The International Space Station had to perform an evasive maneuver yesterday to dodge space debris from a Russian satellite that disintegrated earlier this year. ESA’s ATV (Automated Transfer Vehicle) was used to perform the avoidance maneuver, the first time it had been used for such a maneuver. A few things about this maneuver are interesting. First, this is the first time in five years that the ISS has had to perform a debris avoidance maneuver. Second, the maneuver was unusual in that was a retrograde maneuver, which slows the ISS and brings it to a lower orbit instead of higher. The last time a retrograde maneuver was performed was eight years ago. Third, according to Jim Oberg at MSNBC, the Russians deny that the satellite has broken up. Fourth, however, the Mission Control Center in Moscow carried out the maneuver.
The maneuver began on August 27 at 18:11 CEST (16:11 UT) and finished 5 minutes 2 seconds later.
In the current ISS configuration the ATV, which is docked to the aft end of the Russian Zvezda Service module at the back of the station, is the only vehicle that can carry out this kind of maneuver. First, the station was turned 180 degrees so that ATV’s aft thrusters were at the front of the ISS with respect to the station’s flight profile.
Once turned, Jules Verne ATV used its rear thrusters produce a speed of 1 m/s to slow the Station down, lowering it about 1.5 kilometers (1 mile). The space station orbits between 320-400 km (200-250 miles) above the Earth’s surface.
Usually maneuvers raise the orbital altitude in order to compensate for the continual drag the station encounters from the upper atmosphere. But Oberg reported that “because the station is now operating near the upper end of its allowable altitude range, any further increase could have exceeded the lifting performance of planned docking missions over the next few months. Hence NASA had to make the unavoidable and wasteful choice to go in the opposite direction.”
The satellite was a Russian Cosmos-2421 naval surveillance satellite, launched in 2006 and designed for electronic eavesdropping to keep track of Western military vessels. According to U.S. tracking data, the satellite disintegrated on March 14 into hundreds of pieces, and later disintegrated further resulting in over 500 tracked objects, one of the largest debris clouds in space history. But Russian officials say the satellite has not broken up, but only quit working. Find more info on this at MSNBC.
Once the debris avoidance maneuver was complete, the ISS was turned back to its original orbital attitude, and control of the ATV was handed back to the ATV Control Center in Europe.
NASA launch officials were forced to hit the “destruct” button on an experimental rocket that launched early Friday morning. The launch and subsequent explosion was captured on both amateur and NASA video, and shows the pieces falling back to Earth.
The countdown and initial takeoff Friday morning from a NASA launch facility on Wallops Island, Virginia, went smoothly, said former astronaut Kent Rominger, a vice president in ATK’s (Alliant Tech Systems) launch systems division. “Then (the rocket) appeared to veer south,” he said. To the naked eye the flight didn’t appear to be in trouble, he said, but it was moving off course.
The rocket was a little more than 2 miles high when it was destroyed. A team of officials from NASA and ATK are investigating the incident.
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On August 16th, Iran triumphantly announced that they had sent a rocket into space, transporting a “dummy” satellite into orbit. According to Iranian state TV, the night-time launch of the two-stage Safir-e Omid (or Ambassador of Peace) rocket was a resounding success, transmitting video of the launch amid cheers of delight. The nation has never hidden its space ambitions, and in 2005 Iran launched its first commercial satellite on board a Russian rocket. This confirmed concerns of Russia’s co-operation with the Iranian government to bolster the country’s space-faring ability. However, US officials have spoken out against Iranian claims that Saturday’s launch went as planned; according to one official, Iran’s launch was a “dramatic failure.” Regardless, Iran appears to be upbeat about it’s future in space, and today the Iranian Space Organization Chief has announced that Iran will launch a man into space within a decade…
Tensions between Iran and the West are edgy to say the least. For one, Iran’s nuclear program is causing obvious upset in the region; neighbouring countries concerned the balance of power is shifting toward Iranian President Mahmoud Ahmadinejad’s regime. Israel, in particular, has traded threats with Iran, and its close proximity to Tehran (only 600 miles) only helps to intensify the distrust in the region. Now, if the Iranian claims are to be believed, Ahmadinejad is able to order the launch of domestically built satellites, but more worryingly, this sabre rattling shows to the world they are able to launch long-range ballistic missiles to wherever they like. Combine this missile capability with the pressing nuclear threat (although Iran maintains that the Uranium enrichment is for peaceful purposes only), and we have a huge politically unstable situation. The bad blood between the US and Iran is all too obvious, this will only help to increase tensions.
