Posts Tagged‘moon’

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.

 

Missions to the Moon: A Brief History.

Pop quiz: how many times has man landed on the moon? Whilst most people know the answer is “more than once” few know of more than 2 missions to the moon, namely Apollo 11 and 13. The first is firmly cemented in our history as one of the ultimate achievements of mankind. The second has stuck with us because of the near tragedy that befell those astronauts who, thanks to the brilliance of the NASA personnel, returned to Earth unharmed. Today I’m going to give you a brief history of the 5 other missions that touched down on our celestial sister and why they mean just as much to us as the two that burn so brightly in our minds.

The second mission to land on the moon was Apollo 12, crewed by astronauts Charles Conrad Jr, Richard F Gordon Jr and Alan L Bean. The launch was a dramatic one being launched in the middle of a thunderstorm. Moments after take off the Saturn V rocket was struck by lightening causing the main power source for the command module to go offline. It was at this time that flivght engineer John Aaron made the call that’s widely attributed to saving the entire Apollo 12 mission from abort, telling the astronauts to “Try SCE to AUX” which would switch them onto a backup power supply. No one, apart from Alan Bean, knew what the hell the command meant but Bean made the switch and brought all systems back online. The rest of the mission was quite tame in comparison.

Apollo 12 delivered many scientific instruments to the moon’s surface including a nuclear powered ALSEPthat functioned for almost 8 years after it was deployed. There were also many light hearted moments such as when Bean, the savior of the mission, inadvertenly pointed a new colour camera directly at the sun frying the tube inside. The backup crew for this mission also managed to slip miniature centerfold pictures onto the astronauts mission checkbooks that were on their spacesuits, much to their delight. Bean also attempted to smuggle a camera self timer so that he and Conrad could take a picture together, confusing the image analysts when the film was developed. Bean never got to see this plan through as he misplaced the camera timer during the mission however.

Apollo 14 was crewed by astronauts Alan B Shepard, Stuart A Roosa and Edgar D Mitchell. Unlike its predecessors the launch was smooth and there were little troubles getting into orbit. However there were some problems docking the command module with the lunar lander and the crew, in essence, rammed the lander to get the latches to engage. Upon separating in lunar orbit the lander encountered two major problems, the first being a faulty switch causing the ABORT signal to be sent. Should this happen on approach the lander would automatically abort and return to lunar orbit. The fix required Mitchell to enter in a software patch requiring over 80 keystrokes in the lander’s console. This had the unintended consequence of causing the radar altimeter to not work until they were within 15KM of the moon’s surface, leading to some very tense moments just before touch down.

This mission is also famous for the attempted golf session that astronaut Shepard attempted whilst on the moon’s surface. Shepard said his shot went for “miles and miles” however more realistic estimates show it only went for a few hundred meters, still interesting considering the conditions. Mitchell then decided to start the first lunar olympics by using one of the lunar scoops as a javelin. The backup crew for Apollo 14 stashed their mission patches in every single locker and compartment of the lander and command module, drawing the ire of Shepard every time one would come flying out.

Apollo 15 was something of a technical and scientific marvel and was crewed by David R Scott, Alfred M Woden and James B Irwin. This mission was significant in that the astronauts underwent extensive training in geology prior to flight, all receiving honorary degrees or masters. This mission was also the first to carry one of the famous lunar rovers, even though it was originally slated to be a mission identical to that of its predecessors. It was also the first to carry the SIM bay, a collection of instruments that could perform a multitude of experiments during the time that the astronauts were on the lunar surface. This also necessitated an EVA on the way back to Earth so that the film could be retrieved before reentry.

This mission was important scientifically not only for the wealth of information that was gathered but also for one, distinct object that was brought back: the genesis rock. During the astronaut’s training they were told that if they should find something like this it would not only be a major geological find (as the rock would be almost 4.5 billion years old) it would also provide evidence for the giant impact hypothesis for the moon’s formation. Scott also performed Galileo’s experiment of a feather and a hammer, proving that two objects of differing masses would accelerate at the same rate in a vacuum.

