arcus:an x-ray grating spectrometer on the iss mission and

1
Arcus leverages NASA’s investment in the off-plane gratings that have been in development at the University of Iowa for Constellation-X and IXO. Off-plane gratings have success- IXOO\ ÁRZQ LQ VXERUELWDO URFNHW ÁLJKWV DQG GHVLJQV VLPLODU WR those planned for Arcus have been demonstrated at the NASA/ MSFC stray light facility to reach R = h6h ! OLPLWHG E\ WKH ÀQLWH VRXUFH size. The gratings will be housed in modules that will be paired to the silicon pore optics PRGXOHV VLPSOLI\- ing assembly and alignment. Arcus will observe the end products of structure formation in the form of hot gas beyond the virial radius of galaxies and FOXVWHUV DV ZHOO DV GH- WHFWLQJ ÀODPHQWV LQ WKH IGM itself via absoprtion WR EDFNJURXQG $*1 $V VKRZQ DW ULJKW RQO\ $U - cus has the sensitivity to GHWHFW ÀODPHQWV ZLWK OHVV than 4mÅ EqW. Arcus will also direct- O\ REVHUYH IHHGEDFN DQG winds from supermassive EODFN KROHV LQ WKH IRUP RI warm absorbers with an order of magniture more sensitivity than Chandra RU HYHQ $VWUR+ PHD- suring the velocity and temporal variations in the ionization structure of the jet (see Figure at right). Arcus will study stellar formation and evolution by GHWHFWLQJ DFFUHWLRQ ÁRZV onto young stars as well as XVLQJ ZHDN EXW KLJKO\ VHQ- sitive satellite line diagnos- tics that require high res- ROXWLRQ DQG HIIHFWLYH DUHD as shown at right. Observa- tions of Galactic XRB and EODFN KROH VRXUFHV ZLOO OHQG insights into these systems DQG WKH VWUXFWXUH RI WKH KRW LQWHUVWHOODU PHGLXP DQG KDOR RI WKH 0LON\ :D\ Arcus Design Arcus is an X-ray grating spectrometer mission to be deployed on the International Space Station in response to NASA’s Astrophysics Division plan to announce a SMEX call in Fall 2014 with a cost cap of $125M (FY15). The baseline design uses sub-apertured X-ray silicon pore optics feeding into off-plane gratings to achieve both high spectral resolution with a large effec- tive area. The detector focal plane uses Suzaku-type CCDs. The mission would be ready to be launched and mounted on the ISS in 2020. The mission parameters are R>2500 with >650 cm 2 at the critical O VII wavelength around 22-25Å (~0.5 keV), with an overall bandpass from 8-52Å (0.25-1.5 keV), enabling a wide range of science objectives. These values are similar to those of the grating spectrometers considered as part of the proposed Constellation-X and IXO missions, which were highly ranked by two Decadal surveys. Arcus:An X-ray Grating Spectrometer on the ISS Mission and Science Overview Randall K. Smith 1 5 $OOXUHG 1 0 %DXW] 2 -D\ $ %RRNELQGHU 1 - %UHJPDQ 3 / %UHQQHPDQ 1 1 %ULFNKRXVH 1 ' %XUURZV 4 9 %XUZLW] 5 $ &DUULHU 6 3 &KHLPHWV 1 3 'DLJQHDX 1 $ )DOFRQH 4 A. Foster 1 0 )UHHPDQ 1 5 +HLOPDQQ 2 % +RZOH\ 6 ' +XHQHPRHUGHU 2 - .DDVWUD 7 + 0DUVKDOO 2 5 0F(QWDIIHU 8 ( 0LOOHU 2 - 0LOOHU 3 5 0XVKRW]N\ 9 ) 3DHUHOV 10 5 3HWUH 11 $ 3WDN 11 . 