However, the Iranian celebrations may be short lived. It is notoriously difficult to gain any verification that Iran did launch a two-stage rocket into space, let alone carry a “dummy” satellite into orbit. Yesterday, US officials made an announcement claiming that Iran was falsifying the launch and that the rocket failed soon after launch. Looking at the Iranian news footage, we only see the first few seconds of launch, so these doubts are justified.
“The vehicle failed shortly after liftoff and in no way reached its intended position. It could be characterized as a dramatic failure […] The failed launch shows that the purported Iranian space program is in its nascent stages at best — they have a long way to go.” – Unnamed US official.
Although a failed launch seems highly probable (as we all know, rocket science isn’t easy!), prompting the Iranian government to distribute false information about the “successful” launch to save face, but the US official gives no indication about how the US authorities know the launch was a failure. I think it’s going to be some time before these questions can be answered as neither side will want to reveal too much.
Regardless of the “did it launch or didn’t it” debate, Iran has today announced some pretty lofty plans for their future in space. Iran wants to send a man into space. Within ten years.
According to the Chinese news agency Xinhua, the Iranian Space Organization chief Reza Taghipour will set the exact date for a future manned mission within the year. Apparently, “Iran must win the first place in space technology in the region by the Iranian year of 1400 (the equivalent Christian year of 2021),” according to Xinhua (although it is unclear whether the Chinese source is quoting Taghipour or they are stating a fact). Iran also wants to launch a series of ten domestically-built satellites by 2010 to aid disaster relief operations.
Often it is hard to separate the facts from the fiction in the Middle East, but I can’t help but think these invigorated Iranian space ambitions are a ploy to wield their exaggerated military might in the region. Whether the dummy satellite was put into orbit or not seems to be rather academic, the fallout from the Iranian claim and US counter-claim will have severe consequences for US-Iran relations…
The Daedalus star ship, proposed in the 1970s, would propel itself forward using controlled fusion explosions Credit: Nick Stevens/starbase1.co.uk
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Some sobering news from a recent rocket science conference: It is highly improbable that humans will ever explore beyond the Solar System. This downbeat opinion comes from the Joint Propulsion Conference in Hartford, Connecticut, where future space propulsion challenges were discussed and debated. It is widely acknowledged that any form of interstellar travel would require huge advances in technology, but it would seem that the advances required are in the realms of science fiction and are not feasible. Using current technology would take tens of thousands of years, and even advanced concepts could take hundreds. But above all else, there is the question of fuel: How could a trip to Proxima Centauri be achieved if we’d need 100 times more energy than the entire planet currently generates?
In a previous article on the Universe Today, I explored how long it would take to travel to the nearest star using the slowest mode of transportation (the ion driven 1998 Deep Space 1 mission) and the fastest mode of transportation (the solar gravitational accelerated 1976 Helios 2 mission) currently available. I also discussed the theoretical possibility of using nuclear pulse propulsion (a series of fusion bombs dropped behind an interplanetary spaceship to give thrust), much like the 1970’s Daedalus star ship concept (pictured top).
Unfortunately, the ion drive option would take a whopping 81,000 years to get to Proxima Centauri, our nearest star, and using the Sun for a gravitational assist would still take us at least 19,000 years to reach our destination. That is 2,700 to 600 generations, certainly a long-term commitment! To put these figures into perspective, 2,700 generations ago, homo sapiens had not developed the ability to communicate by speech; 600 generations ago the Neanderthals had only recently become extinct. The nuclear pulse propulsion option seems far better taking only 85 years to travel to our nearest star. Still, this is a very long trip (let’s hope they’d offer business class at least…).
Already there are huge challenges facing the notion of travelling to Proxima Centauri, but in a recent gathering of experts in the field of space propulsion, there are even more insurmountable obstacles to mankind’s spread beyond the Solar System. In response to the idea we might make the Proxima trek in a single lifetime, Paulo Lozano, an assistant professor of aeronautics and astronautics at MIT and conference deligate said, “In those cases, you are talking about a scale of engineering that you can’t even imagine.”
OK, so the speed simply isn’t there for a quick flight over 4.3 light years. But there is an even bigger problem than that. How would these interstellar spaceships be fuelled? According to Brice N. Cassenti, an associate professor with the Department of Engineering and Science at Rensselaer Polytechnic Institute, at least 100 times the total energy output of the entire world would be required for the voyage. “We just can’t extract the resources from the Earth,” Cassenti said during his conference presentation. “They just don’t exist. We would need to mine the outer planets.”
