INFN-LNF, 13-JAN-06, Fundamental Physics [email protected] 1 The LNF Space Climatic...

INFN-LNF, 13-JAN-06, Fundamental Physics WG [email protected]

The LNF Space Climatic Facility (SCF)

• Purpose and status of the SCF

• Science and technology projects at the SCF

S. Dell’Agnello, INFN-LNF for the LARES Collaboration, (PI I. Ciufolini, Univ./INFN-Lecce) the LNF Support Services


Purpose of the SCF• Thermo-optical characterization of LAGEOS/LARES prototypes• Thermal thrusts (TT) due to asymmetric absorption and re-emission

of (IR) radiation by CCRs generate the largest NGP on Lense-Thirring (LT) measurement in GR– LT(due to TT) ~ 2-3%, while LARES goal is LT ≤ 1%

– Governed by slow CCR thermal relaxation time, CCR, never measured in space climate

– Computed CCR = (2000 - 7700) sec: ~ 250 % range !

– TECLIPSE ~ CCR ! TORBIT = 13300 sec

Rubincameffect (from ourNASA/GoddardLAREScollaborator


FE model and thermal simulation

SUN=on, IR=off CCR = 2400 ± 40 sec (2% stat. fit error)

Error on T = 0.5 K

1) Metal (Al T6016) ~ at “room T” (± 2K)2) CCRs (fused silica) “cold” (260-285 K), with slow relaxation time

Sun = off, IR = off at t = 0 TC

CR(K

)

TC

CR(K

)

t(sec)

T =

280

0 se

c


SCF layout (purchased equipment)

• Cryostat (old linac RF cavity)– Vac: < 10-5 mbar– Tshield = 77 K(LN2)

• Solar simulator (TS-Space)– in front of = 40 cm, 4 cm

thick Quartz window– Absolute calib. 1 Sun (AM0)– Uniformity: ± 5%– UV-Vis-IR: 250nm - 3.5m = 35 cm

• Earth IR simulator (in-house) = 30 cm black disk– T = 250 K

• Thermography– RTD/PT100/PT1000– IR camera, Ge window


Our software capabilities• SW for satellite thermo-optical

simulation (“Thermal Desktop”)• FE/FD modelers• IR/VIS optical properties. Also f()• Orbital and radiation simulator• LARES-LNF performed the first ever

thermal simulation of f. silica CCRs– Before, CCR treated as

isothermal• Volumetric radiation (next release):

state-of-art

Retro-reflection

CCR assemblycomponents

Al retainer

KEL-F

KEL-F

CCR

3 Al screws


LNF RD and AD support services• The two technical stalwarts supporting the SCF are

– Cryogenics Service, Accelerator Division. DANE cryo plant (He and N); large Experiment solenoids (KLOE, FINUDA), GW antenna …

– Mechanics, design, metrology Service, Research Division. “I&I” activities at LNF and external Labs

• We acknowledge great support by C. Sanelli (AD) and M. Curatolo (RD) for mission-critical acquisitions (and more)– Thermal Desktop and IR camera

• Non-invasive thermography• 3-17 m, 320 x 240 pixels• T accuracy < 0.1 K• Great for diagnostics of large physics installation• G. Delle Monache certified thermography operator


Status of the SCF

• Design complete. All equipment purchased. Delivery next 2 mo.

• Same LN2 tank as Nautilus. Dedicated TL, vacuum system

• Cryostat tested to 10-5 mbar. Leaks fixed

• RTDs, PT100 T probes. LabView

• Parts inside (shield, fixtures, shrouds, …) painted w/Aeroglaze

• Vac bake, outgassing to be performed with 2nd identical cryostat

• Will start with Earth IR simulator made in-house

DO

NE

NE

XT

LARES:d ~ 30 cm

Earth IR Simulatord = 30 cm

LAGEOS CCR matrix:~ 15 cm

IR camera

60o

Matrix coolerHeater

~ 1 m

~ 2

m


Fund. Physics (FP) & Technology Applications (TA)

• LAGEOS-LP LAser GEOdynamics Satellite-Legacy Project ----> FP and TA

• LARES: LAser RElativity Satellite ----> FP and TA

• GOLEM GNSS Observation via Laser Earth-based Measurement ----

>TA– GNSS = Global Navigation Satellite System– GNSS constellations (≤ 30 sats each): GPS-1-2-3, GLONASS,

GALILEO (EGNOS)• Fundamental physics in Deep Space ? (or a better measurement of thermo-optical systematics …)

