Three Mars missions arrive at same time: UAE’s Hope Probe, China’s Tianwen and finally USA’s Perseverence


Just like London buses, three Mars missions all seemed to arrive at the same time.  While this was mainly due to planetary alignments favouring certain launch and thus arrival dates, inexpert media commentators noted that a “race” had happened and that the United Arab Emirates had won.  Nevertheless, actually it was true that UAE’s HOPE orbiter spacecraft had arrived first.  The Al’ amal (Hope Probe) used a 27 minute burn of six of its thrusters to brake itself into Mars orbit which it entered at 1737 on 9 February.  While the Mars probe was designed by the MBRSC – Mohammed Bin Rashid Space Centre (MBRSC) it used a bus/platform built by the University of Colorado. Its international nature continued with its launched on 19 July 2020 by a Japanese H-2A202 (SRB-A3) rocket.

Illustration showing UAE’s Hope Probe around Mars. Courtesy: MBRSC

UAE thus became the fifth mission to successfully put a probe into orbit around Mars.  The initial 49,380 x 1000 km orbit will later be circularised to its 43,000 km operational orbit inclined at 25 degrees from where it will measure the Martian atmosphere using its instruments.  One of its research objectives is to research how water vapour leaks from the planet and how heat is transferred through the atmosphere.

Next to get to the planet was China’s first interplanetary mission, Tianwen-1, which successfully entered Mars orbit on 10 February.  It fired its 3 kN rocket engine to slow itself into orbit around the planet at 1152 GMT which it enters at circa 1200 GMT.  From its very elliptical orbit of circa 180,000 x 400 km with an inclination of 10 degrees, the orbit will be circularised and slowly lowered. The mission consists of an orbiter, lander and rover with a landing attempt set for late May or early June.  Tianwen was launched on 23 July 2020 by a Long March 5B (Y4).

The 5 metric ton Tianwen was built by CAST and its name in Chinese means “Questions to Heaven” from a poem by Qu Yuan (340 278 BC).  The orbiter has a topography and science mission and carries a high-resolution panchromatic camera (HRC), a medium resolution colour camera (MRC) for Mars surface topography, an HF/VHF radar (OSR) for subsurface structure, a visible to infra-red spectrometer (MMS) for surface mineralogical composition, a magnetometer (MM) for Solar and Martian fields, an analyser (MINPA) for low-energy ions and neutral particles and a detector (MEPA) for high-energy electrons, protons and heavier ions.

Image of Tianwen-1 spacecraft taken by an external remote camera spacecraft during its journey to Mars. Courtesy: CNSA

The rover is expected to last just over 3 months on the surface.  It carries high and medium resolution cameras (NTC) for navigation and surface topography, an ultraviolet to infra-red multispectral camera (MSC) for surface imaging and composition a VHF radar (GPR) for subsurface composition, a magnetometer (MSMFD) for fields near surface and instruments (MMMI) for atmospheric temperature, pressure and wind.

The final mission to arrive – or rather expected to arrive – is the NASA Perseverance Rover.  It was launched on 30 July last year by an Atlas V 541/RL10C-1 rocket. It arrives at Mars on 18 February and is designed to make a direct entry into the Martian atmosphere from the interplanetary transfer orbit.  If landed successfully, the rover is designed to study and collect samples via a variety of instruments as part of its attempt to examine if Mars even sustained biological life.  Some of the samples are later to be recovered by a separate sample return mission.  The rover is also to test out oxygen production technologies on the planet.  It also carries a 2kg camera-equipped helicopter drone called INGENUITY for performance test.

Mars Perseverance Rover’s landing sequence. Courtesy: NASA/JPL-Caltech