For mankind to extend its reach into the stars, we need to come up with a better plan. Even the most advanced forms of propulsion (even anti-matter engines) cannot make the gap seem any less massive. Suddenly the thought of a warp drive seems more attractive…
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Currently, launching 1 pound (.5 kilogram) of payload to space costs about $5,000 USD, so every little bit helps if engineers can cut down on the weight of the spacecraft. Scientists from the University of Michigan have patented their ideas for cutting down the size and weight of the thrusters used in space to maneuver and control the spacecraft. Usually these thrusters are fairly big; they can be as big as a refrigerator. But the new thrusters, called nano-thrusters, could be made into flat, low weight sheets and mounted on the sides of spacecraft. The new type of thrusters would save weight and fuel, while having a longer life as well.
Conventional ion thrusters work by accelerating gas ions to generate force in the opposite direction. But, they waste gas and are limited in lifetime because the accelerated ions damage the engine.
But, according to a report in New Scientist, the new nano-thrusters, developed by Brian Gilchrist and colleagues at the University of Michigan in Ann Arbor, US, avoid these problems.
Each consists of a small chamber of fluid with electrodes inside and a vent at the top. Above that vent more electrodes generate a powerful electric field. The fluid contains nanoparticles just tens of nanometres across that are ionized by electrodes in the chamber. Those charged ions are accelerated by the electric field and ejected from the vent, producing thrust.
These nanothrusters can be used in large numbers on flat panels. To control the spacecraft efficiently, they would probably have to cover large areas of spacecraft. But in the drag-free space environment, it be just like having a second skin on the spacecraft. And they would be much more light-weight than conventional thrusters, and would help cut the costs of launching vehicles to space.
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We’ve all wondered at some point or another what mysteries our Solar System holds. After all, the eight planets (plus Pluto and all those other dwarf planets) orbit within a very small volume of the heliosphere (the volume of space dominated by the influence of the Sun), what’s going on in the rest of the volume we call our home? As we push more robots into space, improve our observational capabilities and begin to experience space for ourselves, we learn more and more about the nature of where we come from and how the planets have evolved. But even with our advancing knowledge, we would be naive to think we have all the answers, so much still needs to be uncovered. So, from a personal point of view, what would I consider to be the greatest mysteries within our Solar System? Well, I’m going to tell you my top ten favourites of some more perplexing conundrums our Solar System has thrown at us. So, to get the ball rolling, I’ll start in the middle, with the Sun. (None of the following can be explained by dark matter, in case you were wondering… actually it might, but only a little…)
10. Solar Pole Temperature Mismatch
Data from Ulysses (D. McComas)
Why is the Sun’s South Pole cooler than the North Pole? For 17 years, the solar probe Ulysses has given us an unprecedented view of the Sun. After being launched on Space Shuttle Discovery way back in 1990, the intrepid explorer took an unorthodox trip through the Solar System. Using Jupiter for a gravitational slingshot, Ulysses was flung out of the ecliptic plane so it could pass over the Sun in a polar orbit (spacecraft and the planets normally orbit around the Sun’s equator). This is where the probe journeyed for nearly two decades, taking unprecedented in-situ observations of the solar wind and revealing the true nature of what happens at the poles of our star. Alas, Ulysses is dying of old age, and the mission effectively ended on July 1st (although some communication with the craft remains).
However, observing uncharted regions of the Sun can create baffling results. One such mystery result is that the South Pole of the Sun is cooler than the North Pole by 80,000 Kelvin. Scientists are confused by this discrepancy as the effect appears to be independent of the magnetic polarity of the Sun (which flips magnetic north to magnetic south every 11-years). Ulysses was able to gauge the solar temperature by sampling the ions in the solar wind at a distance of 300 million km above the North and South Poles. By measuring the ratio of oxygen ions (O6+/O7+), the plasma conditions at the base of the coronal hole could be measured.
Mars, just a normal planet. No mystery here... (NASA/Hubble)
Why are the Martian hemispheres so radically different? This is one mystery that had frustrated scientists for years. The northern hemisphere of Mars is predominantly featureless lowlands, whereas the southern hemisphere is stuffed with mountain ranges, creating vast highlands. Very early on in the study of Mars, the theory that the planet had been hit by something very large (thus creating the vast lowlands, or a huge impact basin) was thrown out. This was primarily because the lowlands didn’t feature the geography of an impact crater. For a start there is no crater “rim.” Plus the impact zone is not circular. All this pointed to some other explanation. But eagle-eyed researchers at Caltech have recently revisited the impactor theory and calculated that a huge rock between 1,600 to 2,700 km diameter can create the lowlands of the northern hemisphere (see Two Faces of Mars Explained).
