InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport)
InSight is a NASA minisatellite lander mission, designed to give the Red Planet its first thorough checkup since it formed 4.5 billion years ago. It is the first outer space robotic explorer to study in-depth the "inner space" of Mars: its crust, mantle, and core. Studying Mars' interior structure answers key questions about the early formation of rocky planets in our inner solar system - Mercury, Venus, Earth, and Mars - more than 4 billion years ago, as well as rocky exoplanets. InSight also measures tectonic activity and meteorite impacts on Mars today. 1) 2) 3) 4)
The lander uses cutting edge instruments, to delve deep beneath the surface and seek the fingerprints of the processes that formed the terrestrial planets. It does so by measuring the planet's "vital signs": its "pulse" (seismology), "temperature" (heat flow), and "reflexes" (precision tracking). This mission is part of NASA's Discovery Program for highly focused science missions that ask critical questions in solar system science.
JPL, a division of Caltech in Pasadena, California, manages the InSight Project for NASA's Science Mission Directorate, Washington. Lockheed Martin Space, Denver, built the spacecraft. InSight is part of NASA's Discovery Program, which is managed by NASA's Marshall Space Flight Center in Huntsville, Alabama.
First Interplanetary CubeSat: The rocket that will loft InSight beyond Earth will also launch a separate NASA technology experiment: two mini-spacecraft called MarCO (Mars Cube One). These suitcase-sized CubeSats will fly on their own path to Mars behind InSight. Their objective is to relay back InSight data as it enters the Martian atmosphere and lands. It will be a first test of miniaturized CubeSat technology at another planet, which researchers hope can offer new capabilities to future missions.
If successful, the MarCos could represent a new kind of data relay to Earth, getting news of a safe landing — and any potential problems — sooner. InSight's success is independent of its co-passengers.
InSight Science Goals: The InSight mission seeks to uncover how a rocky body forms and evolves to become a planet by investigating the interior structure and composition of Mars. The mission will also determine the rate of Martian tectonic activity and meteorite impacts. The InSight mission has two major goals, each with several science investigations, designed to help uncover the process that shaped all of the rocky planets in the inner solar system.
1) To understand how rocky planets formed and evolved, InSight will study the interior structure and processes of Mars by determining:
- The size of the core, what it is made of, and whether it is liquid or solid.
- The thickness and structure of the crust.
- The structure of the mantle and what it is made of.
- How warm the interior is and how much heat is still flowing through.
2) InSight will figure out just how tectonically active Mars is today, and how often meteorites impact it. For this, it will measure:
- How powerful and frequent internal seismic activity is on Mars, and where it is located within the structure of the planet.
- How often meteorites impact the surface of Mars.
Figure 1: Left: Artist's rendition showing the inner structure of Mars. The topmost layer is known as the crust, underneath it is the mantle, which rests on a solid inner core. Right: Measuring the pulse of Mars by determining the level of tectonic activity (impact of meteorites) on Mars (image credit: NASA/JPL-Caltech)
Why Mars? — Previous missions to Mars have investigated the surface history of the Red Planet by examining features like canyons, volcanoes, rocks and soil. However, signatures of the planet's formation can only be found by sensing and studying its "vital signs" far below the surface.
In comparison to the other terrestrial planets, Mars is neither too big nor too small. This means that it preserves the record of its formation and can give us insight into how the terrestrial planets formed. It is the perfect laboratory from which to study the formation and evolution of rocky planets. Scientists know that Mars has low levels of geological activity. But a lander like InSight can also reveal just how active Mars really is.
Starting next year, scientists will get their first look deep below the surface of Mars. That's when NASA will send the first robotic lander dedicated to exploring the planet's subsurface. InSight will study marsquakes to learn about the Martian crust, mantle and core. 5)
Doing so could help answer a big question: how are planets born? - Seismology, the study of quakes, has already revealed some of the answers here on Earth, said Bruce Banerdt, Insight's principal investigator at NASA/JPL (Jet Propulsion Laboratory), Pasadena, California. But Earth has been churning its geologic record for billions of years, hiding its most ancient history. Mars, at half the size of Earth, churns far less: it's a fossil planet, preserving the history of its early birth.
"During formation, this ball of featureless rock metamorphosed into a diverse and fascinating planet, almost like caterpillar to a butterfly," Banerdt said. "We want to use seismology to learn why Mars formed the way it did, and how planets take shape in general."
A Planetary CT (Computed Tomography) Scan: When rocks crack or shift, they give off seismic waves that bounce throughout a planet. These waves, better known as quakes, travel at different speeds depending on the geologic material they travel through.
Seismometers, like InSight's SEIS instrument, measure the size, frequency and speed of these quakes, offering scientists a snapshot of the material they pass through. "A seismometer is like a camera that takes an image of a planet's interior," Banerdt said. "It's a bit like taking a CT scan of a planet."
Mars' geologic record includes lighter rocks and minerals — which rose from the planet's interior to form the Martian crust — and heavier rocks and minerals that sank to form the Martian mantle and core. By learning about the layering of these materials, scientists can explain why some rocky planets turn into an "Earth" rather than a "Mars" or "Venus" — a factor that is essential to understanding where life can appear in the universe.
