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Thursday, April 01, 2010

Phoneix--Space craft (amazing design)

This is not the bird but designed to live with the help of sun - the Mars Phoneix space craft. Again this was collective information from my own readings.

This was the first lander on the Martian polar region and has the privilege of getting snapped by another object in space - the MRO (Mars Reconnaissance Orbiter). The MRO took a poto of Phoneix during its landing - photo shows "Phoneix with parachute" - the last minute stage of its landing on Mars.

It was a first of a kind where a soft landing of a space craft was successfully implemented on another planet. The atmosphere on Mars also handed its help to the success. All other landings on any other planet were on crash mode. Even the rovers on the mars have a landing with air balloon which was also a crash type.

Few statistics of Phoenix:

· Duration of travel from Earth to Mars: 9 months

· Time taken for a signal to be received from Phoneix: 10 minutes

· The speed of Phoneix when it reached Marsian atmosphere: ~15000miles per hour

· The speed has been reduced to 125mph before it touches the ground within 7minutes of its entry into Marsian atmosphere. This was achieved by deploying a parachute that drastically reduced the speed of the craft and also by the friction caused by the atmosphere

· Entire duration of Entry Descent and Landing (called in NASA Terms as EDL): 7 minutes

As mentioned earlier, it takes 10 minutes for any signal to reach Earth, by the time a signal for EDL has been received; we can safely assume all the stages of EDL are over. This gives a challenge as to every decision has to be made by the space craft and not manually controlled from Earth. A point to note is - the signal so far was direct from Phoneix to Earth.

The EDL contains the following steps:

E- Entry - with the help of heat shield to protect the Phoneix from extreme heat. The heat shield surface temperature during entry was expected to be closer to temperature on the surface of the sun (2500F). But the inner temperature was maintained close to a normal room temperature to protect the space craft. This is an amazing achievement.

D- Descent - achieved by deploying parachute which again reduces the speed of the space craft. Once the speed is 125 mph, the heat shield is jettisoned and for the first time the Phoneix is exposed to Martian atmosphere.

L - Landing: The Phoneix should deploy its legs now and start calculating how far it is from surface. Based on which it decides when to leave the parachute. After which it is a free fall from space. Once close to the surface it starts its thrust engine and lands safely on the surface.

Few unknown facts about Phoneix:

Fact 1-Has survived more than the actual duration and worked greatly. Phoneix's last message to Earth was "Triumph" which it sent in binary code to MRO after which it went to sleep mode (dead).

Fact 2-The signal to Phoneix happened via MRO. The order is Phoneix ->MRO->Earth and vice versa. MRO is a satellite launched some time earlier to study the surface of Mars. All communications to Phoenix from Earth happened via MRO. It makes 2 complete rotations on one Martian sols (1 sols = one solar day of Mars). Hence, Phoneix can get the signal from Earth twice a day. They used the first one to send data to Phoneix (via MRO from Earth) and the second one to receive data from Phoneix (via MRO to Earth).

Fact 3-All instructions for the whole day have been sent in the first attempt. The results are received on the second attempt.

Fact 4-Still scientists are trying to establish communication after its dead message due to no light because of Mars winter. There is one more attempt to be made in April 2010 to see if there is a signal of hope from Phoneix.

Fact 5-There was a landing camera installed on the bottom of the space craft to capture the landing of the space craft. At last minute during the body built of Phoneix it was found that turning on the landing camera would disrupt the Phoneix memory. So it was decided not to switch on the camera as it was too late and the date for launching was already near. Phoneix was too late to repair at that stage. (If everything went ok – we would have seen now how exactly Phoneix has landed in his last minutes of descent)

Fact 6-There was also a sound recorder on board to record Martian sound but this was never turned on. Phoneix life time was used to do most of the soil analysis and slowly Phoneix started losing its power because of blooming Martian Winter. At last stage a decision was taken to turn on this mic but it was again too late as Phoneix was into dead mode the next day. So this message could not be delivered to Phoneix. (Again – if this went ok, then we would be playing first sound from Mars in Youtube).