Jul 152015

For the past ten years, I have been thinking about NASA’s New Horizons probe as the space probe that will eventually fly by Pluto if all goes well and its systems perform as expected.

Well, that historic flyby happened today, and New Horizons sent back pictures to prove it. Best of all, it successfully re-established contact after performing its flyby observations. Now we will have to wait many months (more than a year, as a matter of fact) before all the collected data is radioed back to the Earth.

But we already have amazing photos. A sight never seen by a human being up until just over a day ago.

 Posted by at 1:35 am
Apr 302015

OK, I have had some sad good-byes in my blog this month, so here is a bittersweet one.

Earlier this afternoon, NASA’s Messenger probe, the first planetary probe to orbit Mercury, crashed into Mercury’s surface.

Although this means the end of Messenger, it also means that this particular probe fulfilled all expectations and then some: it worked flawlessly until it ran out of fuel and could no longer maintain a stable orbit around Mercury. The information it provided about the Solar System’s innermost planet will no doubt be studied for many years to come.

Good-bye, Messenger, and thanks for all the good work.

 Posted by at 4:50 pm
Jan 162015

Beagle 2 has been found.

Beagle 2 was the British lander component of the European Space Agency’s Mars Express mission. It was supposed to land on Mars on Christmas Day, 2003; however, no radio signal was ever received from the spacecraft. Beagle 2 was considered lost, its fate unknown.

But now, it has been found. Beagle 2, together with its parachute and rear cover, have been spotted by the High Resolution Imaging Science Experiment (HiRISE) camera on board the Mars Reconnaissance Orbiter (MRO) spacecraft, which itself has been orbiting Mars since March 10, 2006.

Imagine: a spacecraft orbiting another planet was able to spot an object barely more than a square meter in size, on that planet’s surface.

We may not yet have humans walking on Mars, but nonetheless, we live in amazing times. Now if only we somehow managed to stop murdering and hating each other, I might even begin to believe that there is hope for us yet…

 Posted by at 11:27 pm
Dec 242014

Year after year, I can find no better way to wish Merry Christmas to all my family, my friends, and all good people on Earth, than with the immortal words of Apollo 8 astronaut Frank Borman from 46 years ago: “And from the crew of Apollo 8, we close with good night, good luck, a Merry Christmas and God bless all of you – all of you on the good Earth.

 Posted by at 3:57 pm
Nov 122014

Judging by the enthusiastic reaction I just saw moments ago on CBC Newsworld, the lander Philae, part of the Rosetta mission to the comet 67P/Churyumov-Gerasimenko, has landed successfully.

This is big. This is the first time a man-made device landed on a comet. It is called “primary exploration”.

It is also big for the European Space Agency. Rosetta is a major deep space mission: the spacecraft spent ten years traveling to this comet.

All in all, wonderful news.

 Posted by at 11:12 am
Oct 302014

Spacecraft sometimes catch a glimpse of the Sun as it reflects off a sea or an ocean. Here is an example:

Except that this example was not captured by Earth-orbiting spacecraft. The sea here is not a terrestrial ocean. It is a hydrocarbon sea of Saturn’s largest moon, Titan.

Just to clarify, the reflection of the Sun is in the upper left of the image, where the outline of the sea is also clearly visible. The redder, arrow-shaped object closer to the center is a cloud formation.

 Posted by at 10:37 pm
May 312014

Yesterday, around 7:17 AM in the morning Eastern time, I took a look at the new NASA site that is streaming Earth-observing video live from the ISS.

While I looked, I noticed a strange plume. It was barely visible, but it was definitely there. As I watched, it was quickly fading away/disappearing behind the horizon, so I was barely able to get a screen capture.

An asteroid impact? A secret nuclear test? Alien invasion? Who knows.

 Posted by at 6:33 pm
Mar 262014

Some details have been released (leaked?) by Inmarsat and the AAIB about their analysis of the flight path of the missing Malaysian airliner. Some details remain frustratingly absent.

