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Posts Tagged ‘NASA’

New images of the European Space Agency’s Beagle 2 have emerged recently, suggesting that it came closer to success than has long been thought. These new images have been analysed more thoroughly and carefully than previous images of Beagle 2, and with the help of a computer simulation it is being suggested that Beagle 2 did not crash land. Instead, this team led by Professor Mark Sims of Leicester University are arguing that Beagle 2 deployed, but not completely correctly. They suggest that, due to not deploying correctly, that it may well have done science for a period of about 100 days, before shutting down due to lack of power. They even suggest that there is a very slim possibility that it is still working.

I do have to take issue, however, with the way this story is worded on the BBC website. It implies that we now know, with certainty, that Beagle 2 operated for some period on the surface of Mars. This is not true. One study has argued that it did. One swallow does not make a summer. This particular team’s analysis and study will need to be looked at by others before we can say with any reasonable certainty that Beagle 2 survived its landing.

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New images of Beagle 2 taken by NASA’s Mars Reconnaissance Orbiter have been analysed by a computer model, suggesting it may have actually worked for a short period of time.

As with any suggestion which flies in the face of conventional wisdom, this claim will need to be checked and followed up by others. But, if the evidence is sufficiently strong that Beagle 2 did not crash, then it will come as a relief to those who worked on it and have long felt that it failed in a crash. Sadly, even if it did work, we have not received any data back from it; and that is not going to change.

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The Schiaparelli space probe has been in the news quite a lot this last week or so. It was due to land on the surface of Mars last Wednesday (19 October), but lost contact about one minute before this. On Friday (21 October) NASA released images taken by its Mars Reconnaissance Orbiter which have led ESA to conclude that Schiaparelli exploded on impact, probably due to a failure of the thruster rockets which were meant to guide it gently down over its last few kilometres of descent. For more on that story, see here. This separate story suggests that the failure of the thruster rockets to burn correctly was due to a computer glitch, and that they only burned for 3 seconds instead of the intended 29 seconds.

What has received far less attention than Schiaparelli is the larger spacecraft which transported it to Mars – the Trace Gas Orbiter (TGO). The TGO was successfully put into orbit about Mars after it and Schiaparelli separated. Whilst ESA scientists worried about the silence of Schiaparelli, they were nevertheless jubilant that the TGO had successfully manoeuvred into orbit about the red planet.

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ESA’s Trace Gas Explorer (TGO) transported the lander Schiaparelli to Mars, and is now successfully in orbit about the red planet.

The TGO’s primary scientific mission is to look for traces of methane emanating from Mars. This is of great scientific interest, because methane could be due to life on Mars. Many bacteria on Earth, in particular those that respire anaerobically, emit methane. The best known example are the bacteria which help digest food in the stomachs of many animals, including us. This is why cows are one of the primary sources of methane emission, the gas is coming from the bacteria in their stomachs.

Methane was first detected in the Martian atmosphere in 2003 by NASA scientists. The following year NASA’s Mars Express Orbiter and some ground-based observations detected methane at the level of about 10 parts per billion. Large temporal and positional variations in the methane concentration were measured between 2003 and 2006, which suggests that the methane is  both seasonal and local.

The other possible source of methane is geological activity. Any methane in the Martian atmosphere is quickly broken down by ultraviolet light from the Sun (there is no ozone layer to protect the molecules from UV light, as there is on Earth). This means that any methane present in the Martian atmosphere but have been recently produced. So, how can we tell the difference between methane due to bacteria and methane due to geological activity?

The key is to look for the presence of other gases along with the methane. If the methane is geological in origin it will be accompanied by sulphur dioxide. If, however, it is due to bacteria it will be accompanied by ethane and other similar molecules. The TGO will be able to measure both the methane and these other gases, and so hopefully will help us determine the origin of the methane. In addition, it will be able to measure and image other things, including sub-surface hydrogen down to a depth of a metre. This will help us better map out the amount and extent of subsurface water ice on Mars.

In all, the TGO has four scientific instruments on it, namely

  1. The Nadir and Occultation for Mars Discovery (NOMAD). This instrument has two infrared and one ultraviolet spectrometer channels.
  2. The Atmospheric Chemistry Suite (ACS) has three infrared spectrometer channels.
  3. The Colour and Stereo Surface Imaging System (CaSSIS) is a high-resolution colour stereo camera which will be able to resolve down to a resolution of 4.5 metres on the Martian surface. Being stereo, it will be able to create an accurate elevation map of the Martian surface.
  4. The Fine-Resolution Epithermal Neutron Detector (FREND), a neutron detector which can indicate the presence of hydrogen in the form of water or hydrated minerals. FREND can detect hydrogen down to a depth of 1 metre in the Martian surface.

