Συνγκρουση της αποστολης SMART-1

Μαγκες,

 

Ενα πολυ ενδιαφερον φαινομενο τους επομενους μηνες ειναι η συγκρουση της αποστολης SMART-1 στην επιφανεια της Σεληνης. Ηδη ειμαι σε επαφη με τον προισταμενο της αποστολης, ο Bernard Foing της ESA, και ο οποιος μου στελνει καθε δελτιο οσον αφορα την αποστολη.

 

Οι προβλεψεις για την συνγκρουση ειναι ενας κρατηρας μεταξυ 5 και 10 μετρα σε διαμετρο αλλα ποιο σημαντικο ειναι το νεφος σκονης που θα δημιουργηθει.

 

Οι τελευταιες εκτιμησεις ειναι για την συνγκρουση να πραγματοποιηθει στις 03/09/2006, ωρα 00.30 +/- 5 ωρες.

 

Πιστευω οτι αντιμετωπιζουμε μια σπουδαια ευκαιρια με επιστημονικο ενδιαφερον και προσφορα. Εκτος απο παρατηρησεις, υπαρχει ενδιαφερον και για φωτογραφικο υλικο και το δευτερο ειναι κατι που με ενδιαφερει εμενα ιδιαιτερα.

 

Θα υπαρχουν δυο-τρεις ευκαιριες το καλοκαιρι οπου ο φωτισμος της σεληνης θα ειναι παρομοιος με αυτον την ημερα της συνγκρουσης και ο οποιος θα μας επιτρεψει δοκιμες εκ των προτερων.

Αντωνη πολυ ενδιαφερον!! keep us posted..

Aντωνη περισσοτερες πληροφοριες για το τι ειναι το smart 1 και γιατι το ριχνουν στην Σεληνη εχουμε?

00:30 ειναι ωρα Ελλαδας;

Θα εχει φεγαρι εκεινη την μερα στην Ελλαδα;(για μενα Γερμανια)

Θα μπορεσουμε να παρατηρησουμε το φαινομενο με τηλεσκοποιο;

Αν ναι,τι τηλεσκοπιο θα χρειαστει για να γινει ορατο το φαινομενο;

Background

 

ESA’s SMART-1 mission launched to the Moon in September 2003, has reached lunar capture in November 2004. Since March 2005, from 400-3000 km lunar science orbit, its instruments have been operating : AMIE miniature high resolution multicolour camera AMIE for lunar geomorphology down to 40 m per pixel, SIR infrared spectrometer (0.9-2.5 microns down to 400 m FOV) for mineralogy, and D-CIXS X-ray spectrometer for elemental composition (Foing et al 2001, 2006). Because of gravitational perturbations by the Earth and the Sun, the SMART-1 orbit will irremediably intersect the lunar surface, having exhausted its main Xe fuel. If we would leave the spacecraft on natural course, it would impact on the far side of the Moon on 17 August 2006. We plan to extend the mission at low altitude, and also allow an impact on the near side, in a dark part near the terminator, under good observations conditions from Earth telescopes and public. From 26 June, we plan to perform for a week a series of new manoeuvers using the hydrazine attitude thrusters to impulse an extra push of some 12 m/s. Only after this is completed successfully, shall we have a better estimate of the date of impact, now calculated to occur on 3 September 2:00 UT with 7 hour uncertainty.

For the current nominal ephemerides, the impact is expected at possible locations of impact near perilune 36 S, 44.2 W, impact 34 S, 44.13 W, altitude 600 m with a descending oblique angle of 1 degree on a ascending slope of 2.5 deg. On previous orbit (-5 hours) the perilune at 36.5 S, 41.4 W is only 400 m above surface. The virtual perilune on orbit after nominal impact is 37 S+- 2 deg , 47 W. Note that according to available topography information from Clementine (only 1 km grid), there is now still a possibility that the impact could take place on the orbit before or after the nominal orbit. We shall use latest topography information (from stereo images, A.C. Cook et al) including from the upcoming months to reduce this uncertainty and finetune the targeting to a most probable time near 0-3 h UT maximising scheduled observations. The parameters of impact are: Low velocity grazing impact 2 km/s, the probe is 290 kg, mostly 200 kg from the Aluminum body of 1 cubic meter, with two solar panels in carbon fiber and AsGa solar cells of 6.5 m length each.

