InSight
The Interior Exploration using Seismic Investigations, Geodesy and Heat Transport mission was a robotic lander designed to study the deep interior of the planet Mars. It was manufactured by Lockheed Martin Space, was managed by NASA's Jet Propulsion Laboratory, and two of its three scientific instruments were built by European agencies. InSight confirmed "marsquakes" on the planet and thus a still active interior.
The mission launched on 5 May 2018 at 11:05:01 UTC aboard an Atlas V-401 launch vehicle and successfully landed at Elysium Planitia on Mars on 26 November 2018 at 19:52:59 UTC. InSight was active on Mars for sols.
InSight objectives were to place a seismometer, called Seismic Experiment for Interior Structure, on the surface of Mars to measure seismic activity and provide accurate 3D models of the planet's interior; and measure internal heat transfer using a heat probe called HP3 to study Mars's early geological evolution. This was intended to provide a new understanding of how the Solar System's terrestrial planets – Mercury, Venus, Earth, Mars – and Earth's Moon formed and evolved.
The lander was originally planned for launch in March 2016. An instrument problem delayed the launch beyond the 2016 launch window. NASA officials rescheduled the InSight launch to May 2018 and during the wait the instrument was repaired. This increased the total cost from US$675 million to US$830 million.
InSight successfully landed on Mars on 26 November 2018. Due to excessive dust on its solar panels preventing it from recharging, NASA put InSight in low-power mode for detecting seismic events in July 2022 and continued monitoring the lander through the operational period ending in December 2022. On 20 December 2022, NASA announced that the InSight lander had lost communications with Earth on 15 December 2022, with the end of the mission being declared on 21 December 2022.
History
Discovery Program selection
InSight was initially known as GEMS, but its name was changed in early 2012 following a request by NASA. Out of 28 proposals from 2010, it was one of the three Discovery Program finalists receiving $3 million in May 2011 to develop a detailed concept study. In August 2012, InSight was selected for development and launch. Managed by NASA's Jet Propulsion Laboratory with participation from scientists from several countries, the mission was cost-capped at US$425 million, not including launch vehicle funding.By reusing the landing system designed for the Mars Phoenix lander, which successfully landed on Mars in 2008, mission costs and risks were reduced.
Schedule issues
Lockheed Martin began construction of the lander on 19 May 2014, with general testing starting on 27 May 2015.A persistent vacuum leak in the CNES-supplied seismometer known as the Seismic Experiment for Interior Structure led NASA to postpone the planned launch in March 2016 to May 2018. When InSight was delayed, the rest of the spacecraft was returned to Lockheed Martin's factory in Colorado for storage, and the Atlas V launch vehicle intended to launch the spacecraft was reassigned to the WorldView-4 mission.
On 9 March 2016, NASA officials announced that InSight would be delayed until the 2018 launch window at an estimated cost of US$150 million. The spacecraft was rescheduled to launch on 5 May 2018 for a Mars landing on 26 November 2018 at 20:00 UTC. The flight plan remained unchanged with launch using an Atlas V launch vehicle from Vandenberg Space Force Base in California. NASA's Jet Propulsion Laboratory was tasked with redesigning and building a new vacuum enclosure for the SEIS instrument, while CNES conducted instrument integration and testing.
On 22 November 2017, InSight completed testing in a thermal vacuum, also known as TVAC testing, where the spacecraft was put in simulated space conditions with reduced pressure and various thermal loads. On 23 January 2018, after a long storage, its solar panels were once again deployed and tested, and a second silicon chip containing 1.6 million names from the public was added to the lander.
Effects of Martian dust and end of operations
The InSight lander, powered by solar panels and batteries, relies on periodic wind gusts called "cleaning events" to reduce dust accumulation on the panels. Elysium Planitia, the landing site of InSight, experienced fewer cleaning events than needed to keep science operations powered. In February 2021, at the start of the Martian winter, InSight's solar cells were producing 27% of capacity due to a thick covering of dust on the panels. At that time, NASA began the process of putting the lander into hibernation mode, shutting down data-gathering instruments on a schedule to conserve enough power to keep the lander electronics warm through the Martian winter. NASA had hoped that weather conditions would improve and allow InSight to store enough energy to come out of hibernation in July 2021.In May 2021, some generation capacity was restored by using the arm to position sand so it could blow onto the solar panels and scour them clean.
NASA determined in May 2022 that there was too much dust on the panels to continue the mission. InSight was generating only one-tenth of the power from the sunlight than it did upon arrival. They put the lander in a low-power mode in July 2022 to continue monitoring for seismic events. NASA continued to monitor InSight until the end of 2022, when the spacecraft missed two consecutive communication attempts.
