Suzaku, Courtesy JAXA

X-ray Imaging Spectrometer (XIS)
HK Monitoring

CCD Temperature Jumps

I sent a script through all of the hk data that I have (all of which was copied from hikari.astro.isas.jaxa.jp:/usr/local/astroe/data/xis) looking for temperature jumps of more than 4C on either the CCD, S?_TCECCR1_CAL, or base plate, S?_TCECCR2_CAL.

As of July 6, 2010 a total of 152 temperature jumps have been found.

Sensor value total jumps up jumps down jumps
XIS0 CCD 22 15 7 (43112 seconds)
XIS0 baseplate 24 13 11
XIS1 CCD 13 10 3 (18256 seconds)
XIS1 baseplate 26 22 4
XIS2 CCD 5 2 3 (18208 seconds)
XIS2 baseplate 13 6 7
XIS3 CCD 6 6 0
XIS3 baseplate 43 29 14

Note that a CCD sensor jump up results in the CCD going colder and a CCD sensor jump down results in the CCD going warmer. CCD temperature jumps up aren't a big impact because the TECs aren't capable of driving the CCDs much more than a a few degrees colder than the setpoint (-90C). However, the CCDs can get very warm (as high as -50C) when the sensor jumps down. Such a warm temperature will impact the performance of the device.

