Phoenix lands
29 May at 21:04 by Wilson
This has been all over the astrosphere, so I don’t really need to talk much about the spectacular success of the Phoenix lander. I just wanted to share this amazing image:
That’s Phoenix, still hanging from its parachute and descending on Mars, as seen by the Mars Reconnaissance Orbiter’s HiRISE camera, with the Heimdall crater in the background. The lander is some 20km in front of the crater, and it can be better seen in the inset. Click on the image for more details and for larger versions of the image. Later on, the same camera photographed the landing site, showing Phoenix, its parachute and the remains of the heat shield very clearly. As everyone knows, the landing went on with no problems, but had anything gone wrong we’d probably know a lot about what happened.
Interestingly enough, Heimdall is the guardian of the gods and of the bridge between Midgard (the Earth) and Asgard (the land of the gods) in the Norse mythology. He seems to have allowed Phoenix through.
Results from the MESSENGER fly-by
16 Jan at 16:43 by Wilson
Science data is a little slow in coming from this Tuesday’s fly-by of Mercury, but according to NASA everything went as planned and the spacecraft seems to be were it was expected to be. The ground-based antennas are busy handling unexpected problems with Ulysses, another mission exploring that area of the Solar System (it just went over the north pole of the Sun), but we should get more info soon.
Meanwhile, the photo illustrating this article is the first one released by NASA (click on the image to enlarge). It was taken 80 minutes after the closest approach, when MESSENGER was already 27,000km away and looking back. It shows parts of the planet that had never been photographed before (they were not seen by Mariner 10), and that’s just the beginning; we can expect many more pictures over the next few weeks, and we can expect to see most of the features of the planet in colour.
First MESSENGER images
11 Jan at 10:48 by Wilson
As I mentioned previously, images from the MESSENGER fly-by of Mercury have started arriving; the one shown here, the first one released by NASA, was taken from a distance of 2.7 million kilometres, just after midnight on 10 January (Melbourne time) (click the image to see a larger version).
MESSENGER will reach its closest approach to Mercury this time around early in the morning of 15 January (again, Melbourne time), when it will be 200km above the surface; images and movies should be released soon afterwards. This is the first time a spacecraft gets close to Mercury since Mariner 10, in 1974.
Watching Mercury
9 Jan at 16:16 by Wilson
Now is a good time to look at that small rock sitting very close to our Sun… Mercury is reaching it maximum eastern elongation, which means that it’s about as far away from the Sun (when seen from Earth) as it is going to get this time around. If you have a nice, flat western horizon, look for it soon after the sunset, slightly north of the place where the Sun disappeared. The sky will still be quite bright by the time Mercury sets, but the best day to see it will be on the 21st. For observers in Melbourne, Mercury will set at 21:41 today and 21:42 tomorrow (the Sun sets at 20:45 and 20:44, respectively). For other locations, check this page from the US Naval Observatory.
But, of course, you may prefer to watch it from a better vantage point. If so, now is a very good time: MESSENGER, the first probe to visit that planet since the late 70s, is less than one week away from its first fly-by. The closest approach, at just 200km from the surface, will happen on the 14th, but the cameras will start to take pictures of the planet tomorrow, and some images should be released soon afterwards.
MESSENGER was launched in August 2004 and is in a very complex and long trajectory that will end up with the probe in orbit of the planet… on 18 March 2011. Two more fly-bys happen before then, one in October 2008 and other in September 2009. The reason for this is that it is very hard to send a probe that close to the Sun without having it go into the Sun; it will use its several planetary fly-bys (two of the Earth, two of Venus and three of Mercury) to match its speed to that of Mercury, enabling it to enter the planet’s orbit with relative ease.
Up there and down here
22 Aug at 0:09 by Wilson
As I write this, space shuttle Endeavour is preparing to return to Earth, one day earlier than expected because of the approach of hurricane Dean. The worry is not so much about bad weather in Florida interfering with the actual landing, but with bad weather in Texas forcing the evacuation of the mission control buildings in Houston. I’m pretty sure everyone will be following the landing closely because of the aforementioned problems with the damaged heat shielding tiles, which NASA chose not to fix (as the process of fixing them could actually make the problem worse). NASA TV will have live coverage of the landing on the web in a few hours.