3RSSHQKDHJHU 1 3 5HLG 1 0 6FKDWWHQEHUJ 2 1 6FKXO] 2 / 9DOHQFLF 11 5 :LOOLQJDOH 12 - :LOPV 13 6 :RON 1 1 6PLWKVRQLDQ $VWURSK\VLFDO 2EVHUYDWRU\ 2 0,7 3 8 0LFKLJDQ 4 3HQQ 6WDWH 8QLY 5 03( 6 /RFNKHHG0DUWLQ 7 6521 8 8 ,RZD 9 8 0DU\ODQG 10 &ROXPELD 8 11 1$6$*6)& 12 8 /HLFHVWHU 13 FAU Arcus Optical & Detector Layout 10 20 30 40 50 Wavelength (Å) 0 200 400 600 800 1000 1200 Effective Area (cm 2 ) XMM-Newton RGS Chandra Gratings Astro-H SXS Arcus ~900 cm at O VII ~575 cm at C VI ~1000 cm from 9-16Å 4 Ir-coated SPO petals w/ O-plane Gratings 96% open Silicon mesh lter base 45 nm polyimide coating 70 nm Al optical blocking lter Suzaku-type BI CCD QE Conclusions The Arcus science goals were highly regarded both by NASA and by the FRPPXQLW\ DV UHÁHFWHG E\ WKHLU PHQWLRQ LQ WKH 1HZ :RUOGV 1HZ +RUL]RQV 'HFDGDO 6XUYH\ :LWK (6$·V GHFLVLRQ WR ODXQFK$WKHQD LQ DV WKHLU / PLVVLRQ WKH JUDWLQJ VFLHQFH UHPDLQV DQ H[FLWLQJ RSSRUWXQLW\ The challenge has been to achieve those goals in a timely fashion and an affordable cost. Arcus is designed to meet the NWHN recommendations DQG FXUUHQW FRQVWUDLQWV DW DQ H[WUHPHO\ DWWUDFWLYH FRVW WKDW FDQ EH ÀW ZLWKLQ a SMEX mission by combining existing technology and the opportunities provided by the ISS. Arcus leverages ESA’s investment in the silicon pore optics over the last decade. 7KHVH RSWLFV DUH SODQQHG IRU XVH LQ $WKHQD LQ ZLWK DQ LPDJLQJ 36) UHTXLUH- PHQW RI ·· DOWKRXJK WKH $UFXV UHTXLUHPHQW RQ WKH RSWLFDO SHUIRUPDQFH LV FORVH WR ·· :KLOH LPSURYHPHQWV LQ WKH RYHUDOO LPDJLQJ FDSDELOLWLHV RI WKH RSWLFV FRQWLQXH nonetheless the current generation of 75/ RSWLFV KDYH WKH UHTXLUHG SHU - formance for use in a grating spec- WURPHWHU $V VKRZQ LQ WKH ÀJXUH DW ULJKW WKH UHOHYDQW LVVXH LV QRW WKH IXOO 36) EXW UDWKHU WKH QDUURZ ´WUDQV- YHUVHµ 36) DORQJ ZLWK WKH SKRWRQV will be dispersed. These data were from an older mirror module (top left) measured at the IRFDO SODQH UHVXOWV IURP WKH FXUUHQW JHQHUDWLRQ RI 632 DUH H[SHFWHG WR LPSURYH $OWKRXJK WKH EHVW PHDVXUHG +(: IRU D 632 PLUURU LV DERXW DUFVHF WKH GDWD VKRZQ KHUH DW ULJKW ÀQG D DUFVHF ):+0 LQ WKH GLPHQVLRQDO SURMHFWLRQ IRU WKH VKRUW D[LV ZKLFK HTXDWHV WR MXVW OHVV WKDQ µ +(: %HORZ WKDW SULPDU\ *DXVVLDQ WKHUH LV D VHFRQG a··*DXVVLDQ ZLWK OHVV DUHD ,Q WKLV VWXG\ WKH SUREH EHDP KDV D GLYHUJHQFH RI µ VR D µ image is basically the geometrical limit. In short: the current silicon pore optics meet the Arcus requirement. Silicon Pore Optics ! %'/ '%. '%+'+% "%)"! % '& /"! ,% %+& '" '%! "- "%)"! -"%& +%,/ &"%#)"! !& " ?: .& ! +&'%& '" =. ,% %+&5 +%,/ ?: " '%"+ ) " 7 " %"+# '" ! &'%+'+%3 +!!5 &+% +!!&3 ,")& 7 "#"&)"! -'! / / B@?: < ' 3 <:: < !5 A &4 B;?:: ",% !#&&3 B<?:: ' ! && 7 !%/ ! "+("-! -! &%, & ! &&"! !& %" %! " "!& '" &+% ,")& 7 #%"& ! '#"% ,%)"! ! %&#"!& '" !! +. !#&& A6?< -' B<:: < '%"+"+' -' B;?::5 A& '% / "- " /"+! &'%& &#%& '% &&2 "- " !"% &'%& ' "%"!2 # ! ! 3 &"%#)"! "+! " #%6&" &3 ! , '+% ,& &" ""!5 &%, '%"! &'' !& '" &+% '#%'+% ! $+%+ &''+& " "%"! & !#&& A6?