A Fuzzy Picture: Each time a quake happens on Mars, it will give InSight a "snapshot" of the planet's interior. The InSight team estimates the spacecraft will see between a couple dozen to several hundred quakes over the course of the mission. Small meteorites, which pass through the thin Martian atmosphere on a regular basis, will also serve as seismic "snapshots."
"It will be a fuzzy picture at first, but the more quakes we see, the sharper it will get," Banerdt said.
One challenge will be getting a complete look at Mars using only one location. Most seismology on Earth takes measurements from multiple stations. InSight will have the planet's only seismometer, requiring scientists to parse the data in creative ways. "We have to get clever," Banerdt said. "We can measure how various waves from the same quake bounce off things and hit the station at different times."
Moonquakes and Marsquakes: InSight won't be the first NASA mission to do seismology. The Apollo missions included four seismometers for the Moon. Astronauts exploded mortar rounds to create vibrations, offering a peek about 100 meters under the surface. They crashed the upper stages of rockets into the Moon, producing waves that enabled them to probe its crust. They also detected thousands of genuine moonquakes and meteorite impacts.
The Viking landers attempted to conduct seismology on Mars in the late 1970s. But those seismometers were located on top of the landers, which swayed in the wind on legs equipped with shock absorbers. "It was a handicapped experiment," Banerdt said. "I joke that we didn't do seismology on Mars — we did it three feet above Mars."
InSight will measure more than seismology. The Doppler shift from a radio signal on the lander can reveal whether the planet's core is still molten; a self-burrowing probe is designed to measure heat from the interior. Wind, pressure and temperature sensors will allow scientists to subtract vibrational "noise" caused by weather. Combining all this data will give us the most complete picture of Mars yet.
JPL, a division of Caltech in Pasadena, manages the InSight Project for NASA's Science Mission Directorate, Washington. Lockheed Martin Space in Denver, Colorado, built and tested the spacecraft. InSight is part of NASA's Discovery Program, which is managed by NASA's Marshall Space Flight Center in Huntsville, Alabama.
NASA's InSight lander opens a window into the "inner space" of Mars. Its instruments peer deeper than ever into the Martian subsurface, seeking the signatures of the processes that shaped the rocky planets of the inner Solar System, more than four billion years ago. InSight's findings are expected to shed light on the formation of Mars, Earth, and even rocky exoplanets.
The lander builds on the proven design of NASA's Mars Phoenix lander. InSight's over 2.4-meter-long robotic arm lifts a seismometer and heat-flow probe from the deck and places them on the surface. The camera on the arm will provide color 3D views of the landing site, instrument placement, and activities. Sensors measure weather and magnetic field variations.
Table 1: Specifications of the InSight Lander
Figure 2: An artist's rendition of the InSight lander operating on the surface of Mars (image credit: NASA/JPL-Caltech)
The spacecraft is the protective "spaceship" that protects the lander during its travel between Earth and Mars. The spacecraft is separate from the launch vehicle that carries the spacecraft and the lander outside of Earth's atmosphere and gravitational pull. The spacecraft includes the mechanical units that safely maneuver the lander through the Martian atmosphere to a landing on Mars.
The three major parts that make-up the InSight spacecraft are:
• Cruise Stage: The Cruise Stage encapsulates the lander and its landing system for travel between Earth and Mars. It includes an aeroshell, which consists of a backshell and a heat shield that protects the lander from harsh forces encountered during launch and landing.
• EDL (Entry, Descent, and Landing) System: The EDL system includes the aeroshell, parachute, and descent vehicle that lower the lander to the Martian surface. The final touchdown is enabled by shock-absorbing legs.
• Lander: InSight's stationary lander is constructed to deploy sensitive instruments on the surface of Mars from where they can directly sense the planets "vital signs."
Lockheed Martin is the InSight prime contractor and is responsible for the complete spacecraft system – cruise stage, aeroshell and the lander itself. Based on a proven spacecraft design from the successful 2007 Phoenix mission, InSight will incorporate the latest avionics technology as well as advanced science instruments. 6) 7)
Figure 3: NASA's InSight Mars lander spacecraft in a Lockheed Martin clean room in Littleton, CO (image credit: NASA/JPL-Caltech/Lockheed Martin)
Figure 4: Illustration of spacecraft and lander components (image credit: NASA/JPL)
Insight Development status
• May 4, 2018: ESA's deep space ground stations in Australia and South America will track the InSight spacecraft on NASA's behalf as it begins its cruise to the Red Planet. 8)
- Set to be launched from Vandenberg Air Force Base in California on an Atlas V at 1105 UTC on 5 May, InSight will bring a lander to Mars to study its interior, with equipment to measure internal heat and detect ‘marsquakes'. InSight's 485 million km journey to Mars will take about six months, beginning soon after it separates from its launcher in Earth orbit.
- Five hours after launch, ESA's deep space ground station at New Norcia in Western Australia, will pick up the signal from InSight. It will maintain contact as a ‘hot backup' at the same time as NASA's own Deep Space Network ground station at Canberra, over on the easterly side of the continent.