In unrelated news, the weather forecast for next Monday Tuesday in Melbourne calls for a mostly sunny day with a top temperature close to 20° (and even above 20, depending on your suburb). Great weather for the lunar eclipse of that night; remember that you can join the Astronomical Society of Victoria on the roof of the Victoria Gardens shopping centre, in Richmond, starting from 6:30pm: a gold coin pays for admission, and you get to use the viewing equipment that will be there to look at the moon and the rest of the night sky (I have no idea how to get on the roof, though; my guess is that one would use the garage lifts). But, of course, the only equipment you need to see the eclipse are your own eyes.
And, should you want to go out on the previous night, Mars and the red star Aldebaran will be very close together, presenting a nice show on the night sky to anyone who’s up and looking east around 3am; the bright stars Betelgeuse, Rigel and Sirius will not be far off, adding to the show. Mars will put on an even better show in December, at the time of its closest approach to Earth, but we can talk more about that then.
The Shuttle problems
15 Aug at 16:24 by Wilson
By now, everyone is certainly aware of the problems found on Endeavour’s insulation tiles, caused by fragments of ice hitting the shuttle during launch. The impact cut a gouge in some insulation tiles, and NASA is still deciding what, if anything, to do about it. The astronauts do have materials to fix the insulation, if necessary, but that is a complicated manoeuvre because, well, the tiles are underneath the shuttle. Damaris Sarria, an astronaut-in-training and Thermal Protection Specialist, discusses the possible solutions in her blog, and NASA has a 3D video of the damaged area.
The impact site was photographed from the ISS before the shuttle coupled to it; since the Columbia accident (caused exactly by fragments of, in that case, foam hitting the underside of the orbiter), it is part of the standard procedure to position the shuttle “upside-down” so that it can be seen from the ISS (I don’t know what will be done in the Hubble repair mission, though).
I thought this would be a good time to talk a little about the reason why the shuttle keeps being hit by debris during launch. At launch, the shuttle is attached to three other large structures: two solid-fuel rocket boosters, one on each side, and the large, orange fuel tank that is the source of all the problems.
The boosters provide most of the thrust to take the orbiter up, and are solely responsible for holding the weight of the fuel tank and the orbiter while still on the launch pad. On launch, 71% of the total thrust is provided by these rockets, and 100% of the smoke you see coming out of the shuttle when it’s already on flight comes from them (most of the “smoke” around the launch pad is actually from the water being used to cool the platform). A failure in one of the boosters is what brought down Challenger, in 1986; a leak ruptured the external tank and caused it to blow up.
The orange external tank carries the fuel for the shuttle’s main engines; these engines don’t provide much of the power needed for lift-off, but they are what takes the shuttle into orbit, accelerating it from 5,000 to over 27,000 km/h after the boosters separate. The tank is the only part of the shuttle that’s not reused; after the engines are turned off, the tank is discarded and falls into the sea (the boosters also fall into the sea, but they have parachutes and are recovered). The landing of the shuttle is mostly unpowered, with aerodynamic braking being used to reduce the speed of the orbiter.
The fuel inside the external tank is liquid oxygen and liquid hydrogen (which burn into water, thus no smoke from it), and herein lies the problem. Liquid hydrogen needs to be cooled down to -252.8 degrees Celsius (just over 20 kelvin), which means that the tank needs to be very well insulated. Because of that, it is covered with a 2.5-centimetre thick coating of polyisocyanurate foam (which also protects the tank for aerodynamic heating during launch).
And this is the foam that falls off during launch. Also, as it is not a perfect insulation, sometimes ice forms on the tank (especially if it’s a humid day and the shuttle has been fuelled for a while before it’s launched), and ice fragments can also fall off. The foam can’t be more securely attached to the tank without increasing weight and cost significantly (it’s worth noting that, in the first few launches of the shuttle, the tank was painted white; that alone adds almost 500kg to the launch weight, and that’s why it’s not done anymore), so there’s no easy solution to the problem.