NOTE: LAGEOS-LP and GOLEM TA submitted to “InnovAction”, Udine, 9/Feb/06


LAGEOS-LP (Legacy Project)

• 1976 NASA/Bendix corp. design. Al sphere, brass core. Quartz CCRs in closed cavities

• 2005, LNF: “Matrix reloaded”


Simulation results

• Various climate conditions: – Sun or Sun ± 5%– Earth IR– Sun then IR or IR then Sun– 45 deg exposure to Sun or IR– Single CCR or matrix– T (Al) = 280, 300, 320 K

• Fit (CCR): 2% (Sun) - 6% (Earth)• But CCR varies with T range, up to

12%• In fact, the constant of the process is

CCR T30

CCR = m c/(4 A T30)

T0 = (Tf-Ti)/2 = T/2

A. Bosco, G. Delle Monache, C. Cantone

If (T) ≤ 0.5 K (CCR)/ CCR ≈ (CCR T30)/(CCR T3

0) ≈ 3%.

BUT: need experiment in the SCF and, conservatively, EXP(T) ≈ 0.1 K


LAGEOS main technological application(s)

• ILRS (Int. Laser Ranging Service) tracks LAGEOS and 30+ satellites. Towards mm level ranging accuracy

• IERS (Int. Earth Reference Service) issues two int. standards for civil and science applications– ITRF (Int. Terrestrial

Reference Frame - cartesian)– ICRF (Int. Celestial Reference

Frame - equatorial)• The impact of the availability,

accuracy and reliability of the ITRF is enormous

• Contributions to IERS: SLR, VLBI, GPS, LLR, DORIS


LAGEOS and the ITRF

• SLR, and mostly the LAGEOS, measure– Tectonic plate motion (via the stations)– Absolute vertical positions and motions– absolute calibration of satellite radar altimeters (meteorology)

• The geo-center (Earth center of mass) is made 100% with the LAGEOS.

• The scale (of length) is also dominated by the LAGEOS• The axis orientation is made 50% by the LAGEOS and 50% by

VLBI• The LAGEOS orbits are mankind’s “fixed stars”• The gold-plated feature of SLR, ie the LAGEOS, is LONG TERM

STABILITY• With a measurement of CCR and with a TT-free LARES we can

provide an important contribution.• ITRF2004 is coming. With a better control on systematics

could it come sooner ?

Option 2: Helmert parameter TY w.r.t. ITRF2000 of weekly ILRS solutions and its monthly running average (combination ILRSA; Jan 2004 - Dec 2004)

From E.C. Pavlis talk on ILRS contribution to IERS (ILRS Oct.

2005 workshop, Eastbourne, UK)

Y-translation [mm]

From E.C. Pavlis talk on ILRS contribution to IERS (ILRS Oct. 2005 workshop, Eastbourne, UK)

Conclusions

• Representative absolute accuracy of SLR observation 1-8 mm

• Satellite orbits fit to about 10 mm WRMS

• ILRS weekly geocenter assessments accurate to 3.3, 2.5 and 5.3 mm for Tx, Ty and Tz (2.8, 2.6, 4.9 for Option 2)

• ILRS weekly global scale assessments accurate to 0.4 ppb (0.3 for Option 2)

• Additionally, ILRS products useful contribution to IERS products

Scale [ppb]


FP: LARES

• While waiting for direct detection of Grav. Waves, the LT is the only measured dynamical effect in GR

if Earth wouldn’t spin d/dt = 0

(CCR) ≤ 5% will make– TTs negligible for LT (node, )– Perigee (also usable for FP !

• much more sensitive to TTs than • very sensitive to new physics ! It’s

similar to a in particle physics

• Change LAGEOS design to build the next-generation test mass to probe gravity in NEO (Near Earth Orbits)

€

˙ Ω LT =2GJEARTH

c 2a3(1− e2)3 / 2


Our new “concept” of test mass

• Weak points of LAGEOS– CCRs: 2/3 TTs– Al rings: 1/3 TTs– Max TT: F ~ 40 nN

• a ~ 10-10 m/sec2

• Proposed solution– Shell-over-the-core (better T

uniformity according to ANSYS)– CCR back-mounting (no more Al rings outside)