- Once Canberra loses contact, the 35 m dish antenna at New Norcia will maintain contact with the mission until it vanishes under the horizon. ESA's second southern-hemisphere deep space ground station at Malargüe in Argentina will pick up the contact two and a half hours after that.
• April 6, 2018: In the early morning hours of May 5, millions of Californians will have an opportunity to witness a sight they have never seen before - the historic first interplanetary launch from America's West Coast. On board the 57.3 m United Launch Alliance Atlas V rocket will be NASA's InSight spacecraft, destined for the Elysium Planitia region located in Mars' northern hemisphere. 9)
Figure 5: NASA's InSight to Mars undergoes final preparations at Vandenberg AFB, CA, ahead of its May 5 launch date Image credit: NASA/JPL-Caltech)
• March 23, 2018: Scientists in Germany are working hard to ensure NASA's next Mars mission, the Insight mission, gets the most accurate data possible. Researchers are currently testing a replica of the probe's SEIS (Seismic Experiment for Interior Structure) instrument package, a combination of six seismometers that will be used to study geologic structures deep beneath the Martian surface. The testing will help scientists back in the United States properly calibrate the real SEIS instrument package. 10) 11)
- The testing is being carried out at the Joint Geoscientific Observatory, or BFO (Black Forest Observatory), in Schiltach, by a team of researchers from KIT (Karlsruhe Institute of Technology) and Stuttgart University. The combination of three short-period seismometers and three broadband seismometers allows the instrument package to target a wide range of frequencies.
- "Ground movement in vertical and two horizontal directions can be measured," BFO researcher Rudolf Widmer-Schnidrig said in a news release.
- The instruments were developed by engineers in France and the United States, and have previously been tested at BFO. Earlier tests focused on a pair of short-period seismometers, while a single broadband seismometer is the focus of the latest round of testing. All the tests will offer a baseline under optimal conditions against which scientists can compare the data returned by the real instrument package.
- "At the BFO, we have excellent measurement conditions. Seismic noise is low. The seismometers supply data with the lowest noise worldwide," Widmer-Schnidrig said.
- Scientists are testing the instruments inside measurement chambers installed in the tunnel system of a former ore mine in the Black Forest. At 150 m beneath Earth's surface, the testing chambers protect instruments from air pressure and temperature fluctuation, as well as interference from communication systems.
Figure 6: Researchers at Germany's BFO (Black Forest Observatory) are calibrating a replica of the SEIS instrument package on NASA's InSight probe(image credit: KIT)
• February 28, 2018: NASA's InSight spacecraft has arrived at VAFB (Vandenberg Air Force Base) in central California to begin final preparations for a launch this May. The spacecraft was shipped from Lockheed Martin Space, Denver, today and arrived at VAFB. InSight will be the first mission to look deep beneath the Martian surface, studying the planet's interior by listening for marsquakes and measuring the planet's heat output. It will also be the first planetary spacecraft to launch from the West Coast. 12)
Figure 7: Personnel supporting NASA's InSight mission to Mars load the crated InSight spacecraft into a C-17 cargo aircraft at Buckley Air Force Base, Denver, for shipment to Vandenberg Air Force Base, California (image credit: NASA/JPL)
• February 22, 2018: NASA's Mars InSight lander team is preparing to ship the spacecraft from Lockheed Martin Space in Denver, where it was built and tested, to Vandenberg Air Force Base in California, where it will become the first interplanetary mission to launch from the West Coast. The project is led by NASA's Jet Propulsion Laboratory in Pasadena, California. 13)
- InSight is the first mission to study the deep interior of Mars. InSight will take the "vital signs" of Mars: its pulse (seismology), temperature (heat flow), and its reflexes (radio science). It will be the first thorough check-up since the planet formed 4.5 billion years ago.
- InSight will teach us about planets like our own. InSight's team hopes that by studying the deep interior of Mars, we can learn how other rocky planets form. Earth and Mars were molded from the same primordial stuff more than 4 billion years ago, but then became quite different. Why didn't they share the same fate?
- InSight will try to detect marsquakes for the first time. One key way InSight will peer into the Martian interior is by studying motion underground — what we know as marsquakes. NASA has not attempted to do this kind of science since the Viking mission. Both Viking landers had their seismometers on top of the spacecraft, where they produced noisy data. InSight's seismometer will be placed directly on the Martian surface, which will provide much cleaner data.
• January 23, 2018: NASA's next mission to Mars passed a key test, extending the solar arrays that will power the InSight spacecraft once it lands on the Red Planet this November. 14)
- The fan-like solar panels are specially designed for Mars' weak sunlight, caused by the planet's distance from the Sun and its dusty, thin atmosphere. The panels will power InSight for at least one Martian year (two Earth years) for the first mission dedicated to studying Mars' deep interior.