< -' B<:: < '%"+"+' -' B;?::5 >& XMM-Newton RGS Chandra Gratings Astro-H SXS O VIII O VII C VI Ne IX N VII N VI Athena (2028) Arcus 5m detection, 500 ksec obs Using 25 blazar LOS with Fx~10 cgs 5mÅ (Athena systematics limit) C V 3mÅ 10 20 30 40 50 Wavelength (Å) 10 100 1000 Line Detection Figure of Merit FoM = [Resolving Power x Eective Area] (cm) Arcus Science 0 100 300 200 100 300 200 X Position (24 μm pixel) Y Position (24 μm pixel) Silicon Pore Optic 20 m focal length 20 plates 6.5 cm geo. area Full HEW ~ 24 arcsec Transverse HEW ~ 1 arcsec Data courtesy cosine Research Arcus Chandra LETGS/HRC-S Astro-H/SXS NH Detection Threshold (cm) Log [Ionization Parameter j] -2 -1 0 1 2 3 4 10 10 10 10 10 1m limit in 100 ksec Detecting warm absorbers in AGN Optics Module 5.5m Extendable & Collapsable Optical Bench (with shroud) Arcus Layout (Deployed) CCDs Focus Mechanism, A/D Electronics, Thermo-Elec Cooler ~1m TBD DFP Mount Point (opt) DFP Mount Point (opt) 2-axis Gimbal FRAM (active) FRAM (passive) International Space Station Grazing Incidence Optics O Plane Grating Modules Incoming X-rays Fine Sun Sensor Re-closable Door (Mass ~ 120 kg, ~1m x 1m area) (Mass ~ 20 kg) Science Instrument Module ~500mm Star Trackers Radiator WiFi Power Cabling (& Data if needed) Metering & Displacement System (Mass ~ 50 kg) The Arcus mission requirements are similar to those that have been pro- posed for the Constellation-X and IXO X-ray grating spectrometers. On WKH ,66 LVVXHV RI PDVV SRZHU DQG GDWD WUDQVPLVVLRQ EHFRPH PXFK OHVV GLIÀFXOW %DVHG RQ WKH 1,&(5 GHVLJQ VWXGLHV ZH H[SHFW DW OHDVW RE- VHUYLQJ HIÀFLHQF\ GXULQJ D \HDU EDVHOLQH PLVVLRQ ZKLFK ZLOO HQDEOH XV to complete all of the science planned for IXO. $UFXV ZLOO XVH DQ KLJK 75/ SUHFLVLRQ RSWLFDO EHQFK VLPLODU WR WKDW RI NuSTAR. The bench carries with it a shroud for stray light control. A full-size prototype of this shroud-enclosed bench has undergone over 200 GHSOR\PHQW F\FOHV GXULQJ JURXQG WHVWLQJ /LNH 1X67$5 DQG $VWUR+ D PHWURORJ\ V\VWHP LV HPSOR\HG WR WUDFN DQG FRUUHFW IRU UHODWLYH PRWLRQ EHWZHHQ WKH RSWLFV DQG WKH IRFDO SODQH GXH WR WKH VOLJKWO\ ÁH[LEOH EHQFK Contamination from other activies on or around the ISS has been a con- FHUQ IRU ;UD\ RSWLFV EXW UHFHQW VWXGLHV HJ 6WHDJDOO HW DO -65 VKRZ WKDW WKHVH SUREOHPV KDYH ODUJHO\ DEDWHG H[FHSW GXULQJ H[- WHUQDO GRFNLQJ RI SD\ORDGV DQG VLPLODU HYHQWV 7KH ÀJXUH DW right shows Arcus in ob- VHUYLQJ PRGH mounted to the FRAM via a two-axis gim- bal system. The EOB system is completely con- tained within the circular ring beneath the op- tical layout. Grating Arrays To achieve the required 650 cm 2 DUHD DW NH9 Arcus uses at least 3 ‘petals’ (goal of 4) op- WLPDOO\ SDFNHG ZLWK VLO- LFRQ SRUH RSWLFV 632 with a ~5m focal length and off-plane grating modules (see right). Each petal will have an individual focal plane GHWHFWRU FRQVLVWLQJ RI D 6X]DNXW\SH EDFNLOOXPLQDWHG &&' show in this diagram as a rectangle near the narrow end of each petal. The modular petal design leaves us substantial freedom to arrange the V\VWHP WR ÀW ZLWKLQ WKH ISS and other mission re- quirements. To maximize the low-en- HUJ\ WKURXJKSXW $U - FXV UHXVHV ÀOWHUV GHYHO- oped for Astro-H and the UW-Madision XQC VRXQGLQJ URFNHW SURJUDP (shown at right). Incoming Light Star Tracker Optics Assembly (incl. Gratings) Deployable Boom Detectors and Control Electronics Internal Metrology System and light-rejecting “sock” (not shown) Gimbals FRAM Support Plate

