InSight mission

Mission Summary

InSight is part of NASA’s Discovery Program. InSight is a mission dedicated to NASA’s efforts to understand the fundamental processes of terrestrial-planet formation and evolution by performing a comprehensive surface-based geophysical investigation of Mars. InSight will provide key information on the composition and structure of an Earth-like planet that has gone through most of the evolutionary stages of the Earth up to, but not including, plate tectonics. Thus, the traces of this history are still contained in the basic parameters of Mars: the size, state and composition of the core, the composition and layering of the mantle, the thickness and layering of the crust, and the thermal flux from the interior. These science objectives could be accomplished by landing nearly anywhere on the surface of Mars. The engineering rationale for landing in Elysium Planitia is described in Section 2.5.

InSight will launch on March 4, 2016 with a 23-day launch period duration, on an Atlas V-401 from the Vandenberg Air Force Base (VAFB) launch facility on a Type 1 trajectory to Mars. After a 7-month cruise, InSight will land on the surface of Mars on September 28, 2016. Following landing there is a p eriod of approximate 69 sols for the deployment and characterization of the instruments. After successful deployment of the instruments, InSight will perform science surface monitoring operations for one Mars year (two Earth years—September 2016 to September 2018).

InSight will address the mission science objectives by focusing on three scientific investigations: seismology, precision-tracking and heat-flow measurements. In order to obtain this information, InSight will use two scientific instruments: a seismometer and a self-penetrating mole trailing an instrumented tether for determining heat flux. In addition, InSight uses an X-band transponder (part of the Spacecraft Telecom Subsystem) to enable two-way precision Doppler tracking of the planet’s rotation. A suite of auxiliary sensors and payload elements, described below, support these measurements.

Mission Objectives

The overall goal of the InSight mission is to improve our understanding of terrestrial planet formation and evolution by understanding the origin and evolution of Mars. InSight investigates Mars’ interior structure, thermal and chemical evolution, and geologic processes. It also determines Mars’ present level of geologic activity and impact flux. InSight reveals the processes of formation and differentiation of the Martian core and crust, and illuminates the evolution of its interior by constraining the following parameters:

• Determine the depth of the crustal-mantle boundary to within ±10 km
• Detect any regional-scale crustal layering with velocity contrast >= 0.5 km/s over a depth interval >= 5 km
• Determine the seismic velocities in the upper 600 km of mantle to within ±0.25 km/s
• Determine whether the outer core is liquid or solid to a 90% confidence level
• Determine the core radius to within ±200 km
• Determine the core density to within ±450 kg/m3
• Determine the heat flux at the landing site to within ±5 mW/m2
• Determine the rate of seismic activity to within a factor of 2 for rates greater than 2x10¹⁸ Nm/yr
• Determine epicenter distance to ±25% and epicenter azimuth to ±20°
• Determine the rate of meteorite impacts to within a factor of 2

InSight Science Team

The science instruments, with an acronym or abbreviation and Principal Investigator (PI) are listed below:

Name	Institute
Bruce Banerdt	Principle Investigator (PI), Jet Propulsion Laboratory (JPL)
Suzanne Smrekar	Deputy PI/Project Scientist, Jet Propulsion Laboratory (JPL)
Robert Fogel	Program Scientist, NASA Headquarters
Philippe Lognonné	SEIS PI, Institut de Physique du Globe de Paris (IPGP)
Tilman Spohn	HP3 PI, DLR Institute of Planetary Research
William Folkner	RISE PI, Jet Propulsion Laboratory (JPL)
Sami Asmar	Jet Propulsion Laboratory (JPL)
Don Banfield	Cornell University
Ulrich Christensen	Max Planck Institute for Solar System Research (MPS)
Véronique Dehant	Royal Observatory of Belgium (ROB)
Raphael Garcia	Institut Supérieur de l'Aéronautique et de l'Espace (ISAE)
Domenico Giardini	Swiss Federal Institute of Technology (ETHZ)
Matt Golombek	Jet Propulsion Laboratory (JPL)
Matthias Grott	DLR Institute of Planetary Research
Troy Hudson	Jet Propulsion Laboratory (JPL)
Catherine Johnson	University of British Columbia (UBC), Planetary Science Institute (PSI)
Günter Kargl	Austrian Academy of Sciences (ÖAW)
Brigitte Knapmeyer-Endrun	Max Planck Institute for Solar System Research (MPS)
Naoki Kobayashi	University Tokyo/Japanese Space Agency (JAXA)
Justin Maki	Jet Propulsion Laboratory (JPL)
David Mimoun	Institut Supérieur de l'Aéronautique et de l'Espace (ISAE)
Antoine Mocquet	Université de Nantes
Paul Morgan	Colorado School of Mines
Mark Panning	University Florida
Tom Pike	Imperial College, London (ICL)
Jeroen Tromp	Princeton University
Renee Weber	NASA-Marshall Space Flight Center (MSFC)
Mark Wieczorek	Institut de Physique du Globe de Paris (IPGP)

Landing Site Selection

InSight will land in western Elysium Planitia on Hesperian plains just north of the dichotomy boundary. The 130 km by 27 km ellipse (E9) is located on smooth plains with Noachian highlands to the south and west, a ridge of Medussae Fossae Formation to the southeast and very young lavas from Athabasca Valles to the east. The E9 ellipse is located at 4.4°N, 135.8°E about 540 km north of the Curiosity landing site (see figure below).

The plains surface on which the InSight ellipse is located is mapped as an Early Hesperian transition unit (eHt) by Tanaka et al. (2014), which could be sedimentary or volcanic. A volcanic interpretation of the plains in the area of the InSight ellipses is supported by: 1) the presence of rocks in the ejecta of fresh craters ~0.2-20 km diameter arguing for a strong competent layer ~20-200 m deep [e.g., Golombek et al., 2013a; Catling et al., 2011, 2012], 2) exposures of strong, jointed bedrock overlain by ~10 m of fine grained regolith in nearby Hephaestus Fossae in southern Utopia Planitia at 21.9°N, 122.0°E [Golombek et al., 2013a], and 3) the presence of wrinkle ridges, which have been interpreted to be fault-propagation folds, in which slip on thrust faults at depth is accommodated by asymmetric folding in strong, but weakly bonded layered material (aka basalt flows) near the surface [e.g., Mueller and Golombek, 2004].

The primary landing safety engineering requirements for InSight landing site selection are [Golombek et al., 2013b]:

1. MOLA elevation below -2.5 km for sufficient atmosphere to slow the spacecraft during entry, descent, and landing
2. Latitude 3°N to 5°N for solar-power margins
3. Ellipse size 130 km × 27 km for ~99% landing accuracy
4. Smooth, flat, radar-reflective surface
5. Thermal inertia >100–140 J m^-2 K^-1 s^-1/2 for a load-bearing surface without substantial fine-graineddust
6. Rock abundance <= 10% for a ~<1% probability of impacting a rock that could damage the base of the lander or impede opening the solar panels
7. Regional (84 m length scale) and local terrain slopes (2-5 m length scale) <15° for radar tracking and touchdown stability

The instrument deployment requirements include: Rock abundance <10% and slopes <15° (same as for landing safely) and a broken up regolith >5 m thick to allow full penetration of the HP3 mole. There are no science requirements on the landing site. All of these requirements are met by ellipse E9.

