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Beagle 2 Failure Theories
Dan East writes "New Scientist has an article discussing the failure of ESA's Beagle 2 Lander. Theories as to why the landing failed include thinner than expected upper atmosphere, extreme atmospheric temperature fluctuations, and possible physical damage to Beagle 2 seen in an image acquired immediately after it separated from Mars Express. Recent data acquired by Mars Express, as well as NASA's Mars Rovers, are helping direct investigations into the failure. So far only around half of Beagle 2's landing ellipse has been imaged in an attempt to locate remnants of the lander. USA Today is also running an AP story on these latest theories."
My friends and I went to the NASA Ames Research Center Mars museum at Moffett Field yesterday and it was pretty cool, in a museum-for-kids kind of way. But there was one fact on display that I simply could not understand, and that the curator on duty could not help me with. I told my friend that I would ask Slashdot, where someone was sure to know, and was only joking, but now that this story has been posted (and although it's only loosely related), what the heck ...
The description of the rover module that is going to be deployed on one of the upcoming Mars missions states that it is designed to last for 3 months or until its solar panels become covered in Mars dust and it can no longer get the solar power that it needs. The question is, if they are going to send up a multi-multi-million dollar craft, why not put some simple wipers on the solar panels so that they can wipe off the dust and get some more use out of the thing?
The curator said that "five hundred people" before me had asked the same question, and that he had never been able to figure out the answer. And of course there MUST be a good reason for this; my closest guess is that the robot wouldn't last for more than 3 months anyway and so they don't bother to include the extra expense and complexity of a motorized wiper system just to keep its solar panels clean for longer than it is expected to live. But there must be a better reason than that, no?
what about possible sightings of the remains of the probe. i came across this story on cnn.
Lets say (using the parents example) the radius of Mars was incorrectly entered (from our less accurate 1988 data vs. our more exact 2001 data) with an error of 1%, so instead of 3375km for polar radius, we have 3341km. This error is furthered in say Newtons Law of Gravity, because the radius is squared, giving a 2% error in just the denomenator of the equation. Obviously there are some margins to counter this, but Distance to Mars, Radius of Mars, Mass of Mars, all equal to many sig figs.
If you're interested in more Mars/Earth info I found this NASA data in my googling.
"The truth suffers from too much analysis"
Similar to what grand prix drivers have on their visors? If an existing appendage on the rover could hook up with a tag and pull such a layer of film off a panel then that could double the solar panels lifetime with little extra weight or complexity?
Boffoonery - downloadable Comedy Benefit for Bletchley Park
It could have even been some sort of physical hardware error. My father used to work for Hughes Aircraft Co. on the AIM-54 Phoenix missile program. The Navy required them to second-source some parts for the missile and named Raytheon as the source. Raytheon was (and still is) known for numerous incidents of stunning ineptitude, and this case was no exception. One of the parts was an arc-shaped metal lever with gear teeth along its edge that acted as a safety for the missile rocket motor to make sure it wouldn't fire until it dropped free from the F-14 firing it. An electric motor would spin a gear meshed with the teeth and, when it got to the end of the arc, the lever would spring free from the gear and ignite the rocket motor. Some Raytheon engineer apparently couldn't read a mechanical drawing and put one too many gear teeth on the arc. When the motor spun the requisite number of times, it would stop with the last tooth of the Raytheon made safety lever still engaged and the rocket motor wouldn't ignite. They only found the problem months later during a live-fire test at China Lake, CA, when an F-14 was firing at an F-86 drone. The missile dropped like a half-million dollar glide bomb. They were pretty pissed at Raytheon over that one. So you never know what's going to monkey-wrench things. Bad metric:standard conversions, one too many gear teeth, a bad diode that worked only long enough to escape detection; There are so many things that can go wrong.
If a job's not worth doing, it's not worth doing right.
wouldn't a positive charge on the surface of the panel keep dust away?
every day http://en.wikipedia.org/wiki/Special:Random
*defends self* Sorry about the bad numbers, I grabbed them from the article. Our two projects cost 820 million. The beagle 2 cost less. It did not need its own rocket, but still, we spent more money, thats a fact. Everyone loves wal-mart because of its low prices. Ever buy something from there then it goes bad a few days after? You know why? Because its cheap. If you want something done right, it is going to cost you money.
