Archive for NASA

Farewell to Spitzer

Posted in The Universe and Stuff with tags , , on January 17, 2020 by telescoper

Just a quick post to advertise the fact that NASA’s Spitzer Space Telescope, which was launched in 2003, is due to be `retired’ at the end of January 2020. Spitzer is an infrared telescope that has done a great number of wonderful things over the past 16 years or so. Here’s a short video giving an overview of the mission.

There will be a live-streamed event next week, on January 22nd 2020, featuring mission members and NASA leadership, at 10am PST (6pm GMT/Irish Time) during which members of the public can ask questions. For more details of this event see here.

Although it’s sad to see the end of one `Great Observatory’, hopefully it would be long before the launch of the James Webb Space Telescope which should be even greater. It certainly has a much bigger budget anyway! JWST is due to be launched in March 2021.

Countdown to Cassini’s Grand Finale

Posted in The Universe and Stuff with tags , , , , on September 12, 2017 by telescoper

In case you didn’t realise, this week sees the end of the superbly successful NASA mission Cassini, which has been exploring Saturn, its ring systems and its many satellites since it arrived there in 2004, including sending the Huygens probe into the largest moon Titan. Its final act will be to plunge into Saturn itself, which it will do on Friday 15th September, taking measurements all the way until it is destroyed. It has already started the final manoeuvre that will end when it enters the planet’s atmosphere. Radio contact with the spacecraft is expected to be lost  just before 1pm GMT.  For further information about this final act, see here.

Cassini was launched in on October 15 1997, so its mission will have lasted  one month shy of twenty years (although there were many years of preparation before that). Although I don’t work on Solar System studies, I have followed the progress of Cassini with great interest over the years primarily because there was a group (led by Carl Murray) working on Cassini (specifically on its imaging system) at Queen Mary when I was there during the 1990s.  I was there in 1997 when the spacecraft was launched, but at that time the rendezvous date with Saturn of 2004 seemed in the unimagineably distant future. Seven years seems a very long time when you’re young!

Anyway, I’m sure Carl (along with all the other scientists working on the Cassini mission) will feel sadness when it all finally comes to an end, but the consolation will be that the mission  has been such a spectacular scientific triumph. Here’s a video about the end of Cassini, showing some of the highlights of the mission and some of the thoughts of the scientists that have been working in it for so long.


The Path of the 2017 Total Solar Eclipse

Posted in The Universe and Stuff with tags , , , on January 6, 2017 by telescoper

I thought I’d share this nice NASA video showing the path of totality of the solar eclipse which will take place on 21st August 2017. This is he determined by the changing position of the shadow cast on the Earth’s surface by the Moon as the Earth rotates beneath it. As you can see the shadow will cross the United States of America from Oregon in the North West to South Carolina in the South East. It even passes over Kansas City on the way, so this promises to be a phenomenon that very many people will experience and enjoy.

Eclipses are not particularly rare: there are at least two every year, but most of these are partial rather than total and it is less common for totality to be witnessed from highly populated areas.

For much more information about the 2017 total eclipse of the sun, see the NASA page here.

Dunes on Mars

Posted in Art, The Universe and Stuff with tags , , , , on November 21, 2016 by telescoper


This isn’t a new picture, but I hadn’t seen it before a friend put in on their Facebook page at the weekend. It isn’t what I first thought it was – a wonderful piece of abstract art – but is, in fact, an equally wonderful photograph of the inside of the Bunge crater on Mars, where a complex pattern of dunes has formed through wind action. The area covered by the image is about 14 kilometers wide.

According to the official NASA webpage: “This image was taken in January 2006 by the Thermal Emission Imaging System instrument on NASA’s Mars Odyssey orbiter and posted in a special December 2010 set marking the occasion of Odyssey becoming the longest-working Mars spacecraft in history.”

The Possible Plumes of Europa

Posted in The Universe and Stuff with tags , , , , , , , on September 27, 2016 by telescoper

I was too busy yesterday to write a post about the latest hot news from the NASA Hubble Space Telescope, so here’s a quick catch-up.

