African Photography Blog

Underwater Photography Tips

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Underwater Photography Tips

As years go by, the world of photography continues to reinvent itself along with the changes in technology. Its pillars continue to come up with better sets of equipment like cameras and constantly come up with new methods and strategies to produce better photograph.

Along with these changes is the emergence of modern photography method that enables man to reach and rediscover the beauty of uncharted territories like the ocean floor. This is called “underwater photography.”

As the term suggests, underwater photography refers to the kind of photography that is done or taken under water. This is quite a breakthrough in the world of photography because underwater lovers such as divers and scuba divers because they can now take photos under the sea and share it with others with the use of modern equipment that can actually work well down under.


Aside from possessing the love and passion for the water and the creatures under, reliable equipment such as an underwater camera is the key factor for successful underwater photography. If you’re a diver who is not so much into underwater photography, you can now purchase disposable underwater cameras just to take photos. But if you would want to pursue a career in underwater photography, you will need much complicated equipment and gadgets.

The first thing you should consider is the camera to be used. In underwater photography, two kinds are usually used: the underwater or waterproof camera and the encased camera that has housing to protect the camera inside. Aside from camera, you should also take time to research and canvass what is the best lens, film, and flash you can use during your shoot.

Aside from the major technicalities and equipment, you should also consider several environmental factors that will greatly affect the quality of your underwater photos such as depth of water and transparency of water, available light, the angle of the sunlight on the top of the water, the backscatter, and the magnifying effect of water.

Here are some additional musts before you dive and click that shutter button:

1. Good or at least average diving skills. In order to be fully prepared for an underwater shoot, the underwater photographer should also possess good diving skills to be comfortable in taking photos.

2. An experienced underwater buddy. This person can serve as your model and can even help you carry your equipment and gear, hold the lights down under, and can even share the momentous experience.

3. Good managing skills—in managing resources, that is. You should learn to manage vital resources such as dive time, body heat, air, battery life, and the like in order to endure the physical strains under water.

4. Reliable camera housing. If you don’t have waterproof

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Photography on Night Safaris in Africa

Taking a photo is not as easy as focusing on the subject and then clicking the camera. It takes more than that. In fact, it takes a lot of intuition and a set of lessons. This is why amateurs in photography need not only experience but also lessons in techniques and of course in the basics.  One of the hardest thing to master is night photography, not only because the subject is hard to find but also because the shadows will make it more difficult for the amateur photographer to take a good shot.

One of the popular adventures in Africa are night safaris within several national parks in Africa. In Uganda, Semuliki Forest is one of the best destinations to enjoy night photography given yhat the park hosts several nocturnal animals that include primates, leopards etc.

Below are some tips that any amateur photographer can use to master night photography.


The first thing of course that amateur photographers need to remember is to choose the location well. Remember that if you are going to do the shoot, you will have valuable equipment with you. There are places in the country especially in the cities that are very dangerous at night. Safety is paramount. If possible, do your explorations with one or two people as you cannot very well conduct your shoot in daylight or under artificial lights.


Another reminder is that batteries often run out easily in cold conditions, so it is best to carry an extra or if you have none, try to fully charge your batteries before going out of the house and proceeding with the shoot. You should also bring a good case for your camera as moisture during the night can easily permeate to your camera.

Other equipment

The best camera to use for night work is actually the one with the manual exposure settings, preferably an SLR (single lens reflex). Automatic cameras are not often recommended, as they are not powerful enough to fight the darkness. Another requirement is a sturdy tripod with a rubber leg to minimize slippage. A cable release is also needed as this will enable you to hold the shutter speed open.


One important thing that an amateur must remember in conducting night photography is the fact that longer exposures are needed for black and white photos compared to ordinary lighting. Color film, on the other hand, will produce shifts in colors.

Use of flash

With insufficient light from the moon, most photographers will supplement the light with a hand-held flashes, a technique known as “painting with light.” Other more sophisticated ones may also use movie lights and torches as additional lights.

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Photographing the African Landscape – Africa Through the Lens

Africa is by far one of the most diverse landscapes in the world and much of it is still undiscovered by the lens. Many photographers would trade a limb to have access to the African landscape yet a great majority of South African photographers seem intent on travelling around the world to photograph landscapes that have been well covered by other photographers, all the while a treasure chest of images lies right under their noses.

Africa holds a treasure chest of landscape photography opportunities. Commercial Fine Art Photography South Africa.

“Mercury Down II” The sun sets and the mercury indicator starts to drop after a very hot day in Namibia – Copyright Mitchell Krog / Living Canvas Photography. All Rights Reserved.