Apollo 16 was crewed by John W Young, T Kenneth Mattingly Jr and Charles M Duke Jr. This mission shared a lot of the same qualities as the Apollo 15 mission, bringing along the SIM and lunar rover as part of their equipment. The launch and journey to the moon could not have gone smoother, with only a malfunction in a backup unit gimbal unit (responsible for aiming the engines) causing brief concern. Many of the issues that plagued Apollo 15 were rectified in this mission, such as allowing the astronauts additional sleep and a change in diet to ensure they wouldn’t suffer electrolyte loss.

This mission brought back the largest single piece of the lunar surface, nick named Big Muley and weighing in at 11kg. Young and Mattingly also took the opportunity to test out the limits of the lunar rover, achieving the highest speed ever set by a vehicle on another planet’s surface at 18KM/h. The rest of the mission was as routine as it could be and the astronauts returned to earth just on a week later with almost 100kg worth of lunar surface material.

Although never scheduled to be Apollo 17 was the last of the Apollo missions and the final time that a human would walk on the surface of the moon. Crewed by astronauts Eugene A Cernan, Ronald E Evans and Harrison H Schmidt Apollo 17 was the first ever night launch of a US human spaceflight. During the trip to the moon the crew took one of the most famous photographs in space history, the one known as the Blue Marble depicting Earth as a beautiful gem hovering in the cold blackness of space. It was also the first mission to carry a scientist astronaut (Schmidtt) as all other astronauts had been selected directly from the military. This was also the longest lunar mission to date, setting no less than 3 time records and boasting the largest lunar surface haul at 110kg.

The landing site for Apollo 17 was actually selected based on observations from the Apollo 15 mission called Taurus-Littrow. This site was chosen as the formations there looked to be lunar bedrock, something that hadn’t yet been acquired. They also investigated some strange orange soil (technically regolith) which turned out to be the result of long gone volcanism that formed glass beads. Overall the mission spanned a phenomenal 12 days and still stands as humanity’s longest ever mission past low Earth orbit.

For a youngster like who despite being too young to experience the stories of the Apollo missions unfolded they still mean a great deal to me. These brave souls took an extreme risk in pushing the human frontier further that it had ever gone before and I rightly salute them for it. I hope one day soon in the future that humanity will return to our celestial sister and hopefully will make our presence there permanent. I know its a hopelessly romantic idea to colonize the harsh, barren environment of the Moon but I know that one day we’ll do it and humanity will be all the better off for doing so.

Solar Flares, Northern Lights and the Luck of Apollo.

Solar flares are one of those well understood phenomena that still manage to inspire all sorts of crazy ideas in people. Whilst many of them never make it past most people’s bullshit detectors there are still those out there that believe that at the end of 2012 a massive solar flare will cause all sorts of trouble on Earth. Of course we know that’s not the case as Earth has been bombarded by these flares for millennia with no such effect being observed. Still whilst solar flares might not be the death of us all they’re still quite interesting and can have quite an impact with our life here on earth.

The most known solar flare related phenomena would be the Aurora Borealis(and the less known but identical Aurora Australis). These are those ghostly lights than can be seen within a certain range in the Arctic and Antarctic regions of our world and come in a wide variety of colours. The lights are caused by charged particles from the sun slamming into the various components of our upper atmosphere causing them to become highly energetic. In order to release this energy they emit photons of light and depending on what the charged particles hit the colors produced will change.

Solar flares are also responsible for wrecking havok with satellites and sometimes even directly with devices here on earth. The events are quite rare however and designing systems with protection against them is usually not cost effective. Most satellites are built with enough shielding and redundancy that they’re only temporarily blinded and similarly earth based systems are usually only affected whilst the flare passes.