Figure 8: This photo shows the completion of one solar panels during the InSight deployment test (image credit: NASA, Lockheed Martin)
Figure 9: The test took place at Lockheed Martin Space just outside of Denver, where InSight was built and has been undergoing testing ahead of its launch (image credit: NASA, Lockheed Martin)
• November 3, 2017: Last month, NASA invited members of the public to send their names to Mars. And the public responded loud and clear. More than 1.6 million people signed up to have their names etched on a microchip that will be carried on NASA's upcoming InSight mission, which launches in May of 2018. 15)
- NASA's Jet Propulsion Laboratory in Pasadena, California, reopened the opportunity after it proved successful in 2015. During that open call, nearly 827,000 names were collected for a microchip that now sits on top of the robotic InSight lander.
- The grand total once a second microchip is added in early 2018 will be 2,429,807 names. Space enthusiasts who signed up this last round shared their downloadable "boarding passes" on social media, complete with the total number of flight miles they've collected by participating in engagement initiatives for other Mars missions.
• September 13, 2017: NASA scientists have found evidence that Mars' crust is not as dense as previously thought, a clue that could help researchers better understand the Red Planet's interior structure and evolution. A lower density likely means that at least part of Mars' crust is relatively porous. At this point, however, the team cannot rule out the possibility of a different mineral composition or perhaps a thinner crust. 16)
- The researchers mapped the density of the Martian crust, estimating the average density is 2,582 kg/m3. That's comparable to the average density of the lunar crust. Typically, Mars' crust has been considered at least as dense as Earth's oceanic crust, which is about 2,900 kg/m3.
- The new value is derived from Mars' gravity field, a global model that can be extracted from satellite tracking data using sophisticated mathematical tools. The gravity field for Earth is extremely detailed, because the data sets have very high resolution. Recent studies of the Moon by NASA's GRAIL (Gravity Recovery and Interior Laboratory) mission also yielded a precise gravity map.
- The data sets for Mars don't have as much resolution, so it's more difficult to pin down the density of the crust from current gravity maps. As a result, previous estimates relied more heavily on studies of the composition of Mars' soil and rocks.
Figure 10: A new map of the thickness of Mars' crust shows less variation between thicker regions (red) and thinner regions (blue), compared to earlier mapping. This view is centered on Valles Marineris, with the Tharsis Montes near the terminator to its west. The map is based on modeling of the Red Planet's gravity field by scientists at NASA/GSFC in Greenbelt, Maryland. The team found that globally Mars' crust is less dense, on average, than previously thought, which implies smaller variations in crustal thickness (image credit: NASA/Goddard/UMBC/MIT/E. Mazarico)
• August 26, 2017: Preparation of NASA's next spacecraft to Mars, InSight, has ramped up this summer, on course for launch next May from Vandenberg Air Force Base in central California — the first interplanetary launch in history from America's West Coast. 17)
- Lockheed Martin Space Systems is assembling and testing the InSight spacecraft in a clean room facility near Denver. "Our team resumed system-level integration and test activities last month," said Stu Spath, spacecraft program manager at Lockheed Martin. "The lander is completed and instruments have been integrated onto it so that we can complete the final spacecraft testing including acoustics, instrument deployments and thermal balance tests." InSight is the first mission to focus on examining the deep interior of Mars. Information gathered will boost understanding of how all rocky planets formed, including Earth.
Figure 11: The Mars lander portion of NASA's InSight spacecraft is lifted from the base of a storage container in preparation for testing, in this photo taken June 20, 2017, in a Lockheed Martin clean room facility in Littleton, Colorado (image credit: NASA/JPL-Caltech, Lockheed Martin)
• September 2, 2016: NASA is moving forward with a spring 2018 launch of its InSight mission to study the deep interior of Mars, following final approval this week by the agency's Science Mission Directorate. 18)
- The InSight mission was originally scheduled to launch in March of this year, but NASA suspended launch preparations in December due to a vacuum leak in its prime science instrument, the Seismic Experiment for Interior Structure (SEIS).
- The new launch period for the mission begins May 5, 2018, with a Mars landing scheduled for Nov. 26, 2018. The next launch opportunity is driven by orbital dynamics, so 2018 is the soonest the lander can be on its way.
Launch: The InSight mission was launched on 5 May 2018 (11:05 UTC), on an Atlas V-401 vehicle of ULA from VAFB, CA. This is the 12th mission of NASA's Discovery Program, managed by the agency's Marshall Space Flight Center in Huntsville, Alabama. InSight is on a 483 million km trip to Mars to study for the first time what lies deep beneath the surface of the Red Planet. 19) 20)
• MarCO (Mars Cube One): The InSight flight will include two experimental 6U CubeSats (MarCO-A and MarCO-B) of NASA/JPL. This will be the first time CubeSats have flown in deep space. If this flyby demonstration is successful, the technology will provide NASA the ability to quickly transmit status information about the main spacecraft after it lands on Mars.
- The two CubeSats will separate from the Atlas V booster after launch and travel along their own trajectories to the Red Planet. After release from the launch vehicle, MarCO's first challenges are to deploy two radio antennas and two solar panels. The high-gain, X-band antenna is a flat panel engineered to direct radio waves the way a parabolic dish antenna does. MarCO will be navigated to Mars independently of the InSight spacecraft, with its own course adjustments on the way.