It seems that Europa, the smallest of the four Galilean moons of Jupiter, may from time to time be releasing “plumes” of water vapour. It has long been speculated that there might be large quantities of liquid water under Europa’s extremely smooth icy crust. Here’s a picture of possible plumes (to the bottom left of the image) in which a high-resolution picture of the surface of Europa has been superimposed.


Picture Credits: NASA/ESA/W. Sparks (STScI)/USGS Astrogeology Science Center

There’s also short video explaining the possible discovery here.

It’s not obvious at first sight that features like that shown above are caused by water erupting through Europa’s surface. On the face of it they could, for example, be caused by the impact of a smaller body. However,  long-term observations of this phenomenon suggest out-gassing is much more likely.  The Hubble Space Telescope’s Imaging Spectrograph was used to study what are essentially Aurorae powered by Jupiter’s strong magnetic field in which the presence of excited states of hydrogen and oxygen provide evidence for the disintegration of water molecules through interaction with electrons in this highly energetic environment. The images were taken when Europa was in front of Jupiter so they are seen were seen in silhouette.

There is also evidence that these appearance of these plumes is periodic, and that they are more likely to occur when Europa is further from Jupiter than when it is closer. A plausible theory is that water is released from cracks in Europa’s surface which open and close owing to a combination of tidal gravitational and magnetic effects.

I wouldn’t say this was definite proof of the water interpretation. These observations push the capability of the Hubble Space Telescope to the limit because the features are so faint. For information here’s what the raw image looks like (left)  and with enhanced contrast (right):



Verification of these results through independent means is clearly an important priority, though likely to prove challenging. The plume interpretation is possible, but whether it is yet probable I couldn’t say!



Evidence for Liquid Water on Mars?

Posted in Astrohype, The Universe and Stuff with tags , , , , , , , , on September 28, 2015 by telescoper

There’s been a lot of excitement this afternoon about possible evidence for water on Mars from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on board the Mars Reconaissance Orbiter (MRO). Unfortunately, but I suppose inevitably, some of the media coverage has been a bit over the top, presenting the results as if they were proof of liquid water flowing on the Red Planet’s surface; NASA itself has pushed this interpretation. I think the results are indeed very interesting – but not altogether surprising, and by no means proof of the existence of flows of liquid water. And although they may indeed provide evidence confirming that there is water on Mars,  we knew that already (at least in the form of ice and water vapour).

The full results are reported in a paper in Nature Geoscience. The abstract reads:

Determining whether liquid water exists on the Martian surface is central to understanding the hydrologic cycle and potential for extant life on Mars. Recurring slope lineae, narrow streaks of low reflectance compared to the surrounding terrain, appear and grow incrementally in the downslope direction during warm seasons when temperatures reach about 250–300K, a pattern consistent with the transient flow of a volatile species1, 2, 3. Brine flows (or seeps) have been proposed to explain the formation of recurring slope lineae1, 2, 3, yet no direct evidence for either liquid water or hydrated salts has been found4. Here we analyse spectral data from the Compact Reconnaissance Imaging Spectrometer for Mars instrument onboard the Mars Reconnaissance Orbiter from four different locations where recurring slope lineae are present. We find evidence for hydrated salts at all four locations in the seasons when recurring slope lineae are most extensive, which suggests that the source of hydration is recurring slope lineae activity. The hydrated salts most consistent with the spectral absorption features we detect are magnesium perchlorate, magnesium chlorate and sodium perchlorate. Our findings strongly support the hypothesis that recurring slope lineae form as a result of contemporary water activity on Mars.

Here’s a picture taken with the High Resolution Imaging Science Experiment (HIRISE) on MRO showing some of the recurring slope lineae (RSL):


You can see a wonderful gallery of other HIRISE images of other such features here.

The dark streaky stains in this and other examples are visually very suggestive of the possibility they were produced by flowing liquid. They also come and go with the Martian seasons, which suggests that they might involve something that melts in the summer and freezes in the winter. Putting these two facts together raises the quite reasonable question of whether, if that is indeed how they’re made, that liquid might be water.