NOMAD and ACS are the two instruments which will measure the methane and other trace molecules in the atmosphere. Twice each orbit, when the Sun is both rising and setting as seen from the TGO, it will use the passage of the Sun’s light through the Martian atmosphere to detect and measure the presence of trace molecules, down to a few parts per  billion (ppb).

The TGO will orbit Mars at an altitude of 400 km, in a circular orbit taking only 2 hours to orbit once. The orbit will be inclined at 74 degrees to the Martian equator.  It was launched on the 14 March, so took just over 6 months to get to Mars. In 2021 ESA plans to land a rover on the Martian surface, but whether this schedule is delayed due to the failure to successfully land Schiaparelli remains to be seen.

 

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Last week, two more Chinese astronauts (or “taikonauts” as they are sometimes known) blasted into space, to spend a month on-board China’s experimental space station Tiangong. They successfully docked with the space station just before 19:30 GMT last Tuesday (18 October). The 30-day stay on the space station will be the longest mission yet undertaken by Chinese astronauts.

This is the latest chapter in an ambitious space programme; China has plans to send manned missions to both the Moon and Mars, although it has not publicly stated a time-line for these two goals. In fact, nothing would boost China’s feeling of becoming the World’s premier superpower than if they were to get to Mars before the USA.

The pace of China’s space programme is impressive. They are spending some US$2.2 billion a year on it, and to-date have sent 11 people into space. They plan to build a permanent space station by 2020, and have already launched 181 satellites into space.

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A summary of some of the key numbers for China’s ambitious space programme.

In 2016 alone it will have launched 20 space missions. I have heard it argued that it is easier for a one-party state like China to achieve ambitious long-term programmes like exploring space than it is for democracies like the US. This is because any programmes suggested and funded in the US can be axed by Congress, or shelved by a new president. Such changes of government do not happen in China. Of course, it is looking increasingly likely that the first US manned mission to Mars will not be undertaken by NASA, but rather by one of the private companies like Space X.

The race is on to get to Mars first, who do you think will be first?

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Earlier this week it was announced that NASA’s Hubble Space Telescope had observed evidence for water geysers shooting from the surface of Europa, one of Jupiter’s larger moons. Here is a link to NASA’s press release. I was on BBC TV talking briefly about this on Tuesday (27 September), the day after NASA’s announcement.

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NASA has announced that the Hubble Space Telescope has observed water geysers emanating from the south pole of Jupiter’s moon Europa.

In fact, this announcement was additional evidence to add to a finding which had first been announced in 2013. In December 2012, astronomers used a spectroscope on Hubble to look in ultraviolet wavelengths at Europa. They found auroral activity near the moon’s south pole, and upon analysis of the spectrum of the UV emission from this auroral activity they found the spectral signatures of hydrogen and oxygen, the constituents of water.

Those 2012 observations have since been followed up using a different method. This time astronomers have observed how the Sun’s light, which is reflected from Jupiter, is affected as it passes Europa. As Europa transited in front of its parent planet, astronomers looked for signs of absorption of this light near the limb of the moon, which would be due to gases associated with Europa. Such a technique can, for example, be used to find and study the atmosphere of an extra-solar planet as it passes in front of its parent star.

Whilst not finding any evidence that Europa has an atmosphere, what the team found was that absorption features were seen near the moon’s south pole. When they calculated the amount and extent of material required to produce these absorption features they found that their results were consistent with the 2012 finding. They calculate that water jets are spewing out from the surface of Europa and erupting to a height of about 160 km from the moon’s surface.

We have had evidence since the Voyager mission in the 1980s that Europa has an ocean of water below its icy surface. This evidence was further enhanced during the Galileo mission in the 1990s. Where there is water there may be life, so it is possible that Europa’s ocean is teeming with microbial life. To find out, we need to directly study the water in this sub-surface ocean.

Unfortunately, due to the thickness of the icy crust covering its ocean, studying this water directly poses a huge challenge. We currently don’t have the capability to drill through such a large thickness of ice, although it is certainly something we would hope to do in the future. This discovery of water jets provides a much easier way to sample the water directly, and so it is quite feasible that NASA and/or ESA could send a probe to fly through the jet, take a sample of the water, and analyse it to see whether there are any signs of microbial life. This is very exciting, and is why this discovery of water geysers erupting on Europa is so important.

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This interesting story about the Mars Curiosity Rover recently came to my attention – that its software has now been upgraded to allow the on-board computer to make decisions about choosing targets for its laser to zap. You can read the NASA press release by following this link.

