20. December 2022
Mission concludes after more than four years on Mars

In­Sight – the end of a sci­en­tif­ic suc­cess sto­ry

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InSight's last selfie
In­Sight's last self­ie
Image 1/7, Credit: NASA/JPL-Caltech

InSight's last selfie

On 24 April 2022, NASA's In­Sight Mars probe took its last self­ie with its cam­era on the robot­ic arm - it was the 1211th Mar­tian day of the mis­sion. The so­lar pan­els were al­ready heav­i­ly cov­ered in Mar­tian dust, which was quite ex­pect­ed af­ter al­most three and a half years of mis­sion du­ra­tion, so it was fore­see­able that the pow­er pro­duc­tion would be suf­fi­cient for few­er and few­er func­tions. On 20 De­cem­ber 2022, af­ter two un­suc­cess­ful com­mu­ni­ca­tion at­tempts - what mis­sion con­trol at the Jet Propul­sion Lab­o­ra­to­ry calls "dead bus mode" - NASA de­clared the In­Sight mis­sion over. With 1446 sols (Mar­tian days; 1 sol equals 24 hours and 39 min­utes), In­Sight has a mis­sion du­ra­tion more than twice as long as planned. In­Sight launched on 5 May 2018 and land­ed on Mars on 26 Novem­ber 2018.
InSight - Mission for geophysical measurements on Mars
In­Sight - Mis­sion for geo­phys­i­cal mea­sure­ments on Mars
Image 2/7, Credit: NASA/JPL-Caltech

InSight - Mission for geophysical measurements on Mars

This artist's im­pres­sion shows the Mars lan­der In­Sight at its de­ploy­ment site in the Ely­si­um Plani­tia plain with un­fold­ed so­lar pan­els, the plat­form with the two an­ten­nas, var­i­ous tech­ni­cal and sci­en­tif­ic com­po­nents, the robot­ic arm with cam­era and the grip­ping mech­a­nism used to place two of the main ex­per­i­ments from the plat­form on­to the ground in front of the probe: On the left, the SEIS (Seis­mic Ex­per­i­ment for In­te­ri­or Struc­tures) seis­mome­ter pro­vid­ed by France for the mis­sion, and on the right, the HP3 (Heat­flow and Phys­i­cal Prop­er­ties Pack­age) ex­per­i­ment de­vel­oped by DLR. In­Sight land­ed on Mars on 26 Novem­ber 2018. Due to a lack of pow­er sup­ply, the mis­sion was de­clared ter­mi­nat­ed by NASA on 20 De­cem­ber 2022.
The Mars Mole Heat flow experiment HP3
The Mars Mole Heat flow ex­per­i­ment HP3
Image 3/7, Credit: DLR (CC BY-NC-ND 3.0)

The Mars Mole Heat flow experiment HP3

The 'Mole', the so-called Mars Mole, is a self-ham­mer­ing heat flow probe de­signed to dig it­self up to five me­tres in­to the Mar­tian soil, drag­ging a teth­er be­hind it to record the in­crease in tem­per­a­ture with in­creas­ing depth. It is part of the HP3 (Heat Flow and Phys­i­cal Prop­er­ties Pack­age) ex­per­i­ment pack­age pro­vid­ed by DLR for the In­Sight mis­sion. How­ev­er, the Mole was un­able to reach the re­quired depth in­to the ground. At the land­ing site, the Mar­tian soil was not as loose as at oth­er land­ing sites, so the Mole was un­able to find a foothold and was on­ly able to pen­e­trate 40 cen­time­tres deep. With the help of the ther­mal con­duc­tiv­i­ty mea­sured dur­ing the Mole's pen­e­tra­tion, the heat flow from the in­te­ri­or of Mars could have been de­ter­mined. Af­ter all, valu­able da­ta about the me­chan­i­cal and ther­mal prop­er­ties of the Mar­tian soil could be col­lect­ed.
Recording marsquake waves with SEIS
Record­ing marsquake waves with SEIS
Image 4/7, Credit: NASA/JPL-Caltech/CNES-IPGP

Recording marsquake waves with SEIS

The "Mars Earth­quake Ob­ser­va­to­ry" SEIS is a seis­mome­ter for mea­sur­ing move­ments in the Mar­tian soil in four dif­fer­ent fre­quen­cies with a to­tal of six sen­sors. The in­stru­ment was de­vel­oped un­der the lead­er­ship of the French space agen­cy CNES. Dur­ing the In­Sight mis­sion, the most sen­si­tive seis­mome­ter ev­er used in plan­e­tary re­search record­ed seis­mic waves from more than 1300 tremors of the Mar­tian soil.
The "smoking gun": a new Martian crater
The "smok­ing gun": a new Mar­tian crater
Image 5/7, Credit: NAS/JPL-Caltech/University of Arizona

