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Huygens set for Titan encounter

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*"Curse of Titan": Every attempt so far to get some idea of what's on the surface has failed. Regular images, IR, radar etc all were blocked by one substance or another in the atmosphere.

Quote[/b] ]

Huygens set for Titan encounter [bBC]

The Huygens spacecraft is ready to make history as it heads for its rendezvous with Saturn's smog-shrouded moon Titan.

On 14 January, Huygens will dive through Titan's atmosphere taking images and readings on the way.

Its scientific investigation of this mysterious world could yield clues to how life first arose on Earth. The robotic lab will hit Titan's atmosphere at 0907 GMT. If all goes well, it will be the furthest from Earth a spacecraft has been landed.

Huygens has been coasting silently towards the Saturnian moon for about 20 days since being released from its mothership.

Fast entry

Four hours before it arrives, the 319kg robotic lab will be woken up by a timer.

This will warm up the probe's instruments to optimise communications between Huygens and its mothership Cassini during the encounter. Data gathered by the spacecraft on its two-and-a-half-hour descent to Titan's surface, should give detailed information on the moon's weather and chemistry.

When the European-built probe enters Titan's atmosphere at an altitude of 1,270km (789 miles) from the surface, it will be travelling at over Mach 20 which is 20 times the speed of sound.  Once friction will slow the probe's descent to about Mach 1.5, it will deploy the first of three parachutes.

If the first and second parachutes open when Huygens is travelling too fast - over Mach 2 - they risk being shredded.

If they open once the spacecraft has slowed to about Mach 1, the probe will become unstable as it descends through the "air". This means the first two chutes must be deployed within a window of just 30 seconds.

Dominated by nitrogen, methane and other organic (carbon-based) molecules, conditions on Titan are believed to resemble those on Earth 4.6 billion years ago. As such, it may tell scientists more about the kind of chemical reactions that set the scene for the emergence of life on Earth.

Scientists hope Friday's spectacle will solve the mystery of what lies on Titan's surface. The probe could land with a thud on an icy-rocky surface, squelch into tar-like gunge, or splash down in an oily sea.

Huygens has spent the past seven years tethered to the Cassini spacecraft, which arrived at Saturn in July 2004

Old Titan thread (I wanted a poll this time):

http://www.flashpoint1985.com/cgi-bin....78;st=0

Personally, I'm thinking it will be a success smile_o.gif

Edit:

ESA Cassini-Huygens Homepage

NASA Cassini-Huygens Homepage

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If the Red Sox can break the curse of the bambino maybe this too shall be broken.

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Nah, it will smack into the defense sheilds, the debris will ricochet off and knock Cassini's antenna's away from Earth, and bump Cassini into terminal fall into Saturn. Yoda's not ready to be found.

But it's still a tossup whether not the whole thing is going to work or not. There was a large writeup about it in IEEE Spectrum a few months back about how a critical communications module from an Italian supplier forgot to compensate for an aspect of Doppler shift. Basically, in doppler shift you get frequency shifting. They remembered to handle frequency drift compensation, but forgot that bps is also related. I forgot how they discovered the problem after launch, but they couldn't test it beforehand in the lab because the vendor didn't want to be friendly with their intellectual property.

Any supposedly that's all fixed, we'll see how it goes.

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hmmm, doppler shift.... that means that either

A) it will become long wave.....

B) the frequency will be unfindable

C) it will turn into microwaves tounge_o.gif

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Yepp, I read about the doppler incident too. That's one bug they actually found. Who knows how many are left?

One thing that I can't understand is the design of the communications system. Apparently Cassini only has one antenna, so it can't receive and send data simultaneously. So they have to wait for the complete transmission from Huygens before they can send any info to Earth. How hard would it have been to add one more antenna? I mean, the thing already weighs a few tons, how much would another few kg hurt?

Second, the implicit trust in timers and the control software is worrying. The probe has been totally autonomous since its departure from Cassini (around Christmas), and we won't get anything from it until Cassini sends it all - after the whole thing is done. For all we know, the probe could be on its merry way to Pluto right now. There's no way of telling.

The third thing that I disapprove of is the incredebly short battery time of the probe. It's got enough juice for a few hours descent and a few minutes on the surface. It seems to me like on a probe that weighs nearly 400 kg, they could have added one or two kg:s of more batteries. It seems such a waste to bring it so far, spend so much money and then just forget about the whole thing after a few minutes operation on the surface.

Well, regardless, I really hope it will have better luck than the Beagle 2 probe that (persumably) smacked into Mars.