It interested me for two reasons. Firstly, it is a reminder that we have two rovers actively studying Mars as I type (the Mars Curiosity Rover and the Opportunity Rover, which has been operating on the surface of Mars since January 2004!). Whereas Opportunity is about the size of a shopping trolley, the Curiosity Rover is about the size of a car, and has a whole suite of scientific instruments to learn more about the geology of Mars. This includes a chemical laboratory, which can analyse the composition of rocks. The laser is used to vaporise nearby rocks which are thought to be of interest. As the laser strikes the rock the gases emitted are analysed by a spectrometer, but Curiosity can also scoop up rock samples and place them in an on-board oven to heat them up and further analyse them.

But, the second interesting thing for me is that this marks a step forward in “artificial intelligence”. Now, I am very far from being an expert in “artificial intelligence”, so someone who knows more about it than I do may well correct much of what I am about to say. However, it is clear that the on-board computers on the Mars Curiosity Rover are now making decisions about potential targets for the rover’s laser, presumably based on analysing images of previous rocks which Mission Control (at the Jet Propulsion Laboratory in Pasadena) have chosen as targets. Thus, the computer has been learning which kind of rocks the geologists/experts on Earth have been choosing, and is now choosing its own based on some criteria of similarities. I find this very interesting (maybe I’m easily pleased!)

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NASA’s Mars Curiosity Rover can now fire its laser on its own, making decisions at to which rocks to fire it at, without mission control’s involvement.

Such computer-based learning and decision making are vital as we continue to explore the Solar System with robotic missions. The delay time between sending a command to a robot on a distant world and getting the response becomes longer and longer as we explore more distant planets and moons. With Mars the delay is not too bad, typically 20 minutes, but with Saturn it is more like 160 minutes between sending a command and getting the response. Nearly 3 hours is too long in some circumstances, so a rover on e.g. Titan in the future would need to be able to make some decisions on its own, after a period of being commanded and learning from those commands.

Having rovers which use artificial intelligence is, in my opinion, still no substitute for having a human being on Mars. The work which the various rovers on Mars have done in the last 12 years could have been accomplished by a skilled geologist in a few days. And, as the excitement over Tim Peake’s 6-month spell on the International Space Station has reminded us, nothing gets us more excited in the matter of space exploration than seeing a human being doing things in space; no matter how impressive are the things that robots can now do.Hopefully, I will see human beings on Mars in my lifetime.

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I have done a few interviews on the BBC in the last week about NASA’s Juno space probe; it is great to see the mission getting such press coverage. You can listen to my BBC Radio Cymru interview here, and my BBC Radio Wales interview here. With all the press coverage there have inevitably been a few misunderstandings, so I thought I would try and explain as clearly as I can what Juno hopes to accomplish and how it will do it.

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Artist’s impression of the Juno spacecraft. Juno is the first space probe sent to such a large distance in the Solar System (5 AUs) to be powered entirely by its solar panels.

Some background on Jupiter

Jupiter is by far the largest planet in the Solar System. All the other planets together would fit into it, and the Earth would fit into it over 1,300 times! Because it is the largest planet in  the Solar System, we believe that it would have dominated the formation of the planets. Once the gas in the central part of the solar nebula (the cloud of gas and dust from which the Sun and Solar System formed) had collapsed to form a nascent star, the disk of material around the still-forming Sun would have started clumping together under gravity and collisions to form the planets.

Because Jupiter is the largest planet, it sucked up most of the material in the disk of the solar nebula. It is mainly hydrogen and helium, as that is what the Sun and most of the Universe is made up of; about 75% hydrogen and 24% helium. But, the details of Jupiter’s composition are mainly based on theory rather than any hard observations.

What are Juno’s (main) scientific goals?

According to NASA’s Juno webpage (click here to go to it), the main objectives of Juno are

  • Determine how much water is in Jupiter’s atmosphere
  • Look deep into Jupiter’s atmosphere to measure composition, temperature, cloud motions and other properties
  • Map Jupiter’s magnetic and gravity fields, which will reveal the deep structure of the planet
  • Explore and study Jupiter’s magnetosphere near the planet’s poles, especially the aurorae, and provide new insights into how the planet’s enormous magnetic field is generated and how it affects the planet’s atmosphere

I will blog about each of these four points over the next few weeks, so let me start with the determination of how much water is in Jupiter’s atmosphere.

How much water is there in Jupiter’s atmosphere?

The reason this is an important question is that the two most popular theories for how Jupiter formed predict different amounts of water. Jupiter is thought to have either formed (i) from the collapse of a massive fragment of the Solar nebula, or (ii) from the build-up of planetesimals. In the first theory, the amount of water would be less than in the second theory, as the rocky planetesimals in the second theory would have been been coated in water-ice and ammonia-ice.