hk date s_time note
S3_TCECCR2_CAL baseplate 20100723 333225671
S0_TCECCR2_CAL baseplate 20100723 333207349
S3_TCECCR2_CAL baseplate 20100720 332898517
S3_TCECCR2_CAL baseplate 20100625 330741981
S0_TCECCR1_CAL CCD 20100618 330186603XIS0 actually got warmer (over -68C) for 6048 seconds
S3_TCECCR2_CAL baseplate 20100609 329428421
S1_TCECCR2_CAL baseplate 20100601 328714139
S1_TCECCR2_CAL baseplate 20100523 327899997
S1_TCECCR2_CAL baseplate 20100507 326538042
S3_TCECCR2_CAL baseplate 20100407 323980258
S3_TCECCR2_CAL baseplate 20100405 323813876
S3_TCECCR2_CAL baseplate 20100313 321773690
S0_TCECCR2_CAL baseplate 20100304 321027672
S3_TCECCR2_CAL baseplate 20100225 320417476
S1_TCECCR1_CAL CCD 20100218 319781380 XIS1 actaully got slightly colder
S1_TCECCR2_CAL baseplate 20100202 318413668
S3_TCECCR2_CAL baseplate 20100112 316614089
S0_TCECCR2_CAL baseplate 20091225 315040721
S1_TCECCR2_CAL baseplate 20091205 313340154
S3_TCECCR1_CAL CCD 20091102 310443331 XIS3 actaully got slightly colder
S3_TCECCR2_CAL baseplate 20090922 306522937
S1_TCECCR2_CAL baseplate 20090825 304513015
S3_TCECCR1_CAL CCD 20090814 303519614 XIS3 actaully got slightly colder
S3_TCECCR2_CAL baseplate 20090805 302823770
S3_TCECCR2_CAL baseplate 20090724 301738296
S0_TCECCR2_CAL baseplate 20090705 300086776
S3_TCECCR2_CAL baseplate 20090701 299778238
S0_TCECCR1_CAL CCD 20090518 295950091 XIS0 actually got warmer (nearly -60C) for 6104 seconds
S3_TCECCR2_CAL baseplate 20090508 295123687
S0_TCECCR2_CAL baseplate 20090501 294525755
S0_TCECCR2_CAL baseplate 20090429 294353247
S1_TCECCR2_CAL baseplate 20090419 293416256
S3_TCECCR2_CAL baseplate 20090414 293008914
S0_TCECCR1_CAL CCD 20090413 292916790 XIS0 actually got slightly colder
S1_TCECCR2_CAL baseplate 20090409 292571528
S3_TCECCR2_CAL baseplate 20090406 292342594
S3_TCECCR2_CAL baseplate 20090323 291110678
S3_TCECCR2_CAL baseplate 20090318 290697578
S3_TCECCR2_CAL baseplate 20090317 290629588
S0_TCECCR1_CAL CCD 20090218 288237707 XIS0 actually got slightly colder
S1_TCECCR2_CAL baseplate 20090128 286480351
S1_TCECCR2_CAL baseplate 20090120 285733937
S0_TCECCR2_CAL baseplate 20090113 285198197
S1_TCECCR2_CAL baseplate 20081231 284082433
S1_TCECCR2_CAL baseplate 20081224 283428748
S0_TCECCR1_CAL CCD 20081206 281905846 XIS0 actually got slightly colder
S0_TCECCR1_CAL CCD 20081027 278416402 XIS0 actually got slightly colder
S3_TCECCR2_CAL baseplate 20081024 278182008
S0_TCECCR2_CAL baseplate 20081024 278156000
S3_TCECCR2_CAL baseplate 20080926 275733992
S0_TCECCR2_CAL baseplate 20080925 275665086
S3_TCECCR1_CAL CCD 20080918 275067712 XIS3 actually got slightly colder
S0_TCECCR1_CAL CCD 20080910 274347247 XIS0 actually got slightly colder
S0_TCECCR1_CAL CCD 20080801 270882239 XIS0 actually got slightly colder
S0_TCECCR2_CAL baseplate 20080625 267743925
S1_TCECCR2_CAL baseplate 20080618 267084119
S3_TCECCR2_CAL baseplate 20080524 264950958
S0_TCECCR1_CAL CCD 20080421 262101914 XIS0 actually got slightly colder
S1_TCECCR2_CAL baseplate 20080408 260980160
S3_TCECCR2_CAL baseplate 20080403 260548540
S3_TCECCR2_CAL baseplate 20080324 259709976
S1_TCECCR2_CAL baseplate 20080223 257089319
S3_TCECCR2_CAL baseplate 20080125 254578699
S3_TCECCR2_CAL baseplate 20080121 254221961
S1_TCECCR2_CAL baseplate 20080119 254049373
S1_TCECCR2_CAL baseplate 20080101 252544217
S3_TCECCR2_CAL baseplate 20071231 252452097
S1_TCECCR1_CAL CCD 20071223 251693549 XIS1 actually went warmer for 5808 seconds
S0_TCECCR1_CAL CCD 20071219 251422777 XIS0 actually got slightly colder
S3_TCECCR2_CAL baseplate 20071217 251244043
S3_TCECCR2_CAL baseplate 20071203 249973701
S0_TCECCR1_CAL CCD 20071105 247611988 XIS0 actually went warmer for 6176 seconds
S1_TCECCR2_CAL baseplate 20071102 247334724
S1_TCECCR1_CAL CCD 20071029 246957358 XIS1 actually went slightly colder
S0_TCECCR1_CAL CCD 20071008 245157822 XIS0 actually went slightly colder
S3_TCECCR2_CAL baseplate 20070921 243702676
S3_TCECCR2_CAL baseplate 20070918 243455932
S0_TCECCR2_CAL baseplate 20070910 242771524
S3_TCECCR2_CAL baseplate 20070909 242617152
S1_TCECCR1_CAL CCD 20070817 240692166 XIS1 actually went slightly colder