There is a difference though. The Beagle was a very low-cost project made for the most part by semi-amateurs at a British university. Huygens on the other hand is old-school ridiculously expensive stuff, made by professionals in the space business.

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Yepp, I read about the doppler incident too. That's one bug they actually found. Who knows how many are left?

One thing that I can't understand is the design of the communications system. Apparently Cassini only has one antenna, so it can't receive and send data simultaneously. So they have to wait for the complete transmission from Huygens before they can send any info to Earth. How hard would it have been to add one more antenna? I mean, the thing already weighs a few tons, how much would another few kg hurt?

Actually Cassini has three antennas. One high-gain and two-low gain for two way communication.

Cassini Craft

The Hyugens is two parts. One the "probe support station" attached to the Cassini probe proper, and the lander (which itself consists of various parts)which will be making the descent. The lander will be sending data directly to the Hyugens base, which in turn will send it to the Cassini orbiter which will be sending the data.

And you should know that a few kg's can always hurt...

Quote[/b] ]

Second, the implicit trust in timers and the control software is worrying. The probe has been totally autonomous since its departure from Cassini (around Christmas), and we won't get anything from it until Cassini sends it all - after the whole thing is done. For all we know, the probe could be on its merry way to Pluto right now. There's no way of telling.

No different than any other mission as far as I know. Only way to control a spacecraft when instantanous communications are not as yet possible.

Quote[/b] ]The third thing that I disapprove of is the incredebly short battery time of the probe. It's got enough juice for a few hours descent and a few minutes on the surface. It seems to me like on a probe that weighs nearly 400 kg, they could have added one or two kg:s of more batteries. It seems such a waste to bring it so far, spend so much money and then just forget about the whole thing after a few minutes operation on the surface.

Actually the descent will take very little power (whatever it takes to release the heat shield at the right moment and initiate parachute deployment). I can't find much about the actual time on site, but this page says that a parachute will deploy slowing for about 15 minutes while the initial measurements are being made. This language leads me to believe that it will live longer than 15 minutes. It also mentions the remaining descent will take about 2.5 hours.

EDIT: Oh yeah...and I voted "It will be a success" because I'm an optimist too tounge_o.gif

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Actually Cassini has three antennas. One high-gain and two-low gain for two way communication.

Cassini Craft

Ok, I suppose that the one-way communication is when they send larger quantities of data, that requires bandwith, while the duplex communication is limited to commands and the orbiter's responses.

Quote[/b] ]The Hyugens is two parts. One the "probe support station" attached to the Cassini probe proper, and the lander (which itself consists of various parts)which will be making the descent. The lander will be sending data directly to the Hyugens base, which in turn will send it to the Cassini orbiter which will be sending the data.

Well, Cassini will first collect the data, and first when the upload is complete, it will send it to Earth.

Quote[/b] ]And you should know that a few kg's can always hurt...

Cassini weighs around 5,500 kg, of which some 3,500 is propellant. Given the obscene amount of turns and twists it does around Saturn (not seldom through thruster control bursts), one would imagine that they could skip a few orbits to pack some batteries.

The Huygens mission is far to short for my liking. I'd like something in the style of the Mars rovers. Granted, they can use solar power on Mars while Titan is too far away for sunlight to be useful. Still, given the cost to get there, why not make more out of it? Slap on a reactor if you have to.

(Good news: We found life on Titan! Bad news: We nuked em' tounge_o.gif )

Quote[/b] ]No different than any other mission as far as I know. Only way to control a spacecraft when instantanous communications are not as yet possible.

I'm talking about leaving some time for corrections should something go wrong, or at least inform us if something has gone wrong (Huygens doesn't have any propulsion system IIRC). Right now it's a 20 day complete blackout. All sort of things could have gone wrong, and if they have, we have really no way of telling what went wrong. So if there was some form of fatal error, we won't be able to learn from it.

Quote[/b] ]

Actually the descent will take very little power (whatever it takes to release the heat shield at the right moment and initiate parachute deployment). I can't find much about the actual time on site, but this page says that a parachute will deploy slowing for about 15 minutes while the initial measurements are being made. This language leads me to believe that it will live longer than 15 minutes. It also mentions the remaining descent will take about 2.5 hours.

Timeline, from ESA, all times CET and "Earth Received" time - i.e. 67 minutes after the actual events have taken place at the spacecraft:

Quote[/b] ]

6.51 Timer triggers power-up of onboard electronics

Triggered by a pre-set timer, Huygens's onboard electronics power up and the transmitter is set into low-power mode, awaiting the start of transmission.

11.13 Huygens reaches 'interface altitude'

The 'interface altitude' is defined as 1270 kilometres above the surface of the moon where entry into Titan's atmosphere takes place.

