June sees Mars an Earth move into a period of solar conjunction, when they are one opposite sides of the Sun relative to one another. These periods of conjunction occur roughly every 26 months (the last having been April 2013), can see communications between Earth and vehicles operating on and around Mars severely disrupted due to interference from the Sun.
To prevent spacecraft at Mars from receiving garbled commands that could be misinterpreted or even harmful, the operators of Mars orbiters and rovers temporarily stop sending any commands. At the same time, communications from the craft to Earth are also stepped down, and science operations scaled back. Nasa started to do this on Sunday, June 7th, and both ESA and the Indian Space Research Organisation will be doing the same. For the two Mars rovers, Opportunity and Curiosity, it means parking up and no driving until after full communications are restored. General science observation will, however, continue.
One slight difference in all this will be with NASA’s newest orbiter at Mars: MAVEN (Mars Atmosphere and Volatile Evolution). This arrived over Mars in September 2014, with the primary mission of determining the history of the loss of atmospheric gases to space and gain insight into Martian climate evolution. As such, MAVEN will continue monitoring the solar wind reaching Mars and making other measurements. The reading will be stored within the orbiter’s memory system and transmitted back to Earth once normal communications have been restored.
MOM Studies Mars’ Volcanoes
Another mission that hasn’t gained much attention since also arriving in orbit around Mars is India’s Mangalyaan (“Mars-craft”) vehicle, which reached Mars on September 24th, 2014. Referred to simply as the Mars Oribiter Mission (MOM) by most, the vehicle reached Mars just 2 days after NASA’s MAVEN orbiter, and like that craft, a part of its mission is focused on studying the Martian atmosphere.
MOM also carries a high-resolution surface imaging camera, and this has been busy returning some magnificent picture of Mars, including the brilliant picture of the planet reproduced above, which shows the north polar ice cap, the almost vertical line of the three massive Tharsis Bulge volcanoes of Ascraeus Mons, Pavonis Mons and Arsia Mons in the centre, the massive rise of Olympus Mons, the largest volcano in the solar system to their left, and the 5,000 kilometre scar of the massive Vallis Marineris to their right.
MOM’s camera is also capable of producing 3D images, and an example of this capability was released by ISRO on June 5th in the form of a dazzling image of Arsia Mons, the southernmost of the equator spanning Tharsis volcanoes. The image was actually captured on April 1st, 2015, and has a spatial resolution of 556 metres, and the camera some 10,707 kilometres from the surface of Mars when the picture was taken.
To give some idea of the scale of this massive shield volcano, it is 435 kilometres (270 mi) in diameter at its base, rises some 20 kilometres (12 miles) in height compared to the mean surface elevation of the planet, and is some 9 kilometres (5.6 miles) higher than the plains on which it sits. The caldera crater at its summit is 110 km (72 miles) across.