S0_TCECCR2_CAL baseplate 20070810 240064436
S3_TCECCR2_CAL baseplate 20070803 239490660 my script didn't find this one, it was reported by Hironori Matsumoto
S1_TCECCR1_CAL CCD 20070720 238214379 XIS1 actually went slightly colder
S0_TCECCR2_CAL baseplate 20070719 238134051
S0_TCECCR1_CAL CCD 20070622 235821891 XIS0 actually went warmer for 6320 seconds
S0_TCECCR2_CAL baseplate 20070609 234736407
S1_TCECCR2_CAL baseplate 20070601 234052003
S1_TCECCR2_CAL baseplate 20070531 233965719
S0_TCECCR2_CAL baseplate 20070501 231368869
S3_TCECCR2_CAL baseplate 20070420 230395212
S0_TCECCR2_CAL baseplate 20070419 230265180
S3_TCECCR1_CAL CCD 20070408 229383806 XIS3 actually went slightly colder
S0_TCECCR1_CAL CCD 20070408 229327926 XIS0 actually went warmer for 6160 seconds
S1_TCECCR2_CAL baseplate 20070401 228729974
S3_TCECCR2_CAL baseplate 20070324 228057630
S3_TCECCR2_CAL baseplate 20070324 228033324
S3_TCECCR2_CAL baseplate 20070312 227052070
S3_TCECCR1_CAL CCD 20070305 226379438 XIS3 actually went slightly colder
S1_TCECCR1_CAL CCD 20070301 226078380 XIS1 actually went warmer for 6280 seconds
S3_TCECCR2_CAL baseplate 20070212 224573404
S3_TCECCR2_CAL baseplate 20070208 224234236
S1_TCECCR2_CAL baseplate 20070115 222217309
S1_TCECCR1_CAL CCD 20070110 221767545 XIS1 actually went slightly colder
S0_TCECCR1_CAL CCD 20061205 218646711 XIS0 actually went warmer for 6176 seconds
S0_TCECCR1_CAL CCD 20061120 217357841 XIS0 actually went slightly colder
S1_TCECCR1_CAL CCD 20061109 216352425 XIS1 actually went warmer for 6240 seconds
S0_TCECCR1_CAL CCD 20061108 216266147 XIS0 actually went slightly colder
S2_TCECCR1_CAL CCD 20061027 215254635 XIS2 actually went warmer for 6288 seconds
S2_TCECCR2_CAL baseplate 20061013 214070401
S1_TCECCR2_CAL baseplate 20061012 214008219
S0_TCECCR1_CAL CCD 20060921 212139567 XIS0 actually went slightly colder
S3_TCECCR2_CAL baseplate 20060821 209493992
S0_TCECCR2_CAL baseplate 20060819 209345540
S2_TCECCR2_CAL baseplate 20060819 209315220
S2_TCECCR2_CAL baseplate 20060730 207550986
S2_TCECCR2_CAL baseplate 20060726 207211798
S3_TCECCR2_CAL baseplate 20060725 207149654
S2_TCECCR1_CAL CCD 20060723 206971046 XIS2 actually went slightly colder
S0_TCECCR2_CAL baseplate 20060701 205096236
S2_TCECCR1_CAL CCD 20060629 204872858 XIS2 actually went slightly colder
S3_TCECCR1_CAL CCD 20060616 203739317 XIS3 actually went slightly colder
S0_TCECCR2_CAL baseplate 20060611 203305616 my script didn't find this one, it was reported by Hironori Matsumoto
S2_TCECCR1_CAL CCD 20060607 202974411 XIS2 actually went warmer for 6208 seconds
S2_TCECCR2_CAL baseplate 20060528 202141593
S0_TCECCR2_CAL baseplate 20060520 201444803
S1_TCECCR2_CAL baseplate 20060515 201049497
S3_TCECCR2_CAL baseplate 20060511 200692151
S1_TCECCR1_CAL CCD 20060511 200686113 XIS1 actually went colder
S0_TCECCR1_CAL CCD 20060511 200679985 XIS0 actually went colder
S2_TCECCR1_CAL CCD 20060420 198859161 XIS2 was actually warm (probably between -85C and -80C) for 5712 seconds
S2_TCECCR2_CAL baseplate 20060418 198668871
S0_TCECCR2_CAL baseplate 20060403 197385983
S1_TCECCR1_CAL CCD 20060310 195282340 XIS1 actually went colder
S1_TCECCR1_CAL CCD 20060217 193499686 XIS1 actually went colder
S0_TCECCR2_CAL baseplate 20060106 189835405
S1_TCECCR1_CAL CCD 20060105 189755219 XIS1 actually went colder
S2_TCECCR2_CAL baseplate 20051230 189267778
S2_TCECCR2_CAL baseplate 20051210 187380188
S0_TCECCR2_CAL baseplate 20051208 187380188
S2_TCECCR2_CAL baseplate 20051202 186824450
S1_TCECCR1_CAL CCD 20051127 186368526 XIS1 actually went colder
S0_TCECCR1_CAL CCD 20051122 185985102 XIS0 actually went colder
S2_TCECCR2_CAL baseplate 20051120 185812540
S2_TCECCR2_CAL baseplate 20051119 185714310
S3_TCECCR2_CAL baseplate 20051112 185103761
S3_TCECCR2_CAL baseplate 20051110 184943713
S0_TCECCR1_CAL CCD 20051004 181729315 XIS0 actually went warmer for 6128 seconds
S1_TCECCR2_CAL baseplate 20050928 181205393
S0_TCECCR2_CAL baseplate 20050905 179199339
S0_TCECCR1_CAL CCD 20050904 179107519 XIS0 actually went colder
S2_TCECCR2_CAL baseplate 20050813 177261498
S2_TCECCR2_CAL baseplate 20050804 176502410