The "smoking gun": a new Martian crater

Al­most ex­act­ly one year ago, on Christ­mas Eve 2021, the SEIS seis­mome­ter on the now com­plet­ed In­Sight mis­sion record­ed the tremor of a me­te­orite im­pact on Mars. The strength of the quake waves reached mag­ni­tude 4. Based on these mea­sure­ments, the lo­ca­tion of the im­pact could be ge­o­met­ri­cal­ly re­con­struct­ed. NASA's Mars Re­con­nais­sance Or­biter probe pho­tographed the fresh crater there with its high-res­o­lu­tion HiRISE cam­era, which was 150 me­tres large and sev­er­al tens of me­tres deep and had formed 3600 kilo­me­tres from the SEIS Mars Earth­quake Ob­ser­va­to­ry. What was al­so as­ton­ish­ing was that hun­dreds of house-sized chunks of ice from a lay­er of ice hid­den be­neath the sur­face were dis­tribut­ed around the crater with the eject­ed ma­te­ri­al dur­ing the im­pact.
Small but mighty: The InSight Mars mission
Small but mighty: The In­Sight Mars mis­sion
Image 6/7, Credit: NASA/JPL-Caltech/Lockheed Martin Space

Small but mighty: The InSight Mars mission

The In­Sight (In­te­ri­or Ex­plo­ration Us­ing Seis­mic In­ves­ti­ga­tions, Geodesy and Heat Trans­port) geo­phys­i­cal re­search sta­tion for Mars built on the de­sign of NASA's Phoenix lan­der, which ex­plored the plan­et's north­ern po­lar re­gion in 2008. In­Sight land­ed on 26 Novem­ber 2018, and on 20 De­cem­ber 2022, NASA de­clared the mis­sion end­ed be­cause the so­lar pan­els could no longer gen­er­ate enough pow­er to com­mu­ni­cate with re­lay satel­lites due to ex­ces­sive degra­da­tion from dust. In­Sight was a NASA Dis­cov­ery-class mis­sion.
InSight landing site
In­Sight land­ing site
Image 7/7, Credit: NASA/JPL/USGS (MOLA); DLR

InSight landing site

NASA's In­Sight space­craft land­ed in the Ely­si­um Plani­tia re­gion on Mars on 26 Novem­ber 2018. In con­trast to oth­er Mars land­ing sites, a lo­ca­tion with­out any con­spic­u­ous ge­o­log­i­cal fea­tures was cho­sen for the mis­sion in or­der to min­imise risk and pro­vide ide­al mea­sure­ment con­di­tions for the geo­phys­i­cal ex­per­i­ments. Since at­mo­spher­ic in­flu­ences can cause slight changes in the flight path dur­ing land­ing, an area is usu­al­ly cho­sen that still con­tains suf­fi­cient safe­ty buffers for land­ing in the event of de­vi­a­tions. This re­sult­ed in a pre-cal­cu­lat­ed "land­ing el­lipse", which in the case of In­Sight was 140 kilo­me­tres long and 30 kilo­me­tres wide.

• NASA declares mission end on 20.12.2022.
• Geophysical station has gone into ‘dead bus’ mode after four years of increasing martian dust accumulation on its solar panels and is unlikely to be able to be contacted by radio.
• InSight landed on Mars in late 2018, becoming the first geophysical mission to do so. It has since recorded over 1300 marsquakes and helped researchers answer important questions about the Red Planet's interior.
• Focus: Mars, planetary science, exploration, spaceflight

The InSight Mars mission is history. On 20 December 2022, NASA declared the mission over. The two attempts from Mission Control Centre at NASA's Jet Propulsion Laboratory (JPL) in Southern California to reach the lander via relay satellites in Mars orbit have been unsuccessful. This almost certainly means that InSight's solar-powered batteries are no longer supplying enough power, a condition engineers call ‘dead bus’ mode. The German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) contributed measuring instruments and a science team to the lander mission. InSight was the first purely geophysical mission to explore Mars. The last radio contact with Earth took place on 15 December 2022.

InSight uses solar energy to recharge the batteries, which is currently no longer sufficiently possible due to the dust accumulation on the solar panels. If, however, wind cleared the panels and a sufficient charge level is reached again, InSight could power up and attempt to communicate. Further contact would then be possible and even a resumption of operation. However, the increasing dust build-up on the solar panels makes this unlikely.

"It is always regrettable when a planetary mission for which you have prepared for more than a decade and then operated for years finally fails to deliver further measurement data," says Heike Rauer, Director of the DLR Institute of Planetary Research in Berlin, looking back on the InSight mission. "On the other hand, the positives absolutely outweigh the negatives: the scientific fruits of preparation and planning have been successfully harvested. We have learned a lot about the internal structure of Mars and are also using this to understand the other Earth-like bodies in the Solar System. Our planetary geophysicists have drawn many important lessons from the measurements."

