{"schemaVersion":1,"recordId":"wtc7-nist-evidence-ledger-v1","reviewedDate":"2026-09-23","buildReviewProvenance":{"reportBytesPinnedBySha256":true,"viewerAndDatasetSnapshot":"site/data/wtc7_nist_review_snapshot.json pins the viewer, model datasets, curated assets, and report bytes by SHA-256; report hashes alone do not identify a reviewed application build.","connectionRegistry":"site/data/wtc7_floor13_connection_evidence.json","scope":"This ledger attributes the storyboard. It does not certify numerical reproduction of NIST's structural calculations."},"evidenceClasses":{"drawing_evidence":"A statement about the documented intact structure, subject to the sheet revision and identified gaps.","nist_analysis":"A result, assumption, or proposed mechanism in NIST's final analytical reports; not a direct observation of hidden steel.","released_model_input":"A released NIST computational input; its numbers are not necessarily an executed result or mapped display field.","other_analysis":"A statement from a separate investigation, kept outside the selected NIST case.","observed_motion":"A visible feature or a value NIST derived from identified photographic or video evidence.","authored_interpolation":"An explanatory display state added for this study, without a claim of simulated displacement or measured timing."},"sources":[{"id":"NIST_NCSTAR_1A","label":"NIST NCSTAR 1A, final report (November 2008)","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1a.pdf","locator":"Printed pages cited per claim; printed p. 1 = PDF p. 43","type":"final_report","localPath":"sources/wtc7/ncstar1a.pdf","sha256":"03c801bc1338533b54c6a64a66f074165c9429a59df11e2f58a19f5da91aef09"},{"id":"NIST_NCSTAR_1_9","label":"NIST NCSTAR 1-9, final structural and fire report (November 2008)","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-9.pdf","locator":"Two-volume combined PDF; printed p. 361 onward has a separate volume-two front matter block","type":"final_report","localPath":"sources/wtc7/ncstar1-9.pdf","sha256":"30addb2699370f89e40bccfdcf4b4a18a7f4fb3bc1c0101bd3fcdec9b892b18f"},{"id":"NIST_NCSTAR_1_9A","label":"NIST NCSTAR 1-9A, final global collapse analysis (November 2008)","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-9a.pdf","locator":"Printed p. 1 = PDF p. 52; January 2009 correction notice on PDF p. 2","type":"final_report","localPath":"sources/wtc7/ncstar1-9a.pdf","sha256":"cde75ab6c5cadd972ef6fc9e1716bf6c9a50518bb31ad02f1b1b5d2b028bd5f4"},{"id":"NIST_2012_ERRATA","label":"NIST WTC 7 correction sheet (January 2009; April and June 2012)","href":"https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=901225","locator":"PDF pp. 1\u20132; corrected Chapter 11 seat dimensions on p. 2","type":"correction","localPath":"sources/wtc7/NCSTAR1-9-errata-2012.pdf","sha256":"d5b006c0580acc73683660ec39eecbc2b4eefeba13d7ecbbf5ffa3787561d9c7"},{"id":"NIST_FOIA_09_11_GLOBAL_INPUT","label":"NIST released WTC 7 LS-DYNA global input without connection models","href":"https://drive.google.com/file/d/1q6n78hESWym5QrDD9EPNkSC6iIslPRlN/view","locator":"wtc7_global_8a_no-conn-matl.k; raw input, not a result history","type":"released_model_input","localPath":"sources/wtc7/nist-foia-09-11/wtc7_global_8a_no-conn-matl.k.gz","localCompression":"gzip from FOIA 09-11 mirror","sha256":"f831290e6c0375dafc0bbeb684099d342ed8df29ab8560df82b21459c041483d","publisherFolder":"https://drive.google.com/drive/folders/1qCUrtgcn1jZZXzxi45ktEhOmcJCGsnzd","mirrorArchive":"https://archive.org/download/911datasets/NIST_FOIA_09-11_Nov_13_2008.zip"},{"id":"NIST_FOIA_09_11_CASE_B_THERMAL","label":"NIST released Case B LS-DYNA thermal loading