11.17 Pilot parachute deploys

The parachute deploys when Huygens detects that it has slowed to 400 metres per second, at about 180 kilometres above Titan's surface. The pilot parachute is the probe's smallest, only 2.6 metres in diameter. Its sole purpose is to pull off the probe's rear cover, which protected Huygens from the frictional heat of entry. 2.5 seconds after the pilot parachute is deployed, the rear cover is released and the pilot parachute is pulled away. The main parachute, which is 8.3 metres in diameter, unfurls.

11.18 Huygens begins transmitting to Cassini and front shield released

At about 160 kilometres above the surface, the front shield is released. 42 seconds after the pilot parachute is deployed, inlet ports are opened up for the Gas Chromatograph Mass Spectrometer and Aerosol Collector Pyrolyser instruments, and booms are extended to expose the Huygens Atmospheric Structure Instruments.

The Descent Imager/Spectral Radiometer will capture its first panorama, and it will continue capturing images and spectral data throughout the descent. The Surface Science Package will also be switched on, measuring atmospheric properties.

11.32 Main parachute separates and drogue parachute deploys

The drogue parachute is 3 metres in diameter. At this level in the atmosphere, about 125 kilometres in altitude, the large main parachute would slow Huygens down so much that the batteries would not last for the entire descent to the surface. The drogue parachute will allow it to descend at the right pace to gather the maximum amount of data.

11.49 Surface proximity sensor activated

Until this point, all of Huygens's actions have been based on clock timers. At a height of 60 kilometres, it will be able to detect its own altitude using a pair of radar altimeters, which will be able to measure the exact distance to the surface. The probe will constantly monitor its spin rate and altitude and feed this information to the science instruments. All times after this are approximate.

12.57 Gas Chromatograph Mass Spectrometer begins sampling atmosphere

This is the last of Huygens's instruments to be activated fully. The descent is expected to take 137 minutes in total, plus or minus 15 minutes. Throughout its descent, the spacecraft will continue to spin at a rate of between 1 and 20 rotations per minute, allowing the camera and other instruments to see the entire panorama around the descending spacecraft.

13.30 Descent Imager/Spectral Radiometer lamp turned on

Close to the surface, Huygens's camera instrument will turn on a light. The light is particularly important for the 'Spectral Radiometer' part of the instrument to determine the composition of Titan's surface accurately.

13.34 Surface touchdown

This time may vary by plus or minus 15 minutes depending on how Titan's atmosphere and winds affect Huygens's parachuting descent. Huygens will hit the surface at a speed of 5-6 metres per second. Huygens could land on a hard surface of rock or ice or possibly land on an ethane sea. In either case, Huygens's Surface Science Package is designed to capture every piece of information about the surface that can be determined in the three remaining minutes that Huygens is designed to survive after landing.

15.44 Cassini stops collecting data

Huygens's landing site drops below Titan's horizon as seen by Cassini and the orbiter stops collecting data. Cassini will listen for Huygens's signal as long as there is the slightest possibility that it can be detected. Once Huygens's landing site disappears below the horizon, there's no more chance of signal, and Huygens's work is finished.

16.14 First data sent to Earth

Cassini first turns its high-gain antenna to point towards Earth and then sends the first packet of data.

Getting data from Cassini to Earth is now routine, but for the Huygens mission, additional safeguards are put in place to make sure that none of Huygens's data are lost. Giant radio antennas around the world will listen for Cassini as the orbiter relays repeated copies of Huygens data.

So it's designed to survive no more than 3 minutes.

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Quote[/b] ]I'm talking about leaving some time for corrections should something go wrong, or at least inform us if something has gone wrong (Huygens doesn't have any propulsion system IIRC). Right now it's a 20 day complete blackout. All sort of things could have gone wrong, and if they have, we have really no way of telling what went wrong. So if there was some form of fatal error, we won't be able to learn from it.

Right. I thought you meant the Cassini (which is usually communicated with on a daily basis) probe itself. As for Hyugens you are correct. Since its release from Cassini we have no way of knowing whether its on its way to Titan or about to crash through my ceiling.

Quote[/b] ]Given the obscene amount of turns and twists it does around Saturn (not seldom through thruster control bursts), one would imagine that they could skip a few orbits to pack some batteries.

As far as I know, orbits are achieved by using Saturns gravity to brake and attain the orbit (though I am sure that thruster corrections and the like are taken often).

Quote[/b] ]The Huygens mission is far to short for my liking. I'd like something in the style of the Mars rovers. Granted, they can use solar power on Mars while Titan is too far away for sunlight to be useful. Still, given the cost to get there, why not make more out of it? Slap on a reactor if you have to.