Each of the figures below contains a plot of the suspect value, the deltaT (between the base plate and the CCD), and the TEC voltage over the interesting time. The vertical lines are the times at which the ehk.t_saa value goes to and from 0.

XIS3 baseplate on 20100723

Updated 2010-07-27
Download PDF

XIS0 baseplate on 20100723

Updated 2010-07-27
Download PDF

XIS3 baseplate on 20100720

Updated 2010-07-27
Download PDF

XIS3 baseplate on 20100625

Updated 2010-07-06
Download PDF

XIS0 CCD on 20100618

Updated 2010-06-22
Download PDF

XIS3 baseplate on 20100609

Updated 2010-06-22
Download PDF

XIS1 baseplate on 20100601

Updated 2010-06-22
Download PDF

XIS1 baseplate on 20100523

Updated 2010-06-22
Download PDF

XIS1 baseplate on 20100507

Updated 2010-06-22
Download PDF

XIS3 baseplate on 20100407

Updated 2010-06-22
Download PDF

XIS3 baseplate on 20100405

Updated 2010-06-22
Download PDF

XIS3 baseplate on 20100313

Updated 2010-06-22
Download PDF

XIS0 baseplate on 20100304

Updated 2010-06-22
Download PDF

XIS3 baseplate on 20100225

Updated 2010-03-02
Download PDF

XIS1 CCD on 20100218

Updated 2010-03-02
Download PDF

XIS1 baseplate on 20100202

Updated 2010-03-02
Download PDF

XIS3 baseplate on 20100112

Updated 2010-01-19
Download PDF

XIS0 baseplate on 20091225

Updated 2010-01-13
Download PDF

XIS1 baseplate on 20091205

Updated 2009-12-09
Download PDF

XIS3 CCD on 20091102

Updated 2009-11-04
Download PDF

XIS3 baseplate on 20090917

Updated 2009-09-22
Download PDF

XIS1 Baseplate on 20090825

Updated 2009-08-28
Download PDF

XIS3 CCD on 20090813

Updated 2009-08-18
Download PDF

XIS3 baseplate on 20090805

Updated 2009-08-11
Download PDF

XIS3 baseplate on 20090724

Updated 2009-08-04
Download PDF

XIS0 baseplate on 20090705

Updated 2009-07-23
Download PDF

XIS3 baseplate on 20090701

Updated 2009-07-23
Download PDF

XIS0 CCD on 20090518

Updated 2009-05-19
Download PDF

XIS3 Baseplate on 20090508

Updated 2009-05-12
Download PDF

XIS0 Baseplate on 20090501

Updated 2009-05-05
Download PDF

XIS0 Baseplate on 20090429

Updated 2009-05-05
Download PDF

XIS1 Baseplate on 20090419

Updated 2009-04-23
Download PDF

XIS3 Baseplate on 20090414

Updated 2009-04-16
Download PDF

XIS0 CCD 20090413

Updated 2009-04-16
Download PDF

XIS1 Baseplate on 20090409

Updated 2009-04-16
Download PDF

XIS3 Baseplate on 20090406

Updated 2009-04-16
Download PDF

XIS3 Baseplate on 20090323

Updated 2009-04-14
Download PDF

XIS3 Baseplate on 20090318

Updated 2009-03-23
Download PDF

XIS3 Baseplate on 20090317

Updated 2009-03-23
Download PDF

XIS0 CCD on 20090218

Updated 2009-02-24
Download PDF

XIS1 Baseplate on 20090128

Updated 2009-02-02
Download PDF

XIS1 Baseplate on 20090120

Updated 2009-02-02
Download PDF

XIS0 Baseplate on 20090113

Updated 2000-01-20
Download PDF

XIS1 Baseplate on 20081231

Updated 2009-01-05
Download PDF

XIS1 Baseplate on 20081224

Updated 2009-01-05
Download PDF

XIS0 CCD on 20081206

Updated 2008-12-09
Download PDF

XIS0 CCD on 20081027

Updated 2008-10-30
Download PDF

XIS3 Baseplate on 20081024

Updated 2008-10-30
Download PDF

XIS0 Baseplate on 20081024