Upload: others

Post on 04-Jun-2022

2 views

Category:

Documents


0 download

TRANSCRIPT

Page 1: Arcus:An X-ray Grating Spectrometer on the ISS Mission and

Arcus leverages NASA’s investment in the off-plane gratings that have been in development at the University of Iowa for Constellation-X and IXO. Off-plane gratings have success-IXOO\�ÁRZQ�LQ�VXERUELWDO�URFNHW�ÁLJKWV��DQG�GHVLJQV�VLPLODU�WR�those planned for Arcus have been demonstrated at the NASA/MSFC stray light facility to reach R = h 6h�!�������OLPLWHG�E\�WKH�ÀQLWH�VRXUFH�size. The gratings will be housed in modules that will be paired to the silicon pore optics PRGXOHV��VLPSOLI\-ing assembly and alignment.

Arcus will observe the end products of structure formation in the form of hot gas beyond the virial radius of galaxies and FOXVWHUV��DV�ZHOO�DV�GH-WHFWLQJ�ÀODPHQWV�LQ�WKH�IGM itself via absoprtion WR�EDFNJURXQG�$*1��$V�VKRZQ�DW�ULJKW��RQO\�$U-cus has the sensitivity to GHWHFW�ÀODPHQWV�ZLWK�OHVV�than 4mÅ EqW. Arcus will also direct-O\�REVHUYH�IHHGEDFN�DQG�winds from supermassive EODFN�KROHV�LQ�WKH�IRUP�RI�warm absorbers with an order of magniture more sensitivity than Chandra RU�HYHQ�$VWUR�+��PHD-suring the velocity and temporal variations in the ionization structure of the jet (see Figure at right). Arcus will study stellar formation and evolution by GHWHFWLQJ�DFFUHWLRQ�ÁRZV�onto young stars as well as XVLQJ�ZHDN�EXW�KLJKO\�VHQ-sitive satellite line diagnos-tics that require high res-ROXWLRQ�DQG�HIIHFWLYH�DUHD��as shown at right. Observa-tions of Galactic XRB and EODFN�KROH�VRXUFHV�ZLOO�OHQG�insights into these systems DQG�WKH�VWUXFWXUH�RI�WKH�KRW�LQWHUVWHOODU�PHGLXP�DQG�KDOR�RI�WKH�0LON\�:D\��

Arcus Design

Arcus is an X-ray grating spectrometer mission to be deployed on the International Space Station in response to NASA’s Astrophysics Division plan to announce a SMEX call in Fall 2014

with a cost cap of $125M (FY15). The baseline design uses sub-apertured X-ray silicon pore optics feeding into off-plane gratings to achieve both high spectral resolution with a large effec-

tive area. The detector focal plane uses Suzaku-type CCDs. The mission would be ready to be launched and mounted on the ISS in 2020. The mission parameters are R>2500 with >650 cm2

at the critical O VII wavelength around 22-25Å (~0.5 keV), with an overall bandpass from 8-52Å (0.25-1.5 keV), enabling a wide range of science objectives. These values are similar to

those of the grating spectrometers considered as part of the proposed Constellation-X and IXO missions, which were highly ranked by two Decadal surveys.

