Active Gamma and Neutron Spectrometric Soil Analysis (AGNESSA) April 16, 2009 Page 1 Active Gamma and Neutron Spectrometric Soil Analysis (AGNESSA) Short description Igor Mitrofanov Institute for Space Research Moscow, Russia

Active Gamma and Neutron Spectrometric Soil Analysis (AGNESSA) April 16, 2009 Page 2 Научные задачи: (1) Измерение состава породообразующих элементов в в веществе поверхности в районе посадки (2) Измерение содержания естественных радиоактивных изотопов элементов K, Th U Измерение гамма- и нейтронного излучения с поверхности Венеры (выполнялось для Луны, Марса, Венеры, Эроса, планируется для Меркурия )

Active Gamma and Neutron Spectrometric Soil Analysis (AGNESSA) April 16, 2009 Page 3 Пример Марса

Active Gamma and Neutron Spectrometric Soil Analysis (AGNESSA) April 16, 2009 Page 4 Venera-13 Недоступность поверхности Венеры

Active Gamma and Neutron Spectrometric Soil Analysis (AGNESSA) April 16, 2009 Page 5 Neutron capture leading to prompt gamma decays: Between pulses. Neutron activation leading to delayed gamma decays: After pulse (seconds to years). PNG GRS SNS

Active Gamma and Neutron Spectrometric Soil Analysis (AGNESSA) April 16, 2009 Page

Active Gamma and Neutron Spectrometric Soil Analysis (AGNESSA) April 16, 2009 Page <3 σ

Active Gamma and Neutron Spectrometric Soil Analysis (AGNESSA) April 16, 2009 Page 8 Taylor et al., 2006

Active Gamma and Neutron Spectrometric Soil Analysis (AGNESSA) April 16, 2009 Page 9 K/Th = 8500 (Venera-8) K/Th = 4000 (Venera-8) K/Th = 1700 (Venera-9) K/Th = 1000 (Venera-9) K/Th = 2600 (Earth Continental Crust)

Active Gamma and Neutron Spectrometric Soil Analysis (AGNESSA) April 16, 2009 Page 10 PNGSNS GRS CEU S/C

Active Gamma and Neutron Spectrometric Soil Analysis (AGNESSA) April 16, 2009 Page 11 PNG is able to produce 10 7 pulses of 14 MeV neutrons, with 10 7 particle in each pulse. Frequency of pulses is changeable by commands from CEU from 10 Hz down to separate pulse. PNG prototype Is DAN instrument for NASA MSL. First flight unit is already delivered to JPL for testing and integration.

Active Gamma and Neutron Spectrometric Soil Analysis (AGNESSA) April 16, 2009 Page 12 Set SNS contains 3 He counters: one has Cd enclosure around the counter, another is open. The measured signals are afterglows of epithermal and thermal neutrons. SNS has prototype, as sensors of DAN Instrument for NASA’s MSL mission (right). Afterglow time profiles are shown for different content of water (below): for open sensors (left), for Cd-enclosed sensors (middle), and for thermal neutrons, as difference between them (right).

Active Gamma and Neutron Spectrometric Soil Analysis (AGNESSA) April 16, 2009 Page 13 Gamma-ray spectrometer with LaBr3 crystal is used to measure afterglow of secondary gamma-rays, induced by neutron pulses. Also, in the passive mode, GRS will measure composition of regolith in the landing site and content of natural radioisotops K, Th and U. GRS has prototype, as gamma-ray sensor of instrument for Russian Phobos- Grunt mission (right). Example of measured spectra of gamma-ray afterglow is shown below. GRS

Active Gamma and Neutron Spectrometric Soil Analysis (AGNESSA) April 16, 2009 Page 14 Central Electronic Unit operate all sensors of the instrument, measures time profiles of after-pulse counting rate, provides HV for sensors, create data frames and support power and telemetry interfaces of spacecraft systems. The logical core of CEU is based on Actel FPGA state machine. CEU prototype, as DE unit of DAN instrument for NASA’s MSL mission (see page 6). The logical board of DAN is shown (right).

Active Gamma and Neutron Spectrometric Soil Analysis (AGNESSA) April 16, 2009 Page 15 No.Instrument parametersValues 1.Total mass (kg) Total operational power (W)16 3.Limits of operational temperature (° C) Dimensions (mm) PNG SNS GRS CEU 125x45x x100x x100x x60x150 5.Data rate TSR session (kbyte) BGD session (kbyte/s) 16 kbyte/session 9 kbyte/readout 6.Data interfaceAny

Active Gamma and Neutron Spectrometric Soil Analysis (AGNESSA) April 16, 2009 Page 16 Preliminary Operational Scheme -40 to -30 min before landing: –Neutron pulse on to measure neutrons and capture gammas from structure. -30 min till landing: –Neutron pulse off to measure activation gammas from structure and natural gammas from U, Th, and K during decent. 0 to 30 min after landing (optional): –Neutron pulse off for calibration. 30 to 60 min after landing: –Neutron pulse on to measure neutrons and capture gammas. 60 min after landing to end of mission : –Neutron pulse off to measure neutron activation gammas and natural gammas from U, Th, and K.

Active Gamma and Neutron Spectrometric Soil Analysis (AGNESSA) April 16, 2009 Page 17 ВЫВОДЫ: 1)Прибор должен решить задачу определения элементного состава вещества в районе посадки 2) Прибор должен предоставить оценку K/Th для района посадки 3) Прибор допускает время жизни на поверхности около 60 мин 4) Прибор имеет высокий уровень разработки 5) Уменьшение массы и энергопотребления допустимо, но с заметным увеличением затрат на ОКР 6) Аналогичный прибор рассматривается для посадочного аппарата НАСА