Relying on the measured frequency of the signal received from the missing jet, they plotted possible courses of the aircraft and they concluded that only the route that took MH370 to the southern Indian Ocean is consistent with the data. Here are the two critical slides from the annex of their released material:

They are clearly quite confident about the validity of their analysis, and they may be right. Still, there are a few potential issues with which I am not comfortable.

The analysis obviously relies on two key assumptions: first, that the aircraft traveled at a constant speed and second, that its transmitter had good frequency stability. I am not familiar with Inmarsat equipment used on board aircraft, but I do know that a frequency drift of a couple of hundred Hz, over a period of time of several hours and under changing environmental conditions, is not at all unusual [Update (2014/03/28): I now know (thanks, Craig!) that Inmarsat equipment uses an oven-controlled oscillator, with a frequency stability of a few 10 Hz or better over the course of a year, so this is a non-issue] for an oscillator that is running at around 1.6 GHz (which, I believe, is the frequency range used by Inmarsat.)

The analysis also relies on the estimated range at the time of final transmission, which is what was used to generate the infamous “arcs” along which the airplane is expected to be found. Presumably, similar estimated ranges are available for all the intermediate data points. However, this range information was not published in the currently released document. [Update (2014/03/28): Intermediate range arcs were, however, published by the Washington Post on March 21 (thanks again, Craig!).]

It is also unclear to me why the northern route can be excluded, as the top slide shows. If the satellite was stationary with respect to the ground, the northern and southern routes would have identical Doppler signatures. Presumably the difference is due to the fact that the satellite, though geostationary, still moves with respect to the Earth’s surface, e.g., because its orbit is inclined. [Update (2014/03/28): The orbital inclination of the satellite in question is 1.6° (once again, thanks, Craig!)] But this is not explained.

Finally, I am also concerned about the large deviations in the early stages of flight between the predicted and observed values and what it says about the validity of the analysis.

Just to be clear, I do not subscribe to conspiracy theories. I do believe that it may have been premature to exclude the possibility that the aircraft made an emergency landing and remained intact in a remote area not far from the location of its last transponder signal, but I may very well be wrong about this. However, I do think that a little more transparency would be useful.

 Posted by at 8:48 am
Feb 122014

China’s first rover on the Moon (and only the seventh rover in the history of space exploration) may be alive.

The concern was that two weeks ago, as the robot was about to retire for the lunar night, it did not properly process commands that were supposed to place it in a night configuration to prevent critical systems from freezing up. It was quite possible that we would never hear from the robot again. But here it is… a signal, strong and loud. I guess in the coming days, the Chinese will reveal what, if any, damage the rover suffered during the long, cold lunar night.

 Posted by at 10:00 pm
Dec 242013

Year after year, as Christmas Eve nears, I recall the Christmas message of Apollo 8 astronaut Frank Borman. Here is what he said in 1968, 45 years ago: “And from the crew of Apollo 8, we close with good night, good luck, a Merry Christmas and God bless all of you – all of you on the good Earth.


 Posted by at 2:52 pm
Sep 202013

Last week, it was all over the news: Voyager 1 has left the solar system.

Except that it really didn’t. Voyager 1’s trajectory is, and will continue to be, dominated by the Sun’s gravity for thousands of years. Voyager 1 is significantly closer to the Sun than Sedna (one of the icy dwarfs in the outer solar system) at aphelion. And then there is the hypothesized Oort cloud, a spherical cloud of planetesimals roughly a light year from the Sun. Voyager 1 will take thousands of years to travel that distance.

Of course, Voyager 1 is way outside the orbit of the outermost planet, Neptune. But that happened decades ago, back in the 1980s. By 1990, Voyager 1 was far enough from the Sun to be able to take its famous “family portrait”, a mosaic that covered six of the eight planets (Mars was too faint, while Mercury was too close to the Sun.)

So what exactly happened this month? Well, Voyager 1 crossed the heliopause, the boundary where the solar wind collides with the interstellar medium. It is also the location where magnetic fields are no longer dominated by the Sun.