input","href":"https://drive.google.com/file/d/1Q7GvyamGrWWUtTV5mgWhewjVxHzETnzQ/view","locator":"WTC7_CaseB_400pm.int; not yet registered to drawing members","type":"released_model_input","localPath":"sources/wtc7/nist-foia-09-11/WTC7_CaseB_400pm.int.gz","localCompression":"gzip from FOIA 09-11 mirror","sha256":"51b1624338dce5da4dc5a91c13d1356338997af0d3fef9cd627b29ee3bbb9447","publisherFolder":"https://drive.google.com/drive/folders/1qCUrtgcn1jZZXzxi45ktEhOmcJCGsnzd","mirrorArchive":"https://archive.org/download/911datasets/NIST_FOIA_09-11_Nov_13_2008.zip"},{"id":"NIST_FOIA_09_11_CASE_B_DAMAGE","label":"NIST released Case B 4.0 h ANSYS-to-global damage element list","href":"https://drive.google.com/file/d/1l-u1Ur5aDPAte6_t0-y3JyLkXgG_F4Nr/view","locator":"Damage_Global_ANSYS_CaseB_4.0hr.k; separate list, not active in the released main deck","type":"released_model_input","localPath":"sources/wtc7/nist-foia-09-11/Damage_Global_ANSYS_CaseB_4.0hr.k.gz","localCompression":"gzip from FOIA 09-11 mirror","sha256":"982a0e4728ec54f84c44bf364ec34cae5f731e66da4bfad40a4b85ca4bd751da","publisherFolder":"https://drive.google.com/drive/folders/1qCUrtgcn1jZZXzxi45ktEhOmcJCGsnzd","mirrorArchive":"https://archive.org/download/911datasets/NIST_FOIA_09-11_Nov_13_2008.zip"},{"id":"NIST_FOIA_09_11_DISCRETE_MASS","label":"NIST released LS-DYNA discrete-mass include","href":"https://drive.google.com/file/d/17hTlynAEyt3o3V7UKe_XaV2j0pKpuosY/view","locator":"discrete_mass.k; included by the global input deck","type":"released_model_input","localPath":"sources/wtc7/nist-foia-09-11/discrete_mass.k.gz","localCompression":"gzip from FOIA 09-11 mirror","sha256":"2c3c350317f0c06c2aca2e9d9ae1e9b489d4a1c44c9268997e550d35c031d7d7","publisherFolder":"https://drive.google.com/drive/folders/1qCUrtgcn1jZZXzxi45ktEhOmcJCGsnzd","mirrorArchive":"https://archive.org/download/911datasets/NIST_FOIA_09-11_Nov_13_2008.zip"},{"id":"NIST_FOIA_09_11_SHELL_INCLUDE","label":"NIST released LS-DYNA shell-element include","href":"https://drive.google.com/file/d/1Qs3sMhjEgOGJkpfYFqBKqKLeekUU-Q6T/view","locator":"elem_thick_to-renum.k; referenced by *INCLUDE_TRANSFORM in the global deck","type":"released_model_input","localPath":"sources/wtc7/nist-foia-09-11/elem_thick_to-renum.k.gz","localCompression":"gzip from FOIA 09-11 mirror","sha256":"c49dcb74d8559e0cbfa4302732dd2c1764bf161389be0ee8e8c3d9a3dbc55e59","publisherFolder":"https://drive.google.com/drive/folders/1qCUrtgcn1jZZXzxi45ktEhOmcJCGsnzd","mirrorArchive":"https://archive.org/download/911datasets/NIST_FOIA_09-11_Nov_13_2008.zip"},{"id":"F13_CONNECTION_EVIDENCE","label":"Floor 13 C44\u2013C79 drawing and connection audit","href":null,"locator":"Individual original sheets and revisions are listed in the evidence registry","type":"local_evidence_registry","localPath":"site/data/wtc7_floor13_connection_evidence.json"},{"id":"E12_13","label":"Frankel E12/13, paired Floor 12/13 erection plan","href":null,"locator":"Sheet E12/13; revision F, 12 August 1985, for added-stud note","type":"original_drawing","registrySourceId":"E12_13"},{"id":"S8_REV_H","label":"Cantor S-8, typical structural framing and slab/deck notes","href":null,"locator":"Sheet S-8, latest released revision H, 5 August 1985; E12/13 cites unavailable revision I","type":"original_drawing","registrySourceId":"S8_REV_H"},{"id":"E117A","label":"Frankel E117A, column tier erection drawing","href":null,"locator":"Sheet E117A, C79 tier map","type":"original_drawing","registrySourceId":"E117A"},{"id":"FRANKEL_1091","label":"Frankel 1091, Column 79 shop drawing","href":null,"locator":"Sheet 1091, A1091 tier and PF/PG material