No room for mistakes with mission to Mars
DUBAI // Firing an orbital probe from Earth, having it travel through space at the correct trajectory before finally entering a level orbit around Mars is a precisely choreographed dance that can allow for no mistakes.
To date, there have been 41 past missions to the red planet, many of them from established space agencies, and only 16 have been a total success.
To ensure that the UAE’s mission achieves its goal, the country’s newly established space agency will have to draw upon the lessons of previous attempts, as well as coordinate closely with international parties to ensure there is no room for failure.
“The majority of things we’ve sent to Mars have failed,” said commander Chris Hadfield, the Canadian astronaut who was in the Emirates last week to meet officials from the country’s nascent space agency.
“However, there have been a lot of lessons learned, and the space agency is going to have to piggyback on a lot of those lessons.
“The physics, the fundamental mechanics of the launch, are the same for everyone. It’s not necessary to start from absolutely zero. There are, however, many ways that those mechanics could be improved upon.”
The UAE has proposed using an orbiter for its mission following the success of Nasa’s Mars Odyssey. Launched in 2001, it has continued to circle the planet for 13 years, regularly beaming back images of its unique geological formations.
To send a satellite from Earth to Mars, the first thing that needs to be carefully taken into account is the Earth’s rotation, its relation to the Sun, and the relative position of Mars.
A journey can take anything from 200 days, in the case of Odyssey, to almost three years, depending on the angle of the launch.
Odyssey was housed in a series of interlocking rockets that first sent it into the Earth’s atmosphere, like a normal satellite. At the precise moment, it was spun out from our planet’s orbit to complete a long journey through the vast emptiness of space.
The journey took it in a wide arc, slightly less than 180 degrees around the Sun, until it reached Mars. At the initial stages of the interplanetary stage, the solar array on the spacecraft was deployed, along with an antenna to communicate with Earth.
In its 200-day mission, scientists at control centres around the world calibrated Odyssey’s scientific payloads. It, in turn, communicated its position to Earth by using star charts for reference and an on board inertial measurement unit.
It was able to fire its on-board thrusters only five times during this stage to correct its course.
At the time of its approach to Mars, Odyssey fired its engines for 22 minutes to be captured by the planet’s gravity. It entered an elliptical, or “egg-shaped” orbit.
It was gradually able to change its orbit into a more regular, circular shape, by a technique known as “aerobraking”.
This involved using the frictional drag of the spacecraft in the upper atmosphere of Mars to lose some of its momentum on each subsequent pass of the planet. It took about a week of minor calibrations and adjustments for the spacecraft to be in the desired orbit, and 45 days after its arrival in Mars’ orbit for the mission to begin.
“It requires massive planning at every stage of the mission,” said Mr Hadfield. “There are questions over how do you make it robust enough to withstand the radiation between planets? How do you make a stable enough fuel? How do you cool your vehicle? How do you provide enough power for the whole lifetime model?
“There are so many things to consider, and so many things that can go wrong. Thankfully, there’s enough examples now that the UAE doesn’t need to start from zero when answering these questions.”
Published: July 27, 2014 04:00 AM