Saturn’s moon Enceladus may have liquid water hidden away at its South Pole. Or so say NASA’s Cassini, the spacecraft dedicated to map out different aspects of the beautiful planet Saturn.
Enceladus is a tiny moon of Saturn, barely measuring 500km across. It’s been a curious object for many years, since it shone brightly in reflected sunlight, the surface being covered by a white layer of water-ice (meaning, frozen water). The surface is fractured into various patterns, indicating erosion in the past. Much of the surface is cratered; objects, mostly small rocky bodies, pulled in by Saturn’s gravity slam into Enceladus. A spectacular display is seen at the South Pole of the moon, where giant plumes of liquid and gaseous water rise, after penetrating the fractured surface. These shine in the Sun’s rays and also provide material to Saturn’s E-ring.
How Cassini Discovered Water
Cassini has made several flybys past Enceladus, in 2010 and in 2012, mapping its surface in great detail as it flew less than 100 km from the surface. It has also mapped the gravitational field of the object and this is what led to the discovery of a possible liquid water reservoir right beneath the surface. During these flybys, the trajectory of Cassini changes slightly due to the gravitational field of the moon. Being a light object, Cassini is quite sensitive to local gravitational fields, and corrects its path accordingly. This means that one can use this information to map out the gravitational field of the moon. If there is a major concentration of mass, like a large mountain, we can feel a positive addition to the field, while a hollow will show up in a negative way.
Cassini, mapping the gravitational field in the South Pole of Enceladus, found that there was a mass deficit on the surface, but a large mass excess abut 30-40 km below the surface. This ‘subsurface anomaly’, meaning a deviation from the standard mass distribution found below the surface, is, ‘compatible with the presence of a regional subsurface sea’, says the paper on the subject.
The next obvious question is this: does this sea of liquid water harbour life? The answer is that we don’t know. For a long time, Jupiter’s Europa was a happy hunting ground for alien-hunters; this status might be usurped by Saturn’s tiny Enceladus. A good, though quite a bit technical, answer can be found in a paper co-authored by Carolyn Porco, head of the Cassini mission here. This, however, predates the recent Cassini discovery and hinges its arguments on the plumes of liquid water seen emerging from the South Pole.
NASA’s Fermi Gamma Ray Telescope has spotted something which should interest every physicist. Looking at the heart of our Milky Way galaxy, Fermi has unequivocally showed a bright gamma-ray glow. Scientists have then removed all known gamma-ray sources and, while it removes quite a bit of the contributing source, it still leaves a bit unaccounted for. We don’t know what’s causing this excess gamma ray glow. Given that gamma rays are some of the most energetic radiations known, it is unlikely that they are caused by some thermal event. The best explanation at the moment is that something unknown – some unknown particles – are annihilating each other and giving off these radiations. The question is then, what are these particles.
These particles ought to be quite heavy; the gamma ray emission hints at their mass. One very likely explanation for these particles is that they are Dark Matter particles. Humorously called WIMPs, short for Weakly Interacting Massive Particles, these heavy particles are likely candidates for Dark Matter (DM). In other words, the gamma ray lines seen by NASA’s Fermi telescope are because of DM annihilation.
Dark Matter 101
But what is DM you ask? DM is conjectured to be a type of matter beyond which we already know about, responsible for about 27% of the total mass-energy of the Universe. It was first hypothesized by Fritz Zwicky to explain why some galaxies can actually rotate as fast as they do without breaking apart. He surmised that there must be some invisible form of matter, which does not have any electromagnetic interaction, and thus doesn’t give off light, but are massive and, thus, can interact via the gravitational force. Today that conjecture stands on firmer grounds, with observations of known deviation from expected rotation speeds spanning thousands of galaxies. DM has been indirectly hinted at by many experiments such as the CoBE, WMAP and the recent Planck experiment, which all map out the distribution of Cosmic Microwave Background Radiation in our Universe. A host of other experiments also detect strong anomalies which can be easily explained away by the DM hypothesis.
In other words, we are quite sure that DM exists.
The clinching evidence would be to a actually detect it and one way is to let it annihilate each other into two known particles. These two particles then annihilate and produce some radiation which we can detect. The heavier the DM particles, the more energetic the final radiation; thus by knowing the final states, we can figure out the masses of the initial particles.
It is to be noted that no-one is jumping up and saying that DM has been found. While the evidence is highly suggestive, it’s not yet clinching, because, as most scientists like to say, not enough data has been collected. They would conservatively err on the side of mundane humility rather than make a mistake making an extraordinary claim.