Landing site selection for InSight has taken about three years. The original Discovery Mission proposal included a reference ellipse in Elysium Planitia that appeared to meet the engineering constraints. At the end of phase A (5/12), the project had identified 16 ellipses and began requesting HiRISE and CTX images [Golombek et al., 2013b]. Within about 1 year CTX had acquired about 90% coverage of these ellipses, that together with HiRISE images, allowed the mapping of terrains. These ellipses included both a smooth terrain that appeared exceptionally benign (very smooth with few rocks) and etched terrain (rougher with higher rock abundance) as well as transitional units [Golombek et al., 2013a; Wigton et al., 2014]. Additional HiRISE images revealed a substantial number of secondary craters that extend in rays ~1400 km to the south of Corinto crater, a fresh crater about 1000 km to the north of prospective landing sites [Golombek et al., 2014a; Bloom et al., 2014]. The project downselected to 4 ellipses in July 2013 that are located dominantly on the smooth terrain [Golombek et al., 2014b].

The Council of Terrains and Council of Atmospheres were established in February 2014 to create data products to assist in surface characterization (e.g., digital elevation, slope and rock maps) and reference atmospheres for entry and descent simulations. During landing site evaluation, HiRISE, CTX and HRSC images were processed into digital elevation maps, MOLA data were examined to identify steep slopes at 100 m length scale, HiRISE data were used to create photoclinometry slope maps and rock maps, radar and SHARAD data were analyzed to understand reflectivity and subsurface layering, thermal data were examined to understand the physical properties of surface materials, terrain units were mapped in CTX and HiRISE images, and rocky ejecta craters were mapped and fracture and fragmentation theory applied to the Elysium plains to understand regolith thickness. The second project down selection occurred in January 2015, which provisionally selected ellipse E9. Project certification of the ellipse will occur in the fall of 2015.

Thermophysical properties of the landing ellipse in remote sensing data and comparison to existing landing sites [e.g., Golombek et al., 2008] suggests the InSight surfaces are composed of cohesionless sand or low cohesion soils [Golombek et al., 2013a]. The albedo and dust cover index are similar to dusty and low-rock abundance portions of the Gusev cratered plains [Golombek et al., 2006] and dust devil tracks are common in HiRISE images. Mapping of rocky ejecta craters in extensive HiRISE images of the ellipses indicates a broken up regolith produced by cratering since the Hesperian that is 5-13 m thick [Warner et al., 2014; Pivarunas et al., 2015], likely similar to the impact generated regolith at the Gusev cratered plains [e.g., Golombek et al., 2006] and thus conducive for full penetration of the HP³ mole.

Mission Planning

The following sections describe the phases of the InSight mission, from launch through the end of surface operations. The timeline and primary activities are summarized for each phase.

Launch, Cruise, Approach, and EDL Phases

The current baseline launch window for InSight extends from March 4 to March 26, 2016. For a launch on any date during this window, Entry, Descent, and Landing (EDL) will occur September 28, 2016. Cruise operations concentrate on monitoring the health and performance of the flight systems and navigating the spacecraft to Mars. Spacecraft engineering subsystems checkouts, calibration activities, and instrument payload aliveness checkouts are performed early during cruise operations. Other than the checkouts/calibrations 24 days post-launch, all payloads are off during this phase.

During the cruise to Mars, the spacecraft will perform Trajectory Correction Maneuvers (TCMs). The last 60 days before landing compromise the approach phase, involving additional trajectory correction maneuvers. Entry, descent, and landing activities occur within ~10 minutes prior to landing on Mars. InSight uses a heatshield, parachute, and thruster-controlled lander descent stage to reach the surface. Immediately after touchdown, the lander configures itself for landed operations including deploying both solar arrays and taking an image using the ICC.

Deployment

Instrument deployment begins when the solar arrays are deployed and the lander is in a safe and communicative state. Instrument deployment operations take approximately 42 to 60 sols and cover assessment of the landed workspace, determination of instrument deployment sites, deployment of the instruments (HP³ and SEIS, including the WTS), and the release of the HP³ mole. The figure below provides an overview of all the activities required for successful deployment of the instruments. During this phase, the lander, its surrounding environment, and the workspace are characterized, the payload elements are checked out, weekly RISE measurements are acquired, and the critical data collected on Sol 0—the landing sol—are relayed to Earth. After the Science Team has selected suitable deployment sites within the workspace, the IDA places the SEIS (and covering WTS) and HP³ instruments on the surface of Mars. At that point instrument calibration and science data collection commences and the HP³ mole is released for penetration activity.