 

 

 

Scientific rationale

 

Quantitative spectrometry of lunar dust mineralogy

Coordinated measurements from the ground allow to obtain spectrometric information constraining the mineralogy of key sites targeted by SMART-1. In particular the infrared range from 2 – 20 microns would allow a constraint on the present lunar minerals (pyroxene, olivine), complementary to SMART-1 diagnostics (AMIE camera colour ratio with 0.95 micron pyroxene band, and SIR 0.9 -2.5 micron spectrometry). The spectral energy distribution can provide quantitative characteristics such as mineralogical composition, porosity, crystallinity, size distribution and space weathering.

The thin upper lunar surface layers have been exposed to cosmic rays and solar particles that modifies the upper layers (space weathering) probed by remote sensing imaging and spectroscopy, and weakens the mineralogical signatures. Comparative observations of the ejected dust reflectance will allow to probe the soil properties of the one meter subsurface and their signature during the impact and ejecta.

 

Physics and diagnostics of impact at low velocity

Ground based and flyby observations of Deep Impact event (A Hearn et al, Meech et al, Harker et al, Sugita et al , 2005) have provided key measurements to constrain the subsurface properties of comet 9P/Tempel 1. Some of the modelling and observational methods can be adapted for the conditions of the SMART-1 low velocity lunar impact.

The thermal and dynamic evolution of the thermal flash and ejecta can constrain the understanding of impact processes such as dust acceleration, gravity controlled excavation, and strength related effects. The monitoring of spacecraft volatiles released after impact can help simulating and understanding processes occurring on volatile rich natural impactors.

An observation of an impact on dry soil conditions can be a control experiment for future impact experiments for diagnostic of polar ices.

 

Modelling of the controlled SMART-1 impact

 

We have called on the modeller experts to model the impact and predict what could be the impact flash magnitude in the visible or infrared, and ejecta dynamics. We expect the impact to be in the strength regime where the material strengths of both the impactor and regolith control the crater geometry, eject and plume properties. The kinetic energy if of 600 MJ and depth of penetration could be of order of meter. Using Holsapple (2002, 2003) criteria and scaling laws it is not expected to have a silicate melt for this impact. It could give a 10-80 m3 excavation volume of which 80 % will be a cold ejecta plume. The thermal flash magnitude would be 7.4 if half of the kinetic energy was converted into heat , however at this 2 km/s low velocity models predict a very low efficiency and an estimate of 16 magnitude from published scaling laws is more realistic (Koschny and Gruen, Koschny 2006). The flash duration could be as short as 20 milli seconds. We should also monitor the speed and dynamics of ejecta and dust clouds that could be followed in the Earthshine or in sunlight, other transient changes, and the characteristics of impact crater and deposited ejecta. Ejecta, total mass, speed distribution, fraction with vertical V> 200m/s reaching sunlight. These phenomena could be accessible to telescopes.

 

Predicted effects of the impact and proposed observations:

• Thermal flash (bolometric magnitudes 7 –16 during 1 s in infrared depending on efficiency 0.5-0.001)

• In addition to thermal effects, we expect the emission from volatile elements onboard N2 H4 decomposing in NH3 and H compounds detectable in Paschen and Brackett (or even Balmer if the excitation temperature is sufficient). One notes that for Hiten impact (300 kg, 2.7 km/s, 1 kg hydrazine) a flash signature detected in the K band was ascribed to Br gamma enission. Other probe signatures may be detectable (Al melting at 600 deg C, C graphite )

• A crater size of 5-10 m is expected. The volume of material ejected will be essentially made of dust with dominant size around 15 microns (normalized per area) and the effective area of ejecta could be 25 km2. This will lead to obscuration of the underground soil in the first minute after impact, and partial obscuration letter. The ejecta can be also traced in Earth shine reflected light giving a level of V=17 per km2 accessible to large telescopes (1500 photon per 10 sec for a 2 m class telescope). Small telescopes are able to image the Earth shine on the Moon, even with modest resolution 1.5 arcsec they would be able to detect the excess brightness of the effective area of elongated ejecta with excess magnitude 13-14 due to their higher albedo.