NASA has always been enthusiastic about its social media presence, be it videos on YouTube, short updates on Twitter or live video feeds on Ustream. Beginning Friday, NASA has now taken Instagram to the moon.
The new @nasa account on Instagram launched this Friday with classic vintage images of the moon and earth. NASA plans to use the account to inspire the public with new content and keep them updated on the image sharing platform.
NASA has since posted pictures of the launch of the agency’s Lunar Atmosphere and Dust Environment Explorer (LADEE) from Virginia. In two days alone the account has managed to amass a following of 51K and continues to grow like the rockets they keep pushing out.
Instagram has a large populace that wants to look at inspiring pictures that are not of the facial or edible kind, and NASA understands that. Press Secretory Lauren Worley said. “Instagram has a passionate following of users who are hungry for new and exciting photos. We believe we have some of the most engaging images on and off the planet — and we can’t wait to engage with Instagrammers.”
A darling of NASA and of the general public, the Kepler Space Telescopes, dedicated to looking at extra-solar planets, may be soon ending its run. A recent hardware failure on the Kepler has led experts to give Kepler just one more year.
Kepler had four reaction wheels, which keep Kepler steady and able to focus unerringly at distant stars and planets. Kepler really needs three wheels to achieve this job, but has four just in case. Earlier, in July, 2012, one of these wheels had broken down, putting engineers slightly on the edge. Kepler, however, continued to function as well as it always did.
On 9th May, engineers found Kepler in automatic safe mode, since something was wrong. To their dismay, they found that one of the three remaining wheels had malfunctioned. Kepler’s days seemed numbered.
Kepler stares at faraway world, shielding its own cameras from the glare of the Sun. However, light from the Sun hits the craft (and, in fact, fuels it) and exerts pressure on it, called radiation pressure. No matter how small this is, this is enough to throw Kepler a bit off its line of sight. And this is where the wheels come in, ensuring that the photons are not the nuisance that they really are.
Engineers are scrambling for ideas to save Kepler. They are trying to use the boosters to compensate for the reaction wheels, but this won’t give the stability that Kepler enjoyed. Its planet watching days may be over.
A recent blast from a dying star has left astronomers, gaping in awe at the sheer magnitude. A distant eruption, classified now as a Gamma Ray Burst (GRB) and named GRB 130427A, has now set the record for the brightest GRB ever. NASA’s Swift satellite and Fermi-LAT, both specialized for the gamma ray part of the spectrum, have recorded this mind-boggling event. Julie McEnery, project scientist for NASA’s Fermi-LAT, said that this was a “shockingly, eye-wateringly bright” burst.
What are GRBs?
Gamma Ray Bursts are the most powerful explosions known to mankind that occur in the Universe, ranked second right after the Big Bang itself. GRBs occur when an extremely massive star collapses into a massive black hole, and the material falling into the black hole heats up so much that it radiates in the gamma ray region of the spectrum. These jets of gamma rays puncture the material envelope of the dying star and can be detected from a long distance. Unlike smaller supernova (which happen for moderately large stars), GRBs are responsible for throwing out a large amount of energy in the surrounding space, often energizing the gas around and making it glow. The duration for such a burst might last from a few milliseconds to minutes or even hours and the burning embers can often be seen for days and months. We generally count the time for which the radiation energy exceeds the GeV (giga-electron volt) threshold, which is about a billion times more energetic than visible light.
For our present GRB, the GeV radiation lasted for hours and it was observed by Fermi-LAT, a space based gamma ray telescope, for a long time. Even ground based telescopes caught more than a glimpse of the GRB. The Swift satellite caught the first glimpse, as it is designated to do, during one of its rounds. Energetic emissions were recorded by Fermi-LAT, with one of the gamma ray lines having an energy of 94 GeV.
Apart from the strong gamma emission lines in the spectrum, there are also lines present in the infrared, visible and radio wavelengths. These were detected by ground-based telescopes. The distance of the burst was estimated to be 3.6 billion light years away, which is actually quite small when it comes to GRBs. This falls within the 5% of the closest GRBs ever recorded.
This is exciting and a lot of backup measurements will follow this initial detection.
NASA’s Solar Dynamics Observatory (SDO) has observed an incredible whip-like filament extending high above the sun’s surface. Pictured below, the filament measures one half million miles long. To put that in perspective, the earth’s circumference at the equator is approximately 25,000 miles.