Earth is actually quite well protected from these energetic particles by our large magnetic field. However the field is distorted by the constant bombardment of solar particles, stretching it out into an elongated tear drop shape around the earth. Solar flares stretch the magnetic field even further and eventually the magnetic loop breaks, snapping back and draging the energetic solar particles with it. This protective barrier doesn’t extend very far past earth however and that poses risks not only to our satellites out in space, but also to our brave space explorers.

Space is a dangerous place at the best of times but there some areas that are safer than others. For nearly all of space history all our astronauts have been sent into Low Earth Orbit (LEO). There are two distinct advantages to this, the first being that it requires quite a lot less energy to achieve LEO than any other orbit. The second is that this orbit sits them comfortably within earth’s magnetosphere significantly reducing the amount of shielding required on the spacecraft, although most modern craft are quite well shielded despite this. Back in the heydays of the Apollo program however the vehicles that took our astronauts to the moon and back weren’t so quite well guarded and this could have led to disaster.

You see beyond the protection of Earth’s magnetosphere any craft and it’s occupying astronauts would be laid bare to the full fury of the sun’s wrath. This poses a significant risk as the sun is quite capable of delivering a fatal dose of radiation in some of its more extreme moments. Luckily for the the only astronauts to ever leave earth’s protective sphere no events ever occurred during their missions to and from our celestial sister. Had any of them been on a moonwalk or EVA during such an event the consequences would have been quite dire as whilst the spacesuits might protect astronauts from the hard vacuum of space they do little to stop the radiation. Fortunately the space craft that brought them there would’ve been sufficient shields to reduce the lethal dose to something more manageable, but it wouldn’t be a pleasant experience.

Solar flares are one of those things that are both beautiful in sight yet terrifying in their magnitude. They are something that we will have to consider if we want to make any long journeys into our solar system or establish a permanent presence outside our earth’s protective shell. Realistically they’re just another engineering challenge that I’m sure we’ll overcome but until then I’m sure we can all enjoy a few pictures of what a flare looks in space when it strikes our atmosphere:

NEO, The Moon and Mars.

NASA’s in a real pickle at the moment. After having their budget repeatedly slashed year after year by various governments looking to save a few dollars and the scope of their works ever increasing they’re now faced with the challenge of choosing their future direction. A white house panel recently convened on the subject and had several proposals put forth, half of them requiring a cash injection to the beleaguered agency to the tune of $3 billion a year. It would seem the idea of visiting a Near Earth Object (NEO) has gained some traction recently:

BOULDER, Colo. – Call it Operation: Plymouth Rock. A plan to send a crew of astronauts to an asteroid is gaining momentum, both within NASA and industry circles.

Not only would the deep space sojourn shake out hardware, it would also build confidence in long-duration stints at the moon and Mars. At the same time, the trek would sharpen skills to deal with a future space rock found on a collision course with Earth.

In Lockheed Martin briefing charts, the mission has been dubbed “Plymouth Rock – An Early Human Asteroid Mission Using Orion.” Lockheed is the builder of NASA’s Orion spacecraft, the capsule-based replacement for the space shuttle.

If they are to follow such a plan (assuming it came from the white house panel’s proposals) it does have some interesting consequences for NASA. First of all it’s one of the more expensive options, meaning that their budget would need to be increased to cope with it. Secondly it would see the shuttle program extended for another year delaying its retirement until 2011. It would also see NASA divert their focus from the shuttle replacement Ares-I in favour of using commercial options like SpaceX’s Falcon 9, only relying on their launch capabilities as a backup. The last, and probably most important aspect, would be that America would no longer cease its involvement in the International Space Station in 2015, instead continuing until 2020. All of these points show a shift from traditional NASA thinking and it has me wondering where the push is coming from.

In all honesty visiting a NEO would make for an interesting mission. It would be a long duration flight of around 6 months with a maximum of a couple weeks spent actually in and around the object in question. The real benefit of such a mission isn’t so much in the science we can do at the asteroid (we’ve already done that) but in the verification that the new hardware is capable of such long duration flights. It’s definitely a step forward in terms of capability, but will it really serve as the stepping stone for manned missions to Mars and beyond?