- NASA's two MarCO CubeSats will be flying past Mars in November 2018 just as NASA's next Mars lander, InSight, is descending through the Martian atmosphere and landing on the surface. MarCO will provide an experimental communications relay to inform Earth quickly about the landing.
- The MarCO mission is described in a separate file on the eoPortal.
Table 2: Aerojet Rocketdyne propulsion throughout the Insight mission 21)
The InSight cruise phase begins soon after separation from the launch vehicle when the spacecraft completes the launch phase. Cruise ends when the spacecraft is about 60 days from entry into the Martian atmosphere, beginning with approach. 22)
During cruise, the InSight lander is tucked inside its protective aeroshell, with the aeroshell attached to the cruise stage. The spacecraft makes several corrections to its trajectory by firing the cruise stage engines, with the first one just 10 days after launch. The purpose of these is to fine-tune the flight path so it hits just the right entry point at the top of the Martian atmosphere on landing day.
Orbit of InSight (Ref. 3):
• Very fast, type-1 trajectory: 6.5-month cruise to Mars
• Landing: November 26, 2018 on the landing site Elysium Planitia, Mars.
• Two-month deployment phase
• Two years (one Mars year) science operations on the surface; repetitive operations
• Nominal end-of-mission: November 24, 2020
Figure 12: Illustration of InSight trajectory to Mars (image credit: NASA/JPL)
Figure 13: Illustration of the InSight spacecraft with deployed solar panels during the cruise phase (image credit: NASA)
Some of the key activities during the cruise phase include:
- Health checks and maintenance of the spacecraft in its cruise configuration.
- Monitoring and calibration of the spacecraft and subsystems.
- Attitude correction turns (adjusts) to maintain the antenna pointing toward Earth for communications and to keep the solar panels pointed toward the Sun for power).
- Navigation activities, including trajectory correction maneuvers, to keep track of InSight's position and precisely control it prior to approach.
- Preparation for entry, descent, and landing and surface operations, including communication tests used during entry, descent, and landing.
EDL (Entry, Descent, and Landing): EDL begins when the spacecraft reaches the Martian atmosphere, about 128 km above the surface, and ends with the lander safe and sound on the surface of Mars six minutes later. 23)
For InSight, this phase includes a combination of technologies inherited from past NASA Mars missions such as NASA's Phoenix Mars Lander. This landing system weighs less than the airbags used for the twin rovers or the skycrane used by the Mars Science Laboratory. The lean landing hardware helps InSight place a higher ratio of science instruments to total launch mass on the surface of Mars.
Compared with Phoenix, though, InSight's landing presents four added challenges:
• InSight enters the atmosphere at higher velocity 6.3 km/s vs. 5.6 km/s.
• InSight has more mass entering the atmosphere — about 608 kg vs. 573 kg.
• InSight lands at an elevation of about 1.5 km higher than Phoenix did, so it has less atmosphere to use for deceleration.
• InSight lands during northern hemisphere autumn on Mars, when dust storms are known to have grown to global proportions in some prior years.
InSight will use a combination of parachutes and onboard engines to gently lower itself down to the Martian surface. The entire landing will last just seven minutes, and if it's successful, the spacecraft will spend the next two years studying Mars and its interior.
The InSight mission will place a stationary lander near Mars' equator (Figures 14 and 15). With two solar panels that unfold like paper fans, the lander spans about 6 meters. Within weeks after the landing — always a dramatic challenge on Mars — InSight will use a robotic arm to place its two main instruments directly and permanently onto the Martian ground, an unprecedented set of activities on Mars.
Figure 15: Illustration of the deployed InSight Lander on Mars showing the main components of the lander and the two maon experiments (image credit: (image credit: NASA/JPL-Caltech)
Figure 16: Mars Lander Deck of NASA's InSight Mission: This view looks upward toward the InSight Mars lander suspended upside down. It shows the top of the lander's science deck with the mission's two main science instruments SEIS and HP3 plus the robotic arm and other subsystems installed. The photo was taken on 9 Aug. 2017, in a Lockheed Martin clean room facility in Littleton, Colorado (image credit: NASA/JPL-Caltech, Lockheed Martin) 25)
• May 23, 2018: NASA's InSight lander has made its first course correction toward Mars. The lander is currently encapsulated in a protective aeroshell, which launched on top of an Atlas V 401 rocket on May 5 from Vandenberg Air Force Base in Central California. Yesterday, the spacecraft fired its thrusters for the first time to change its flight path. This activity, called a trajectory correction maneuver, will happen a maximum of six times to guide the lander to Mars. 26)
- "This first maneuver is the largest we'll conduct," said Fernando Abilleira of JPL, InSight's Deputy Mission Design and Navigation Manager. "The thrusters will fire for about 40 seconds to impart a velocity change of 3.8 m/s to the spacecraft. That will put us in the right ballpark as we aim for Mars."
