NOMAD successfully entered orbit around Mars

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NOMAD successfully entered orbit around Mars.


ExoMars 2016 is a joint mission between the European Space Agency (ESA) and the Russian Federal Space Agency (Roscosmos). On March 14th 2016, it was launched from the Baikonur Cosmodrome in Kazachstan on a Russian Proton Launcher. After a journey of 7 months and 500 million kilometers, the Trace Gas Orbiter (TGO) spacecraft, carrying the science instruments and the entry, descent and landing demonstrator module (EDM) known as Schiaparelli, had the Red Planet Mars in their sights. On October 16th, 2016, the ExoMars2016 mission entered a critical phase: the separation of the lander Schiaparelli from the orbiter TGO and preparation for landing on Mars & Mars Orbit Insertion (TGO).

 
Trace Gas Orbiter correctly placed into orbit around Mars …

On October 17th, at 04:42 CEST the TGO completed an orbit raising manoeuvre as planned. Without the manoeuvre, the TGO spacecraft would, like Schiaparelli, remain on a collision course with Mars. The engine was fired for about 106s and TGO’s orbit was raised by several hundred km ‘above’ the planet, ahead of its planned orbit insertion on October 19th. Signal with the TGO was reacquired after the burn indicating that TGO and its passenger NOMAD are on a safe course towards and around Mars.
On October 19th, at the same time the Schiaparelli was taking is final critical descent hurdles, the TGO performed its Mars Orbit Insertion manoeuvre through a 139 minute burn, reducing the spacecraft's speed and direction by more than 1.5 km/s. As such the TGO entered, as planned, a highly elliptical orbit that takes it from between 230 and 310 km above the surface to around 98000 km every 4.2 days. NOMAD made it safely to its new home.
ESA teams at the European Space Operations Centre (ESOC) in Darmstadt, Germany, continued to monitor the good health of their second orbiter around Mars, which joins the 13-year old Mars Express, on which OIP’s Visual Monitoring Camera, known as the Mars Webcam, was adopted last summer as a fully professional science instrument.



Credit ESA/ATG medialab: The Trace Gas Orbiter carrying the 4 science payload orbiting around Mars.

 

 
Schiaparelli crash-landed on Mars …

TGO’s companion had a less fortunate encounter with Mars. During the 7 month journey, all went smooth, but only in the last 40 seconds prior to landing on Mars, the theory and practice did not match up.

During the final descent stages, Schiaparelli’s signal was lost and could not be picked-up in the following hours. After review of the essential data downlinked by Schiaparelli’s loyal companion TGO, it became clear that the atmospheric entry and associated braking occurred exactly as expected, with events diverging from what was expected after the ejection of the back heat shield and parachute.

• The parachute deployed normally at an altitude of 12km and a speed of 1730 km/h.
 
• The vehicle's heatshield, having served its purpose, was released nominally at an altitude of 7.8 km.
 
• As Schiaparelli descended under its parachute, its radar Doppler altimeter functioned correctly. However, saturation of the Inertial Measurement Unit (IMU), which measures the rotation rates of the vehicle, had occurred shortly after the parachute deployment. Its output was generally as predicted except for this event, which persisted for about one second.
 
• When merged into the navigation system, the erroneous information generated an estimated altitude that was negative – that is, below ground level. This in turn successively triggered a premature release of the parachute and the backshell, a brief firing of the braking thrusters and finally activation of the on-ground systems as if Schiaparelli had already landed. In reality, the vehicle was still at an altitude of around 3.7 km

What followed is clear .. Schiaparelli crashed on the Red Planet, nearly spot-on at the foreseen landing zone. A day later NASA’s Mars Reconnaissance Orbiter (MRO) imaged the landing / crash site and essential features (parachute, heatshields, impact crater, ..) could be observed. With Schiaparelli crash-landed on Mars, the DECA instrument was declared “lost in action” ..

More information can be found here.


 

Success and disappointment walk hand in hand ..

“We have an impressive orbiter around Mars ready for science and for relay support for the ExoMars rover mission in 2020," says Jan Wörner, ESA's Director General. "Schiaparelli's primary role was to test European landing technologies. Recording the data during the descent was part of that, and it is important we can learn what happened, in order to prepare for the future."