• The normal component of the velocity will be of order 130 m/s, therefore we may expect a tiny fraction of ejecta f that has enough vertical velocity above 280 m/ s to reach sunlight. This would correspond will have for the solar phase angle of 100 degree, a magnitude V=11.5 - 2.5 log (f/1%), a signal as bright as 11.5 magnitude detectable by amateur astronomers even if only 1 % of ejecta reach this vertical speed.

• The key interest of large telescopes will be their hability to collect enough photons and angular resolution down to 0.4 arcsec seeing or using adaptive optics to detect the flash impact, resolve the structure of the ejecta and their dynamics down to few hundred m resolution, as well as trace the dynamics of the weak hydrazine gas plume.

• A special care will have to be taken to limit and correct the straylight coming from the illuminated part of the half Moon beyond the terminator at 60 arcsec East from the impact.

Near infrared and Thermal infrared spectroscopy can be used to diagnose some of the mineral properties from the expected cool ejecta (absorbed reflectance due to silicates and size distribution effects). Also Near IR spectroscopy will measure the Brackett emission lines due to H compounds released by hydrazine. Even after the short lived thermal flash, there can be a remnant excess temperature of several above the initial 100 K night time lunar soil temperature, their cooling can be monitored with infrared thermal imaging for a few hours .

• Some Exospheric effects are expected such as neutral emission production, that can be monitored with visible spectroscopy of species such as Na, K. It is expected that these effects will be weak, local and short lived.

 

• Note that the kinetic velocity of SMART-1 is less than a 1 kg meteorite arriving at 40 km/s natural speed, or of previous more massive modules impacted during the Apollo era. The effects will be even more localized due to the smaller and oblique velocity.

 

• Crater size (5-10 m) and morphology could be only accessed from the next lunar orbiters or from interferometric instruments. The morphology of ejecta may be elongated over several kms along the initial orbital velocity and is within range of high resolution or adaptive optic imaging.

 

We are conducting SMART-1 observations of previous impact sites, (such as rangers, Apollo modules and Muses A Hiten), to characterize possible ejecta, and we shall make prior monthly observations of the site area of impact . We have also identified a number of natural larger impact craters that we are observing under different illumination, phase angle conditions to characterize the topography, roughness, colours and mineralogy of crater units and ejecta. Some lunar sites are also used for radiometric multiwavelength calibrations.

We propose to observe some of these targets with ground based observations to extend the wavelength coverage enhancing the SMART-1 and spacecraft data interpretation.

 

References:

A Hearn M. et al, Science 310, 258 (2005)

Basilevsky A et al, Scientific objectives and selection of targets for the SMART-1 Infrared Spectrometer (SIR); Planetary & Space Science, 52, 1261 (2004)

Foing B H, et al, SMART-1 mission to the moon: Status, first results and goals Technology and science goals; Adv. Space Research 37, 6-13 (2006)

Foing B H et al, The Science Goals of SMART-1; Earth, Moon & Planets, 85-86 523-531 (2001)

Harker D.E. et al, Science 310, 278 (2005)

Koschny D. and Gruen E., Icarus 154, 402 (2001)

Meech K.J. et al, Science 310, 265 (2005)

Sugita S. et al , Science 310, 177 (2005)

 

Technical and scheduling constraints

• Orbit inclination 90.6 deg, from North to South

• If no maneuver Impact on 17 Aug on far side -> needed maneuver

• 2.6 kg hydrazine maneuver Maneuver on 23 June –8 July delta V 12 m/s, adjustement slots 26 July, 30 Aug

• Current impact prediction 3 sept 2006 2:00 UT +- 7 hours on near side in dark, near first quarter terminator

• Orbit prediction, perilune <200 km 10 July, < 120 km 7 aug

• Effect of topography (current altimetry, stereo, new observations)

• Possible locations of impact :

– perilune 36 S, 44.2 W, impact TBC 34 S, 44.13 W

– Previous orbit (-5 hours) , impact 36.5 S, 41.4 W

– Orbit after: impact 37 S+- 2 deg , 47 W

• Speed 2 km/s, grazing 1 deg over 2-8 deg slope ,

• Artificial comet: 285 kg including 1 m3 body, 200 kg Aluminum, 3 kg Hydrazine N2H4, 0.26 kg Xenon, epoxy, 14 m carbon fiber arrays

• Radio observations of S band carrier can be made for monitoring probe disappearance and final impact

• Optical observations of the V=19 magnitude spacecraft can be done over non illuminated Moon after 27 August, and in particular up to 4 mn before impact, or previous orbits.