bill","type":"original_drawing","registrySourceId":"FRANKEL_1091"},{"id":"FRANKEL_9100","label":"Frankel 9100, Floors 8\u201321 connection plan","href":null,"locator":"Sheet 9100, C79 seat and special 9135 callout","type":"original_drawing","registrySourceId":"FRANKEL_9100"},{"id":"FRANKEL_9114","label":"Frankel 9114, beam-to-column seat detail","href":null,"locator":"Sheet 9114, Column 79 connection family","type":"original_drawing","registrySourceId":"FRANKEL_9114"},{"id":"FRANKEL_0901","label":"Frankel 0901, standard beam-to-beam fin plate","href":null,"locator":"Sheet 0901; not automatically assignable to all four east beams","type":"original_drawing","registrySourceId":"FRANKEL_0901"},{"id":"FRANKEL_9135","label":"Frankel 9135, special W24-to-built-up-girder connection","href":null,"locator":"Sheet 9135; exact 3004 variant assignment unresolved","type":"original_drawing","registrySourceId":"FRANKEL_9135"},{"id":"SSC_3004","label":"Steel Structures Corp. 3004, W24\u00d755 shop drawing","href":null,"locator":"Sheet 3004, distinct beam variants and west-web holes","type":"original_drawing","registrySourceId":"SSC_3004"},{"id":"WEIDLINGER_ASSESSMENT","label":"Weidlinger/Thornton Tomasetti WTC 7 assessment (separate interpretation)","href":"https://s3.amazonaws.com/tt_assets/pdf/WTC_7_Collapse_Analysis_and_Assessment_Report.pdf","locator":"Appendix A p. A-33 / PDF p. 119 for its composite-girder interpretation","type":"separate_investigation","localPath":"sources/wtc7/WTC7-weidlinger-collapse-analysis-assessment-report.pdf"},{"id":"WTC7_IMAGERY_AUDIT","label":"Local WTC 7 imagery and corpus audit","href":null,"locator":"Video sampling findings; shot-level time and rights review pending","type":"local_audit","localPath":"analysis/wtc7-reconstruction-review/imagery-audit.md"}],"claims":[{"id":"f13-girder","text":"The paired Floor 12/13 plan identifies the C44\u2013C79 receiver as A2001, W33\u00d7130.","evidenceClass":"drawing_evidence","sourceRefs":[{"sourceId":"E12_13","locator":"Sheet E12/13, A2001 callout"}],"limits":"The individual physical Floor 13 fabricated piece and exact end workpoints are unresolved."},{"id":"c79-tier-map","text":"Floor 13 intersects the A1091 C79 tier below the model schedule splice at elevation 469 ft.","evidenceClass":"drawing_evidence","sourceRefs":[{"sourceId":"E117A","locator":"C79 tiers"},{"sourceId":"FRANKEL_1091","locator":"A1091 shop sheet"}],"limits":"The schedule splice is not an independently registered physical joint at Floor 13."},{"id":"typical-slab-deck","text":"The released S-8 typical assembly specifies 3 in. metal deck and 2.5 in. concrete above it.","evidenceClass":"drawing_evidence","sourceRefs":[{"sourceId":"S8_REV_H","locator":"Typical slab/deck note"}],"limits":"This does not establish Floor 13 panel boundaries, deck direction, or A2001 stud count."},{"id":"f13-a2001-girder-studs","text":"The released E12/13 scan does not give a legible stud count at A2001; it refers additional stud information to unavailable S-8 revision I.","evidenceClass":"drawing_evidence","sourceRefs":[{"sourceId":"E12_13","locator":"Revision F added-stud cross-reference"},{"sourceId":"S8_REV_H","locator":"Available earlier typical revision"}],"limits":"Physical stud presence, count, and composite fraction remain unset."},{"id":"c79-physical-seat-detail","text":"The original connection family uses a seated C79 girder with a top clip and stiffener.","evidenceClass":"drawing_evidence","sourceRefs":[{"sourceId":"FRANKEL_9100","locator":"Floors 8\u201321 connection plan"},{"sourceId":"FRANKEL_9114","locator":"C79 seat detail"},{"sourceId":"FRANKEL_1091","locator":"Column material bill"}],"limits":"The 9114 and 1091 seat-plate lengths differ by 5/8 in.; the exact physical bearing polygon, A2001 cut end, and plate orientation are unresolved."