The end of the mission loomed over the course of the last few months and came as no surprise. After more than four years, the mission duration had exceeded expectations by a factor of two. The Interior Exploration Using Seismic Investigations, Geodesy and Heat Transport (InSight) mission was NASA's eighth mission to land on Mars since 1976 and the first to be devoted almost exclusively to geophysical investigations. The solar panels were designed in such a way that they would provide enough energy for the originally planned lifetime of one Mars year (two Earth years), despite dust accumulation. In the end, they lasted long enough to extend the mission duration by a second Mars year.

Flight over the In­Sight land­ing site in Ely­si­um Plani­tia
On 26 Novem­ber 2018, the NASA In­Sight probe land­ed on Ely­si­um Plani­tia on Mars at 4.5 de­grees north and 135.9 de­grees east. This video shows an over­flight over the land­ing site and its sur­round­ings. The video was based on a dig­i­tal ter­rain mod­el gen­er­at­ed with stereo im­age da­ta ac­quired by DLR's High Res­o­lu­tion Stereo Cam­era (HRSC) of the DLR.
Credit: DLR (CC-BY 3.0).

Almost everything succeeds as planned

The focus of the mission was to measure the heat balance and seismic activity inside the planet in order to gain important information about its structure, the flow of heat from the core and mantle to the surface and, derived from this, its thermal evolution. The primary instruments for acquiring these measurements were the Heat Flow and Physical Properties Package (HP3) provided by DLR and the Seismic Experiment for Interior Structures (SEIS) seismometer developed by the French space agency CNES. It is the NASA Mars mission with by far the most significant European contribution to date. NASA Science Director Thomas Zurbuchen hailed the mission as a great success.

Robotic arm helps mole dig below the surface

Unfortunately, the affectionately named Mars ‘Mole' probe of DLR’s HP3 did not fully deliver the expected measurements (click here to read the logbook of Principal Investigator, Tilman Spohn, former Director of DLR's Institute of Planetary Research), because the heat flow probe could not successfully penetrate to the required depths beneath the Martian surface. HP3 and the Mole kept the team busy for more than two years. Originally, the Mole was supposed to penetrate to a depth of five metres and drag a tether with temperature sensors behind it. "This would have allowed us to measure how the temperature rises with depth. With the help of the thermal conductivity measured during the Mole's descent, we could have directly determined the heat flow from the interior of Mars," explains Tilman Spohn. "This would have helped us to classify the evolution of Mars from a hot origin to its current, almost entirely cold state."

The Mars Mole, designed as a self-hammering probe capable of penetrating through the familiar loose, sandy soil of other missions, was unable to find a foothold in the unexpectedly hard soil around InSight’s surroundings. The instrument was eventually able to bury its 40-centimetre probe just below the surface, collecting some valuable data on the mechanical and thermal properties of the martian soil despite its setback. "These data will be very helpful for future exploration of Mars by humans or robots trying to dig into the Martian subsurface," Tilman Spohn continues. The fact that the Mole was finally able to burrow in is thanks to a team effort by engineers from JPL and DLR. They used the InSight lander's robotic arm in a creative way to give the Mole additional support. The arm and its small scoop were primarily designed to place scientific instruments on the surface of Mars. Eventually, though, they even helped clear some of the dust from InSight's solar panels as the power waned.

Seismometer provides ‘ground-breaking’ data

In the SEIS experiment, however, the successful recordings of waves propagating through the Martian crust were of enormous scientific value. Between early 2019 and the end of the mission, seismic waves from more than 1300 ‘events’ – tremors in the martian soil – were recorded. These include mostly waves generated by marsquakes that occurred at different locations in the Martian crust during the discharge of tectonic stresses, but some of these waves were triggered by asteroid impacts. In these cases, even the location of the impacts could be reconstructed from the data and, in several cases, confirmed using images acquired by the Mars Reconnaissance Orbiter. The two largest related craters measure more than 100 metres in diameter.

Caused by tectonic activity, these marsquakes provide important clues about the structure of the Red Planet. The reflection of these seismic waves at the boundaries between the solid rock mantle and the liquid core finally allowed the size of the martian core to be determined precisely. Its diameter is between 3600 and 3700 kilometres, which is at the upper end of the size estimated before the mission. For comparison, the total diameter of Mars is just under 6800 kilometres. Seismic waves passing through the core also provide clues to its internal structure and composition. The complementary auxiliary instruments on board also provided important data, such as the DLR RAD radiometer, which is part of HP3. RAD recorded the daily change in the surface temperature by measuring infrared radiation. This made it possible to collect important data for characterising the thermal properties of the martian soil.