 

 

 

Requested observations (to be completed for specific telescopes and instruments)

 

Observations to be conducted under high solar elevation for multiwavelength and infrared mineral spectrometry, low elevation for topography. In addition for target impact sites at same representative phase and distance from terminator to reduce and calibrate the straylight aspects.

 

Visible imaging

- possibly with a field 30-60 arcsec

 

Infrared imaging field 30 -60 arcsec

- resolution 0.5 arcsec

- adaptive optics resolution when possible (VLT Yepu NACO 9 AUG, Hawaii

 

Visible spectroscopy long slit along the north south direction (for targets as well , as impact time monitoring) ( VLT FORS1, TNG)

 

Infrared spectroscopy long slit along the north south direction

 

Contacts:

VLT FORS1, Melipal VISIR , Yepu NACO Aug, NTT (Ehrenfreund, Foing, Hainaut, Leibundgut)

TNG ( Cremonese, Barbieri)

WHT/INT (Ehrenfreund)

OGS (Sodnik)

US, Hawaii Obs ( K. Meech, D. Wooden)

12 m mm L. Zaris

6 m Zelentchuk, Crimea ( M. Zhodachenko )

Subaru infrared spectroscopy and imaging ( Sugita, Kato)

SALT ( P. Sarre, TBD)

Calar Alto (Ortiz, Lara)

Amateur coordination (Talevi, Ansari, Lawton)

 

 

Time for observations: (the Moon is observed in first hours of night at phases from 50 to 100 %)

4-17 sept possibility of detection of smart-1 impact illuminated ejecta blankets

3 sept 1 h UT +- 7 hours (nominal impact window)

2 sept general rehearsal

6 & 7 Aug support to SMART-1 target overfly + other targets

3/4 or 4/5 Aug, close moon phase (within 0.5 day of impact date) + other targets

10 & 11 July support to SMART-1 target overfly, sun elevation 27 deg + other targets

6/7 July night same moon phase as impact date + other targets

23 June – 4 July SMART-1 maneuver

Mid April- Mid June: SMART-1 push broom colour targeted observations

Until mid april : mid solar elevation studies and spot pointing

 

Note that SMART-1 will overfly the candidate impact targets from 120 km under solar illumination on Aug 6.7 UT (from 120 km , solar elevation 11 deg) and July 10.7 UT (from 200 km, solar elevation 27 deg) and coordinated observations could be considered from Earth for intercalibration.

 

Observations of the impact site at the same moon phase (29.53 days interval) and in dark at similar distance from terminator as 3 Sept 1h UT should be performed on 6/7 July nights, 3/4 or 4/5 Aug, would allow to minimize and quantify the straylight aspects, and gain operational experience. For large field of view instruments note that this corresponds to meteor streams of Aquarids and Pegasids, and there is a possibility to calibrate the magnitude of observable lunar meteors in these illumination conditions. (check angles of arrival).

 

At these dates other targets (calibration and key coordinated studies) are also observed.

Targets to be observed (lunar coordinates) :

36 S, 44.2 W perilune, impact 34 S, 44.13 W

36.5 S, 41.4 W, 400 m near distance closest lookup above surface at perilune and second probable impact site at Previous orbit (-5 hours)

37 +- 2 deg S , 47 W Orbit after baseline: (+5 hours) , third probable impact site

 

Other targets of interest for coordinated observations of mineralogy:

Tycho LC10 -43.40 348.90 East Large crater; gabbroic plutons

Alphonsus ALP1 -13.70 356.00 DMD, dark halo crater

Apollo 16 AP16 -9.00 15.50 Landing site, calibration check

Apollo 14 AP14 -3.70 342.50 Landing site, calibration check

Luna 16 LC34 -0.40 56.18 Luna 16 landing site

Apollo 11 PC4 0.67 23.47 Landing site

Reiner GammaREI4 4.95 298.70 swirl

Luna 24 LU24 12.50 62.25 Landing site area, calibration check

Apollo 17 PC9 20.19 30.77 Landing site

Aristarchus ARI2 23.23 313.47 Aristrachus crater, Crustal mat.