Updated 2008-10-30
Download PDF

XIS3 Baseplate on 20080926

Updated 2008-10-09
Download PDF

XIS1 Baseplate on 20080925

Updated 2008-10-09
Download PDF

XIS3 CCD on 20080918

Updated 2008-10-09
Download PDF

XIS0 CCD on 20080910

Updated 2008-10-09
Download PDF

XIS0 CCD on 20080801

Updated 2008-08-07
Download PDF

XIS0 Baseplate on 20080625

Updated 2008-07-01
Download PDF

XIS1 Baseplate on 20080618

Updated 2008-07-01
Download PDF

XIS3 Baseplate on 20080524

Updated 2008-05-27
Download PDF

XIS0 CCD on 20080421

Updated 2008-04-29
Download PDF

XIS1 Baseplate on 20080408

Updated 2008-04-15
Download PDF

XIS3 Baseplate on 20080403

Updated 2008-04-08
Download PDF

XIS3 Baseplate on 20080324

Updated 2008-03-25
Download PDF

XIS1 Baseplate on 20080223

Updated 2008-03-04
Download PDF

XIS3 Baseplate on 20080125

Updated 2008-01-29
Download PDF

XIS3 Baseplate on 20080121

Updated 2008-01-29
Download PDF

XIS1 Baseplate on 20080119

Updated 2008-01-22
Download PDF

XIS1 Baseplate on 20080101

Updated 2008-01-08
Download PDF

XIS3 Baseplate on 20071231

Updated 2008-01-08
Download PDF

XIS1 CCD on 20071223

Updated 2008-01-08
Download PDF

XIS0 CCD on 20071219

Updated 2008-01-08
Download PDF

XIS3 Baseplate on 20071217

Updated 2007-12-18
Download PDF

XIS3 Baseplate on 20071203

Updated 2007-12-06
Download PDF

XIS0 CCD on 20071105

Updated 2007-11-06
Download PDF

XIS1 baseplate on 20071102

Updated 2007-11-05
Download PDF

XIS1 CCD on 20071029

Updated 2007-11-01
Download PDF

XIS0 Baseplate on 20071008

Updated 2007-10-09
Download PDF

XIS3 Baseplate on 20070921

Updated 2007-09-25
Download PDF

XIS3 Baseplate on 20070918

Updated 2007-09-21
Download PDF

XIS0 baseplate on 20070910

Updated 2007-09-11
Download PDF

XIS3 Baseplate on 20070909

Updated 2007-09-11
Download PDF

XIS1 CCD on 20070817

Updated 2007-08-23
Download PDF

XIS0 baseplate on 20070810

Updated 2007-08-14
Download PDF

XIS3 CCD on 20070803

Updated 2007-08-07
Download PDF

XIS1 CCD on 20070720

Updated 2007-07-31
Download PDF

XIS0 Baseplate on 20070719

Updated 2007-07-31
Download PDF

XIS0 CCD on 20070622

Updated 2007-07-03
Download PDF

XIS0 Baseplate on 20070609

Updated 2007-06-12
Download PDF

XIS1 Baseplate on 20070601

Updated 2007-06-12
Download PDF

XIS1 Baseplate on 20070531

Updated 2007-06-12
Download PDF

XIS0 Baseplate on 20070501

Updated 2007-05-08
Download PDF

XIS3 Baseplate on 20070420

Updated 2007-05-08
Download PDF

XIS0 Baseplate on 20070419

Updated 2007-05-08
Download PDF

XIS3 CCD on 20070408

Updated 2007-04-10
Download PDF

XIS0 CCD on 20070408

Updated 2007-04-10
Download PDF

XIS1 Baseplate on 20070401

Updated 2007-04-10
Download PDF

XIS3 Baseplate on 20070324

Updated 2007-04-10
Download PDF

XIS3 Baseplate on 20070324

Updated 2007-04-10
Download PDF

XIS3 baseplate on 20070312

Updated 2007-03-20
Download PDF

XIS3 CCD on 20070305

Updated 2007-03-20
Download PDF

XIS1 CCD on 20070301

Updated 2007-03-07
Download PDF

XIS3 baseplate on 20070212

Updated 2007-02-13
Download PDF

XIS3 baseplate on 20070208

Updated 2007-02-13
Download PDF