For the budding and professional landscape photographer there is virtually endless landscape photographic opportunities in Africa and Southern Africa. South African photographer Mitchell Krog is no stranger to the African landscape and spends many months a year exploring, discovering and capturing breathtaking images of the beautiful African landscapes. Mitchell chooses to completely avoid re-capturing images which have been captured a million times or more, “I just don’t see the point in photographing things that have are captured 100 times a day when there is just so much that has NOT even been photographed yet” he says.

Photographing the African Landscape, South African Photographer Mitchell Krog is regularly exploring, discovering and capturing breathtaking images of the African landscape. This image from the mountainous Drakensberg area of South Africa captures a beautiful sunrise over the beautiful landscape of this area of Kwazulu Natal.

“Drakensberg Sunrise” – The sun rises over the beautiful and majestic mountainous region of the Drakensberg of South Africa. Copyright Mitchell Krog / Living Canvas Photography. All Rights Reserved.

The greatest parts of the undiscovered African landscape are only accessible via foot and often many kilometers of walking can be involved simply to capture one image. As Mitchell Krog says, “This is the game unfortunately and quite simply if you’re not willing to go the extra “mile”, excuse the pun, you will not return home with any new or unique images that have not been captured already. The Drakensberg region of South Africa, of which the greatest area lies within the province of Kwazulu Natal, is a good example. Photographers seeking to cover this area really need to go many extra miles to get to unique locations and in the Drakensberg there literally is endless locations on offer. The Drakensberg is so diverse and the landscape is ever changing, the light is so dramatic that you could sit and photograph the same scene every day for 365 days and not one image would be the same, it is for this very reason that I can say the landscape opportunities of the Drakensberg are endless.”

Cape Town and the Western Cape of South Africa offer many landscape photography opportunities. A great majority of the Cape has been well covered by photographers but much like the Drakensberg, the Cape is mountainous and the light is dramatic and there are still many opportunities awaiting the photographer. This panorama of Table mountain and the Cape peninsula taken by South African photographer Mitchell Krog.

“Table Mountain at Dusk” – One of the most photographed mountains in the world, Table Mountain. Copyright Mitchell Krog / Living Canvas Photography. All Rights Reserved.

Similarly the Western Cape region of South Africa is also very mountainous and has some very dramatic landscapes. The Cape weather is rather unpredictable but this coupled with dramatic light seems to make for a good recipe for excellent landscape photography opportunities. The Cape is one of the most photographically covered regions of South Africa but this does ot mean that there is not still many landscape photography opportunities in store for the visiting photographer. No doubt South Africa will see many international photographers visiting our shores as the World Cup Soccer draws closer and it will be interesting to see how fresh eyes portray our beautiful landscapes.
Copyright – Living Canvas Photography / African Photography Blog – Duplication in part or whole is expressly forbidden. All images and photographs are copyright to Mitchell Krog & Living Canvas photography and may not be used without prior permissions. All images are available in limited and regular edition print series on archival quality papers and canvas through the web site – You may syndicate articles from this blog using our RSS feeds but all syndicated articles must link back to the original content on this site. Please see the Copyright page for more information.

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Chasing The Storm – Lightning Photography

Lightning Storms are one of the most incredible forces of nature. The sheer force of a lightning strike is enough to power a city for months on end but man has not yet learned to harness and store this incredible energy source provided free of charge by nature. As Summer approaches in South Africa, the first rains and electrical storms for the season are already brewing and we’ll soon see what kind of storm activity nature has in store for use this season. Acclaimed South African Lightning and Storm Photographer Mitchell Krog shares some of his images, views and experiences with lightning photography.

Danger Written In The Sky

Multiple Lightning Strikes Light Up The Summer Night Sky. If Only Man Could Learn To Harness This Energy. For many years SA photographer Mitchell Krog has watched and studied electrical storms and to this day still stands in utter amazement at this incredible force of nature. In recent years he acquired the equipment and skills to finally capture them on film and he has produced an endless array of breathtaking images. For Mitchell it is not about simply capturing a lightning strike on film but more importantly capturing the entire scene and telling a story through his images. “With any form of photography if you can captivate a viewers attention, draw them into an image, tell them a story and have them study it for more than just a few seconds you have imprinted an ever lasting memory” says Mitchell. Lightning photography can be a very lonely passtime, only those with enough dedication, patience and endurance to be out at strange hours of the night will stand a chance of capturing unique, sometimes once in a lifetime images.

