STARDUST : NASA’s Comet Sample Return mission
Cometary dusts collected : Jan. 2, 2004
Earth return : Jan. , 2006.
Artist concept depicting STARDUST
spacecraft flyby comet Wild-2 to
collect dust particles.
Comet Wild2’s nucleus and the
outflowing jets. Image taken by
STARDUST onboard camera
http://stardust.jpl.nasa.gov
Cometary dusts analyzed by onboard TOF MS
?
Mass spectrum of a detected stardust by CIDA
TOF MS during the flyby of comet Wild2
J. Kissel et al., Science, Vol 304, P.1774 (2004)
DUST-BUSTER --- An Isotope TOF-MS for stardust
Chun-Yen
Wally F.
Typhoon
Jerry E.
Mike J.
Igor V.
Chen1
Calaway2
Lee1
Moore2
Pellin2
Veryovkin2
1:
Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan
2: Material Science Division, Argonne National Laboratory, USA
Supernova Theory and Nucleosynthesis workshop, July 17, 2004
Goal: look for large isotope effect in small grains
Dust size ~ 1 µm, ~10-12 gram, ~ 1010 atoms
3σ ~ 10% effect
Cover as many as isotope ratios over large mass range in order to
examine the structure of individual source star of solar system nuclides.
TOF
Secondary
neutrals
sample
(Full mass range)
VUV
Single-photon
ionization
Ion Sputtering
Laser desorption
Picture of the SPIRIT instrument at APS–developed by the ANL group.
Instrument efficiency measured > 12%
We are using SPIRIT to develop SI-TOF MS for isotope analysis; DUST-BUSTER at
IES is ongoing.
Ionization potentials of atomic elements vs. laser wavelength
16
Free
Electron
Laser
to
24 eV
N
Ionization potential (eV)
14
O
12
S
C
10
Se
Zn
B
8
Mg
Ge
Fe
Si
Ca
Ti
Au
157 nm (F2 excimer)
Zr
Ni Cu
193 nm (ArF excimer)
213 nm (Nd-YAG x5)
Cr
6
Ga
Li
4
Sr
K
2
0
0
10
20
30
Atomic number Z
40
80
Ion optics simulation of the new instrument design
3D SIMION software was used to simulate, predict transmission and useful yield
for the new reflectron time-of-flight (TOF) mass spectrometer.
97.22% before
Reflectron
95.29% after
Reflectron
Photoionization volume
4x4x3 mm3
Target
95 %
transmitted to
detector
Assembled DUST-BUSTER parts
Photo-ion extraction system
Reflectron side view
Ion beam bending & detection housing
Reflectron front view
IES Instrument Galley
VG spectrometer
Home of DUST-BUSTER
DUST-BUSTER
MAT spectrometer
5
detector analog signal (10 mV)
Fe
58,60,61,62,64
2
Ni
56
Fe2
56
FeOH
FeNi
52
deviatoin to normal value(%)
Cape York iron meteorite
54,56,57,58
54
56
58
60
62
64
66
68
70
72
74
76
110
115
mass (amu)
Ni-58/60
Ni-61/60
Ni-62/60
-10
Ni-64/60
1
-10
-5
0
-15
-15
-1
-0.1 +/- 0.6
-10
-11.7 +/- 1.9
-7.1 +/- 1.1
-14.0 +/- 1.9
120
-1
-2
-0.9 +/- 0.5
5 4 ,5 6 ,5 7 ,5 8
C a p e Y o rk
iro n m e te o rite
Fe
5
detector analog signal (10 mV)
0
Fe-54/56
5 8 ,6 0 ,6 1 ,6 2 ,6 4
52
54
56
58
60
62
Ni
64
66
m a s s (a m u )
detector analog signal (10 mV)
30
40,42,44,46,48
Ca
5
deviation to normal (%)
Ca-42/40
20
10
23.0 +/- 8.8
Titanite: C aTiS iO 5
earth low er crust
28
S iO
38 39 40 41 42 43 44 45 46 47 48 49 50 51 52
m ass (am u )
detector analog signal (105 mV)
40
2
CaO
28
Si2
Titanite: CaTiSiO5; earth lower crust
28,29,30
1
Si
40,42,44,46,48
48
TiO
46,47,48,49,50
Ca
Ti
28
SiO
25
30
35
40
45
50
55
60
65
deviation to normal value (%)
mass (amu)
Ti-47/48
Ti-46/48
20
10
Ti-49/48
35
20
10
5
Ti-50/48
10
30
0
-10
0
14.0 +/- 0.4
-3.2 +/- 0.6
0
6.7 +/- 0.5
2.2 +/- 0.3
25
31.5 +/- 1.2
29.7 +/- 2.0
1.1 +/- 1.7
13.2 +/- 0.8
70
10
5
(%)
0
-5
Ti group
TiO group
0
δTi-46/48
4.7 +- 0.5
-10.8 +- 1.1 -5
δTi-47/48
-4.0 +- 1.1
-9.0 +- 0.8
-10
-10
-15
60
40
20
0
δTi-49/48
δTi-50/48
35.5 +- 10.9 10
11.2 +- 7.3
5
0
6.7 +- 2.2
3.1 +- 0.9
detector analog signal (105 mV)
CPX: MgCaSi2O6, earth mantle
28,29,30
Si
44
1
27
Al
24,25,26
Mg
23
Na
20
Ca
28
SiO
27
AlOH
25
40
Ca
24
MgO
30
35
40
45
40
CaO
28
Si2
50
55
deviation to normal value(%)
mass (amu)
30
Mg-25/24
Si-29/28
Mg-26/24
Si-30/28
30
250
-5
20
25
240
-10
10
20
23.6 +/- 0.9
-7.0 +/- 1.3
241.6 +/- 5.3
243.2 +/- 3.5
19.2 +/- 2.7
13.4 +/- 1.7
60
Conclusions
Mass spectrometer is promising.
Efficiency > 10%; Isotope ratio measurements are reproducible to within
3% level on most cases.
Next :
DUST-BUSTER : speed up assembling and test runs
Comet samples : prey for safe return with pristine stardusts
Experiments : investigate to minimize the molecular interference effects,
such as reducing the forming of hydrides, oxides, hydroxides etc.
Instrument improvements needed:
Higher mass resolving power (m/∆m >3500) to resolve MgH, SiH
molecular interferences.
Large detector dynamic range to cover good precision measurements on
both high and low abundance elements in one single experiment.