Michel Denis, ExoMars 2016 Flight Operations Director summarized it nicely: “ExoMars 2016 is on … We have a mission around Mars”!

Europe’s Mars exploration can start! And we (OIP Sensor Systems) are part of this!

 


DECA’s final moments …

DECA’s operation was planned during Schiaparelli’s descent from the moment the rear heatshield was jettisoned until the switch-ON of the thrusters. In this phase the Inertial Measurement Unit (IMU) recorded wrong data, but the DECA operated nominally, as was demonstrated by recovered housekeeping data that was sent to TGO.
Few housekeeping data related to the Descent Camera were retrieved, but from these it is understood that the small camera did perform as expected. It was observed that the camera was switched on, did a warm-up for 5 seconds and started image acquisition.
Unfortunately it was planned to downlink the captured images only after landing on Mars. As a consequence of the landing ‘anomaly’ the images remain forever on Mars .


 
ESA’s new Mars orbiter (TGO) prepared for science …

In November 2016, 1 month after arrival, the Trace Gas Orbiter tested its four science instruments during two orbits of Mars.


Credit: ESA/ATG medialab: Artist's impression of the ExoMars 2016 Trace Gas Orbiter (TGO) science payload side.

 

On November 20th, NOMAD was switched on for a session of 8 days of observations in a high elliptical orbit around Mars (MCO - Mars Capture Orbits). The 3 channels of NOMAD (SO, LNO and UVIS) have been operated and show nominal behavior! Also NOMAD’s conditions (power, temperature, detector cool down, etc) are as expected.
Slit images and spectra of sun observation in SO, LNO and UVIS have been successfully acquired by the 3-suite spectrometer. A great achievement for the NOMAD team who is now looking forward to the science phase of 2018, now only 1 year of aero-braking away.

 
 
Credit BIRA: (a) NOMAD’s SO-channel spectrum of a sun observation; (b) LNO-channel slit image and (c) UVIS-channel spectrum of sun observation.
 
More information can be found here.

 


NOMAD’s first look at the Martian atmosphere ..

TGO's main goal is to make a detailed inventory of rare gases that make up less than 1% of the atmosphere's volume, including methane, water vapour, nitrogen dioxide and acetylene. Of high interest is methane, which on Earth is produced primarily by biological activity.

The two instruments tasked with this role have now demonstrated they can take highly sensitive spectra of the atmosphere. During the test observations last week, the ACS payload focused on carbon dioxide, which makes up a large volume of the planet's atmosphere, while the NOMAD payload homed in on water .. with success.

The main science mission will only begin once TGO reaches a near-circular orbit about 400 km above the planet's surface after a year of 'aerobraking' – using the atmosphere to gradually brake and change its orbit. Full science operations are expected to begin by March 2018.


Credit Copyright: ESA/Roscosmos/ExoMars/NOMAD/BISA/IAA/INAF/OU: First look at the Martian atmosphere with the discovery of water vapour (LNO and SO-channels) [left] and solar spectrum with atmospheric absorptions by solar features (UVIS-channel) [right].




OIP has now 2 operational payloads orbiting Mars ..

From October 19th onwards, OIP is pleased to announce that we have 2 scientific payloads orbiting Mars. The disappointed of not having the descent images from the DECA is flushed away by seeing nice sun observation spectra coming from the NOMAD spectrometer, which looks in great shape. Also the modest Mars Webcam onboard Mars Express is providing the scientist valuable information of Mars weather conditions.

The DECA team has the comfort that the camera performed as planned.

More information on the Mars Webcam: Mars Webcam blog 
More information on NOMAD science: NOMAD webstory (BIRA)



Credit: OIP Sensor Systems. Mars Webcam (left) and NOMAD spectrometer (right). Instruments are not to scale




Next milestones …

TGO is now preparing for the 1-year long aerobraking phase which will start in spring 2017 and lasting till spring 2018. All science instrument will be silent in this period.




For more information:

Contact Lieve De Vos, Director Space Department, +32 55 333 836, e-mail ldv@oip.be
OIP Sensor Systems, Westerring 21, B-9700 Oudenaarde