G. Delle Monache


New (KATIA) model from the ground up

M. A. FranceschiT. Napolitano

Grooved W alloycore for ultimate eddycurrent suppression


Specs

• Outer diameter: 320 mm• Mass: ~ 123 kg *• S/M: ~ 2.6 x 10 -3 m2/kg * (Lageos ~ 2.8 x 10 -3 m2/kg)• Jz/Jx: ~1.03 *• Jz: ~ 0.886 kg · m2 *• CCR mounting: from inside• CCR heat transfer: “shell over the core”• Outer shell material: Al alloy (Cu alloy)• Inner core material: W alloy• Ring Material: KEL-F• Structural screws: Stainless Steel (Ergal)

* adjustable parameters

Density(kg/m3)

Al alloy 2700Cu alloy 8900W alloy 16900÷18500

Thermal Conductance(W/mK)

Al alloy 200Cu alloy 391W alloy 137


Prototype to study feasibility• New design needs accurate test before

we can convince the LARES collaboration

• KATIA-to-CAM• Tested machining of =10cm half-shell• Surveyed proto with CMM• All OK !• Purchased final mills and Al for full size

prototype (=30cm)• NEXT:

– Full “LARES-mini”– Full size proto


Full LARES FEM and thermo-optical analysis

• Major constraint for analysis– FEM: < 20000 nodes– Matrix proto in SCF feasible

on average WinPC– Full proto and/or orbit

simulation very demanding

• CCR: automatic meshing gives way too many nodes, ~ 450 !– Mesh “by hand” and use all

tips, tricks and symmetries: got down to 110 nodes/CCR

– 102 CCRs: total 11220 nodes

C. Cantone

110 nodes

1st step: FEM (meshing) with ANSYS


The half-shell

• ANSYS brick elements: 3513 nodes

• ANSYS shell elements: 1344 nodes

2nd step: embed CCRs in theShell in THERMAL DESKTOP


TA: GOLEM (GNSS Obs. via Laser Earth Meas.)

• Only 2 GPS-2 and 4 GLONASS satellites have traditional fused silica CCRs. Very difficult SLR, due to distance (> 20000 Km, vs 6000 Km of LAGEOS): only at night, with the best meteo and best “core” stations. Too resource consuming. Glonass not very collaborative

• GNSS: enormous impact in all many fields. IGS (Int. GPS/GNSS Service). But GPS/GLONASS is proprietary/military at heart

• GALILEO changes the picture: ONLY civil use …. AND:– 100 CCRs on each and every one of the 30 satellites !!!– 5,000 US$/CCR 15 USM$ worth of CCRs

• Future: cannot afford the weight of traditional CCRs. Innovative, metal, hollow CCRs are mandatory

• GPS-3 will have HOLLOW METAL CCRs. GALILEO ?


Collaboration on GPS-3

• Proposed to us in Sep-Dec 05 by NASA/ILRS-GSFC (Goddard Space Flight Center, Greenbelt; ~ Washington) after we presented the SCF project in June 05 at GSFC

• Collaborate in testing the functionality of Be OR Al hollow CCR for GPS-3. Our contribution will be

– Test of mech. and thermo-optical properties in the SCF– Simulation of the above for independent verification

• GOAL: selection of the flight model, and …..• Hollow CCRs work: LNF has used them on a few m range. BUT no long

term experience in space. Few test CCRs flown at few hundred Km• Made in 3 pieces, glued (Be; LNF) or bolted (Al; GSFC)• Most severe problem is CCR warping in space climate, which could

prevent light return. 300-400 K CCR T variation ? G. Delle Monache is starting to work on this


GOLEM

• The project is taking shape– Will not cost us money, and will put the SCF to excellent

use– They are helping us to setup a LASER-TEST system for

LARES– We asked a fellowship (”assegno di ricerca” to LNF)

• The next generation GNSS (Galileo, GPS-3)– MW-ranged with ?? m accuracy. Well, single orbits don’t

close to better than 20-30 cm (V.J. Slabinski, our LARES collaborator, at GPS Conference, November 05, London )

– LASER-ranged with mm to cm level accuracy

• GPS and SLR fully complementary. With GALILEO and GPS-3 we will have the best combination. SLR will provide GNSS the needed long term absolute calibration and stability


Laser-test system for LARES/GOLEM

Purchased:1) Nd-Yag laser (ILRSRecommended)2) He-Ne laser3) Firewire system,DAQ and analysis Software and2 CCD camera to study theFar Field Diffraction Profile (FFDP).

Cannot launch LARES withoutPerforming FFDP characterization.


