Investigators who probed into the ill-fated attempt of European Space Agency's Schiaparelli at landing on the surface of planet Mars last year have concluded that the spacecraft was ill-prepared for the mission.
What Went Wrong With Schiaparelli
A report of the result of the investigation, which was released on Wednesday, May 24, revealed that the spacecraft was very close to having a successful touchdown on the Red Planet on Oct. 19 last year but the engineers did not realize how jarring the lander's parachute descent could be, which had consequential effects that doomed the mission.
Scientists noted that the probe's six-minute descent went as anticipated with Schiaparelli able to enter Mars's atmosphere correctly and protected by its heat shield from getting burned up.
Three minutes after it entered the Martian atmosphere, the probe experienced "unexpected high rotation" that led to saturation of one of the craft's instruments that tracks spin rate.
The input to the Inertial Measurement Unit, or IMU, which exceeded the programmed measurement range, resulted in a major altitude error in the spacecraft's guidance, navigation and control system software. The computer then decided that the spacecraft was below ground level when it was in fact still 2 miles up.
As a result, Schiaparelli released its parachute and backshell early. It also fired its landing thrusters for only three seconds instead of the supposed 30 seconds.
The spacecraft then plunged destructively hitting the Martian surface at a speed of about 335 miles per hour. The crash left a crater that was later imaged by the high-resolution cameras of NASA's Mars Reconnaissance Orbiter.
Root Causes Of The Failed Mission
The authors of the report believe that the spacecraft may have still landed safely on the Martian surface after the wrong handling of IMU data had there been other checks and balances.
The investigators ruled out a fault with the IMU itself and identified several other root causes that led to the failure of the mission, and these include insufficient computer modelling of the parachute dynamics, problems with subcontractors' management, inadequate approach to detecting faults and the guidance software's inadequate handling of the IMU data.
"Interestingly, had the saturation not occurred and the final stages of landing had been successful, we probably would not have identified the other weak spots that contributed to the mishap," said ESA director general Jan Woerner. "As a direct result of this inquiry we have discovered the areas that require particular attention that will benefit the 2020 mission."
Lessons From Schiaparelli
Several recommendations were made as a result of the investigation and prior to sending another rover to Mars in 2020. Schiaparelli is a technology demonstrator that was supposed to provide learning experience needed for the joint ESA and Roscosmos ExoMars mission.
Among the recommendations is to ask the U.S. space agency, which has successfully landed Martian spacecraft on the Red Planet seven times, to validate the computer models that are used for planning the ExoMars rover mission's entry and descent to the Martian surface in 2021.
