Posts Tagged‘satellite’

MESSENGER: Mercury’s First Artificial Satellite.

Mercury is a strange little beast of a planet. It’s the closest planet to our sun and manages to whip around it just under 88 days. Its “days” are 59 earth days long and whilst it’s not tidally locked to our parent star (like the moon is to us, always showing the same face to the earth) it is in a 3:2 spin-orbit resonance. This has led to some interesting phenomena when we’ve sent probes to image it as the only probe to ever visit it, Mariner 10, only managed to image 45% of the planet’s surface on it’s 2 encounter trip with the tortured little planet. That all changed a few years ago when MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) made its first approach to Mercury in January 2008 and sent back images of the as of yet unseen side of the planet. Ever since then MESSENGER has been on a long trajectory that will eventually bring it into orbit with Mercury and it will begin it’s year long mission of observations.

It just so happens that that day is today.

MESSENGER has been in space for an extremely long time, almost 7 years. You might be wondering why it has taken this craft so long to reach Mercury and the answer requires that you understand a little about orbital mechanics. You see as a heavenly body, in this case a satellite, moves closer to another body it will tend to speed up. This is known as the conservation of angular momentum and it’s the same principle that governs the increase in speed when you bring your arms in closer whilst you’re spinning. Thus for a satellite that’s launched from Earth to be able to orbit Mercury it has to shed all that extra speed so it can match up to it, otherwise it would just whiz right past it. Since doing this with a rocket is rather expensive (the fuel required would be phenomenal) NASA instead opts to shed velocity by a complicated set of maneuvers between planets, each of which removes a portion of the satellite’s velocity. This is cheap fuel wise but means the space craft will have to endure many years in space before it reaches its destination.

As I write this MESSENGER is making its final preparations to insert itself into an orbit around Mercury.  MESSENGER hopes to demystify the diminutive planet by providing hi-resolution imaging of the planet (there’s still 5% we haven’t seen yet), doing chemical analysis to determine the planet’s makeup and attempting to figure out why Mercury has a magnetic field. Probably the most interesting part of MESSENGER will be the last part as our current theories on planet formation point to Mercury being much like our moon with a solid core and no magnetic field to speak of. The presence of one there suggests that part of Mercury’s core is still molten and raises a number of questions over how planets and natural satellites like our moon form. It will also be the first ever artificial satellite of Mercury, something that still eludes many of the other planets in our solar system.

This is the kind of science that NASA really excels at, the stuff that just hasn’t been done before. It’s really amazing to see NASA flex their engineering muscle, designing systems that survive in the most unforgiving environment we know for decades and still function as expected. The next year will be filled with all kinds of awesome discoveries about our tortured little cousin Mercury and I for one can’t wait to see how the analysis of its magnetic field changes the way we model planet formations in the future.

 

Argh I Have Conroy in my Space! Get it out, Get it out!

I’m sure the regular readers of my blog know that I’m not the biggest fan of Senator Conroy, mostly because of his idiotic support of the Internet filter which I’m vehemently against. However he’s been distancing himself more and more from that piece of legislation and seems to be shifting most of his focus on the National Broadband Network, something that I definitely support in principal but still disagree with parts of the proposed design. You can then imagine my surprise when I heard the words Conroy and space in the same sentence, especially considering that Australia is still in the infancy stages of, you know, actually doing anything in space:

The minister, who last week announced he would take the axe to Telstra’s monopoly, told a Tamworth forum that he is prepared to do whatever it takes to solve coverage issues in rural and remote Australia.

He says he will not rule out Australia sending its own satellites into space to ensure adequate coverage.

“If we can’t do a deal with operators who’ve got satellites in the sky, we’re actually looking to do it ourselves,” he said.

Now when I first read this I had one of those moments when the scientific part of my brain shuts down and I go into gullible mode. Think that this might lead to Australia developing a small launching capability in order to support the government’s satellite program. Of course this isn’t going to happen, especially considering the kind of infrastructure that would be required and the hired help we’d have to bring in from overseas. In reality the government would probably be buying the infrastructure from overseas partners and launching them from either America or Russia, with China still being an outside possibility.

Seeking to disprove his idea even before it got off the ground I decided to look into the costs of setting up such infrastructure. A good example to base this off is Iridium, a company specializing in delivering such a capability. Currently they have a network of 66 active satellites with 7 in orbit spares, for a total of 73. They’re relatively cheap satellites, coming in at around US$5 million each fully constructed. That doesn’t take into account the launch costs however, and the majority of them were launched in bundles of 5 on top of a Delta-II rocket which costs about $50 million per launch (the wiki article cites 1987 dollars as the cost). That’s about $15 million per satellite up there and whilst I’m sure we won’t need the coverage of the Iridium network you’re still looking at a price tag in the AU$100 million area, which is actually quite doable even with just the initial funding for the NBN of $4 billion.

It’s a very interesting idea and it illustrates the issue for providing broadband to rural areas. As someone who lived in a not-so-rural-but-still-far-out area for most of his life I can attest to the sorry levels of Internet available. I was a mere 30 minutes outside of Canberra yet the only way for me to get any kind of broadband was satellite for many years. That changed when a company supplying wireless broadband set up shop in the area, although their service at the time was a little questionable and it appears that they’ve decided to charge everyone for the set up costs now (to the tune of $1500, no less). The situation is getting better, but not by much.

Conroy’s idea of creating a satellite network as part of the NBN is a solid idea, and I can only hope that it would lead to many larger ISPs buying satellite capability from the NBN which would drive competition and lower prices. The barrier to entry for being a competitor with this capability is currently far too high for any real competition to happen so a new satellite wholesaler makes quite a lot of sense if you’re looking to increase broadband penetration.

Good on you Conroy.