},{"id":"f13-east-beam-girder-shear-plates","text":"Four identified W24\u00d755 east beams feed A2001; the precise mating connector for each is not yet reconciled.","evidenceClass":"drawing_evidence","sourceRefs":[{"sourceId":"E12_13","locator":"A/B/C/K3004 east beam marks"},{"sourceId":"FRANKEL_9100","locator":"9135 special callout and 0901 default"},{"sourceId":"FRANKEL_9135","locator":"Special eight-bolt detail"},{"sourceId":"SSC_3004","locator":"Six west-web holes in beam variants"}],"limits":"Do not assign one invented physical connector to all four beams."},{"id":"nist-c79-corrected-seat-analysis","text":"NIST's specified analytical representation used a 12 in. C79 bearing seat, with 5.5 in. axial and 6.25 in. lateral travel criteria.","evidenceClass":"nist_analysis","sourceRefs":[{"sourceId":"NIST_NCSTAR_1_9","locator":"Printed pp. 481\u2013482 and 527; PDF pp. 547\u2013548 and 593"},{"sourceId":"NIST_2012_ERRATA","locator":"June 2012 changes, PDF p. 2"}],"limits":"The errata says the analysis already used these corrected values. They do not determine the unresolved physical seat polygon or a universal failure threshold."},{"id":"nist-noncomposite-girder","text":"NIST treated the interior girders as noncomposite in this analysis.","evidenceClass":"nist_analysis","sourceRefs":[{"sourceId":"NIST_NCSTAR_1_9","locator":"Printed pp. 15 and 525; PDF pp. 59 and 591"}],"limits":"This analytical assumption does not settle physical A2001 stud status."},{"id":"weidlinger-composite-girder","text":"A separate Weidlinger assessment modeled a different composite-girder interpretation.","evidenceClass":"other_analysis","sourceRefs":[{"sourceId":"WEIDLINGER_ASSESSMENT","locator":"Appendix A p. A-33 / PDF p. 119"}],"limits":"Comparison only; this separate investigation is not an input to the selected NIST case."},{"id":"damage-and-fire-context","text":"NIST reported WTC 1 debris damage on the south and west sides and uncontrolled fires on Floors 7\u20139 and 11\u201313 after sprinkler water was lost.","evidenceClass":"nist_analysis","sourceRefs":[{"sourceId":"NIST_NCSTAR_1A","locator":"Printed pp. 20\u201321; PDF pp. 62\u201363"},{"sourceId":"NIST_NCSTAR_1_9","locator":"Chapters 5 and 9"}],"limits":"Exterior damage and visible flames are observed/inferred to different degrees; no footage observes hidden C79 connections."},{"id":"thermal-case-and-handoff","text":"The selected global case applies debris damage, Case B temperatures, and the 16-story ANSYS fire-induced damage at 4.0 h, including affected Floor 14 framing.","evidenceClass":"nist_analysis","sourceRefs":[{"sourceId":"NIST_NCSTAR_1_9","locator":"Printed pp. 531, 535, 571\u2013573; PDF pp. 597, 601, 637\u2013639"},{"sourceId":"NIST_NCSTAR_1_9A","locator":"Printed pp. 56\u201358, 77\u201380; PDF pp. 107\u2013109, 128\u2013131"}],"limits":"4.0 h is elapsed thermal-model time, not a civil-clock time or a global-solver duration. The 3.5 h variant is separate. The released FOIA files are partial inputs and have not been shown to reproduce this selected run."},{"id":"released-nist-inputs-status","text":"NIST released a WTC 7 LS-DYNA geometry input, a Case B thermal loading deck, and a separate 4.0 h damage list in FOIA 09-11.","evidenceClass":"released_model_input","sourceRefs":[{"sourceId":"NIST_FOIA_09_11_GLOBAL_INPUT","locator":"Global deck without connection models"},{"sourceId":"NIST_FOIA_09_11_CASE_B_THERMAL","locator":"Case B thermal load rows"},{"sourceId":"NIST_FOIA_09_11_CASE_B_DAMAGE","locator":"Separate 4.0 h damage list"}],"limits":"The released main deck ends at 4.5 solver seconds, before its thermal load curve's 6.5 s offset; its damage include is commented out. These files do not supply a verified selected-run response history or a temperature field for the current 3D view."