Buzz Aldrin thinks not, and he’s been an advocate for NASA to focus on going directly to Mars for quite some time. His plan does seem incredibly sensible to me as collaborating with other space faring nations whilst pushing the envelope in terms of deep space exploration means that NASA can get the best of both worlds. I’m sure that Roscosmos and the ESA would jump at the opportunity to establish a presence on the moon as they did with the ISS. The main issue that Buzz hits on quite succinctly is that NASA should be actively seeking collaboration from international partners for projects such as a moon base as these have significant scientific benefits. It would be hard to justify it as a stepping stone to Mars and beyond, but as an international effort it almost looks like a no-brain-er.

It’s a troubling time for NASA as they’ve been presented with a whole swath of options and are faced with the hard choice of cutting back on their core programs or attempting the next-to-impossible by squeezing more cash out of congress. The next year will see many changes happen with the impending retirement of the shuttle and the realization of fully private launch capabilities so we can rest assured that NASA’s future won’t be in question for much longer.

I just wish they’d make up their minds about the shuttle so I can plan my trip over there to see the last shuttle launch 😉

Luna.

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Our crater faced neighbour in the darkness of space is none other than the Moon. The only other celestial body to be visited by us humans it has been something of a curiosity to us for countless milennia and it is only recently that we’ve come to realise a few things about this ball of dust and rock that don’t quite seem to add up. Today I’d like to introduce a couple things that are not-so-common knowledge about our celestial cousin and give you a run down on what they mean for us here back on earth.

Firstly it’s massive and not just because it weighs a lot. Current estimates of its mass peg it somewhere around 7.347 7 × 1022 kg or around 1.23% of that of Earth and that’s the kicker right there. If you look at any other planet with another orbiting body the relationship of planet to moon mass is no where near that high. The most comparable planet would be Mars with its moons Phobos and Deimos, which weigh in at a measly 0.0000016% and 0.00000023% of their hosts respectively. It’s a similar story for moons of other celestial bodies, especially when you consider a moon like Lo or Europa which are about the same size as our moon but are orbiting the gas giant Jupiter. Our moon is then somewhat of a enigma and its presence has caused many interesting phenomena on our Earth. This then begs the question: How the heck did something that huge manage to get trapped with us?

There’s a lot of theories about its creation. If you were to look at other planets and extrapolate a hypothesis from them your first conclusion would be that we captured another celestial object. Again the mass of the moon says otherwise, as the Earth isn’t large enough to capture something of that size without some other forces acting which we can’t seem to account for. Another possibility is that the Moon and Earth formed at the same time however the composition difference between the Moon and Earth is significant enough to throw this theory into question. Additionally, all the previous theories also fail to account for the amount of spin the Earth/Moon system has, which leaves the current best hypothesis: something hit us. The idea is that another body on a similar orbit around our sun eventually came too close and of course this lead to a massive collision. This theory still has its problems, but for now it’s the best idea we have.

Another fun fact about the Moon is that it’s covered in a fine powder referred to as regolith. Due to the lack of geological activity and zero atmosphere the surface of the Moon is for the most part, stagnant. Any reshaping of the Moon’s surface occurs in the form of asteroid impacts. These have the tendency to smash whatever they hit into a lot of small pieces and over the course of the several billion years of it’s existence the Moon has taken quite a few hits. This has lead to the entire surface being covered in around 4 meters of fine dust that is best described as crushed glass. Regolith is one of the main issues facing an established lunar base as it’s quite coarse and loves to stick to everything. Plus it’s not the best thing in the world to get in your lungs either.

The Moon is a wonder for anyone on Earth and I love the fact that so much of it is still a complete mystery to us. I can’t wait for the day when we make a permanent presence on the Moon as the things we could accomplish there would be amazing. For now I’ll just keep gazing upwards for a look at the Moon whenever it floats by.

P.S. If you want to know more may I suggest here and here.