Bonus mystery: Does the Mars Curse exist? According to many shows, websites and books there is something (almost paranormal) out in space eating (or tampering with) our robotic Mars explorers. If you look at the statistics, you would be forgiven for being a little shocked: Nearly two-thirds of all Mars missions have failed. Russian Mars-bound rockets have blown up, US satellites have died mid-flight, British landers have pock-marked the Red Planet’s landscape; no Mars mission is immune to the “Mars Triangle.” So is there a “Galactic Ghoul” out there messing with our ‘bots? Although this might be attractive to some of us superstitious folk, the vast majority of spacecraft lost due to The Mars Curse is mainly due to heavy losses during the pioneering missions to Mars. The recent loss rate is comparable to the losses sustained when exploring other planets in the Solar System. Although luck may have a small part to play, this mystery is more of a superstition than anything measurable (see The “Mars Curse”: Why Have So Many Missions Failed?).
8. The Tunguska Event
Artist impression of the Tunguska event (www.russianspy.org)
What caused the Tunguska impact? Forget Fox Mulder tripping through the Russian forests, this isn’t an X-Files episode. In 1908, the Solar System threw something at us… but we don’t know what. This has been an enduring mystery ever since eye witnesses described a bright flash (that could be seen hundreds of miles away) over the Podkamennaya Tunguska River in Russia. On investigation, a huge area had been decimated; some 80 million trees had been felled like match sticks and over 2,000 square kilometres had been flattened. But there was no crater. What had fallen from the sky?
This mystery is still an open case, although researchers are pinning their bets of some form of “airburst” when a comet or meteorite entered the atmosphere, exploding above the ground. A recent cosmic forensic study retraced the steps of a possible asteroid fragment in the hope of finding its origin and perhaps even finding the parent asteroid. They have their suspects, but the intriguing thing is, there is next-to-no meteorite evidence around the impact site. So far, there doesn’t appear to be much explanation for that, but I don’t think Mulder and Scully need be involved (see Tunguska Meteoroid’s Cousins Found?).
7. Uranus’ Tilt
Uranus. Does it on its side (NASA/Hubble)
Why does Uranus rotate on its side? Strange planet is Uranus. Whilst all the other planets in the Solar System more-or-less have their axis of rotation pointing “up” from the ecliptic plane, Uranus is lying on its side, with an axial tilt of 98 degrees. This means that for very long periods (42 years at a time) either its North or South Pole points directly at the Sun. The majority of the planets have a “prograde” rotation; all the planets rotate counter-clockwise when viewed from above the Solar System (i.e. above the North Pole of the Earth). However, Venus does the exact opposite, it has a retrograde rotation, leading to the theory that it was kicked off-axis early in its evolution due to a large impact. So did this happen to Uranus too? Was it hit by a massive body?
Some scientists believe that Uranus was the victim of a cosmic hit-and-run, but others believe there may be a more elegant way of describing the gas giant’s strange configuration. Early in the evolution of the Solar System, astrophysicists have run simulations that show the orbital configuration of Jupiter and Saturn may have crossed a 1:2 orbital resonance. During this period of planetary upset, the combined gravitational influence of Jupiter and Saturn transferred orbital momentum to the smaller gas giant Uranus, knocking it off-axis. More research needs to be carried out to see if it was more likely that an Earth-sized rock impacted Uranus or whether Jupiter and Saturn are to blame.
6. Titan’s Atmosphere
False colour image of Titan's atmosphere. Credit: NASA/JPL/Space Science Institute/ESA
Why does Titan have an atmosphere? Titan, one of Saturn’s moons, is the only moon in the Solar System with a significant atmosphere. It is the second biggest moon in the Solar System (second only to Jupiter’s moon Ganymede) and about 80% more massive than Earth’s Moon. Although small when compared with terrestrial standards, it is more Earth-like than we give it credit for. Mars and Venus are often cited as Earth’s siblings, but their atmospheres are 100 times thinner and 100 times thicker, respectively. Titan’s atmosphere on the other hand is only one and a half times thicker than Earth’s, plus it is mainly composed of nitrogen. Nitrogen dominates Earth’s atmosphere (at 80% composition) and it dominates Titans atmosphere (at 95% composition). But where did all this nitrogen come from? Like on Earth, it’s a mystery.