The selection of the instrument deployment sites will be governed by the Instrument Site Selection Working Group (ISSWG) and consist of four main phases:

1. Initial qualitative assessment of the workspace
2. Systematic mapping of the workspace
3. Quantitative assessment of four prospective sites
4. Certification of two prospective sites

Analysis data products utilized in this assessment include: 4 mm Digital Elevation Maps (DEMs), maps of the slope, roughness, surface normal, and tilt, terrain and soil maps with soil physical properties assessment, rock map with size-frequency distribution and shadow map, SEIS noise map, HP³ thermal map, instrument tether routing, and mole penetrability assessment.

Due to the nature of the deployment timeframe, a rapid analysis of lander and payload telemetry is performed to assess the health and safety of the engineering subsystems and the status of instrument deployment activities. During this phase, InSight personnel will be co-located at JPL and work on a modified Earth-time schedule in which the start of the shift on Earth will track Mars time, sliding forward from 6 AM until it reaches 1 PM. After this point, the downlink from Mars arrives too late in the day on Earth to allow commands to be generated before a reasonable end of shift (a 10-hour shift is planned for deployment). Operations will be nominally planned daily with two floating days off per week. Due to the intensive and highly scripted nature of the deployment phase, limited, if any, time is expected to be available for ancillary science to be added during this phase. Operational support for the IDA is only planned for the deployment timeframe. Any IDA operation after the deployment phase is on a best efforts basis.

Science Monitoring

The science monitoring operations begin after the instruments have been placed on the surface. During this phase, SEIS monitoring starts and the HP³ mole penetrates to its final depth. During the science monitoring operations, SEIS and HP³ are in nominal data collection mode and gather science data autonomously and continuously and store this data in the instruments’ nonvolatile memory. The lander nominally provides continuous power to SEIS and HP³ throughout this phase, collects data from the instruments during every full wake up, and relays the data to Earth, usually twice per sol. The lander powers on the RISE X-band communications system for one-hour an average of four times per week during which Doppler-tone monitoring sessions with the DSN are performed. The radiometer (part of HP³) is commanded to take four 1-hour measurements during each sol for five minutes duration each, and every Ls ~ 15°, an hourly radiometer measurement campaign is undertaken lasting one entire sol with one measurement per hour for five minutes duration in each instance. The active TWINS’ boom is swapped several times per sol to account for changing wind direction.

Since the lander is solar powered, the life of the lander is driven by Mars’ diurnal cycle. Lander communications are determined by when orbiter overflights allow for UHF relay, typically twice per day at 3 AM and 6 PM LMST. The lander spends the majority of the science monitoring operations asleep. On a typical sol, the lander wakes up every three hours to check the battery state of charge, to run FSW diagnostics and fault-protection checks, and to collect housekeeping data. During two of the daily wake cycles the lander stays awake for an additional time to process science data and relay the data to an orbiter asset. Although science data are relayed back to Earth twice per sol, commands are relayed to the lander only once per week. A representative sol from the science monitoring operations is depicted in the figure below.

Science monitoring operations are simple and routine. No ground-in-the-loop is required under nominal conditions. The flight team works on Earth time, and only during the nominal 8-hr prime shift. All operations teams reside at their respective institutions, and the SEIS and HP³ IOTs work standard shifts for the time zone of their institutions. Operations are performed using a strategic process/timeline with sequences for the lander uplinked a week at a time. The rapid turnaround process supported during instrument deployment will no longer be used, although anomaly resolution will continue to be supported in that manner. Seismic and APSS event data selection by the instrument and science teams will be performed. Operations processes and interfaces will accommodate time differences for nominal operations between the different institutions supporting Science Monitoring operations.