Phoenix near landing.
Published on May 23, 2008 at 11:57 pm.
1 Comment.
Filed under Mars, space exploration.
Wow, it’s been a long and difficult month for me. It has been one thing after another all month. As my regular readers can see, I have not been keeping up with Astroprof’s Page much this month. In fact, this has been the slackest month, I think, since I started blogging!
So, it is perhaps fitting that I begin with writing about the Phoenix Mars mission. It is about to land on Mars (in a bit under two days). The Phoenix was named for the mythical bird, the phoenix. According to legend, the phoenix at the end of its life built a nest and then burst into flames. The bird and the nest were consumed by the fire, leaving nothing but ashes. Then, a new phoenix emerged from the ashes. The phoenix never really died, it was reborn. According to legend, it could not be killed either. It would heal itself from any injury. If injured bad enough, it would simply burn and be reborn whole. It is from this story that the phrase “rising from the ashes” got its start.
And rising from the ashes is what this mission is about. The Phoenix mission concept dates back over a decade. We’ve suspected that Mars at one time had a lot of water for decades — ever since the Viking orbiters sent back pictures that showed what looked like dry river beds. We didn’t have proof of that until recent missions. Water is important. Without it, there is no life. But, water does not mean that there is life. It only means that there could be life (Of course, we are talking about life as we know it. But, if it is not life as we know life, would we recognize it as life? Just what is life?). We know that the polar regions are places where there are ice caps. Some of the ice in the ice caps is frozen carbon dioxide. But, some of the ice is believed to be water. Almost all of the missions to land on Mars have been to regions near the planet’s equatorial regions. That make sense, because that would be where the planet is warmest. But, studies of the polar regions are also important. That is why NASA decided to send a spacecraft to land near the southern polar regions. Unfortunately, that mission failed. Communications were lost with the lander as it entered the atmosphere. It was never heard from again. An analisis of the mission suggests that perhaps the landing engines shut off while the lander was still too far above the surface of the planet to survive the fall that resulted from premature engine shutdown.
The loss of the Mars Polar Lander and its sister ship, the Mars Climate Orbiter, temporarily put the brakes on NASA’s exploration of Mars. However, Mars exploration resumed. And, another mission to the Martian polar regions emerged from the ashes of the previous mission’s failure. That is the Mars Phoenix lander. It was launched August 4, last year. It is scheduled to land on Mars on May 25, 2008.
This new lander was built using lessons learned from earlier missions (successes and failures). There is every reason to hope for success. However, landing will be awfully stressful for the folk on the Phoenix team. Mars it rough on spacecraft. Over half of the space missions to Mars have failed. Over half of the missions that have tried to land on Mars have failed, too. I cover this in my planetary astronomy class, and I often play the rather humorous YouTube video clip here about the failures.
So, you can bet that they’ll be biting their names Sunday night when this thing approaches Mars. The Phoenix lander will enter the atmosphere, experience intense atmospheric heating and G-forces, slow to a reasonable speed to deploy a parachute to slow it more. Then, it will drop away and fire its own landing rockets until it comes to rest on the Martian surface. It will then deploy its solar panels and try to contact Earth. There is a lot that can go wrong. The Martian atmosphere is not well understood, so we don’t know exactly how high it will be when it encounters its strongest stresses. If something goes wrong at that point, it may burn up. Or, the parachute might not deploy and it will be dashed to pieces on the Martian surface. Or, the parachute might not detach and it gets tangled up in it. Or, the rockets might fire too early or too late. Or, they may shut off early. Or, it might land on a large rock, tipping it over. Or, it might land on the edge of a crater or hill, causing it to roll over. If any of those things happened, then we might never hear from it. Of course, not hearing from it doesn’t mean that it is lost. After all, it might just be having a tough time finding Earth to send a signal back, or it may have a radio malfunction, or there may be any number of other things. So, if they don’t hear from it, they’ll just keep listening and biting their finger nails. It will be a very anxious time for them. But, if everything works, they will be overjoyed. That’s how these sort of missions go.
So, let’s wish Phoenix good luck.
-Astroprof
Ed Davies on May 24, 2008 at 7:58 am: 1
“If any of those things happened, then we might never hear from it. Of course, not hearing from it doesn’t mean that it is lost. After all, it might just be having a tough time finding Earth to send a signal back, or it may have a radio malfunction, or there may be any number of other things.”
Hmmm, from what I’ve read it’ll be talking all the way through entry, descent and landing on UHF to all three of the active orbiters - apart from a few minutes of ionization blackout, of course. Presumably the UHF transmission is omnidirectional so there shouldn’t be any problems with finding Earth or whatever. In other words, they might lose the signal at some point but it’s not a case of waiting to hear from the spacecraft, other than after ionization blackout.
It’s good that there are now three orbiters there to follow along (a bit of exploration infrastructure) and that the lessons of previous missions (I’m thinking of Polar Lander and Beagle) about telemetry during descent have been acted on. Doing communications during the landing might not be the optimum thing for any individual craft but is beneficial to the overall Mars exploration program as any failure’s lessons can be learned less speculatively.
Like the video. In a back-to-front sort of way it’s a good reminder of just how big Mars is.