Titan is such an interesting moon and is fast becoming the prime target to search for life. Not only does it have a thick atmosphere, its surface is crammed full with hydrocarbons thought to be teeming with “tholins,” or prebiotic chemicals. Add to this the electrical activity in the Titan atmosphere and we have an incredible moon with a massive potential for life to evolve. But as to where its atmosphere came from… we just do not know.
5. Solar Coronal Heating
Coronal loops as imaged by TRACE at 171 Angstroms (1 million deg C) (NASA/TRACE)
Why is the solar atmosphere hotter than the solar surface? Now this is a question that has foxed solar physicists for over half a century. Early spectroscopic observations of the solar corona revealed something perplexing: The Sun’s atmosphere is hotter than the photosphere. In fact, it is so hot that it is comparable to the temperatures found in the core of the Sun. But how can this happen? If you switch on a light bulb, the air surrounding the glass bulb wont be hotter than the glass itself; as you get closer to a heat source, it gets warmer, not cooler. But this is exactly what the Sun is doing, the solar photosphere has a temperature of around 6000 Kelvin whereas the plasma only a few thousand kilometres above the photosphere is over 1 million Kelvin. As you can tell, all kinds of physics laws appear to be violated.
However, solar physicists are gradually closing in on what may be causing this mysterious coronal heating. As observational techniques improve and theoretical models become more sophisticated, the solar atmosphere can be studied more in-depth than ever before. It is now believed that the coronal heating mechanism may be a combination of magnetic effects in the solar atmosphere. There are two prime candidates for corona heating: nanoflares and wave heating. I for one have always been a huge advocate of wave heating theories (a large part of my research was devoted to simulating magnetohydrodynamic wave interactions along coronal loops), but there is strong evidence that nanoflares influence coronal heating too, possibly working in tandem with wave heating.
Although we are pretty certain that wave heating and/or nanoflares may be responsible, until we can insert a probe deep into the solar corona (which is currently being planned with the Solar Probe mission), taking in-situ measurements of the coronal environment, we won’t know for sure what heats the corona (see Warm Coronal Loops May Hold the Key to Hot Solar Atmosphere).
4. Comet Dust
Comets - where does their dust come from?
How did dust formed at intense temperatures appear in frozen comets? Comets are the icy, dusty nomads of the Solar System. Thought to have evolved in the outermost reaches of space, in the Kuiper Belt (around the orbit of Pluto) or in a mysterious region called the Oort Cloud, these bodies occasionally get knocked and fall under the weak gravitational pull of the Sun. As they fall toward the inner Solar System, the Sun’s heat will cause the ice to vaporize, creating a cometary tail known as the coma. Many comets fall straight into the Sun, but others are more lucky, completing a short-period (if they originated in the Kuiper Belt) or long-period (if they originated in the Oort Cloud) orbit of the Sun.
But something odd has been found in the dust collected by NASA’s 2004 Stardust mission to Comet Wild-2. Dust grains from this frozen body appeared to have been formed a high temperatures. Comet Wild-2 is believed to have originated from and evolved in the Kuiper Belt, so how could these tiny samples be formed in an environment with a temperature of over 1000 Kelvin?
The Solar System evolved from a nebula some 4.6 billion years ago and formed a large accretion disk as it cooled. The samples collected from Wild-2 could only have been formed in the central region of the accretion disk, near the young Sun, and something transported them into the far reaches of the Solar System, eventually ending up in the Kuiper Belt. But what mechanism could do this? We are not too sure (see Comet Dust is Very Similar to Asteroids).
3. The Kuiper Cliff
The bodies in the Kuiper Belt (Don Dixon)
Why does the Kuiper Belt suddenly end? The Kuiper Belt is a huge region of the Solar System forming a ring around the Sun just beyond the orbit of Neptune. It is much like the asteroid belt between Mars and Jupiter, the Kuiper Belt contains millions of small rocky and metallic bodies, but it’s 200-times more massive. It also contains a large quantity of water, methane and ammonia ices, the constituents of cometary nuclei originating from there (see #4 above). The Kuiper Belt is also known for its dwarf planet occupant, Pluto and (more recently) fellow Plutoid “Makemake”.