},{"id":"f13-thermal-response","text":"In NIST's model, thermal expansion of one-sided east floor beams loaded the C44\u2013C79 girder laterally while the exterior frame moved comparatively little.","evidenceClass":"nist_analysis","sourceRefs":[{"sourceId":"NIST_NCSTAR_1_9","locator":"Printed pp. 525\u2013527; PDF pp. 591\u2013593"}],"limits":"A static highlighted state is explanatory. It is not a measured temperature or displacement field."},{"id":"f13-bolt-shear-horizontal-loss","text":"In NIST's seated-connection mechanism, bolt shear removed horizontal restraint while the girder still had vertical support on its seat.","evidenceClass":"nist_analysis","sourceRefs":[{"sourceId":"NIST_NCSTAR_1_9","locator":"Printed p. 527; PDF p. 593"}],"limits":"Bolt shear alone is not walk-off or loss of vertical bearing."},{"id":"f13-girder-walkoff","text":"NIST placed C44\u2013C79 girder buckling and walk-off between 3.7 h and 4.0 h of Case B heating, after which its modeled vertical bearing at C79 was lost.","evidenceClass":"nist_analysis","sourceRefs":[{"sourceId":"NIST_NCSTAR_1_9","locator":"Printed pp. 527, 530; PDF pp. 593, 596; Figures 11-46\u201311-48"},{"sourceId":"NIST_2012_ERRATA","locator":"Corrected travel criteria, PDF p. 2"}],"limits":"Timing is an interval in the thermal model; no precise physical A2001 displacement path is established."},{"id":"local-f13-f14-floor-failure","text":"In the global model, weakened northeast floor sections around C79\u201381 on Floors 13 and 14 failed after the 4.0 h damage handoff.","evidenceClass":"nist_analysis","sourceRefs":[{"sourceId":"NIST_NCSTAR_1_9","locator":"Printed pp. 572\u2013573; PDF pp. 638\u2013639; Figure 12-42"},{"sourceId":"NIST_NCSTAR_1_9A","locator":"Printed pp. 79\u201380; PDF pp. 130\u2013131"}],"limits":"These are northeast sections, not entire Floor 13 or Floor 14 plates. The Floor 14 girder west from C79 to C76 remained attached, despite failure of the northeast floor section."},{"id":"floor-cascade-to-five","text":"NIST calculated a sequential downward floor failure around C79 until debris accumulated at the stronger Floor 5 slab.","evidenceClass":"nist_analysis","sourceRefs":[{"sourceId":"NIST_NCSTAR_1A","locator":"Printed p. 22; PDF p. 64"},{"sourceId":"NIST_NCSTAR_1_9","locator":"Printed pp. 572\u2013573; PDF pp. 638\u2013639"}],"limits":"The internal floor cascade was not directly observed on street video."},{"id":"c79-buckling-initiation","text":"NIST identified C79 buckling eastward after loss of floor restraint between Floors 5 and 14 as the initiating local event for global collapse.","evidenceClass":"nist_analysis","sourceRefs":[{"sourceId":"NIST_NCSTAR_1A","locator":"Printed pp. 22\u201323 and 39; PDF pp. 64\u201365 and 81"},{"sourceId":"NIST_NCSTAR_1_9","locator":"Printed pp. 572\u2013573; PDF pp. 638\u2013639"}],"limits":"Some northward restraint remained at seated girders; the report does not describe every tie as absent."},{"id":"east-core-and-penthouse","text":"The selected global model buckled C79 first, then C80 and C81, while eastern floor failures pulled down the east penthouse support region.","evidenceClass":"nist_analysis","sourceRefs":[{"sourceId":"NIST_NCSTAR_1_9","locator":"Printed pp. 572\u2013579, 605; PDF pp. 638\u2013645, 671"},{"sourceId":"NIST_NCSTAR_1_9A","locator":"Printed pp. 76\u201380; PDF pp. 127\u2013131"}],"limits":"C80/C81 failures overlap the earliest penthouse movement. Unsupported spans were C79: Floors 5\u201314; C80: 5\u201315; C81: 7\u201315. Only C79\u2019s eastward buckle direction is encoded; other individual buckle directions and shapes are not established by this illustration."