Laser ranging in the solar system

• LLR (Lunar Laser Ranging)– De Sitter effect with historic Apollo 11, 14, 15 (US) and

Lunakhods (USSR)– Apache Point Lunar Laser-ranging Observatory (APOLLO)– “The accelerated universe and the moon”, G. Dvali 2004

• Mercury and Mars– Successful ranging to Marcury satellite and to Mars

Global Surveyor (the farthest SLR ever ! J. Mc Garry et al).

– Martian rovers for accurate altimetry

• LATOR (Laser Astrometric Test Of Relativity)• LISA-PathFinder• ….• Technology application: SPQR (Eneide mission) on

ISS


Probing gravity in the outer solar system

(Disclaimer: unavoidable,1-slide, simple introduction - then I’ll tell you right away

one specific item where the SCF can give a specific contribution) • NEO: LAGEOS (and we hope also LARES !)• Terrestrial planets: ~50 yrs of space research• In the outer SS (Jupiter and beyond) the only probe

with adequate navigation capabilities are the PIONEERS: accurate and robust navigation system, spanned the whole SS– VOYAGERS: Deep Space, but factor 50 worse navigation– GALILEO (not the GNSS): inaccurate, up to Jupiter only– CASSINI: being studied, but still, only up to Saturn


The Pioneer Anomaly

• Doppler data (1987-1998, 40-70.5 AU) provide clear anomalous deceleration. Pioneer Explorer Collaboration.

aP = (8.74 1.33) 10-10 m/s2

– ~9 times the largest LAGEOS TT due to Solar-Yarkovsky

• Most likely systematic effect is asymmetric TT due to forward-backward asymmetric (HGA ?) thermo-optical parameters (existing and/or induced by the on-board RTG activity)– Propulsion system ?

• Novelty: full engineering telemetry data (1972-2002) retrieved from old VAX hw and available by JPL, AS OF NOW

Anomaly kicks off at Saturn,10 AU, reached in 3.5 yrs


How can we contribute ?

• I contacted the PI, Slava G. Turyshev of JPL. Potential items of interest– Re-analysis of full set of Pioneer data IN CONJUNCTION

with telemetry data• What a good topic for thesis or fellowship

– Thermal modeling of the Pioneers

• New mission design


New mission: Deep Space Gravity Probe

The option the PI from JPL (S. Turyshev) pushes for that and we like


Conclusions

• The SCF is a 1m x 2m climatic thermo-vacuum test facility designed to test the functionality of small payloads and for the characterization of test masses

• Projects:– Our INFN-GR2 commitment: LAGEOS-LP and LARES– GOLEM (proposed to LNF by NASA/Goddard) and DSGP (on-

going contact with NASA/JPL)

• This is the integrated activity that we submitted to the LNF management in Sep-Dec 05

• Expect first measurements by beginning of March 06


Fused silica (suprasil T19) CCR thermo-optical

properties

SuprasilMaterialPropriety Int Ext

Aluminum KEL-F

Conductivity[W/(mm*K)]

0.00085 0.237 0.0002088

Specific Heat[J/(kg*K)]

753 900 900

Density[kg/mm^3]

2.2e-006 2.702e-006 2.13e-006

Solar 0.15 0.15 0.42 1Absorptivity/Emissivity1 Infrared 0.81 0.81 0.2 0.93

Solar 0.849 0.849 0 0Transmissivity2Infrared 0 0 0 0Solar 0 0 0 0Specularity3Infrared 0 0 0 0Solar 1 1 0 0Transmissive

Specularity4 Infrared 1 1 0 0Solar 1.46 0.684931 1 1Refractive

Indices Ratio Infrared 1 1 1 1

1 Quanta parte di energia viene assorbita ed emessa per irraggiamento2 Quanta parte di energia incidente attraversa il solido; la soma di questo numero con ilprecedente deve essere minore uguale ad uno: il complemento ad uno di questa sommarappresenta l’energia riflessa.3 Indice della maniera in cui viene riflessa la porzione di energia riflessa: 0 implica che l’energiae’ riflessa in maniera perfettamente diffusa (i.e. omogeneamente in tutte le direzioni) mentre 1implica che la porzione di energia riflessa lascia la superficie in maniera perfettamente specularerispetto al fascio incidente.4 Ha lo stesso significato del parametro precedente, ma rispetto alla porzione di energia cheattraversa il solido.

INFN-LNF, 13-JAN-06, Fundamental Physics [email protected] 1 The LNF Space Climatic...

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