A solar filament is tethered to the sun’s photosphere and jets out towards the corona. It is a cooler material and thus the contrast can be observed. Below, you can see a video from NASA’s SDO which shows the incredible phenomenon.
The Solar Dynamics Observatory was launched back in February of 2010. Since the time of its launch, the SDO has brought back stunning video and photos of never seen before views of our Sun. According to NASA the purpose of the SDO is as follows:
The Solar Dynamics Observatory (SDO) will be taking a closer look at the Sun, the source of all Space Weather. Space Weather affects not only our lives here on Earth, but the Earth itself, and everything outside its atmosphere (astronauts and satellites out in space and even the other planets).
Space weather is a serious issue for astronauts and satellite developers. Because we enjoy the benefits of being surrounded by Earth’s atmosphere, we only have to worry about little things sunburns and using sunscreen. Outside the confines of our atmosphere though is a much larger danger. Extreme radiation coming from the Sun’s surface can be perilous to our astronauts, so getting a better understanding of this is critical for their safety. Communications satellites are not exempt from solar related problems either.
While NASA was busy peering into deep space to find the origins of life, an ancient life-form had left an indelible print right in its own back yard. Noted dinosaur hunter, Ray Stanford, went hunting on the property of NASA’s Goddard Space Flight Center based on a “hunch” he had. Incredibly, he found what he was looking for, a cretaceous era dinosaur footprint belonging to a large herbivorous nodosaur.
Pictured below, you can see the imprint left behind by the ancient creature. “This was a large, armored dinosaur,” Stanford said. “Think of it as a four-footed tank. It was quite heavy, there’s a quite a ridge or push-up here. … Subsequently the sand was bound together by iron-oxide or hematite, so it gave us a nice preservation, almost like concrete.”
Stanford, a self-taught dinosaur tracker, has a history of significant finds in Maryland. He found the first ever fossilized nodosaur hatchling. Nodosaurs were a relative of the better-known ankylosaurs. They were large plant eaters that lumbered low to the ground. Stanford has also found prints of Maryland dinosaurs that they don’t even have bones for yet. In a Washington Post article, Johns Hopkins University expert David Weishampel speaking about Ray’s collection said, “the best collection of footprints we have from early Cretaceous era of the East Coast”.
Below, you can see an embedded NASA’s Flickr share with pictures and videos.
Right now NASA personnel are treating the area as sensitive, as they do not want anyone to damage or try to steal the fossil. They hope to be able to open some type of public display in the future.
As I sit here wearing my NASA t-shirt, I feel like I am back in my old college speech class when the professor asked us to give a persuasive speech about something we didn’t believe in. You have to understand that I am a huge fan of NASA. I am fascinated by the idea of space exploration. Ever since I was a tiny boy, I can always remember looking up at the Milky Way and just being overcome by the feeling that I was adrift in space. I totally understand why some believe the stars can tell the future. The Universe is so vast, so amazing, it’s easy to look up and think, “The answers must be out there somewhere.” Unfortunately for me lately, I have reached a new stage in my life that when I look at the world around me, I suddenly come to the conclusion that we seriously need some answers down here before we go searching for answers up there. Of course, this stage in my life just happens to coincide with one of NASA’s crowning achievements, which is putting the Mars Curiosity Rover on the ground. Believe me when I say that I am extremely proud of the work the NASA team did to put Curiosity on the surface of Mars, but I have to say that now is not the time.
Prestige and Politics
NASA is fighting for its life right now. The political climate in the U.S. is the worst I have seen in my 40 years of living. There are many who reminisce about a time when the U.S. could really flex its muscle and do something that no other country could do. After World War II, the U.S. was filled with euphoria. Full of confidence and pride, the U.S. was more than willing to join in the international pissing match by joining the arms race. No way were we going to be outdone by the likes of the Soviet Union. Putting a man on the moon made us the best of the best. Now, fast forward to today. The baby boomers have inherited the country. They are the spoiled brat children of the so called “greatest generation”, having little if any clue what it was like to strap on a pair of work boots and really earn anything. They were the hippies, free lovers, draft dodgers, the “me” generation. They are something to be mocked by most of the world. Even our European neighbors have seemingly forgotten who it was that bailed them out of the grip of tyranny. I guess the point I am making here is that as incredible as it is to land this rover on Mars, the prestige factor just isn’t there like it was for the NASA of the 60’s and 70’s. If you don’t believe me, test yourself. Think back to where you were when the U.S. launched the first space shuttle into space. Think about the fascination and the hoopla surrounding that event. Try to match the events of this recent trip to mars with the excitement of that day. If it’s about prestige then consider this mission a fail.
