Schiaparelli EDM lander

''Schiaparelli'' EDM () was a failed Entry, Descent, and Landing Demonstrator Module (EDM) of the ExoMars programme—a joint mission of the European Space Agency (ESA) and the Russian Space Agency Roscosmos. It was built in Italy and was intended to test technology for future soft landings on the surface of Mars. It also had a limited but focused science payload that would have measured atmospheric electricity on Mars and local meteorological conditions.

Launched together with the ExoMars Trace Gas Orbiter (TGO) on 14 March 2016, ''Schiaparelli'' attempted a landing on 19 October 2016. Telemetry signals from ''Schiaparelli'', monitored in real time by the Giant Metrewave Radio Telescope in India (and confirmed by ''Mars Express''), were lost about one minute from the surface during the final landing stages. On 21 October 2016, NASA released an image by the '' Mars Reconnaissance Orbiter'' showing what appears to be the lander's crash site. The telemetry data accumulated and relayed by ESA's ExoMars Trace Gas Orbiter and ''Mars Express'' were used to investigate the failure modes of the landing technology employed.

Namesake

The ''Schiaparelli'' Entry, Descent, and Landing Demonstrator module is named for Giovanni Schiaparelli (1835–1910), an astronomer active in the 19th century who made Mars observations. In particular, he recorded features he called ''canali'' in his native Italian. His observations of what translates as channels in English inspired many. The dark streaks on Mars are an albedo feature which is related to dust distribution; these albedo features on Mars slowly change over time, and in the last few decades have been monitored by Mars orbiters. Schiaparelli is famous for making hand-drawn maps of Mars during its 1877 oppositions with Earth with an optical refracting telescope. He was also the first astronomer to determine the relationship between comet debris and yearly meteor showers.

Other things named for Schiaparelli include the main-belt asteroid 4062 Schiaparelli, named on 15 September 1989 (), the lunar crater Schiaparelli, the Martian crater Schiaparelli, Schiaparelli Dorsum on Mercury, and the 2016 ExoMars EDM lander.

The mission was named in November 2013; previously it was known as the Exomars Entry, descent and landing Demonstrator Module, or ExoMars EDM for short. Another name was ExoMars ''static lander'', however some designs for what was the static lander are quite different due to various stages of design and program restructuring. Another name, especially for both orbiter and lander together is ''ExoMars 2016''.

Origins and development

The EDM traces itself back to the ESA Aurora programme, which has the goal of human exploration of space, and thus producing missions that are building blocks to support this goal. ExoMars originated out of this, and provides context for understanding the EDM. Schiaparelli forms an important "block" of learning how to land heavy payloads on Mars, which is vital to future crewed missions. Another "block" is the ExoMars rover, which is intended to demonstrate among other things the ability to traverse several km/miles on the surface of Mars. The Aurora program is focused on two types of the mission, one are larger flagship spacecraft and the other are smaller missions specifically meant to offload risk from the larger missions.

In 2005 the ESA council approved 650 million Euros for a Mars rover and static lander. At this time the idea was for a single launch bringing both a Mars Exploration Rover class rover and instrumented static lander to Mars with a simpler cruise stage;in this case the static lander both landed the rover and performed its own studies. However to accomplish its mission goals within the constraints of using a Soyuz rocket for launch, the rover was budgeted for just 6 kg. To enable a larger rover, the Ariane V, Atlas V, and Proton were evaluated. Rovers from 180 kg up to 600 kg were considered, and eventually the idea of test lander to offload risk from the rover lander arose, which fitted well with a two-launch strategy allowing a heavier orbiter and a heavier rover on the second launch.

Early in development, the lander was to be carried by a dedicated cruise stage called the ''Carrier Module''. Eventually, the Trace Gas Orbiter mission was merged into ExoMars, becoming the carrier for the EDM.

Overview

Although the lander crashed, the data transmitted from ''Schiaparelli'' are expected to provide ESA and Roscosmos with the technology for landing on the surface of Mars with a controlled soft landing. This technology will be used by the ''Rosalind Franklin'' rover, part of the ExoMars programme, which was due to launch in 2022. The rovers' launch has been delayed as a consequence of the Russian invasion of Ukraine. In July 2022, ESA terminated its cooperation on the project with Russia. , the launch of the rover is not expected to occur before 2028 due to the need for a new non-Russian landing platform.

Pre-launch

The descent module ''Schiaparelli'' and orbiter completed testing and were integrated to a Proton-M rocket at the Baikonur cosmodrome in Baikonur in mid-January 2016. TGO and EDM arrived at Baikonur in December 2015. In February the spacecraft was mounted to the Briz-M upper stage, and in early March that was attached to the Proton rocket.