- Especially at the beginning of that cruise, navigators rely on NASA's DSN (Deep Space Network ) to track the spacecraft. The DSN is a system of antennas located at three sites around the Earth. As the planet rotates, each of these sites comes into range of NASA's spacecraft, pinging them with radio signals to track their positions. The antennas also send and receive data this way.
• On 5 May 2018, ESA's 35 m-diameter deep-space radio dish at New Norcia, Western Australia, monitored NASA's InSight spacecraft providing critical tracking support during launch and early operations on its journey to Mars. 27)
- ESA's New Norcia station maintained contact with InSight and its two MarCOs CubeSats as backup to NASA's own Deep Space Network ground station at Canberra, on the easterly side of the continent.
- "NASA requested our support because, at this time of year, the southern hemisphere has very good visibility of the trajectory to Mars," explained Daniel Firre, the Agency's ESA-NASA cross-support service manager. "This meant our Australia station was ideally located to provide back-up support to their DSN station at Canberra."
InSight sensor/experiment complement: (SEIS, HP3, RISE, IDS, APSS)
InSight is equipped with three principal instruments designed to probe the interior of Mars–none of which will take pictures, analyze minerals, or dig up soil samples as other Mars landing missions have done. The only cameras on board InSight will be used primarily to aid in the deployment of the main science instruments.
In addition to its principal instruments, InSight will carry wind, temperature and pressure sensors to monitor atmospheric conditions at the landing sight, as well as a magnetometer to measure disturbances produced in Mars' ionosphere.
InSight's cameras, which are primarily for guiding the placement of the SEIS and HP3 instruments on the ground, will also serve in taking pictures of the surrounding landscape—something we have come to expect from our Mars landers and rovers, even if InSight's main mission is to look where cameras cannot see.
SEIS (Seismic Experiment for Interior Structure) instrument
SEIS is a seismometer, supplied by France's space agency, CNES, with collaboration from the United States (JPL), the United Kingdom (Imperial College), 28) Switzerland (ETH -Swiss Federal Institute of Technology, Zürich ) and Germany (MPS- Max Planck Institute for Solar System Research). 29) Shielded from wind and with sensitivity fine enough to detect ground movements half the diameter of a hydrogen atom, it will record seismic waves from "marsquakes" or meteor impacts that reveal information about the planet's interior layers.
The objective of SEIS is to measure the pulse of Mars by studying waves created by marsquakes, thumps of meteorite impacts, and even surface vibrations generated by activity in Mars' atmosphere and by weather phenomena such as dust storms.
The SEIS instrument will be placed onto the surface of Mars. The instrument has a mass of 29.5 kg, a power consumption of up to 8.5 W, a vacuum chamber volume of 3 liters, and a data volume of ~38 Mbit/day. The PI (Principal Investigator) of SEIS is Philippe Lognonné of IPGP (Institut de Physique du Globe de Paris, or Institute of Earth Physics) of Paris, University Paris Diderot, Paris, France. 30) 31) 32)
The SEIS seismometer is based on a six-axis hybrid instrument composed of: 33)
- a sphere including three VBB (Very Broad Band) seismic probes and their temperature sensors,
- three SP (Short Period) seismic probes and their temperature sensors,
- an acquisition electronics box (e-box: SEIS AC, SEIS DC/DC, ASICS) and the feedback boards for the VBB, SP probes and the MDE deployment system,
- a deployment system (DPL),
- a software (S/W).
Its mass is about 3 kg.
Its power consumption varies around 1W depending on the modes.
SEIS seismometer main performances are:
• VBB: -9 m s-2 Hz-½ from 10-3 up to 10 Hz
• SP: < 5 x 10-8 m s-2 Hz-½ from 10-2 up to 100 Hz.
Figure 17: A VBB pendulum beside the evacuated sphere that houses it (image credit: IPGP/Sodern/CNES)
Figure 18: The sphere (image credit: CNES)
The sphere harbors the VBB probes (long period seismometers). It is the "noble part" of the instrument. It has House Keeping for the best functioning of the VBB probes.
• It has a thermal screen and torlon plots to reduce the temperature variations of the seismometers as much as possible
• It keeps the probes in vacuum
• It contains temperature sensors (House Keeping - HK) and inclinometers for the exploitation of the data measured by the VBB.
How does it work? -The spring and the pendulum mass are perfectly balanced. When the ground moves, the pendulum begins to move. This movement is registered by the DCS sensor. The balance mechanism can adjust the pendulum balance in real use conditions (poorly known gravity, levelling flaw, influence of the temperature on the pendulum balance). The pivot should enable the rotation of the mobile part around its axis without any friction.
The proximity electronics transforms these characteristics in easily measured tension. It is transmitted to the acquisition electronics. The feedback coil allows the servitude of the pendulum to improve the performances (increase of the bandwidth). The intensity that runs in the coil is delivered by the feedback board "SEIS-FB" located in the e-box. This intensity is generated depending on the measurement of the pendulum displacement.