"Cowardice in a race, as in an individual, is the unpardonable sin." --Teddy Roosevelt
NASA's Viking Mission to Mars was composed of two spacecraft, Viking 1 and Viking 2, each consisting of an orbiter and a lander. The primary mission objectives were to obtain high resolution images of the Martian surface, characterize the structure and composition of the atmosphere and surface, and search for evidence of life.
how does that mean they had no idea the air was so thin?
every day http://en.wikipedia.org/wiki/Special:Random
In the case of a simple flight software error, not only would the boneheaded engineer that wrote the code have screwed up, but also the organization that is supposed to validate and test the software (and they are usually fairly independent, if things are set up correctly).
Another thing I've encountered with working on NASA spacecraft is that the systems engineering is just a bitch - the thing is so complex nobody really understands how it works from one end to the other. The guidance guys may have this slick new way to do an inertion burn - but they don't realize the duty cycle on the engine will create a heat load that the thermal system can't dissipate - and the thermal guys don't know the first thing about how the engine and guidance works so they don't catch it until it's too late. Misunderstanding of complex systems is often a problem that leads to failures.
Surface pressure: 6.36 mb at mean radius (variable from 4.0 to 8.7 mb depending on season)
[6.9 mb to 9 mb (Viking 1 Lander site)]
Surface density: ~0.020 kg/m3
Scale height: 11.1 km
Total mass of atmosphere: ~2.5 x 1016 kg
Average temperature: ~210 K (-63 C)
Diurnal temperature range: 184 K to 242 K (-89 to -31 C) (Viking 1 Lander site)
Wind speeds: 2-7 m/s (summer), 5-10 m/s (fall), 17-30 m/s (dust storm) (Viking Lander sites)
Mean molecular weight: 43.34 g/mole
Atmospheric composition (by volume):
Major : Carbon Dioxide (CO2) - 95.32% ; Nitrogen (N2) - 2.7%
Argon (Ar) - 1.6%; Oxygen (O2) - 0.13%; Carbon Monoxide (CO) - 0.08%
Minor (ppm): Water (H2O) - 210; Nitrogen Oxide (NO) - 100; Neon (Ne) - 2.5;
Hydrogen-Deuterium-Oxygen (HDO) - 0.85; Krypton (Kr) - 0.3;
Xenon (Xe) - 0.08
now- from pathfinder Meteorology
It was mid-summer in the northern hemisphere of Mars when Pathfinder landed. The Pathfinder Lander is at 19.33 N, 33.55 W. The Viking 1 Lander touched down at 22 N, 50 W, 2 km below datum elevation on 20 July 1976, and is used for many of the comparisons below.
The pressures measured over the first three days average about 6.75 mb, 10% to 20% smaller than those recorded by the Viking 1 Lander during the same season 21 years ago (note that this result is consistent with the elevation difference of about 100 meters between the Mars Pathfinder and Viking 1 landing sites). The pressure showed a slight decline over the first few weeks but is now starting to rise slowly. This rise should continue through December, 1997. The pressure rise is concurrent with the slow shrinking of the southern polar cap, now at its maximum extent, as the southern winter ends.
Temperatures measured from the top of the 1 meter mast on Mars Pathfinder varied from daily highs of about 260 K (+8 F) to lows of 196 K (-107 F). This is about 10 K degrees (18 F degrees) warmer than Viking 1 Lander measurements made at 1.6 meters. The sol-to-sol temperatures have been very repeatable over the first 30 sols, and should continue until about 60 sols after landing, after which they will start to show more variation.
Preliminary wind speed estimates give late evening and early morning prevailing winds from the SSE, which shifted in the early afternoon to be from the N to NE. This is very similar to what Viking 1 found at this time of year. During the day, winds were light at only a few km or miles per hour. At night the wind speed increased to about 10 to 20 mph (16 - 32 kph) from the south.
The repeatable weather patterns of northern summer found by Viking 1 have been verified by Pathfinder so far. These include diurnal (day-night) pressure changes and semi-diurnal changes by as much as 4.5% due to atmospheric thermal tides.
Interruptions in the normal pattern of temperature drops observed on a few nights may indicate water in the atmosphere is condensing as fog. Humidity measurements are planned later in the mission.
On sol 25, temperature sampling was done at 4-second intervals for the whole day. Temperature fluctuations by 15 to 20 K (30 to 40 degrees F) were observed over minutes or seconds at some periods, suggesting turbulent boundary-layer mixing between the warmer near-surface region and cooler layers above that. A "dust devil" was also detected passing by the lander on sol 25, and later high resolution sampling has detected more dust devil signatures.
More detailed information and historical weather reports are available at the Mars Pathfinder project weather page. Raw and reduced data are available online at http://atmos.nmsu.edu/PDS/data/mpam_0001/aareadme. htm
Pathfinder used a parachute... didn't anyon notice how hard it hit? the fact that pressure and temperatures change so mu
every day http://en.wikipedia.org/wiki/Special:Random
why not stick a magnet to the bottom of the solar panels?