The Kuiper Belt is already a pretty unexplored region of the Solar System as it is (we wait impatiently for NASA’s New Horizons Pluto mission to arrive there in 2015), but it has already thrown up something of a puzzle. The population of Kuiper Belt Objects (KBOs) suddenly drops off at a distance of 50 AU from the Sun. This is rather odd as theoretical models predict an increase in number of KBOs beyond this point. The drop-off is so dramatic that this feature has been dubbed the “Kuiper Cliff.”
We currently have no explanation for the Kuiper Cliff, but there are some theories. One idea is that there are indeed a lot of KBOs beyond 50 AU, it’s just that they haven’t accreted to form larger objects for some reason (and therefore cannot be observed). Another more controversial idea is that KBOs beyond the Kuiper Cliff have been swept away by a planetary body, possibly the size of Earth or Mars. Many astronomers argue against this citing a lack of observational evidence of something that big orbiting outside the Kuiper Belt. This planetary theory however has been very useful for the doomsayers out there, providing flimsy “evidence” for the existence of Nibiru, or “Planet X.” If there is a planet out there, it certainly is not “incoming mail” and it certainly is notarriving on our doorstep in 2012.
So, in short, we have no clue why the Kuiper Cliff exists…
2. The Pioneer Anomaly
Artist impression of the Pioneer 10 probe (NASA)
Why are the Pioneer probes drifting off-course? Now this is a perplexing issue for astrophysicists, and probably the most difficult question to answer in Solar System observations. Pioneer 10 and 11 were launched back in 1972 and 1973 to explore the outer reaches of the Solar System. Along their way, NASA scientists noticed that both probes were experiencing something rather strange; they were experiencing an unexpected Sun-ward acceleration, pushing them off-course. Although this deviation wasn’t huge by astronomical standards (386,000 km off course after 10 billion km of travel), it was a deviation all the same and astrophysicists are at a loss to explain what is going on.
One main theory suspects that non-uniform infrared radiation around the probes’ bodywork (from the radioactive isotope of plutonium in its Radioisotope Thermoelectric Generators) may be emitting photons preferentially on one side, giving a small push toward the Sun. Other theories are a little more exotic. Perhaps Einstein’s general relativity needs to be modified for long treks into deep space? Or perhaps dark matter has a part to play, having a slowing effect on the Pioneer spacecraft?
How do we know the Oort Cloud even exists? As far as Solar System mysteries go, the Pioneer anomaly is a tough act to follow, but the Oort cloud (in my view) is the biggest mystery of all. Why? We have never seen it, it is a hypothetical region of space.
At least with the Kuiper Belt, we can observe the large KBOs and we know where it is, but the Oort Cloud is too far away (if it really is out there). Firstly, the Oort Cloud is predicted to be over 50,000 AU from the Sun (that’s nearly a light year away), making it about 25% of the way toward our nearest stellar neighbour, Proxima Centauri. The Oort Cloud is therefore a very long way away. The outer reaches of the Oort Cloud is pretty much the edge of the Solar System, and at this distance, the billions of Oort Cloud objects are very loosely gravitationally bound to the Sun. They can therefore be dramatically influenced by the passage of other nearby stars. It is thought that Oort Cloud disruption can lead to icy bodies falling inward periodically, creating long-period comets (such as Halley’s comet).
In fact, this is the only reason why astronomers believe the Oort Cloud exists, it is the source of long-period icy comets which have highly eccentric orbits emanating regions out of the ecliptic plane. This also suggests that the cloud surrounds the Solar System and is not confined to a belt around the ecliptic.
So, the Oort Cloud appears to be out there, but we cannot directly observe it. In my books, that is the biggest mystery in the outermost region of our Solar System…
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India will send their first mission to the Moon in September. Chandrayaan-1 has been built and will be launched from Indian soil and sent on a mission to study the lunar surface. The Indian Space Research Organization (ISRO) will use its highly successful Polar Satellite Launch Vehicle (PSLV) to get the lunar probe into space. This is an impressive mission for a small space agency, making huge strides in the exploration of space…
It seems like everybody is doing it these days. First, Russia did it (in 1959) by landing a probe on the lunar surface and taking pictures of the far side of the Moon. Then the Soviets put the first artificial lunar satellite into orbit in 1966. Not to be out done, President Kennedy had already begun the US quest to get man on the Moon, and in 1969 the superpower achieved that goal. For a long time it was only the two competitors in the Space Race who had visited the Moon, but in 1990, Japan joined the “Lunar Club” (with the Hiten spacecraft). Then in 1997 Hong Kong (China) succeeded in two flybys (HGS-1, a commercial satellite). Eventually, in 2006, the European SMART-1 space vehicle made it into lunar orbit. But since then, it’s been China (with the Chang’e program) and Japan (with SELENE, or “Kaguya”) who have been most active around the natural satellite.