Figure 19: The VBBs are oblique pendulums. The displacement sensor is constituted of electrodes placed on the fixed and mobile parts. The electrical characteristics thus constituted form an image of the position of the sensor's mobile part (image credit: CNES)
• In May 2017, the flight model sphere, the seismometer's primary subsystem, has passed its first validation tests. The flight model sphere is the primary subsystem for the SEIS instrument. It was designed by Sodern under the supervision of the Institut de Physique du Globe de Paris (IPGP) and delivered to CNES on 27th April. Tests were performed by Sodern and completed on 30 April 2017.34)
- Initial tests were successful, and further testing on the fully-assembled instrument were authorised. It was transferred to Intespace facilities in Toulouse for vibration tests, completed on 19th May. All requirements were met, and SEIS will be delivered to Lockheed Martin at the end of July so it can be integrated to the InSight lander.
• August 28, 2017: A bench checkout of InSight's Seismometer Instrument was also conducted in a Lockheed Martin clean room facility in Littleton, Colorado. 35)
Figure 20: The SEIS instrument undergoes a checkout for the spacecraft's ATLO (Assembly, Test and Launch Operations) in this photo taken July 20, 2017, in a Lockheed Martin clean room facility in Littleton, Colorado (image credit: NASA/JPL-Caltech, Lockheed Martin)
HP3 (Heat-Flow and Physical Properties Probe)
HP3 is a heat probe, designed to hammer itself to a depth of 3 to 5 meters and measure the amount of energy coming from the planet's deep interior. The heat probe is supplied by the German Aerospace Center, DLR, with the self-hammering mechanism from Poland. The PI of the HP3 instrument is Tilman Spohn of DLR.
• Heat flow provides InSight into the thermal and chemical evolution of the planet by constraining the concentration of radiogenic elements, the thermal history of the planet and the level of its geologic activity.
• Surface heat flow is measured by determining the regolith thermal conductivity, k, and the thermal gradient dT/dz.
• Measuring the thermal gradient undisturbed by the annual thermal wave
• Accurately measuring the thermal conductivity in an extremely low conductivity environment.
HP3 is a self-penetrating temperature and thermal conductivity probe to determine heat flow. HP3 consists of a so-called "Mole", which will hammer itself into the subsurface. The mole pulls an instrumented tether behind it, which is equipped with temperature sensors to determine the thermal gradient in the ground. The mole is targeted for a depth of 5 m below the surface. In addition to the temperature sensors, the mole is equipped with heating foils, which will be used to determine the thermal conductivity of the regolith by operating the mole as a modified line heat source. 36) 37) 38)
Figure 21: System assembly overview of the HP3 elements (image credit: DLR)
Figure 22: Photo of the HP3 penetrating mole mechanism (image credit: DLR)
Table 3: Subsystem development of the penetrating mole
Figure 23: Illustration of HP3 mole subsystems developed by the various institutions (image credit: DLR)
Figure 24: Designation of HP3 mole elements (image credit: DLR)
Deep penetration tests were conducted to verify the operation of the instrument.
• Stroke rate: 1 stroke per 4 seconds
• Penetration rate: 5m in ~27 hrs
• Rates primarily determined by available power/voltage from lander.
The instrument package will be placed near the lander, and a self-hammering spike will pound itself as deep as 5 meters into the ground, like a meat thermometer stuck into a turkey. Trailing behind this "spearhead" will be a tether with temperature sensors strung along its length, spaced 10 cm apart.
Variations in temperature measured at different depths underground will show how much and how fast heat is flowing upward through the crust. From these data, the temperature of Mars' core and the history of its cooling off over time can be estimated.
Mars–like Earth–once had a magnetic field that shielded the planet from the effects of the "solar wind" flowing from the sun. It is now mostly vanished and researchers hope that understanding Mars' thermal history will reveal what happened.
Earth's magnetic field shields our planet from the solar wind, and without that protection our atmosphere would experience direct exposure, and slowly be "eroded" away into space.
The HP3 instrument has a mass of ~3 kg, a maximum power consumption of 2 W while burrowing underneath the surface, a total volume of 20 liters and a data volume of ~ 350 Mbit over the course of the mission.
Figure 25: Photo of the development team and the HP3 flight unit which is ready for delivery after extensive tests and reviews (image credit: DLR)
RISE (Rotation and Interior Structure Experiment)
RISE tracks Mars' reflexes as the Sun pushes and pulls it in its orbit. RISE is an X-band Doppler tracking experiment to measure rotational variations of the planet. These observations will provide detailed information Mars' deep inner core. They will help determine on the depth at which Mars' core becomes solid, and which other elements, besides iron, may be present. By measuring the Doppler shift of InSight's radio transmissions to Earth, precision measurements of Mars' rotation can be made—in much the same way that the speed of a car can be measured by a police radar gun. Aspects of a planet's rotation–not just speed of spin, but also cyclic wobbles, the precession and nutation, of its axis–can tell us what's going on inside, in terms of internal structure.
The RISE instrument has two directional antennas designed with a central axis pointing 28º above the horizon, with one antenna pointing nearly east and the other pointing due west. LaRa (Lander Radioscience) antennas are omnidirectional in azimuth approximately covering the Earth elevation range between 30º and 55º.