Science background
Seismic vibrations
Both Viking spacecraft carried seismometers mounted on their landers, and in 1976 vibrations were picked up from various lander operations and from the wind. However, the Viking 1 lander's seismometer did not deploy properly and did not unlock; the locked seismometer could not operate.The Viking 2 seismometer unlocked; it operated and returned data to Earth. One problem was accounting for other data. On Sol 80, the Viking 2 seismometer detected an event. No wind data were recorded at the same time, so it was not possible to determine whether the data indicated a seismic event or wind gust. Other lacking data would have been useful to rule out other sources of vibrations. Two other problems were the location of the lander and that a certain level of wind on Mars caused a loss of sensitivity for the Viking 2 seismometer. To overcome these and other issues, InSight had many other sensors, was placed directly on the surface, and also had a windshield.
Despite the difficulties, the Viking 2 seismometer readings were used to estimate a Martian geological crust thickness between at the Viking 2 lander site. The Viking 2 seismometer did detect vibrations from Mars winds complementing the meteorology results. There was the aforementioned candidate for a possible marsquake, but it was not particularly definitive. The wind data did prove useful in its own right, and despite the limitations of the data, widespread and large marsquakes were not detected.
Seismometers were also left on the Moon, starting with Apollo 11 in 1969, and also by Apollo 12, 14, 15 and 16 missions and provided many insights into lunar seismology, including the discovery of moonquakes. The Apollo seismic network, which was operated until 1977, detected at least 28 moonquakes up to 5.5 on the Richter scale.
One of the aspects of the InSight mission was to compare the Earth, Moon, and Mars seismic data.
On 4 May 2022, a large marsquake, estimated at magnitude 5, was detected by the seismometer on the InSight lander.
On 25 October 2023, scientists, helped by information from InSight, reported that the planet Mars has a radioactive magma ocean under its crust.
Planetary precession
Radio Doppler measurements were taken with Viking and twenty years later with Mars Pathfinder, and in each case the axis of rotation of Mars was estimated. By combining this data, the core size was constrained, because the change in axis of rotation over 20 years allowed a precession rate and from that the planet's moment of inertia to be estimated. InSight measurements of crust thickness, mantle viscosity, core radius and density, and seismic activity were planned to result in a three- to tenfold increase in accuracy compared to previous data.Objectives
The InSight mission placed a single stationary lander on Mars to study its deep interior and address a fundamental issue of planetary and Solar System science: understanding the processes that shaped the rocky planets of the inner Solar System more than four billion years ago.InSight primary objective was to study the earliest evolutionary processes that shaped Mars. By studying the size, thickness, density and overall structure of Mars's core, mantle and crust, as well as the rate at which heat escapes from the planet's interior, InSight was intended to provide a glimpse into the evolutionary processes of all of the rocky planets in the inner Solar System. The rocky inner planets share a common ancestry that begins with accretion. As the body increases in size, its interior heats up and evolves to become a terrestrial planet, containing a core, mantle and crust. Despite this common ancestry, each of the terrestrial planets is later shaped and molded through the poorly understood process of differentiation. InSight mission's goal was to improve the understanding of this process and, by extension, terrestrial evolution, by measuring the planetary building blocks shaped by this differentiation: a terrestrial planet's core, mantle and crust.
The mission was designed determine if there is any seismic activity, measure the rate of heat flow from the interior, estimate the size of Mars's core and establish whether the core is liquid or solid. This data would be the first of its kind for Mars. It was also expected that frequent meteor airbursts would provide additional seismo-acoustic signals to probe the interior of Mars. The mission's secondary objective was to conduct an in-depth study of geophysics, tectonic activity and the effect of meteorite impacts on Mars, which could provide knowledge about such processes on Earth. Measurements of crust thickness, mantle viscosity, core radius and density, and seismic activity should result in a three- to tenfold increase in accuracy compared to current data. This was the first time a robotic lander dug this deep into the Martian crust.
In terms of fundamental processes shaping planetary formation, it is thought that Mars contains the most in-depth and accurate historical record, because it is big enough to have undergone the earliest accretion and internal heating processes that shaped the terrestrial planets, but small enough to have retained signs of those processes. The science phase is expected to last for two years.
In March 2021, NASA reported, based on measurements of over 500 Marsquakes by the InSight lander on the planet Mars, that the core of Mars is between, about half the size of the core of Earth, and significantly smaller than thought earlier, suggesting a core of lighter elements.