Life on Mars?
NASA’s Mar’s Exploration Program Page details some of the history and the driving forces that lead NASA to explore Mars to begin with. Here is an excerpt from their website which I believe tells it all:
Among our discoveries about Mars, one stands out above all others: the possible presence of liquid water on Mars, either in its ancient past or preserved in the subsurface today. Water is key because almost everywhere we find water on Earth, we find life. If Mars once had liquid water, or still does today, it’s compelling to ask whether any microscopic life forms could have developed on its surface. Is there any evidence of life in the planet’s past? If so, could any of these tiny living creatures still exist today? Imagine how exciting it would be to answer, “Yes!!”
That my friends is truly the driving force is it not? The quest for life elsewhere is like a maddening life’s purpose for some. It confounds me sometimes when I try to reason out why we are so driven to find life somewhere else in the Universe. Are we really that lonely down here? I am no fool. I realize there are hundreds of reasons to want to find life on Mars, but let me ask this question; What has humanity done for life on this planet to deserve the distinction of finding life on another? Could it be because we are such good stewards of the world we live in? Does life not thrive everywhere we set our feet? I say this facetiously. In my opinion, we humans excel in selfish ambition, mindlessness, and destruction. Just think for a moment and imagine if we absolutely find evidence of life on Mars. Do you think that it will draw humankind closer together and improve life here on earth? Frankly, I don’t feel humanity is ready to find life elsewhere. As humanity stands today, and if we find life on Mars, I believe all of the traits which I previously stated we excel in will come to the forefront. The religious zealots will deny it. The atheists will revel that God is a man-made concoction. Braggarts will brag and the ambitious will start their money making engines. I don’t even want to imagine the political rhetoric. In the shadow of all this will be the poor who cannot get a hand up, the diseased who are waiting on miracles to save their lives, endangered species of whom humanity is both their biggest threat and only hope, and a world that groans for peace.
This is one invasion that everyone is delighted about! Man invaded Mars again, with the giant Mars Science Laboratory, Curiosity, the new Mars Rover, landing on Mars today. The whole payload managed to touchdown on the Red Planet, maneuvering itself with utmost perfection. Remember, all of this happened when Earth was blind to whatever was happening on Mars!
Touchdown and cheers
Things worked out like clockwork. The projected times all matched the real times to a few seconds! If you were watching the live stream from the NASA/JPL control room, you’d know the atmosphere in the room as each stage of the rover was accomplished.
There was a loud cheer when the parachute was deployed, a louder one when the back heat shield separated from the main body and the loudest was reserved for when the rover touched down and the magic words ‘Touchdown confirmed’ were spoken out. The almost childish celebrations that ensued involved people hugging each other, clapping frantically and many breaking down in tears. The scene was one of the most emotional ones you’ll ever see – a perfect antidote to the misrepresentation of science and scientists as emotionless entities.
Images and cheers
The next loud cheer occurred when the Odyssey spacecraft took a grainy 64×64 pixel image, just 4 KB in size, showing one of the wheels of Curiosity on the Martian surface. Odyssey soon sent a higher resolution picture, 256×256 pixel wide. The next image was that of the shadow of Curiosity on the surface of Mars. Never have such tiny images generated so much cheer – and tears!
Here is a video of the control room, showing that dramatic scenes.
The new Mars Rover, Curiosity, is poised to land on the Red Planet at 0524 GMT on 6th August. There have been no reported delays or corrections for tomorrow. The final path corrections were made today, and now Curiosity is out there on its own. From the time the Rover, called Mars Science Laboratory or MSL, enters the atmosphere to the time it touches down, the whole world will hold its breath. This is to so-called “seven minutes of terror”.
In this article, I’ll give you everything you need to know about the landing – the time, the place and more. Buckle up!
Landing: The Time!
If everything goes smoothly, Curiosity should touch down at 0731 CET (Central European Time) or 0531 GMT. I will take you through these seven minutes before they happen in this article. The times (all in GMT) given below are all expected times as given by ESA and NASA:
Time: T–6 min, 41 sec; 05:24:34 AM
At an altitude of 125 km, the Curiosity payload sheds two 75-kg tungsten weights. This reduces the weight, but it still can’t fly. Perhaps Allen Chen, JPL’s operations for entry, was paraphrasing Douglas Adams when he said “We’re flying like a brick”. The spacecraft’s internal gyroscopes have to all coordinate to keep the spacecraft aimed at the Gale Crater. The target is barely 20 km across.
