The GEMS (GEophysical Monitoring Station) SEISmometer

Journal of Geophysical Research, 1977

A three-axis short-period seismometer has been operating on the surface of Mars in the Utopia Planitia region since September 4, 1976. During the first 5 months of operation, approximately 640 hours of highquality data, uncontaminated by lander or wind noise, have been obtained. The detection threshold is estimated to be magnitude 3 to about 200 km and about 6.5 for the planet as a whole. No large events have been seen during this period, a result indicating that Mars is less seismically active than earth. Wind is the major source of noise during the day, although the noise level was at or below the sensitivity threshold of the seismometer for most of the night during the early part of the mission. Winds and therefore the seismic background started to intrude into the nighttime hours starting on sol 119 (a sol is a Martian day). The seismic background correlates well with wind velocity and is proportional to the square of the wind velocity, as is appropriate for turbulent flow. The seismic envelope power spectral density is proportional to frequency to the -0.66 to -0.90 power during windy periods. A possible local seismic event was detected on sol 80. No wind data were obtained at the time, so a wind disturbance cannot be ruled out. However, this event has some unusual characteristics and is similar to local events recorded on earth through a Viking seismometer system. If it is interpreted as a natural seismic event, it has a magnitude of 3 and a distance of 110 km. Preliminary interpretation of later arrivals in the signal suggest a crustal thickness of 15 km at the Utopia Planitia site which is within the range of crustal models derived from the gravity field. More events must be recorded before a firm interpretation can be made of seismicity or crustal structure. One firm conclusion is that the natural background noise on Mars is low and that the wind is the prime noise source. It will be possible to reduce this noise by a factor of l0 s on future missions by removing the seismometer from the lander, operation of an extremely sensitive seismometer thus being possible on the surface. The Viking seismic experiment design was constrained by strict weight, power, and data allocations and perturbed by the conflicting demands of the other on-board experiments. The weight constraint precluded an ultrasensitive seismometer of the Apollo class or a broadband seismometer. The original desire to offload the seismometer was sacrificed because of the Paper number 7S0408.

Journal of Geophysical Research: Planets

Since the InSight lander (Banerdt et al., 2013) successfully deployed its extremely sensitive seismometer (Lognonné et al., 2019) together with a complete geophysical observatory on the surface of Mars, an unprecedented continuous data stream has become available that has opened new avenues to understanding the red planet. The first results include new observations of atmospheric (Banfield et al., 2020) and magnetic phenomena (Johnson et al., 2020). Seismological data from the very broad band (VBB) instrument that is part of the Seismic Experiment for Interior Structure (SEIS) package (Lognonné et al., 2019) have demonstrated that Mars is seismically active (Banerdt et al., 2020; Giardini et al., 2020), and information

Nature Geoscience, 2020

Space Science Reviews

By the end of 2018, 42 years after the landing of the two Viking seismometers on Mars, InSight will deploy onto Mars' surface the SEIS (Seismic Experiment for Internal Structure) instrument; a six-axes seismometer equipped with both a long-period three-axes Very Broad Band (VBB) instrument and a three-axes short-period (SP) instrument. These six sensors will cover a broad range of the seismic bandwidth, from 0.01 Hz to 50 Hz, with possible extension to longer periods. Data will be transmitted in the form of three continuous VBB components at 2 sample per second (sps), an estimation of the short period energy content from the SP at 1 sps and a continuous compound VBB/SP vertical axis at 10 sps. The continuous streams will be augmented by requested event data with sample rates from 20 to 100 sps. SEIS will improve upon the existing resolution of Viking's Mars seismic monitoring by a factor of ∼ 2500 at 1 Hz and ∼ 200 000 at 0.1 Hz. An additional major improvement is that, contrary to Viking, the seismometers will be deployed via a robotic arm directly onto Mars' surface and will be protected against temperature and wind by highly efficient thermal and wind shielding. Based on existing knowledge of Mars, it is reasonable to infer a moment magnitude detection threshold of M w ∼ 3 at 40 • epicentral distance and a potential to detect several tens of quakes and about five impacts per year. In this paper, we first describe the science goals of the experiment and the rationale used to define its requirements. We then provide a detailed description of the hardware, from the sensors to the deployment system and associated performance, including transfer functions of the seismic sensors and temperature sensors. We conclude by describing the experiment ground segment, including data processing services, outreach and education networks and provide a description of the format to be used for future data distribution.

Icarus

Seismic measurements are an important tool for exploration of planetary interiors, but may not be included in missions due to perceived complexity in placement of sensitive instruments on the surface. To help address this concern, we assess the fidelity of recordings of ground motion by an instrument placed on the deck of the engineering model of the Mars Science Laboratory compared with an identical instrument placed on the ground directly beneath. Comparison of the recordings reveals clear recordings of teleseismic earthquakes on both instruments. The transfer function between the instruments demonstrates the deck instrument is affected by resonance frequencies of the lander, and does not faithfully record ground motion at these frequencies or higher. In addition, additional decoherence is observed near 1 Hz during periods of strong airflow due to air conditioning cycling. However, excellent coherence and a transfer function near 1 can be observed in the important seismic band between 2 and 30 seconds at all times and extending up to the lander resonances during the night time when air conditioning was not running. This suggests a deck-mounted seismic instrument may be able to provide valuable science return without requiring additional deployment complexity.

Science, 2021

Single seismometer structure Because of the lack of direct seismic observations, the interior structure of Mars has been a mystery. Khan et al. , Knapmeyer-Endrun et al. , and Stähler et al. used recently detected marsquakes from the seismometer deployed during the InSight mission to map the interior of Mars (see the Perspective by Cottaar and Koelemeijer). Mars likely has a 24- to 72-kilometer-thick crust with a very deep lithosphere close to 500 kilometers. Similar to the Earth, a low-velocity layer probably exists beneath the lithosphere. The crust of Mars is likely highly enriched in radioactive elements that help to heat this layer at the expense of the interior. The core of Mars is liquid and large, ∼1830 kilometers, which means that the mantle has only one rocky layer rather than two like the Earth has. These results provide a preliminary structure of Mars that helps to constrain the different theories explaining the chemistry and internal dynamics of the planet. Science , ab...

1991

short-period instruments arranged in a triangle around a broadband observatory-class three-component sensor. Sets of these small triads should be emplaced in larger triangular patterns, approximately 3500 km on a side, one each in the eastern and western hemispheres of Mars. Tentative locations for large triangle vertices consistent with the various scientific objectives include (l)west of Ascraeus Mons, north of eastern Valles Marineris, and in the southern highlands and (2) in the Elysium province, in the Isidis Basin, and in the northern lowlands.

Revista Itinerários, 1993

Análise semiótica da peça Bodas de Sangue de Garcia Lorca

Positive self talk is Cognitive-Behavioral Therapy (CBT) coping skill that has been around for quite some time. Positive self talk is known to be effective for many types of mental health conditions. This activity is focused on using positive self talk to cope with anxiety. However, there is a slightly different spin on the concept. For some people, being positive does not come naturally. This can be due to a variety of issues possibly stemming from childhood or it can be a personality trait. Whatever the reason, it can be easier to start with “Realistic Self Talk” as an easier to identify with method for starting a dialogue with ourself to overcome challenges. This worksheet takes you through the process of learning to practice realistic self talk to cope with anxiety and other stressful life challenges. Learning to have an encouraging but realistic dialogue with ourselves can be a life changing way to cope when things seem overwhelming or difficult to face

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