Patience required – quakes limited to the Martian summer

When the seismometer went into operation at the beginning of 2019, not a single initial Mars quake was detected in the recordings for several weeks – much to the alarm of the InSight team. "We were already calculating what it would mean for our theories not to register any quakes," recalls Martin Knapmeyer, a seismologist at DLR's Institute of Planetary Research who is involved in the SEIS experiment, conveying the nervousness felt by the team in the first weeks of the mission in 2019. "When things did get going much later, it became clear that the noise of the wind in the region of the InSight landing area, where it was currently winter, masked all signals of marsquakes. On top of this, we were later able to prove that the frequency of these quakes is actually lower in winter than in summer."

Later, on 'warm' spring and summer evenings in the Elysium Planum region in which InSight landed, there was almost no wind. This made for ideal measurement conditions, primarily between sunset and midnight. Ultimately, more than 1300 marsquakes could be registered. Many of them originated in the Cerberus Fossae region, 1500 kilometres away from InSight. This corresponds roughly to the distance between Cologne and Mount Etna in Sicily. In the Cerberus Fossae region, the last volcanic activity took place less than 200,000 years ago, and the observed quakes exhibit characteristics similar to those of volcanic regions of the Earth, such as the Eifel region in Germany. "However, this does not mean that a new volcanic eruption is to be expected here in the near future," Knapmeyer adds, assessing the measurements.

At last, numerical values for the thickness of the Martian crust

From the study of variations in the Red Planet’s gravitational field, which alter the altitudes of Mars orbiters by tiny amounts, it has long been known that the martian crust has a regionally varying thickness. For decades, efforts have been made to use seismic measurements to measure not only the relative but also the absolute thickness of the crust. With InSight, this has now been achieved. Initially this was only done for the landing site. However, by registering surface waves from some of the stronger marsquakes, it also became possible to determine the crustal thickness along the path of these waves. "This means that numbers can now finally be attached to the 'contour lines' of the crust thickness," says Knapmeyer, highlighting another important result of the mission. The average thickness of the crust is between 24 and 72 kilometres, which is somewhat thinner than earlier, more indirect investigations had shown.

Diverse missions on Mars

There are three active on the surface of Mars: NASA's Curiosity rover, which landed in 2012 in the Gale crater; the Perseverance rover, which landed in Jezero crater in 2021, and the Chinese mission Tianwen 1, which comprises the Zurong rover and landing station. In orbit around Mars are NASA's Mars 2001 Odyssey probe (since 2001), the European Space Agency (ESA) Mars Express orbiter (since 2003), equipped with DLR's High Resolution Stereo Camera (HRSC), NASA's Mars Reconnaissance Orbiter (since 2006), NASA's MAVEN atmospheric orbiter (since 2014), ESA's ExoMars Trace Gas Orbiter (since 2016), the orbiter of China's Tianwen-1 mission (since 2021), and the United Arab Emirates' Al-Amal orbiter (since 2021).

About the InSight Mars mission

The InSight mission was conducted by the Jet Propulsion Laboratory (JPL) in Pasadena, California, under contract to NASA's Science Directorate. InSight is a mission of the NASA Discovery Programme. The Space Agency at DLR funded a contribution from the Max Planck Institute for Solar System Research to the French Seismic Experiment for Interior Structure (SEIS) instrument with funds from the Federal Ministry for Economic Affairs and Climate Action. DLR researchers are involved in the evaluation of the SEIS data. DLR especially contributed the Heat Flow and Physical Properties Package (HP3) experiment, which is equipped with the Mars ‘Mole’ and was operated by the Microgravity User Support Center (MUSC) in Cologne.

Contact
  • Falk Dambowsky
    Ed­i­tor
    Ger­man Aerospace Cen­ter (DLR)

    DLR Cor­po­rate Com­mu­ni­ca­tions
    Telephone: +49 2203 601-3959
    Linder Höhe
    51147 Cologne
    Contact
  • Matthias Grott
    HP³ and SEIS project sci­en­tist and mem­ber of the In­Sight sci­ence team; fo­cus on heat flow and ther­mal con­duc­tiv­i­ty mea­sure­ments; build­ing in­stru­ments.
    Ger­man Aerospace Cen­ter (DLR)
    In­sti­tute of Plan­e­tary Re­search, Plan­e­tary Geodesy
    Telephone: +49 30 67055-419

    Contact
  • Martin Knapmeyer
    HP³ and SEIS project sci­en­tist and mem­ber of the In­Sight sci­ence team
    Ger­man Aerospace Cen­ter (DLR)
    In­sti­tute of Plan­e­tary Re­search
    Plan­e­tary Physics
    Rutherfordstraße 2
    12489 Berlin
    Contact
  • Prof. Dr. Tilman Spohn
    Ex­ec­u­tive Di­rec­tor
    In­ter­na­tion­al Space Sci­ence In­sti­tute (IS­SI)
    Hallerstraße 6
    3012 Bern/Schweiz
    Contact
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