Both rovers carry magnets supplied by Denmark for experiments to analyze martian dust. Dust covers much of Mars' surface and hangs in the atmosphere, occasionally rising into giant dust storms. One of the magnets is designed to exclude any magnetic dust particles from landing in the center of a target area. During Spirit's time on Mars, dust has accumulated on other parts of the target while the center has remained "probably the cleanest area anywhere on the surface of the rover," said Dr. Morten Madsen, science team member from the Center for Planetary Science, Copenhagen, Denmark.
"Most, if not all of the dust particles in the martian atmosphere are magnetic," Madsen said. Another of the magnets is within reach of the rover's robotic arm. Examination of dust on the target by instruments on the end of the arm will soon yield further information about the composition of the dust, he said.
every day http://en.wikipedia.org/wiki/Special:Random
Money spent is no guarantee of success.Just look at the Mars Polar Lander or even the Mars Climate orbiter(That one did'nt even need to land, although I believe bits of it inadvertently did).
Landing on planets is hard. You are basically in a barely controlled death dive, in which a number of separate actions must complete for you to pull out of it. Even if that bit works there is no guarantee of where you will land.
The pity about beagle 2 is that it showed you could do space exploration on a reasonable budget. If it had worked we could of planned lots more cheap probelets round the solar system.
Choose your allies carefully, it is highly unlikely you will be held accountable for the actions of your enemies
Our spaceprogram is certainly modest compared to yours, but ESA is working hard towards some great goals in the future. Check out the ESA homepage for info on the different space science projects, such as Planck, Rosetta, Venus Express... and add to that the bold new program Aurora, which aims to put men on the moon as well as Mars. I certainly hope it will happen some day. And I also hope that ESA's budget will be greatly increased.
They showed the parachute being tested on the local news here in the East of England a couple of years ago. First was footage of the NASA parachute test rig being flown beneath a B-52 with chase planes flying next to it. Cut to a shot of the Beagle parachute test: a bloke in a tethered hot air balloon above some bleak East Anglian airfield. The test consisted of him chucking the chute out of the basket with an iron weight attached. Then cut to testing parachute lift by towing it behind a Land Rover in a hangar. Total cost looked like maybe five hundred quid.
We can't accurately predict the atmosphere (weather) here on earth, even with dozens of satellites, hundreds of radar stations, and thousands of automated stations that monitor localized atmospheric conditions. How do you expect ESA to predict the weather on Beagle 2's landing day using 20 year old data?
If you'll remember, NASA adjusted the Rover's landing parameters immediately before landing, forcing the parachute to deploy sooner to compensate for lower atmospheric density. That very well may have saved the mission, because the chute still deployed at a lower altitude than expected.
Either Beagle 2's landing sequence was such that it could not be tweaked en route, or ESA overlooked the opportunity to make such an adjustment.
A final note. Many have suggested that spacecraft, such as the Mars Rovers, use nuclear power instead of solar power to vastly increase their operational lives. One of the main excuses I've seen to NOT use such power (besides the lobbying of tree-huggers) is to purposefully limit the mission lifetime, so resources can quickly be shifted to new science. However the 3 recent landings (Rovers and Beagle 2) have shown we do need to keep track of the weather on Mars a bit closer. If the rovers had a nuclear power source then once they broke down (as in not able to drive around or operate the arm), they could become fixed position weather stations. The data provided could aid in adjusting future landings, which could potentially save hundreds of millions of dollars.
Dan East
Better known as 318230.
Beagle 2 was released from Mars Express whilst the probe was on a ballistic trajectory and before Mars Express went into orbit (indeed if it hadn't ejected Beagle 2, Mars Express would have been unable to enter orbit).
We know where Mars Express was, we know in what direction it was facing, how fast it was travelling and when Beagle 2 was released. Since the probe had no engines it had to follow a simple path to the surface.
So we can say with absolute confidence that Beagle 2 hit the upper edges of the Martian atmosphere. After that, all else is speculation until some wreckage is found.
Best wishes,
Mike.
The first thing that springs to mind is that any kind of wiper wiping dust across could scratch the panels
And that was the first thing I thought of too, but then a simple rational hit me-- if you're going to end up writing off your multi-million dollar probe due to dust buildup anyway, you might as well scratch some solar panels and extend that life. Wait till it gets bad, dust, bad, dust... At that points there's no reason NOT to do it.
Weight is a legitimate issue, but then, how much could a wiper wiper assembly possibly weigh? Of course, everything had to be built to withstand the rigors of reentry, so who knows.
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