Liftoff

The launch occurred at 09:31 GMT (15:31 local time) on 14 March 2016. Four rocket burns occurred in the following 10 hours before the descent module and orbiter were released. A signal from the orbiter was received at 21:29 GMT that day, confirming that the launch was successful and the spacecraft was functioning properly. Shortly after separation from the probes, the Briz-M upper booster stage exploded a few kilometres away, without damaging the orbiter or lander.

Cruise, separation and arrival

After its launch, the Trace Gas Orbiter (TGO) and EDM traveled together coasting through space towards Mars. During this time the EDM was powered from an umbilical power line to the TGO, thus preserving the EDM's limited internal batteries. A deep space manoeuvre was executed by the TGO main engine in two legs on 28 July and on 11 August in order to target the entry flight path angle and the landing site. On 14 October 2016, the TGO did a final adjustment to its trajectory before the separation of Schiaparelli. The launch mass of the two spacecraft together is 4332 kg including the 600 kg ''Schiaparelli'' module. This was the heaviest spacecraft yet sent to Mars. The journey from Earth to Mars in 2016 took about 7 months.

On 16 October 2016, the TGO and EDM separated, the orbiter heading for Mars orbit insertion and the EDM for Mars atmospheric entry. Prior to the separation, the EDM was spun up 2.5 RPM (see also spin stabilization) and then released at a velocity of about 1 km/h relative to TGO. The EDM was designed to go into a lower-power hibernation mode for about 3 days while it traveled solo to Mars. The EDM came out of hibernation about an hour and a half prior to reaching the Martian atmosphere. Meanwhile, after the separation, the TGO adjusted its trajectory for its Mars orbit insertion and by 19 October 2016 performed a 139-minute rocket engine burn to enter Mars orbit. On the same day, the ''Schiaparelli'' module arrived at Mars traveling at and engaged in its prime task of entry, descent, and landing. After a successful atmospheric entry, the module's speed was reduced from the 5.8 km/s entry value to a few hundred m/s due to the drag force provided by the atmosphere of Mars. During this phase of the flight, a heat shield was used to protect the payload from the severe heat load. The parachute was triggered by the on-board software when the accelerometers detected a given non-gravitational acceleration value of 9 m/s², as expected. After having reached the sub-sonic regime by means of the nominally-inflated parachute, the ''Schiaparelli'' module experienced an anomaly causing the backshell and parachute release to occur earlier than expected and preventing the retrorockets from slowing the descent. The hard touch-down location, reconstructed using data from the Mars Reconnaissance Orbiter, was identified quite close to the expected landing site, about 6.4 km short-range from it. The TGO entered Mars' orbit and it underwent several months of aerobraking to adjust its speed and orbit, with science activities beginning in late 2017. The TGO will continue serving as a relay satellite for future Mars landing missions until 2022. (PDF)

Landing site

The landing site chosen was Meridiani Planum, a Martian plain prized by Mars landers for its flat terrain and low elevation that gives a spacecraft time and distance to slow down before reaching the ground. The EDM cannot avoid obstacles during its descent, so it was important to pick a large flat area with a minimum of obstacles. The landing ellipse is about 100 km long by 15 km wide, centered at 6° west and 2° south running east–west, with the eastern edge including the ''Opportunity'' rover landing site, and near Endeavour crater where it was still operating when the EDM was launched and when it attempted to land. The ''Opportunity'' rover (MER-B) landing site is called the ''Challenger Memorial Station''. It was also thought that the EDM would have a chance of arriving when Mars experienced its global dust storms, and thus gain knowledge about the atmosphere under these less common conditions. The site is also known to be scientifically interesting; the ''Opportunity'' rover discovered a type of iron mineral that forms in the presence of water, so it is theorized there was a significant amount of water there in the past.

Dust storm goal

The landing was planned to take place on Meridiani Planum during the dust storm season, which would have provided a chance to characterise a dust-loaded atmosphere during entry and descent, measure the dust's static electricity charge—typically produced by charge transfer on contact between particles—and to conduct surface measurements associated with a dust-rich environment.

Global dust storms have occurred at least nine times since 1924 including 1977, 1982, 1994, 2001 and 2007; the 2007 dust storms nearly ended the functioning of the solar-powered U.S. Mars Exploration Rovers ''Spirit'' and ''Opportunity''. Global dust storms obscured Mars when the ''Mariner 9'' orbiter arrived there in 1971, and it took several weeks for the dust to settle down and allow for clear imaging of the surface of Mars. It was predicted that Mars global dust storms were likely to occur in the fall of 2016, but they had not started when the EDM attempted its landing. Global dust storms hit in the summer of 2018, cutting off light to the solar powered Opportunity rover which was still operating nearby to the Schiaparelli landing site.

Entry, descent, and landing events sequence

The ''Schiaparelli'' lander separated from the TGO orbiter on 16 October 2016, three days before arrival at Mars, and entered the atmosphere at on 19 October 2016 (see also Mars atmospheric entry

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