Apollo 15 AP15 26.10 356.30 Landing site, calibration check

Gruithuisen Delta1 35.90 320.45 Delta dome, early volcanism

 

Timing of impact Moon visibility

Perth CapeT. OHP Paris CalarAlt Tenerife Brazil LaSilla KittPk Hawaii

Sunset 10:03 16:29 18:13 18:38 18:38 19:27 21:34 22:25 01:52 04:37

End civtwilight 10:27 16:54 18:43 19:10 19:04 19:51 21:56 22:49 02:15n 04:59 n

Moonset ( 2 sept) XX 22h49 00:08n 01:36 n X 7:43 08:03 11:42

sun 10 deg below, Moon 66%

00:30 ειναι ωρα Ελλαδας;

Οχι αλλα UT ...

 

Θα εχει φεγαρι εκεινη την μερα στην Ελλαδα;(για μενα Γερμανια)

Πρωτο τεταρτο αλλα η συγκρουση θα γινει στα συνορα μερας-νυκτας ...

 

Θα μπορεσουμε να παρατηρησουμε το φαινομενο με τηλεσκοποιο;

Αμε!

 

Αν ναι,τι τηλεσκοπιο θα χρειαστει για να γινει ορατο το φαινομενο;

Ειναι καπως αγνωστο απο την εννοια οτι δεν γνωριζουν ποσο εντονο θα ειναι το νεφος σκονης αλλα εχουν υπλογησει το μεγεθος (λαμπροτητα) και ειναι ευνοικο. Μαλιστα αν η συγκρουση ειναι στη σκια (αριστερα πλευρα των συνωρων μερα-νυκτα), θα ειναι ακομα ποιο ευκολο η παρατηρηση/φωτογραφηση.

Aντωνη περισσοτερες πληροφοριες για το τι ειναι το smart 1

Ηταν μια αποστολη με διπλο στοχο ... (1) δοκιμη νεων κινηρων (ιονικη προωθηση) και (2) χαρτογραφηση της σεληνης

 

και γιατι το ριχνουν στην Σεληνη εχουμε?

Εχουν εξαντληθει τα καυσηματα και ειναι ευκαρια για μια τελευταια "επιστημη".

 

Ενα προσφατο τευχος του ΓΕΩΤΡΟΠΙΟ ειχε ενα αρθρο απο τον κ. Δαγκλη (καθ. Πανεπιστημιου Αθηνων και μελος του Αστεροσκοπιου Αθηνων) οπου περιεγραψε την αποστολη πληρης.

signomi aristarxe

alla to ινγκλιs mou ισ βερυ μπατ

ι ντοντ αντερσταντ γιου γουατ γιου σε΄ι΄

 

Γιατι θελουν να κανουν χαρτογραφηση τις σεληνης;

Απο οτι ξερω εχει χαρτογραφηθει η σεληνη εδω και πολλα χρονια!

Γιατι θελουν να κανουν χαρτογραφηση τις σεληνης;

Απο οτι ξερω εχει χαρτογραφηθει η σεληνη εδω και πολλα χρονια!

Ναι μεν αλλα αυτη τη φορα εγινε απο χαμηλοτερο υψος και μαλιστα απο πολο σε πολο ....

λετε να βγαλουν επιτελους και καμια φωτογραφια της απο χρονια παρατημενης σεληνακατου εκει;

 

ειμαι πολυ περιεργος.............

Αυτο το γενικοτερο ενδιαφερον για την σεληνη ξερετε γιατι υπαρχει εε??

Για μια μελοντικη βαση στην σεληνη, αλωστε ειναι απολυτα λογικο.

θα υπαρξει μεγαλος ανταγωνισμος

αφου και η Κινα εχει μπει στο παιχνιδι