Archive for NASA

R.I.P. Gene Parker (1927-2022)

Posted in The Universe and Stuff with tags , , on March 16, 2022 by telescoper
Professor Gene Parker, May 18, 2017. (Photo by Jean Lachat)

I was very sad to hear via the NASA website of the death, yesterday at the age of 94, of Professor Eugene N. Parker (known to all as “Gene”). He was best known for his work on solar magnetism and the solar wind, but he made important contributions across a wide range of astrophysics; he wrote an excellent book entitled Cosmical Magnetic Fields: Their Origin and Activity which I bought many years ago. Most recently NASA’s Parker Solar Probe was named in his honour.

I only met Gene Parker once, many years ago, and was a bit in awe of him because of his intellectual reputation but he came across as a very likeable and friendly man.

We have lost a giant in the field of astrophysics who leaves a huge legacy and will be greatly missed. I send my condolences to his family, friends and colleagues at the University of Chicago where he worked since 1955.

Rest in Peace, Professor Eugene N. Parker (1927-2022).

Top Ten JWST Facts!

Posted in The Universe and Stuff with tags , , on December 4, 2021 by telescoper

The James Webb Space Telescope looks nothing like the Hubble Space Telescope shown here.

As excitement mounts ahead of the launch of the James Webb Space Telescope (JWST) later this month I thought I would, as a service to the community, for the edification of the public at large, and despite popular demand, present my list of Top Ten JWST Facts.

  1. The JWST spacecraft will orbit the Sun near the Second Lagrange Point, L2, because it took so long to get built that tickets were no longer available for L1.
  2. JWST cost $10bn but its telescope is so sensitive that it can see back to redshifts greater than ten, meaning that it sees light that was emitted when its budget was less than $1 bn.
  3. To provide secure backup storage of the complete JWST data set, NASA has commandeered the world’s entire stock of 3½ inch floppy disks.
  4. As well as observing the Universe’s first galaxies and revealing the birth of stars and planets, JWST will look for signs that there might be intelligent life somewhere in the Universe.
  5. JWST’s unique 6.5m deployable mirror was  especially designed by experts from the IKEA company in Sweden who are famous for making items for ‘easy self-assembly’.
  6. The angular resolution of JWST is  0.1 arc seconds, which means  it could resolve a football at a distance of 550 km (or even further if it had Sky Sports).
  7. The Near-Infrared Spectrograph on JWST will be able to make simultaneous measurements of up to 100 sources while at the same time making a cup of coffee and washing the dishes.
  8. The BBC will be shortly be broadcasting a new 26-part TV series about JWST. Entitled WOW! JWST! That’s Soo Amaazing… it will be presented by Britain’s leading expert on infra-red astronomy, Professor Brian Cox.
  9. Er…
  10. That’s it.

The 2020 Decadal Survey

Posted in Science Politics, The Universe and Stuff with tags , , on November 4, 2021 by telescoper

Delayed by a year, the 2020 US Decadal Survey of Astronomy -full title Pathways to Discovery in Astronomy and Astrophysics for the 2020s – is now out.

It’s a hefty document of more than 600 pages so I haven’t had time to do anything but skim it. The top priority for NASA for the next decade seems to be a 6-m class space telescope capable of imaging Earth-like worlds orbiting sun-like stars, something that can’t be done with much larger telescopes from the ground though the plan does involve bringing very large ground-based telescopes (the Giant Magellan Telescope in Chile and the Thirty Metre Telescope in Hawaii) into service more quickly than currently scheduled. Any new space telescope won’t be built and launched on the timescale of course: it probably won’t fly until the 2040s by which time I’ll probably be retired,

I also noticed in the section on the Cosmic Microwave Background we have

Recommendation: The National Science Foundation and the Department of Energy should jointly pursue the design and implementation of the next generation ground-based cosmic microwave background experiment (CMB-S4).The panel suggests that third-generation CMB experiments aligned with CMB-S4―specifically, the SPO (South Pole Observatory) and the “nominal” version of the SO (Simons Observatory)―be high priorities for federal support.

The clarifications in parentheses are my additions.

The shopping list is a lot longer than these items however. There is plenty of discussion in the media already. See, for example, here. I may comment further if time allows.

UPDATE: there is a very user-friendly interactive overview of the survey here.

This is of course an American survey but Astronomy is a truly international enterprise so astronomers all round the globe will be studying it and trying to work out its implications for their own research environment.

And of course there’s a box below for comments from you!

JWST: Nice Telescope, Shame about the Name…

Posted in LGBT, Science Politics, The Universe and Stuff with tags , , , , , , , on October 17, 2021 by telescoper
The JWST deployable mirror undergoing tests

I heard last week that the ship carrying the James Webb Space Telescope (JWST) arrived safely in French Guiana and is now being prepared for launch on an Ariane-5 rocket at the European Space Agency’s facility at Kourou. Since the telescope cost approximately $10 billion there was some nervousness it might have been hijacked by pirates on the way.

I’m old enough to remember JWST when it was called the Next Generation Space Telescope NGST); it was frequently discussed at various advisory panels I was on about 20 years ago. Although the basic concept hasn’t changed much – it was planned to be the successor to the Hubble Space Telescope working in the infrared and with a deployable mirror – at that time it was going to have an even bigger mirror than the 6.5m it ended up with, was going to be launched in or around 2010, and was to have a budget of around $600 million. About a decade ago cost overruns, NASA budget problems, and technical hitches led to suggestions that it should be cancelled. It turned out however that it was indeed too big too fail. Now it is set for launch in December total cost greater than ten times the original estimate.

I know many people involved in the JWST project itself or waiting to use it to make observations, and I’ll be crossing my fingers on launch day and for the period until its remarkable folding mirror is deployed about a fortnight later. I hope it goes well, and look forward to the celebrations when it does.

There is a big problem with JWST however and that is its name, which was changed in 2002 from the Next Generation Space Telescope to the James Webb Space Telescope after James E. Webb, a civil servant who was NASA’s chief administrator from 1961 to 1968.

It’s not uncommon for scientific space missions like this to be named after people once the proposal has moved off the drawing board and into serious planning. That happened with the European Space Agency’s Planck and Herschel to give two examples. In any case Next General Space Telescope was clearly never anything but a working title. Yet naming this important mission after a Government official always seemed a strange decision to me. Then news emerged that James Webb had enthusiastically cooperated in a McCarthyite purge of LGBT+ people working in government institutions, part of a wider moral panic referred to by historians as the Lavender Scare. There have been high-profile protests (see, e.g., here) and a petition that received over a thousand signatures, but NASA has ruled out any change of name.

The main reason NASA give is that they found no evidence that Webb himself was personally involved in discrimination or persecution. I find that very unconvincing. He was in charge, so had responsibility for what went on in his organization. If he didn’t know then why didn’t he know? Oh, and by the way, he didn’t have anything to do with infrared astronomy either…

It’s a shame that this fantastic telescope should have its image so tarnished by the adoption of an inappropriate name. The name is a symbol of a time when homophobic discrimination was even more prevalent than it is now, and as such will be a constant reminder to us that NASA seems not to care about the many LGBT+ people working for them directly or as members of the wider astronomical community.

P.S. As an alternative name I suggest the Lavender Scare Space Telescope (LSST)…

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

dunes

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.

europa

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):

raw_image

 

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):

Mars_Water

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:

 

Spectroscopy

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!