For Hyugens that would have to be a small reactor. Cassini is the probe that has a tiny reactor I believe and uses an ion-engine. I remember when it was launched there were protestors out demending the launch and mission be srubbed because if the craft blew up it would vaporize half of Florida. Morons.

Quote[/b] ]So it's designed to survive no more than 3 minutes.

Indeed that is not a long time. Is the service life related to original mission deisgn or enviroment encountered?

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I'm really excited about this as well. Hopefully when I get up to go to school tomorrow I'll be able to see some photos of the surface of Titan. Do you know if the countdown thing on Cassini's website(about 12 hours now) is the time that it will actually start hitting the atmosphere or the time that we'll get the signal? I also think it would be better if they had some more time to do stuff but I bet the insanely cold temperatures make it very difficult for something to last very long. And if it hits Titan's equivalent of water then I doubt it will last more than a few seconds.

And slightly off topic:

I'm also interested in the New Horizons mission(if all goes well budget wise) to Pluto. Pluto's the only planet not to have been visited by a probe or atleast had one fly by. Unfortunately it (from what I've heard) would probably just fly by Pluto and go Kuiper Belt to look for mini-planets. I guess to get it all the way out to Pluto in a reasonable amount of time it would have to go fast enough that it would take a lot of fuel to slow down to get into an orbit around Pluto, but still....

And I've heard about NASA thinking about sending balloons and flying things to Mars in the next 5-10 years, which sounds very neat.

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For Hyugens that would have to be a small reactor. Cassini is the probe that has a tiny reactor I believe and uses an ion-engine. I remember when it was launched there were protestors out demending the launch and mission be srubbed because if the craft blew up it would vaporize half of Florida. Morons.

Yeah, Cassini has a plutonium reactor to run the electrical systems. As for propulsion, it uses a standadard hydrogen propellant for its thrusters.

There have been only two spacecraft so far with ion-engines. One was a testbed that only made a quick test of the technology. That was NASA's Deep Space 1. The other one is in orbit around the moon rigth now - ESA's SMART-1. IIRC it flew loops around the inner solar system for a few years to get a sufficient speed.

Quote[/b] ]Indeed that is not a long time. Is the service life related to original mission deisgn or enviroment encountered?

I think that's by design.

edc:

Quote[/b] ]And I've heard about NASA thinking about sending balloons and flying things to Mars in the next 5-10 years, which sounds very neat.

Heh, I doubt they'll be sending balloons to the moon  wink_o.gif

But yes, I agree that it is the right direction to take and that it will be interesting.

The same goes for ESA's Aurora Project. To start with several return-sample missions to Mars fairly soon (in 5-6 years) planned. The idea is to in the end put a human on Mars.

And that's what I would like to see - more investments in human spaceflight.

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Option D)

Kooky yawns, scratches himself, gets another beer and thinks Titan is a country in some south-east Asian country he's never heard of.

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I can't wait for the decent neither ,actually the craft will be on Titan for about two hours and a half. (with the decent incalculated wich will take most part)

Apart from the picture's ,a thourough study will be done of the elements in titan's atmosphere ,rightt now most people are anxious to know if there are element's there like liquid water (there is probably lots of frozen water due to the cold) methane and other elements wich could create almino-acid's ,basicly building blocks of life.

Some scientists make the assumption that Titan is kinda like a planet that could have life on it in the future ,or a kinda earth in it's embryonic stadium.

The thought is that titan is full of liquid methane sea's ,basicly zippo fuel ,makes you think about the prospect's of comercial use of Titan with all that fuel.

As it has enough fuel localy to get a rocket lifted out of it's atmosphere ,with some robotic plants out there in the future we could maybe let it send that stuff home or act as a fuel station for further space travel. In any case ,enough fuel there to solve the heating problem of a possible colon there in the long future.

voted for "it will be a succes" ,because i sincerly hope it will be ,i have waited for that decent for years.

Oh and thumbs up for way more money to space flight ,hopefully the USA could disband a few devissions from it's humongues army and stick it in there.But i think Space flight will begin to realy lift of when there will be actually something to gain from it ,like resources (cash) or living space.

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I wonder if contractors get bonuses for a successful mission.

I really wanted to predict success until I read about the doppler oversight.

If heavier rare earth elements are more abundant in the out solar system then maybe Titan's atmosphere has a lot of heavier noble gases like Neon and Argon evolved from longterm radioactive decay.  On the other hand there might also be a lot of Fluorine and Chlorine which would eat the probe apart before you could say Beagle III.