Arcus:An X-ray Grating Spectrometer on the ISSMission and Science Overview

Randall K. Smith1��5��$OOXUHG1��0��%DXW]2��-D\�$��%RRNELQGHU1��-��%UHJPDQ3��/��%UHQQHPDQ1��1��%ULFNKRXVH1��'��%XUURZV4��9��%XUZLW]5��$��&DUULHU6��3��&KHLPHWV1��3��'DLJQHDX1��$��)DOFRQH4��A. Foster1��0��)UHHPDQ1��5��+HLOPDQQ2��%��+RZOH\6��'��+XHQHPRHUGHU2��-��.DDVWUD7��+��0DUVKDOO2��5��0F(QWDIIHU8��(��0LOOHU2��-��0LOOHU3��5��0XVKRW]N\9��)��3DHUHOV10��

5��3HWUH11��$��3WDN11��.��3RSSHQKDHJHU1��3��5HLG1��0��6FKDWWHQEHUJ2��1��6FKXO]2��/��9DOHQFLF11��5��:LOOLQJDOH12��-��:LOPV13��6��:RON1

16PLWKVRQLDQ�$VWURSK\VLFDO�2EVHUYDWRU\��20,7��38��0LFKLJDQ��43HQQ�6WDWH�8QLY���503(��6/RFNKHHG�0DUWLQ��76521��88��,RZD��98��0DU\ODQG��10&ROXPELD�8���111$6$�*6)&��128��/HLFHVWHU��13FAU

Arcus Optical & Detector Layout

10 20 30 40 50Wavelength (Å)

0

200

400

600

800

1000

1200

Effe

ctive

Are

a (c

m2 )

XMM-Newton RGSChandra Gratings

Astro-H SXS

Arcus~900 cm2

at O VII

~575 cm2 at C VI

~1000 cm2 from 9-16Å

4 Ir-coated SPO petals w/ O"-plane Gratings 96% open Silicon mesh #lter base 45 nm polyimide coating 70 nm Al optical blocking #lter Suzaku-type BI CCD QE

Conclusions

The Arcus science goals were highly regarded both by NASA and by the FRPPXQLW\��DV�UHÁHFWHG�E\�WKHLU�PHQWLRQ�LQ�WKH������1HZ�:RUOGV��1HZ�+RUL]RQV�'HFDGDO�6XUYH\��:LWK�(6$·V�GHFLVLRQ�WR�ODXQFK�$WKHQD�LQ������DV�WKHLU�/��PLVVLRQ��WKH�JUDWLQJ�VFLHQFH�UHPDLQV�DQ�H[FLWLQJ�RSSRUWXQLW\���The challenge has been to achieve those goals in a timely fashion and an affordable cost. Arcus is designed to meet the NWHN recommendations DQG�FXUUHQW�FRQVWUDLQWV�DW�DQ�H[WUHPHO\�DWWUDFWLYH�FRVW�WKDW�FDQ�EH�ÀW�ZLWKLQ�a SMEX mission by combining existing technology and the opportunities provided by the ISS.

Arcus leverages ESA’s investment in the silicon pore optics over the last decade. 7KHVH�RSWLFV�DUH�SODQQHG�IRU�XVH�LQ�$WKHQD�LQ�������ZLWK�DQ�LPDJLQJ�36)�UHTXLUH-PHQW�RI��··��DOWKRXJK�WKH�$UFXV�UHTXLUHPHQW�RQ�WKH�RSWLFDO�SHUIRUPDQFH�LV�FORVH�WR��··��:KLOH�LPSURYHPHQWV�LQ�WKH�RYHUDOO�LPDJLQJ�FDSDELOLWLHV�RI�WKH�RSWLFV�FRQWLQXH��nonetheless the current generation of 75/��RSWLFV�KDYH��WKH�UHTXLUHG�SHU-formance for use in a grating spec-WURPHWHU��$V�VKRZQ�LQ�WKH�ÀJXUH�DW�ULJKW��WKH�UHOHYDQW�LVVXH�LV�QRW�WKH�IXOO�36)��EXW�UDWKHU�WKH�QDUURZ�´WUDQV-YHUVHµ�36)�DORQJ�ZLWK�WKH�SKRWRQV�

will be dispersed. These data were from an older mirror module (top left) measured at the IRFDO�SODQH��UHVXOWV�IURP�WKH�FXUUHQW�JHQHUDWLRQ�RI�632�DUH�H[SHFWHG�WR�LPSURYH�$OWKRXJK�WKH�EHVW�PHDVXUHG�+(:�IRU�D�632�PLUURU�LV�DERXW����DUFVHF��WKH�GDWD�VKRZQ�KHUH�DW�ULJKW�ÀQG�D�����DUFVHF�):+0�LQ�WKH���GLPHQVLRQDO�SURMHFWLRQ�IRU�WKH�VKRUW�D[LV��ZKLFK�HTXDWHV�WR�MXVW�OHVV�WKDQ��µ�+(:���%HORZ�WKDW�SULPDU\�*DXVVLDQ��WKHUH�LV�D�VHFRQG�a�··�*DXVVLDQ�ZLWK�OHVV�DUHD���,Q�WKLV�VWXG\��WKH�SUREH�EHDP�KDV�D�GLYHUJHQFH�RI��µ��VR�D��µ�image is basically the geometrical limit. In short: the current silicon pore optics meet

the Arcus requirement.

Silicon Pore Optics

����!����%��������'/���'%�.������ �� �������� ������ �� ����� ��

�'%+�'+%���"% �)"!�

�%���� �'��&���/"!��,�%����%���+&�'"���'�% �!���"-��"% �)"!�-"%�&��

�+%,�/���&"%#)"!���!�&�"��?:�����.��&��!����+&'�%&�'"�=.�,�%����%���+&5���+%,�/�?:��"��'�%"+��������)����"�7��"�����%"+#�'"��!��&'%+�'+%�3���+!��!��5�����&+%����+!��!��&3�,��"��)�&�7��" #"&�)"!�-�'��!�����/���/��

B@?:�� <�����'� ��3�<::�� <� �!5����A��&��4���B;?::�",�%���!�#�&&3���B<?::��'� ���

�������������

��!�� �&&�7��!�%�/��!�"+(�"-�!������-�!��

�&�%,����&��!��� �&&�"!���!�&��%" �%�!���"���"!&�'"� ��&+%��,��"��)�&�7�#%"���&��!��'� #"%���,�%��)"!��!�%�&#"!&��'"����!��!�������+.�

��!�#�&&�A6?<��-�'��B<::�� <����'�%"+��"+'�-�'���B;?::5�A�&���

�'����%�������/����

"-��"�/"+!��&'�%&���&#�%&��'���%���&�&2�"-��"�!"% ���&'�%&����'��"%"!��2�

��#�����!��!�3���&"%#)"!��"�+ !�"��#%�6&�"�����&3��!��,'+%��,&�&�"����""��!�5� �&�%,��������'%"!���&�'����'����!�&�'"� ��&+%��'� #�%�'+%���!���$+����%�+ �&'�'+&�"���"%"!�����&�

��!�#�&&�A6?<��-�'��B<::�� <����'�%"+��"+'�-�'���B;?::5��>�&����

XMM-Newton RGS

Chandra Gratings

Astro-H SXS

O VIII O VII C VINe IX N VII N VI

Athena (2028)

Arcus

5m�detection, 500 ksec obsUsing 25 blazar LOS with Fx~10-11 cgs

5mÅ (Athena systematics limit)

C V

3mÅ

10 20 30 40 50Wavelength (Å)

10

100

1000

Line

Det

ectio

n Fi

gure

of M

erit

FoM = [Resolving Power x E#ective Area]0.5 (cm)

Arcus Science

0 100 300200

100

300

200

X Position (24 µm pixel)

Y Po

sitio

n (2

4 µm

pix

el)

Silicon Pore Optic20 m focal length20 plates 6.5 cm2 geo. area Full HEW

~ 24 arcsec

Transverse HEW ~ 1 arcsec

Data courtesy cosine Research

Arcus

Chandra LETGS/HRC-S

Astro-H/SXS

NH

Det

ectio

n Th

resh

old

(cm

-2)

Log [Ionization Parameter j]-2 -1 0 1 2 3 41017

1018

1019

1020

1021

1m limit in 100 ksecDetecting warm absorbers in AGN

Optics Module

5.5m

Extendable & Collapsable Optical Bench (with shroud)

Arcus Layout (Deployed)

CCDs

Focus Mechanism,A/D Electronics,Thermo-Elec Cooler

~1m

TBD

DFP MountPoint (opt)

DFP MountPoint (opt)

2-axisGimbal

FRAM (active)

FRAM (passive)

International Space StationG

razi

ng In

cide

nce

Opt

ics

O!