The goals of RISE are to deduce the size and density of the martian core through estimation of the precession and nutation of the spin axis. The precession and nutation estimates will be based on measurements of the relative velocity of the InSight lander and tracking stations on Earth. The velocity is related to the Doppler shift of radio signals transmitted from the tracking stations to the lander where they are detected and re-transmitted back to Earth. Doppler measurements are crucially important for navigation of the spacecraft from launch to arrival on Mars. The RISE measurement requirements can be met without any additional equipment but do place constraints on the locations of antennas on the lander. 39)
RISE will use very precise tracking from onboard radio communication devices to look for small variations in planetary rotation. That can give us information about the deep, internal structure of Mars. For example, not much is known right now about the density and size of Mars's core. The RISE experiment should decrease this uncertainty by a factor of 10 or so. This will help answer questions like why Mars had no magnetic field for most of its history, yet continues to be volcanically active. We will also get a good idea of the thickness of Mars's crust at the landing site and the current tectonic activity level on Mars, which is impossible to do from orbital observations.
Figure 26: Illustration of possible models for the interiors of Earth, Mars, and the Moon. One model suggests that Mars' core may have a radius equal to half of the planet's (image credit: NASA/JPL-Caltech)
Data from the RISE experiment will add to similar measurements made years ago on the Viking and Pathfinder missions, and should give scientists what they need to calculate the size and density of Mars' core and mantle, furthering our understanding of how rocky planets like Mars and Earth formed.
The RISE instrument consists of two Medium-Gain ‘horn' Antennas (MGAs) on the lander deck, and an X-band radio transponder and transmitter in the lander's equipment bay, where electronics can be shielded from the harsh, cold conditions of space. The instrument has a total mass of 7.3 kg (2.8 kg for antennas, 4.4 kg for transponder and transmitter), the power consumption is 78 W (operated up to one hour per day), volume of 19.8 liters total.
IDS (Instrument Deployment System)
IDS is a robotic arm to deploy the SEIS and HP3 to the surface, and two cameras to support a variety of operations. IDS is comprised of IDA (Instrument Deployment Arm), an arm-mounted IDC (Instrument Deployment Camera), a lander-mounted ICC (Instrument Context Camera), and control software. IDS is responsible for precision instrument placement on a planetary surface that will enable scientist to perform the first comprehensive surface-based geophysical investigation of Mars. 40)
IDA has 1.9 m reach with four degrees of freedom: yaw (shoulder azimuth) and three pitch joints (shoulder elevation, elbow, and wrist). Each joint has a temperature sensor and heater with a dust seal to prevent contamination of the motor and gearbox. IDC allows visual confirmation of deployment steps, as well as acquisition of the stereo image pairs used to create a 3D map of the workspace. IDC also provides engineering images of solar arrays, payload deck, and instruments. ICC provides context images and redundant worksite imagery.
SNC (Sierra Nevada Corporation) of Sparks, Nevada supplied actuators in the grapple mechanism on the 2.4 m long IDA (Instrument Deployment Arm), which will be used to place the seismometer and heat probe instruments on the Martian surface. The grapple on the robotic arm helps secure each piece of hardware the arm lifts with its five mechanical fingers. The IDA will place a seismometer on the Red Planet's surface to detect Marsquakes and also will release a probe that digs five meters down into Mars' interior, deeper than any previous mission. 41)
Figure 27: A view of the mockup arm, end effector, and lander top deck of Insight (left), and a sequence of three graphics representing instrument deployment (right), image credit: NASA/JPL
APSS (Auxiliary Payload Sensor Suite)
APSS is a complement of sensitive environmental sensors to measure wind velocity, atmospheric temperature and pressure, and the magnetic field.
The atmospheric pressure fluctuations on Mars will induce an elastic response in the ground that will create a ground tilt, detectable as a seismic signal on SEIS. This ground tilt due to atmospheric pressure variations is anticipated to be a major seismic signal on the SEIS instrument . It is planned to reduce the atmospheric seismic signal by making use of a pressure sensor that will be part of the InSight APSS (Auxiliary Payload Sensor Suite). Decorrelation techniques will be used to remove the pressure signal from the seismic signal. The pressure sensor will be on the InSight lander and, thus, almost collocated with the seismometer. 42)
Ground segment - Communications with Earth
NASA's InSight mission uses the NASA's DSN (Deep Space Network), an international network of antennas that provides communication links between planetary exploration spacecraft and their mission teams on Earth. 43)
The Deep Space Network consists of three deep-space communications complexes placed approximately 120 degrees apart around the world: at Goldstone, in California's Mojave Desert; near Madrid, Spain; and near Canberra, Australia. This strategic placement permits constant links to distant spacecraft even as the Earth rotates on its own axis.
As with previous Mars landers and rovers, the InSight mission relies on Mars-orbiting spacecraft to relay data from the spacecraft to the antennas of the Deep Space Network.
Figure 28: Photo of the Goldstone 70 m antenna (image credit: NASA)
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The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: "Observation of the Earth and Its Environment: Survey of Missions and Sensors" (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. - Comments and corrections to this article are always welcome for further updates (email@example.com