20.93 0.09) allowed us to derive an upper limit for its nucleus size of D 10 km. We estimated its dust production rate to be Qd 10 kg s1 at 6.2 au (just after its perihelion passage), resulting in a timescale for the surface blanketing process of approximately tens of years, which is very short with respect to typical dynamical lifetime inside the group. Future monitoring of 523676 (2013 UL10) is needed to further constrain the blanketing model for active centaurs and its timescale
A colour portrait of the interstellar comet 2I/Borisov
No full textThe aim of this paper is to report on the results of a multicolour observing campaign performed at the LBT on the interstellar comet 2I/Borisov during three epochs while target was approaching its perihelion: UBVRI images have been observed in October and December 2019, when the comet was at ∼2.3 and 2.0 au from the Sun, respectively. Comet Borisov presented a rather complex morphology, especially in the December observing epoch, when a bi-lobate structure on a global scale was visible, with a jet-like structure characterised by a disconnection event, probably due to the presence of an active area on the nucleus' surface combined with its rotational properties. U – B colour, measured for the first time for this comet, monotonically decreases as Borisov approaches perihelion, from 0.35 ± 0.05 in October 19th to −0.07 ± 0.05 in December 2nd; B – V colour shows a more chaotic behaviour, with values for October epochs quite similar to solar colours, and a higher value of 0.76 ± 0.04 in December 2nd, probably due to a combination of an increase of the B flux (CN emission) and of an increase in V flux (due to C2). V – R and R–I colours derived in both the October and December observing epochs depict a scenario of a coma slightly redder than the Sun, with a RI-reddening value of ∼11%/1000 Å and ∼5%/1000 Å, respectively. The R- Afρ at the reference aperture of r ∼104 km from the optocentre slightly decreases from ∼100 cm (October) to ∼ 70 cm (December), showing that the Borisov's dust environment is quite similar to those of Short Period Comets of our Solar System. The application of a first-order photometric model, with the plausible scenario of grains with radius a = 100 μm and bulk density ρd = 1000 kg/m3 moving at vd in the range of 3–30 m/s, allows to derive a dust production rate Qd decrease from a range of 3–25 kg/s in October to a range of 2–18 kg/s in December. All these results confirm that the interstellar comet 2I/Borisov has a coma environment quite similar to that of the Short Period Comets (mostly Jupiter Family targets) orbiting in our inner Solar System
The optical design and preliminary optomechanical tolerances of the high resolution imaging channel for the BepiColombo mission to Mercury
No full textThe High Resolution Imaging Channel of the SIMBIO-SYS instrument for the BepiColombo mission to Mercury
No full textESA BepiColombo space mission, to be launched in 2013, shall visit Mercury
planet, carrying a complex of instruments with very high performances. The results of the
mission shall certainly provide a fundamental jump in our knowledge about the planet closest
to the Sun. The SIMBIO–SYS instrument is a system integrating a stereoscopic imaging
channel, a high spatial resolution imaging channel and a visual and infrared hyper–spectral
imager channel. SIMBIO–SYS has been selected by ESA in the payload of the Mercury
Planetary Orbiter (MPO) of the BepiColombo mission. The high spatial resolution imaging
channel will have the primary task to provide images with 5 m pixel scale from periherm
(400 km from planet surface). This approach will allow us to identify key surface features
(craters, scarps, lava flows and plains) and to study their relation with internal processes, as
well as the effect of external processes, such as meteor bombardment
Optical design of an high resolution imaging channel for the Bepi Colombo space mission
No full textThis paper describes the optical design criteria and expected image quality of the High Resolution Imaging Channel (HRIC), which is part of the Spectrometers and Imagers for Mercury Planetary Orbiter (MPO) BepiColombo Integrated Observatory SYStem (SIMBIO-SYS) suite, for imaging and spectroscopic investigation of Mercury. SIMBIO-SYS has been selected by ESA as part of the scientific payload of the ESA BepiColombo mission to Mercury. HRIC has the main objective of characterising Mercury surface features with a very high spatial resolution in the visible. The optical design has been optimised to achieve the stringent scientific requirement of 5 m ground pixel size at 400 km from the planet surface. The adopted catadioptric optical configuration provides a resolution of 2.5"/pixel for a pixel size of 10 micron. The focal ratio is F#8 in order to be diffraction limited at 400 nm and to optimise radiometric flux and overall mechanical dimensions. The optical design solution includes two hyperbolic mirrors optimized with a dioptric camera, in order to correct the field of view of 1.47°, covered by a detector of 2k x 2k pixels. The mixed (reflective + refractive) solution guarantees a good balance of achieved optical performances and optimisation of resources (mainly volume and mass). The adopted configuration corrects and transmits well over the whole band of observation (400 - 900 nm)
The cometary activity of Centaur P/2004 A1 (LONEOS)
No full textP/2004 A1 (LONEOS) is one of the few active objects in the dynamical class of Centaurs. It has been recently injected into an inner orbit with a perihelion distance q = 5.5 au. The aim of this paper is to characterize the dust coma of this peculiar object, 2.5 yr after its first ‘new’ perihelion passage inside the Solar system. Broad-band visible images taken at the TNG telescope in 2007 February were analysed in order to characterize the dust coma of the Centaur: it was still quite active at rh = 6.5 au post-perihelion, with a coma and a well-developed wide tail-like structure, with a measured R-Afρ= 162 ± 10 cm in an aperture radius ρ= 104 km. The (V − R) colour and the reddening values depict a scenario of a slightly red dust coma. A dust mass-loss rate of inline image = 133 kg s−1 is derived from a photometric model, consistent with a scenario of a quite constant emission rate along the Centaur orbit. An upper limit for the Centaur radius of 3.5 km is derived by some realistic hypotheses on CO molecular production rate and on the mean grain scatterer size in the coma. Dynamical lifetime estimates compared to modelled loss rate result in a radius lower limit of 0.5 km, indicating therefore that the Centaur size is likely of the same order of magnitude of the short-period comets
An analysis of possible asteroids flyby for the ESA JUICE mission
No full textBefore reaching Jupiter and its icy moons, the ESA JUpiter ICy moons Explorer (JUICE) spacecraft will travel similar to 8 years within the inner Solar System, entering the asteroid Main Belt (MB) twice. This is a unique opportunity to flyby and investigate at close range one or more asteroids, as previously done by other missions. In order to identify multiple asteroids as possible targets of opportunity for the JUICE cruise phase, we developed a new code, called Automatic Asteroid Search Toolkit (A(2)ST), which determines the minimum distance between the orbit of similar to 140.000 asteroids and the spacecraft. From the list of potential objects ordered by range, we identify asteroid (1650) Heckmann and (223) Rosa as two objects of particular scientific interest. (1650) Heckmann is a-30 km-size inner MB member of the Polana asteroid family and it belongs to a taxonomical group (F-type) that has never been observed at close range. On the contrary (223) Rosa is an outer-80 km-size dark MB asteroid (X-type or T-type) whose origin is not yet fully understood. Indeed, it may be a collisional fragment of the Themis family or a primitive dark planetesimal that formed in the outer Solar System. The in-situ observation of both targets by the JUICE mission would widely expand the knowledge of the Solar System formation and evolution, as well as the compositional structure of the Main Belt, hence maximising the scientific return of the full mission
How to make science from opportunity: Searching for possible asteroids flyby for the ESA JUICE mission
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