},{"id":"east-penthouse-kink-observed","text":"NIST set collapse-reference zero at the first observed kink in the east-penthouse roofline viewed from the north.","evidenceClass":"observed_motion","sourceRefs":[{"sourceId":"NIST_NCSTAR_1_9","locator":"Printed p. 572; PDF p. 638; Figure 12-46"}],"limits":"This observation anchor is 16.0 s on the selected global solver clock, not the solver's t=0."},{"id":"precollapse-horizontal-motion","text":"NIST derived approximately \u00b12 in. east-west motion starting about 6 s before the east-penthouse reference event from video analysis.","evidenceClass":"observed_motion","sourceRefs":[{"sourceId":"NIST_NCSTAR_1_9","locator":"Printed p. 598 and Appendix C; PDF pp. 664 and 753 onward"}],"limits":"The contemporaneous modeled floor cascade is an inference, not an observed internal event."},{"id":"core-westward-progression","text":"NIST's selected global model propagated failures broadly westward. Debris damaged Truss 2 and associated framing, contributing to failures of C77 and C78; C76 and further core columns followed. Some western columns failed ahead of intervening rows.","evidenceClass":"nist_analysis","sourceRefs":[{"sourceId":"NIST_NCSTAR_1_9","locator":"Printed pp. 581\u2013586, 606; PDF pp. 647\u2013652, 672; Figures 12-54\u201312-60"}],"limits":"Internal column failures were not directly observed. Broad westward progression is not a uniformly advancing front; the animation uses overlapping schematic stages, not per-column solver times."},{"id":"exterior-onset-baseline","text":"In the debris-damaged baseline, exterior columns buckled predominantly between Floors 7 and 14 as global descent began.","evidenceClass":"nist_analysis","sourceRefs":[{"sourceId":"NIST_NCSTAR_1_9","locator":"Printed pp. 585\u2013590 and 600; PDF pp. 651\u2013656 and 666"},{"sourceId":"NIST_NCSTAR_1_9A","locator":"Printed pp. 76\u201377; PDF pp. 127\u2013128"}],"limits":"The no-debris-damage variant buckled exterior columns higher, approximately Floors 17\u201329; keep run results separate."},{"id":"roofline-observed-trajectory","text":"NIST tracked a point near the center of the north-face roofline in Camera 3 video, fitted displacement, then derived velocity and Stage 2 acceleration from that fitted/video trajectory.","evidenceClass":"observed_motion","sourceRefs":[{"sourceId":"NIST_NCSTAR_1_9","locator":"Printed pp. 600\u2013603; PDF pp. 666\u2013669; Figures 12-75\u201312-77"}],"limits":"Acceleration is a derived estimate, not a directly recorded video series. Apply the curve only to the tracked roof feature."},{"id":"roofline-three-stages","text":"NIST's fitted north-face descent has Stage 1 from 0\u20131.75 s, Stage 2 from 1.75\u20134.0 s at an estimated 32.2 ft/s\u00b2, and Stage 3 from 4.0\u20135.4 s with lower acceleration.","evidenceClass":"observed_motion","sourceRefs":[{"sourceId":"NIST_NCSTAR_1_9","locator":"Printed pp. 601\u2013603; PDF pp. 667\u2013669; Figure 12-77"}],"limits":"Those times start at first north-face motion, 6.9 s after the east-penthouse observation anchor."},{"id":"late-simulation-uncertainty","text":"NIST cautioned that debris breakup and interactions make later detailed modeled progression increasingly uncertain.","evidenceClass":"nist_analysis","sourceRefs":[{"sourceId":"NIST_NCSTAR_1_9","locator":"Printed pp. 599\u2013600; PDF pp. 665\u2013666"}],"limits":"Do not present exact late debris trajectories as measured or uniquely solved."}]}