And now there is a new kid on the block: India. One of the most populous nations in the world is pushing ahead with its own aspirations for lunar exploration. Although comparatively small, the Indian space agency ISRO was established in 1972 to develop space-based technologies in the aim of enriching the nation’s economy. Until the early 1990’s, India had to rely on Russia to launch payloads into space, but 1994 saw the first successful launch of the powerful Polar Satellite Launch Vehicle (PSLV), lifting domestic and commercial satellites into orbit. Now the PSLV will launch India’s most valuable payload yet, the Chandrayaan-1 lunar orbiter and impactor. It is scheduled for launch on September 19th.
In a speech on India’s 61st Independence Day from the historic Red Fort in Delhi, the Indian Prime Minister Manmohan Singh called the Chandrayaan-1 mission “an important milestone” for the nation. However, although a date has been set for launch, some of the text seemed a little uncertain. “This year we hope to send an Indian spacecraft, Chandrayan, to the moon. It will be an important milestone in the development of our space programme,” Singh said. Whether the “we hope” was accidental or whether the launch date is only tentative remains to be seen.
Regardless, the mission appears to be good to go, obviously a huge boost to national pride. “I want to see a modern India, imbued by a scientific temper, where the benefits of modern knowledge flow to all sections of society,” he continued.
Falcon 1 lifts off from Kwajalein Atoll, South Pacific August 2nd (SpaceX)
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On August 2nd, SpaceX made the surprise announcement that the third flight of the Falcon 1 rocket system would launch at 8pm (PST) that day. The world rushed to watch the first commercial flight of this impressive private-sector rocket via the web from a live feed on board. The first launch attempt was aborted due to a minor parameter fluctuation of 1% out of “normal” operating conditions, but the launch crew very quickly re-fuelled and prepared Falcon 1 for a second launch attempt within the hour. The second launch attempt appeared to be flawless, Merlin 1c engine roaring to life, lifting the rocket into the atmosphere. All seemed good, SpaceX seemed on track and very confident. However, minutes into the flight, the live video feed was cut and it was being reported an anomaly had occurred. It wasn’t until later in the week that SpaceX CEO Elon Musk gave details about the “anomaly.” SpaceX recently released video footage of the entire launch, up to the point where the stage separation problem occurred, spinning the ill-fated vehicle out of control…
So what did happen on that frustrating Sunday evening? On August 6th, Elon Musk announced the findings of the investigation into the launch anomaly. According to the launch engineers, the SpaceX Merlin 1c engine in the first stage performed perfectly. Even after the false-start on the launchpad, the engine was ready to go within the hour. This fast turnaround from launch abort to re-launch is a huge advantage for the company, a great testament to the flexibility of the technology SpaceX has developed in-house. The problems started during stage separation at an altitude of 35 km.
The problem arose due to the longer thrust decay transient of our new Merlin 1C regeneratively cooled engine, as compared to the prior flight that used our old Merlin 1A ablatively cooled engine. Unlike the ablative engine, the regen engine had unburned fuel in the cooling channels and manifold that combined with a small amount of residual oxygen to produce a small thrust that was just enough to overcome the stage separation pusher impulse. – Elon Musk, Aug. 6th statement.
From this statement and from viewing the video, it would seem that during first stage separation a small amount of fuel left over creating a small thrust just after the stages were forced away from one another (a.k.a. “stage separation pusher impulse”). At separation, it would appear that just as the first stage was beginning to fall away from Falcon 1, it regained some forward thrust, making it crash into the second stage engine. This small thrust anomaly prevented the spent first stage from falling clear of the igniting second stage. This sequence of events is captured in the series of screenshots below:
The Falcon 1 separation anomaly at an altitude of 35 km. From left to right: First stage separation appears to be going well until frame 3. Frame 4 shows the first stage thrust back into the second stage. Frame 5 shows the second stage firing when the first stage is not clear, Falcon 1 tumbles out of control (SpaceX)
As the first stage was not clear, the second stage engine fired into the spent first stage. This would have caused a loss in control in rocket trajectory. However, the SpaceX editors appear to cut the video from the instant the second stage fires to when the rocket is in full tumble, blacking the frames out in between with the text “Faring Separation.” It’s not obvious what this means and there is no mention of it in the accompanying text. Most probably it means the camera was blown away from the rocket after second stage ignition.