So in this sense, Voyager 1 has indeed crossed into the interstellar medium. The particles its instruments sample are the particles found in interstellar space, not particles emitted by the Sun.

So it is a significant milestone, but it is somewhat misleading to suggest that “Voyager 1 has left the solar system”, which we heard so many times in the past several days.

 Posted by at 4:40 pm
Sep 032013

One of the giants of the golden era of science-fiction, indeed a co-author of one of the most influential science-fiction novels of all time, The Space Merchants, passed away yesterday, just a few weeks shy of his 94th birthday.

I think it would be a fitting tribute if a future space probe took his ashes to Venus and scattered it in the planet’s atmosphere.

 Posted by at 11:12 am
Jul 202013

I spent a part of yesterday afternoon speed-reading Konstantin Kakaes’s new e-book, The Pioneer Detectives. It’s a short book (still well worth the $2.99 Kindle price) but it reads very well and presents a fair picture of our efforts researching the origin of the anomalous acceleration of the Pioneer 10 and 11 spacecraft.

Yes, I was one of those “detectives”. (In fact, I still consider myself one, as I don’t believe our job is quite done yet; we still owe the community a detailed account of our research and an update of our Pioneer Anomaly review before we can move on with a clean conscience.) So I have an insider’s view of this very intriguing story.

I had a chance to talk with Kakaes at length when he visited me here in Ottawa last year. Over the years, I learned to be apprehensive when talking to journalists; often, the words they put in your mouth bear little resemblance to what you actually said to them when interviewed. I was relieved that this was not the case now: at no time did I feel compelled to cringe while reading the book.

So I really enjoyed Kakaes’s telling of our story. Indeed, I think I learned a thing or two about presenting a complex subject to a non-specialist audience. Kakaes, an accomplished science journalist, manages to do so without dumbing it down with excessive oversimplifications.

One person whose views may not be as favorable is the original discoverer of the Pioneer anomaly, John Anderson. I am told that Anderson is not fond of our results. Kakaes believes that this is because Anderson is “blinded by his desire to believe in something new, in something unexplained. He wants so badly not to know.” Yes, scientists are people, too, and the prospect that a discovery you made, once thought profound, may just be an engineering fluke is not an easy one to swallow. Kakaes does what a responsible journalist must do: he tries to paint an objective picture, which sometimes includes unflattering bits. Yet I think that John Anderson has more scientific integrity than Kakaes gives him credit for.

And to be perfectly honest, I am also disappointed with our own results. When I first read about the Pioneer anomaly (as an outsider, long before my involvement) it seemed to fit perfectly into the big scheme: namely that perhaps the same physics that was responsible for significant deviations from Einstein’s and Newton’s predictions on cosmological and galactic scales might also be responsible for a small but measurable deviation here in the solar system. This was a fantastic prospect!

Sadly, it was not to be. What once seemed like a revolutionary, paradigm-shifting result has been reduced to a small footnote in the history of gravitational physics. Yet I think that our story is nonetheless intriguing. Kakaes seems to think so, too, judging by his book. A book that I am happy to recommend.

 Posted by at 6:55 pm
Jun 092013

The other night, Curiosity was working late.

You walk around on the surface of a planet, and it is pitch dark. Suddenly, you spot a light on the horizon. It’s steady; it’s artificial. You conclude that it’s a sign of civilization.

And indeed it is. What you see is an artificial light… but it belongs not to a living creature but to a robotic explorer. One that was created by a civilization a couple of hundred million kilometers away. A civilization that only invented electric lighting just over two centuries earlier.


I find it eerily beautiful to see an artificial light bathing the rocky surface of an alien planet.

 Posted by at 10:26 pm
Apr 202013

It’s official (well, sort of): global warming slowed down significantly in the last decade and a half.

No, this does not mean that the climate skeptics were right all along. Far from it: their attacks on science, their ad hominem attacks on scientists, their conspiracy theories are all nonsense.

What it does mean, though, is that the climate alarmists were not exactly right either. Overstating the case did not help. Far from creating public support, it may have in fact fueled climate skepticism.