If you look at an astronomy textbook the interior model of Jupiter shows a solid core, but we have never actually observed this core.

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A model of the interior of Jupiter. We believe that it has a rocky core, with a region of hydrogen under such extreme pressure that it takes on metallic properties and can conduct electricity. But, we have no direct observations of the interior.

Therefore, measuring the amount of both water and ammonia should help us decide which theory is closer to the truth. Water, ammonia, carbon dioxide and methane are examples of what we call ‘ices’ in astronomy, as in the environment of the Solar System all of these compounds can exist as gases but also as solids.

The water and ammonia will be measured by a microwave radiometer. This instrument consists of six antennae measuring the radiation at 600 MHz, 1.2, 2.4, 4.8, 9.6 and 22 GHz. These are the only microwave frequencies which are able to pass through the thick Jovian atmosphere. These radiometers will measure the abundance of water and ammonia down to a pressure of 200 bar, which corresponds to a depth below the cloud tops of 500 to 600 km. This is a small fraction of the radius of Jupiter, which is about 70,000 km, but it is still further below the cloud-tops than we have so far been able to study.

In the next blogpost on Juno, I will talk about how it will measure the gravitational and magnetic fields of Jupiter.

 

 

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Later this morning (Monday 4 July) I will be on BBC radio talking about NASA’s Juno mission to the planet Jupiter. This is the latest space probe to be sent to study the largest planet in the Solar System, and follows on the highly successful Galileo spacecraft which studied Jupiter in the 1990s.

Juno left Earth in August 2011 and is due to arrive at Jupiter today. But, in order to go into orbit about the planet a rocket needs to be fired to slow the spacecraft down and put it into orbit. This is due to happen tomorrow (Tuesday 5 July). The rocket engine which will do this was built in England. If the ‘burn’ fails, the mission will fail, as the space probe will just hurtle past Jupiter and continue on into the outer Solar System.

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NASA’s Juno satellite was launched in August 2011 and arrives at Jupiter this week. It will be put into a polar orbit about the planet, but with a highly elliptical orbit which will take it out beyond Callisto’s orbit. Each orbit will take 14 days.

What are Juno’s scientific objectives?

In addition to studying Jupiter, the Galileo spacecraft spent a great deal of time studying her four large moons; Io, Europa, Ganymede and Callisto. Galileo was in an equatorial orbit. Juno, on the other hand, will be put into a polar orbit. Its main objective is to study Jupiter, rather than its moons.

Jupiter is what is known as a gas giant. It is mainly hydrogen, and contains more mass than all the other planets in the Solar System put together. In fact, it is a failed star; if it were some 10 times more massive it would have had enough mass to ignite hydrogen fusion in its core. Even though it is not burning hydrogen, it is still leaking heat left over form its collapse into a planet 4.5 billion years ago.

In the last 20 years we have discovered many Jupiter-like planets orbiting other stars. Most of these are much closer to their parent star than Jupiter is to the Sun, and this has raised questions about how gas giants can be so close to their parent star, and how is Jupiter where it is in our Solar System? Jupiter is about five times further away from the Sun than the Earth is, and much further away than the Jupiter-like planets we have found around other stars. Did Jupiter start off closer to the Sun and get kicked further out, or did it migrate inwards from further away? We don’t know.

Some of the things Jupiter hopes to determine are

  • the ratio of oxygen to hydrogen in Jupiter’s atmosphere. By determining this ratio it will effectively be measuring the amount of water, which will help distinguish between competing theories of how Jupiter formed.
  • the mass of the solid core believed to lie at the planet’s centre, deep below the very thick and extensive atmosphere. This also has implications for its origin.
  • the internal structure of Jupiter – it will do this by precisely mapping the distribution of Jupiter’s gravitational field.
  • its magnetic field to better understand its origin and how deep inside Jupiter the magnetic field is created.
  • the variation of atmospheric composition and temperature at all latitudes to pressures greater than 100 bars (100 times the atmospheric pressure at sea level on the Earth).

Juno has a funded operational lifetime of about 18 months. In order to better study the interior of Jupiter, the spacecraft will plunge into the planet’s atmosphere in February of 2018, making measurements as it does so.

++UPDATE++

Juno’ rocket successfully fired at about 3:20 UT today (Tuesday 5 May) and is now in orbit about Jupiter. It will complete two large 53-day orbits before being inserted into its 14-day orbit for science operations. This 14-day orbit is highly elliptical, and at its closest the probe will come to within 4,300 km of the cloud tops. 

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