XIS1 baseplate on 20070115

Updated 2007-02-13
Download PDF

XIS1 CCD on 20070110

Updated 2007-02-13
Download PDF

XIS0 CCD on 20061205

Updated 2006-12-13
Download PDF

XIS0 CCD on 20061120

Updated 2006-11-29
Download PDF

XIS1 CCD on 20061109

Updated 2006-11-29
Download PDF

XIS0 CCD on 20061108

Updated 2006-11-29
Download PDF

XIS2 CCD on 20061027

Updated 2006-11-29
Download PDF

XIS2 Baseplate on 20061013

Updated 2006-10-18
Download PDF

XIS1 Baseplate on 20061012

Updated 2006-10-18
Download PDF

XIS0 CCD on 20060921

Updated 2006-09-27
Download PDF

XIS3 baseplate on 20060821

Updated 2006-08-23
Download PDF

XIS0 baseplate on 20060819

Updated 2006-08-23
Download PDF

XIS2 baseplate on 20060819

Updated 2006-08-23
Download PDF

XIS2 baseplate on 20060730

Updated 2006-08-02
Download PDF

XIS2 baseplate on 20060726

Updated 2006-07-26
Download PDF

XIS3 baseplate on 20060725

Updated 2006-07-26
Download PDF

XIS2 CCD on 20060723

Updated 2006-07-26
Download PDF

XIS0 baseplate on 20060701

Updated 2006-07-05
Download PDF

XIS2 CCD on 20060629

Updated 2006-07-05
Download PDF

XIS3 CCD on 20060616

Updated 2006-06-19
Download PDF

XIS0 baseplate on 20060611

Updated 2006-06-14
Download PDF

XIS2 CCD on 20060607

Updated 2006-06-14
Download PDF

XIS2 baseplate on 20060528

Updated 2006-06-05
Download PDF

XIS0 baseplate on 20060520

Updated 2006-05-22
Download PDF

XIS1 baseplate on 20060515

Updated 2006-05-22
Download PDF

XIS3 baseplate on 20060511

Updated 2006-05-12
Download PDF

XIS1 CCD Temp on 20060511

Updated 2006-05-12
Download PDF

XIS0 CCD Temp on 20060511

Updated 2006-05-12
Download PDF

XIS2 CCD Temp on 20060420

Updated 2006-04-25
Download PDF

XIS2 baseplate Temp on 20060418

Updated 2006-04-21
Download PDF

XIS0 baseplate Temp on 20060403

Updated 2006-04-10
Download PDF

XIS1 CCD Temp on 20060310

Updated 2006-03-13
Download PDF

XIS1 CCD Temp on 20060217

Updated 2006-02-20
Download PDF

XIS0 Base Temp on 20060106

Updated 2006-01-09
Download PDF

XIS1 CCD Temp on 20060105

Updated 2006-01-09
Download PDF

XIS2 Base Temp on 20051230

Updated 2006-01-05
Download PDF

XIS2 Base Temp on 20051210

Updated 2005-12-12
Download PDF

XIS0 Base Temp on 20051208

Updated 2005-12-09
Download PDF

XIS2 Base Temp on 20051202

Updated 2005-12-05
Download PDF

XIS1 CCD Temp on 20051127

Updated 2005-11-28
Download PDF


XIS0 CCD Temp on 20051122

Updated 2005-11-28
Download PDF


XIS2 Base Temp on 20051120

Updated 2005-11-28
Download PDF


XIS2 Base Temp on 20051119

Updated 2005-11-28
Download PDF


XIS3 Base Temp on 20051112

Updated 2005-12-05
Download PDF


XIS3 Base Temp on 20051110

Updated 2005-11-16
Download PDF


XIS0 CCD Temp on 20051004

Updated 2005-11-16
Download PDF


XIS1 Base Temp on 20050928

Updated 2005-11-16
Download PDF


XIS0 Base Temp on 20050905

Updated 2005-11-16
Download PDF


XIS0 CCD Temp on 20050904

Updated 2005-11-16
Download PDF


XIS2 Base Temp on 20050813

Updated 2005-11-16
Download PDF


XIS2 Base Temp on 20050804

Updated 2005-11-16
Download PDF




MKI     
MIT
Last updated: Fri Aug 6 12:57:10 EDT 2010
email: fergason@space.mit.edu