Plan

e G

ratin

g M

odul

es

IncomingX-rays

FineSun

Sensor

Re-closableDoor

(Mass ~ 120 kg,~1m x 1m area)

(Mass ~ 20 kg)Science Instrument Module

with opticalbench stowed

~500mm

StarTrackers

Radiator

WiFi

Power Cabling(& Data if needed)

Metering &Displacement System

(Mass ~ 50 kg)

The Arcus mission requirements are similar to those that have been pro-posed for the Constellation-X and IXO X-ray grating spectrometers. On WKH�,66��LVVXHV�RI�PDVV��SRZHU��DQG�GDWD�WUDQVPLVVLRQ�EHFRPH�PXFK�OHVV�GLIÀFXOW��%DVHG�RQ�WKH�1,&(5�GHVLJQ�VWXGLHV��ZH�H[SHFW�DW�OHDVW�����RE-VHUYLQJ�HIÀFLHQF\�GXULQJ�D���\HDU�EDVHOLQH�PLVVLRQ��ZKLFK�ZLOO�HQDEOH�XV�to complete all of the science planned for IXO.$UFXV�ZLOO�XVH�DQ�KLJK�75/�SUHFLVLRQ�RSWLFDO�EHQFK�VLPLODU�WR�WKDW�RI�NuSTAR. The bench carries with it a shroud for stray light control. A full-size prototype of this shroud-enclosed bench has undergone over 200 GHSOR\PHQW�F\FOHV�GXULQJ�JURXQG�WHVWLQJ��/LNH�1X67$5�DQG�$VWUR�+��D�PHWURORJ\�V\VWHP�LV�HPSOR\HG�WR�WUDFN���DQG�FRUUHFW�IRU���UHODWLYH�PRWLRQ�EHWZHHQ�WKH�RSWLFV�DQG�WKH�IRFDO�SODQH�GXH�WR�WKH�VOLJKWO\�ÁH[LEOH�EHQFK�Contamination from other activies on or around the ISS has been a con-FHUQ�IRU�;�UD\�RSWLFV��EXW�UHFHQW�VWXGLHV��H�J��6WHDJDOO�HW�DO��������-65����������VKRZ�WKDW�WKHVH�SUREOHPV�KDYH�ODUJHO\�DEDWHG��H[FHSW�GXULQJ�H[-WHUQDO�GRFNLQJ�RI�SD\ORDGV�DQG�VLPLODU�HYHQWV���7KH�ÀJXUH�DW�right shows Arcus in ob-VHUYLQJ�PRGH��mounted to the FRAM via a two-axis gim-bal system. The EOB system is completely con-tained within the circular ring beneath the op-tical layout.

Grating Arrays

To achieve the required 650 cm2�DUHD�DW�����NH9��Arcus uses at least 3 ‘petals’ (goal of 4) op-WLPDOO\�SDFNHG�ZLWK�VLO-LFRQ�SRUH�RSWLFV��632��with a ~5m focal length and off-plane grating modules (see right).

Each petal will have an individual focal plane GHWHFWRU��FRQVLVWLQJ�RI�D�6X]DNX�W\SH�EDFN�LOOXPLQDWHG�&&'�show in this diagram as a rectangle near the narrow end of each petal. The modular petal design leaves us substantial freedom to arrange the V\VWHP�WR�ÀW�ZLWKLQ�WKH�ISS and other mission re-quirements.

To maximize the low-en-HUJ\�WKURXJKSXW��$U-FXV�UHXVHV�ÀOWHUV�GHYHO-oped for Astro-H and the UW-Madision XQC VRXQGLQJ�URFNHW�SURJUDP�(shown at right).

IncomingLight

Star Tracker

Optics Assembly(incl. Gratings)

Deployable Boom

Detectors andControl Electronics

Internal MetrologySystem and light-rejecting“sock” (not shown)

Gimbals

FRAM Support Plate