The routine of inspecting the shuttle from the ISS seems to be the best procedure to deal with the problem of damage to tiles from falling debris, especially considering that the shuttle is not going to be used for much longer; it’s indeed best that NASA spend its money and energy in the next generation of vehicles, rather than trying to re-engineer the aging shuttles. Still, that will make every launch and landing very tense for all involved, including interested amateurs like me and you.
Endeavour was launched
9 Aug at 14:40 by Wilson
Space shuttle Endeavour was launched this morning from Florida, as 8:36am Melbourne time (6:36pm yesterday, Florida time). STS-118 takes with it a new segment for the International Space Station, almost three thousand kilos of supplies and equipment and, more importantly, a school teacher.
Barbara Morgan was the back-up crew member for Christa McAuliffe on STS-51, the ill-fated Challenger flight of January 1986. After that, she continued working with NASA and eventually completed a full astronaut training program; this is her first flight, and she is the first teacher to successfully fly into space.
Endeavour is expected to land in 11 days, back in Florida, weather permitting. As with the previous missions, the shuttle will be thoroughly inspected while in orbit to ensure that it is fit to re-enter the atmosphere. NASA has pictures and videos of the launch, and will have all the updates as the mission progresses.
Phoenix
6 Aug at 16:35 by Wilson
Somehow, I allowed the whole month of July to go by without a single post here. And now, this blog comes back from its own ashes, nicely tying with the launch of the new Mars Lander…
Phoenix was, finally, launched last Saturday at 5:26am Florida time (7:26pm Melbourne time), and it should land on 25 May next year (no word on the expected time of the landing so far) near the north pole of the red planet.
The Phoenix lander is very different from its more famous cousins, the rovers Spirit and Opportunity; Phoenix will not move across the planet once it touched down. Instead, it will make detailed studies of the area on which it lands with the explicit intent of finding water. With that goal, it will land on an arctic region (close to, but outside, the polar ice cap) that seems to have a high amount of water under the ground (these observations were made by the Mars Odyssey orbiter) and will use an impressive array of instruments to explore its neighbourhood.
Most impressive of all is its robotic arm, which is almost 2.4 metres long and capable of digging up to half a meter into the soil; it is expected to reach a hard layer of ice before going that deep, though, and if it does it will scrape the ice to get samples, which will then be analysed by a collection of devices, including optical and atomic-force microscopes, a gas analyser and a conductivity probe. It also carries a full weather station and an stereo imaging camera, not to mention a further camera positioned at the tip of its arm.
This is the third lander intended for a polar region of Mars; the previous ones, the Mars Polar Lander, failed at landing due to human error in its programming. Let’s hope that the Phoenix fares better; we shall now in 9 months.
Moon return promotional video
27 Apr at 17:01 by Wilson
NASA has released this very cool promotional video for the return mission to the Moon:
I mean, it’s ostensibly from NASA, but I couldn’t find the original source; I got the link from NASAwatch. There’s also a hi-res version for those who want a better video than you can get from YouTube.
New Horizon flies by Jupiter
28 Feb at 15:40 by Wilson
As I write this, the New Horizons probe is less than 5 minutes away from its closest approach to Jupiter, on its way to Pluto. It is using Jupiter’s gravitational pull to gain speed, which will allow it to get to Pluto much earlier than it would normally. Still, it will take 8 more years to get there: the closest approach to Pluto will happen on 14 July 2015 (Bastille Day).
New Horizons was launched just over one year ago, on 19 January 2006, and the fact that it made it to Jupiter in less than 14 months is a good demonstration of how fast this probe is (and the fact that the trip to Pluto will still take almost 10 years is a good demonstration of how large our solar system is…). The gravity-assist manoeuvre around Jupiter is accelerating it to over 83,000 km/h (from just under 70,000) and will send it flying through Jupiter’s magnetosphere “tail”, the result of the interaction between the solar wind and Jupiter’s magnetic field; New Horizons will be the first probe ever to fly through this area, and the data it sends back should be interesting.
After that (from June onwards, probably) the probe will mostly hibernate until it meets Pluto, as there is nothing really interesting on the way there. Jupiter data should start appearing in New Horizon’s web site soon, and you can use the same web site to follow the probe’s progress through the outer solar system.
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