The anomaly was down to what has been called a “thrust transient” and Musk points the blame at the tiny thrust that couldn’t be measured on the ground during test firing as the force generated was simply too small to be detected. However, in the vacuum of zero-gravity space, any thrust, large or small, matters:
The question then is why didn’t we catch this issue? Unfortunately, the engine chamber pressure is so low for this transient thrust — only about 10 psi — that it barely registered on our ground test stand in Texas where ambient pressure is 14.5 psi. However, in vacuum that 10 psi chamber pressure produced enough thrust to cause the first stage to recontact the second stage – Elon Musk, Aug. 6th statement.
Although this event is an obvious set back, and deeply saddening for SpaceX and the owners of the payloads Falcon 1 was supposed to put into orbit, lessons have been learnt and Musk is positive the next launch will be a total success. After all, no one said rocket science was easy…
Long, lonely trips to Mars could pose psychological challenges for astronauts.
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Psychologists meeting this week at the American Psychological Association’s 116th Annual Convention are taking the time to discuss the challenges astronauts will face on the longer missions planned for NASA’s return to the moon and missions to Mars. Presenters at the first every symposium to address the psychological aspects of long-term spaceflight outlined the mental health challenges and introduced a new interactive computer program that will help address psychosocial issues in space. Psychologists said longer missions mean astronauts will be faced with immense psychological pressures as they adjust to being so far away from Earth, which could lead to depression and interpersonal conflicts. “Lessons learned from the past, research in extreme environments, training, conditioning, and countermeasures for psychological stress are some of the things NASA is in the process of addressing for the upcoming age of exploration,” said psychologist Marc Shepanek, PhD, from the Office of the Chief Health and Medical Officer at NASA.
Previously, not much thought had been given to the mental health of astronauts. These strong, intelligent and gifted astronauts seemed almost above psychological concerns. But these types of issues were brought to the forefront of everyone’s attention when astronaut Lisa Nowak was charged with attempted murder in a bizarre love triangle involving another astronaut. Historically, astronauts have been reluctant to admit to mental or behavioral health problems for fear of being grounded.
Psychologist James Carter, PhD, and his colleagues are in the process of developing a suite of interactive computer programs, dubbed the Virtual Space Station, using input from 13 veteran long-duration NASA astronauts who have flown on the International Space Station, Mir and Skylab. The system is being evaluated in a set of randomized controlled clinical trials. This interactive program will help astronauts prevent, detect, assess and manage their own psychosocial problems. They will learn how to cope with depression and how to resolve conflicts with other astronauts.
“Behavioral health problems can interfere with the success of the mission, especially on long-duration space flights like missions to the International Space Station, the moon and Mars. These self-guided software tools will provide private and immediate access to treatments even though the patient may be many miles from Earth,” Carter said in prepared remarks. The Virtual Space Station has already been deployed in Antarctica.
However, as astronauts aim to explore a new planet, the one they leave behind could be foremost on their minds. They will have limited contact with their families and radio communications with Mission Control will be delayed, possibly for as long as 40 minutes. In her presentation, family sociologist Phyllis Johnson, PhD, analyzed interviews with astronauts who had spent an extended amount of time in space. The astronauts identified what they felt was the role of NASA, themselves and their families in creating a “home away from home” during their flights. “For example, they emphasized the importance of regular communication regarding work, publicity and education, all of which provide connection to Earth and helped to reduce the perception of isolation,” said Johnson.
Psychologists also looked to history for guidance in future space missions. “The closest analogue to Mars exploration is the exploration of Earth,” said psychologist Peter Suedfeld, PhD. “Both maritime and terrestrial explorers struck off into the unknown, often for many years at a time.” Like space explorers, they had little or no communication with home, and had to devise ways of coping with unforeseen and unfamiliar hardships and dangers. Psychologists are re-examining sea and land voyagers’ diaries, logs and letters for a glimpse into how these explorers dealt with boredom, rebelliousness and dissent. They said it may be best way to predict some aspects of future long-duration missions.
Artist's impression of a solar sail. Image credit: NASA
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Last week we talked about rockets. How they work and their limitations. This week we’re going to look at the future of propulsion systems. From the ion engines that are already working to explore the Solar System to the prototype solar sails to futuristic technologies like magnetic sails, and bussard ramjets. This is how we’ll travel to other stars.