What is new about the latest results that adds to the superb detail revealed by the HIRISE images – is that there is spectroscopic information that yields clues about the chemical composition of the stuff in the RSLs:



The black lines denote spectra that are taken at two different locations; the upper one has been interpreted as indicating the presence of some mixture of hydrated Calcium, Magnesium and Sodium Perchlorates (i.e. salts). I’m not a chemical spectroscopist so I don’t know whether other interpretations are possible, though I can’t say that I’m overwhelmingly convinced by the match between the data from laboratory specimens and that from Mars…

Anyway, if that is indeed what the spectroscopy indicates then the obvious conclusion is that there is water present, for without water there can be no hydrated salts. This water could have been absorbed from the atmospheric vapour or from the ice below the surface. The presence of salts would lowers the melting point of water ice, so this could explain how there could be some form of liquid flow at the sub-zero temperatures prevalent even in a Martian summer. It would not be pure running water, however, but an extremely concentrated salt solution, much saltier than sea water, probably in the form of a rather sticky brine. This brine might flow – or perhaps creep – down the sloping terrain (briefly) in the summer and then freeze. But nothing has actually been observed to flow in such a way. It seems to me – as a non-expert – that the features could be caused not by a flow of liquid, but by the disruption of the Martian surface, caused by melting and freezing, involving  movement of solid material, or perhaps localized seeping. I’m not saying that it’s impossible that a flow of briny liquid is responsible for the features, just that I think it’s far from proven. But there’s no doubt that whatever is going on is fascinatingly complicated!

The last sentence of the abstract quoted above reads:

Our findings strongly support the hypothesis that recurring slope lineae form as a result of contemporary water activity on Mars.

I’m not sure about the “strongly support” but “contemporary water activity” is probably fair as it includes the possibilities I discussed above, but it does seem to have led quite a few people to jump to the conclusion that it means “flowing water”, which I don’t think it does. Am I wrong to be so sceptical? Let me know through the comments box!



Pluto and the Pavilion

Posted in Biographical, Football, History with tags , , , , , on July 14, 2015 by telescoper

This is a busy week in many ways and for many reasons, but the main activity revolves around Graduation at the University of Sussex; the ceremony for graduates from my School (Mathematical and Physical Sciences) takes place on Thursday which gives me a couple of days to practice the pronunciation of the names I have to read out!

Anyway, last night there was a very Commemoration Dinner in the Dining Room of Brighton Pavilion:


The decor is a little understated for my tastes, and in any case I was among a group of about 40 guests who were seated elsewhere owing to the popularity of the event. In fact I was in the Red Drawing Room, which as its name suggests is, er, red:


Anyway, the dinner itself was splendid with particularly fine wine to boot. One of the topics of conversation was the forthcoming flypast of Pluto by the NASA New Horizons spacecraft. As the token astrophysicist on my table I tried my best to answer questions about this event. In fact the closest approach to Pluto takes place about 12.50 pm today (BST) but it will take some time for the images to be downloaded and processed; data transmission rates from the outer edge of the Solar System are rather limited! After passing Pluto, the spacecraft will carry on out of the Solar System into interstellar space. One thing I didn’t know until this morning was that the discoverer of Pluto, Clyde Tombaugh, expressed a wish that when he died his ashes should be sent into space. In fact, they are on New Horizons,  being carried past the planet object he found just 85 years ago. I find that very moving, but it’s also so inspiring that such a short time after Pluto was discovered a spacecraft is arriving there to study it. We humans can do great things if we put our minds to them. Science provides us with constant reminders of this inspirational fact. Unfortunately, politics tends to do the opposite…

I hope to provide a few updates with images from New Horizons if I get time. Here to whet your appetite is today’s stunning Astronomy Picture of the Day, showing Pluto and its largest moon, Charon, in the same frame:


Here’s a close-up of Pluto from yesterday:


And if that isn’t enough, click here for a simulation of the detail we expect to see when New Horizons reaches its closest approach to Pluto.