Time: T–5 min, 26 sec;
The Earthly package is in free-fall. The atmospheric drag increases the surface temperature to about 21000C. Carbon tiles, specially made to handle such high temperatures, protect the precious load inside. Curiosity is nestled safely inside this package.
Time: T–2 min, 28 sec; 05:28:46 AM
The parachute deploys! It’s nearly 16 meters in diameter! The hearts of all the NASA and ESA engineers are in their mouths. The parachutes are one of the parts most likely to fail, even though that failure possibility is quoted at 1%. This will be a real test for the parachutes, since they have only cushioned drops for much lighter payloads. The altitude from ground is 11km and the payload is still travelling faster than sound at an estimated 425 m/s.
Time: T–2 min, 4 sec; 05:29:07 AM
The heat shield separates! The payload starts sensing the ground approaching. The current altitude is just 8 km and the payload is now moving at 125 – 130 m/s, still too fast to make a proper landing. Crucially, three radar antennas switch on and this is how it knows how far the ground is. The data is useful for the craft to adjust its actions. For the first time, the craft has eyes and its guidance system can kick in.
Time: T– 53 sec; 05:30:40 AM
The back-shell separates. Finally, the world gets a glimpse of the new Rover! The back-shell flies off with the parachute! Curiosity drops down towards the surface, cushioned by the thrust of eight retrorockets. The altitude is less than 2 km from the surface and the craft is moving at a speed of 80 m/s.
Time: T–20 sec; 05:31:17 AM
The sky crane is deployed! This is a complete transformation from previous landings by NASA. So why this sudden transformation? Simple – Curiosity is just too heavy. This calls for a new arrangement – the wheel suspension system can be used as a landing gear. The main craft, Curiosity, then drops down as a thread unspools from the sky crane. The craft gently drops down at a nice pace of 0.75 m/s.
Time: T–0 sec; 05:31:37 AM
Landing: The Place
The site of the touchdown is Gale Crater. The crater is 154 km wide, but the target area is just 20 km. The High Resolution Stereo Camera (HRSC) on the Mars Express spacecraft has just sent back a very interesting picture of the landing area. The image is a false colour image as shown below:
The image suggests the presence of water-based minerals, which might form the basis of life. The lower elevated areas are shown in purple and this forms the target landing area. But don’t miss out on the elevation right in the middle – it’s called Mount Sharp and rises to 5.5 km above the crater floor. Scientists want the rover to land closest to this mountain, as the geologic features there are “very interesting”. The rover will land in the depression, scour around for interesting geologic artifacts and then trudge towards the elevation.
The Eyes and Ears of Curiosity
Meanwhile, the Mars Express will be eyes and ears of the Mars Science Laboratory. The Mars Express Lander Communication (MELACOM) will be switched on at 0205 GMT on 6th August, long before the touchdown.
M-Ex starts recording
Radio signals transmitted by the Mars Rover will be recorded by the Mars Express starting from 05:09 to 05:37 GMT. (For CET times, just add two hours.) This is when the MELACOM receiver switches off and the Mars Express starts off from the dark area of Mars to point at Earth.
M-Ex starts transmitting
The Mars Express starts transmitting recorded signals back to Earth at 06:10 AM (GMT). The data will be transmitted for over 40 minutes with the transmitter shutting down at about 06:42 AM. The only thing left to do for ESA is to transfer the data to NASA.
The Final Words
We’ll be there with you when the massive Mars Rover, weighing in at 900 kg, touches down on the surface. The leaps made have not only been in terms of the technology packed in the machine, but also in the new ways devised to land a very heavy craft precisely on the surface of another planet. The unexpected hurdle came in the form of the black out for the “seven minutes of terror”, during which Curiosity will land, but NASA will be completely blind to it.
So what can go wrong? Charles Bolden, NASA administrator, has a very simple answer – “All sorts of things can go wrong”.
What about all the simulations of worst-case scenarios, rigorous testing of each part and lessons learnt from previous missions? Shouldn’t they be enough? Steven lee, mission’s control systems manager, working in JPL has the perfect closing line:
Probably the overall biggest risk is our lack of imagination.