The basic science is not wrong. Take a gas like CO2 that is transparent to visible light but absorbs IR a little more efficiently. Pump it into the atmosphere. Visible sunlight still reaches the surface, but less heat escapes radiatively to space at night. So, the surface gets warmer. Simple. This much was known back in the 19th century, to people like Fourier in 1827, Tyndall in 1872, and last but not least, Arrhenius from Sweden who, in 1896, actually calculated the amount by which the Earth would warm up, or cool, if the amount of CO2 were to change in the atmosphere.

But the devil is in the details. The Earth’s atmosphere is not just a column of static, transparent air with various amounts of CO2. It is a turbulent thing, with many feedback mechanisms, some positive, some negative. The oceans play a big role. Foliage plays a big role. Changes in industrial practices, fewer particulates in the air, play a big role. And so on.

And we also know that the Earth’s climate is not exactly a fragile little thing. After all, it has been relatively stable over geological timescales, allowing life to flourish and evolve. So I always thought that it is rather preposterous to assume that a few hundred years of industrial pollution can do what geological upheavals, global catastrophes, and so on could not: tip the balance and cause a runaway effect.

So we are left with the basic questions. How much will the climate change in the foreseeable future? What are its effects on humanity? And what can we do about all this?

The answer, I fear, remains as elusive as ever. And ridiculous schemes like “carbon trading” don’t help either.

 Posted by at 10:40 pm
Apr 162013

There is another ambitious Mars project in the works: unlike Inspiration Mars, the Mars One project aims to send colonists to Mars, people determined to live out the rest of their lives on the Red Planet, with no return ticket.


I wrote about how I would be willing to risk a very dangerous, very uncomfortable 501-day flight to Mars and back. But staying there for good? Now that’s another matter. Leaving the Earth in the company of a dozen or so other people, knowing that from now on, those will be the only people you will ever see face to face? That you will never see a blue sky again, hear a bird sing, or swim in the sea?

Fortunately, this is not a choice I’ll ever have to make. Unlike Inspiration Mars, the Mars One project is not (to the best of my knowledge) looking for middle-aged couples as participants.

 Posted by at 3:29 pm
Apr 162013

In all the excitement (okay, I wasn’t that excited. But, I was busy) I almost forgot to celebrate an anniversary: it was 40 years ago on April 5 that Pioneer 11 was launched at Cape Canaveral.

In a recent Letter to the Editor published in the newsletter of the American Physical Society, a correspondent suggested that Pioneer 11 may still reveal some anomalous behavior. I do not believe this to be the case. While it is true that our investigation of Pioneer 11 was not as thorough as our investigation of Pioneer 10 (due, in part, to the fact that we have less Doppler data from Pioneer 11) there are no statistically significant inconsistencies.

This Letter also reveals two misconceptions about the anomaly. One is that if the anomaly is Earth directed, which would presumably be inconsistent with a thermal cause. This is not so: quite the contrary, since the spin axis and the Earth direction mostly coincide, an Earth directed anomaly is exactly what one would expect to see in case of a thermal cause. Second, I don’t think it is even relevant to say that “a new physics cause may still be possible”. Of course new physics is always possible. But before one can speculate about new physics, “old physics” must be excluded, i.e., there must be an incontrovertible demonstration that conventional physics cannot account for the observed phenomena. This is not the case for the Pioneer anomaly: conventional physics comfortably accounts for the anomalous acceleration. Sure, there are small discrepancies that are within the margin of error, but you don’t fish for new physics within the margine of error. That’s not the way science is supposed to work.

 Posted by at 9:55 am
Apr 102013

A few moments ago, my wife looked up through our skylight and lo and behold, saw a moving star.

Not just any moving star; it turned out to be the International Space Station, in all its still sunlit glory over the late evening Ottawa sky.

I once managed to capture the ISS through my cellphone; the picture turned out to be surprisingly good, even showing (I think) the somewhat rectangular shape of the station.

Anyhow, I hope Chris Hadfield is having a great time up there.

 Posted by at 9:45 pm