:fingers crossed:

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I wonder if contractors get bonuses for a successful mission.

I really wanted to predict success until I read about the doppler oversight.

Well, a bit positive in context was that this was discovered when they did a full systems simulation/test on the ground after launch. So it was found using a systematic test procedure, it was not just "Shit! We forgot the Doppler rate!", "Where are my car keys?" etc

Anyway, some two hours ago, Huygens's onboard electronics (if everything went according to plan) were activated and it's compuer booted. In little about three hours, it starts it entry into the atmosphere.

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Huygens begins its Titan descent [bBC]

Quote[/b] ]

The Huygens spacecraft has sent back its first signal on its historic descent to Saturn's moon Titan.

Early on Friday Huygens began its dive through Titan's atmosphere, taking images and readings as it parachuted towards the surface.

Its scientific investigation of this mysterious world could yield clues to how life first arose on Earth.

Ground controllers detected Huygens' signal showing it was alive via a network of sensitive radio telescopes. European Space Agency (Esa) officials said that this was a "good sign." The probe still has a couple of hours to go on its journey to the moon though.

"It has entered the atmosphere, and entered it correctly," said Roberto Lo Verda, a spokesman for Esa.

"We know the batteries are switched on, the parachute has deployed and it has slowed down sufficiently."

It had also powered-up its systems to prepare to transmit data to the Cassini spacecraft.

If all goes well, it will be the furthest from Earth a spacecraft has been landed. Huygens has been coasting silently towards the exotic world for 20 days since being released from its mothership Cassini. Fast entry

Titan is veiled by a thick orange haze which obscures its surface features. Huygens could land with a thud on ice and rock, squelch into tar-like gunge, or splash down in an oily sea. The spacecraft will take a total of 750 images during its two-and-a-half-hour descent, shedding light on this cosmic enigma.

"This should provide a spectacular new view of Titan and hopefully a much greater understanding of this mysterious world," said Marty Tomasko, principal investigator on the Descent Imager/Spactral Radiometer instrument on Huygens. Professor John Zarnecki, principal investigator on the surface science package on Huygens, has made no secret of his wish to land on an extraterrestrial ocean.

"I'm pleased that my instrument has got something to measure a liquid surface, a solid surface and something in between," he told the BBC News website.

"Despite the flybys of Titan by Cassini we still don't know [what its surface is like]."

Data gathered by the spacecraft should give detailed information on the moon's weather and chemistry.

The sounds of Titan's stormy atmosphere will be recorded with an onboard microphone, and scientists hope that they will even hear lightning strikes. When the European-built probe enters Titan's atmosphere at an altitude of 1,270km (789 miles) from the surface, it will be travelling at over Mach 20 which is 20 times the speed of sound.

Once friction slows the probe's descent to about Mach 1.5, it will deploy the first of three parachutes, pulling off the rear cover that protects Huygens from the fierce heat as it enters Titan's atmosphere. The means the first two chutes must be deployed within a window of just 30 seconds.

Dominated by nitrogen, methane and other organic (carbon-based) molecules, conditions on Titan are believed to resemble those on Earth 4.6 billion years ago. As such, it may tell scientists more about the kind of chemical reactions that set the scene for the emergence of life on Earth. Huygens has spent the past seven years tethered to the Cassini spacecraft, which arrived at Saturn in July 2004.

So far so good smile_o.gif

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Little after 8amPST, 11amEST the data signal is suppose to be sent back to mission control.

GANBATTE NE!

EDT: In about an hour Cassini is suppose to point back to Earth. They haven't heard from Cassini for about 7 hours (part of the mission while it recieves data from Hyugen presumably).

EDIT2: This NASA TV is cracking me up! biggrin_o.gif

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Radio telescopes on Earth were able to detect that Huygens was still transmitting well beyond the time when it should have landed.

thumb.gif

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They just said they are receiving initial data! Wo0t!

EDIT: Confirmed....they are receiving the data!

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Radio telescopes on Earth were able to detect that Huygens was still transmitting well beyond the time when it should have landed.

thumb.gif

Beyond the time that Cassini was pointed towards it? Is there other way to receive the data?

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First images...

Mimas_Bonestell.jpg

wink_o.gif

Radio telescopes on Earth were able to detect that Huygens was still transmitting well beyond the time when it should have landed.

thumb.gif

Beyond the time that Cassini was pointed towards it? Is there other way to receive the data?

Not data.  The radio telescopes are only just barely sensitive enough to detect the existence of a signal.

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I was gonna post a "first image from Titan" photo too. Except mine was gonna be the Monolith tounge_o.gif

In the end I was just to damn lazy biggrin_o.gif

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