The Big Detour

A passenger aircraft destined for Lanseria airport bypasses a massive storm cell. Missing dinner and spending many lonesome hours outside comes with the job of photographing lightning storms. From Mitchell Krog’s Lightning Photography Portfolio. (Copyright Mitchell Krog – All Rights Reserved)

As with any form of photography, timing is of the essence. If you are unprepared, unwilling or unable to drop whatever you are doing at a moments notice you will miss opportunities. “I cannot tell you how many evenings I have rushed out of the house just minutes before dinner was ready only to return home several hours later, but nature waits for no man and if you are quick to seize the opportunity you will reap the rewards” says Mitchell. Mitchell’s Fire and Ice series, capturing a grassland fire which was started by lightning strikes was one such occasion. He explains – “I was cooking dinner when I heard thunder approaching, I took a quick look outside and saw the sky glowing red from a grass fire, I dropped everything, rushed outside and managed to capture a few frames of this scene before the storm extinguished the fire it had started. This entire window of opportunity lasted a mere 20-30 minutes and was at it’s best stage for around 5-10 minutes.”

Fire and Ice

An early Spring lightning storm starts a grass fire and is capture here with strikes falling around and into the fire. Minutes later the storm extinguishes the fire it started and the moment is gone. From Mitchell Krog’s Fire and Ice Lightning Photography Series.

Safety is an important part of watching and photographing lightning storms. Finding a safe location with a good view is of the essence, you need to be able to see the storm approaching and be able to determine if you are in any way in the path of danger. “If your view is in any way blocked a storm can sneak up right behind you so a 360 degree view is preferable, you also need somewhere safe to escape to. I’ve often been watching a storm in one direction when right behind me another one is brewing, so I always keep a watch all around me. Standing outside with a metal tripod and an electrically charged camera when strikes are falling too close is asking for trouble” says Mitchell. Mitchell insists that climbing on the roof of your house or any metal structure is a big no-no and could quickly cost you your life and he always promotes safe lightning photography. “There is just no image worth losing your life over” he adds.

Killer Storm

Credits to Mitchell Frog (2007)

On the 23rd of November 2007 this mammoth supercell emitting lightning strikes up and out of it’s core was captured by Mitchell Krog. The strikes emanating from the centre of this storm cell were kilometres in length and streaked across the night sky. This same evening several massive storm cells circulated through Gauteng and claimed lives in their path.

Credits to Mitchell Krog  – You can buy his lightning photos here

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Using HDR in Wildlife & Landscape Photography

So you can HDR but can you do it in one shot and without filters? Blending, challenge, exposure, filters, HDR, high dynamic range, highlights, image, Landscape, midtones, ND, neutral density, Photography, shadows, single

High Dynamic Range or HDR in it’s shortened form has opened up many new avenues for photography. HDR is a process of blending multiple exposures together to better reproduce the dynamic range of the scene and for the most part it’s a very useful tool indeed. I myself have done many experiments into HDR using bracketing of frames to produce multiple exposures which I can later blend BUT all that blending does take up a lot of time in post processing.

Just doing one image blend with 7 exposures with some fine tuning and manual blending included you can easily spend 1-2 hours to get the image perfect. In some cases it might be worth it to take a very special moment you captured on film and to spend that time working the image to perfection. While this can and does produce some very special effects within images I still find HDR, no matter how well executed, to lack something truly special, an ambience that only a single shot exposure carries.

One exposure requires finding the perfect moment to capture the image.

While some may argue that we’re now in the digital world and we must all move to new and wonderful ways of processing images I say yes and no to that argument. I will use HDR when I find it necessary and with many shoots I will bracket exposures regardless but my primary goal is always to get it right with one exposure. I find simply bracketing exposures on every shoot with the intention of later blending and “fixing” it in photoshop makes one a rather lazy photographer because you tend to find a recipe, set up, compose, bracket and go home to fix. Guilty as charged.

While this approach may be perfectly okay for some I enjoy photography because it challenges my mind. I myself got into a trap for a short while of merely relying on bracketed exposures for nearly all shoots. There were many days when I was too lazy to get out filters and do it properly so it was much easier to just bracket my exposures and do the hard work later in Photoshop.

In the end I was just finding HDR was totally lacking something very special, HDR just looked too perfect and NOT at all how the eye saw it. HDR fanatics (myself included) continually fool themselves into believing that the end product they produce through HDR and image blending is a faithful representation of what they saw, but of the many many photographers I know only a few ever take real notice of what the scene really looks like. The others have their eyes stuck permanently behind the viewfinder relying solely on the camera to capture all the necessary bits of information. I make a point of studying very carefully the scene’s I record and do my best to etch them in my mind, right down to the tiniest details and by doing so I manage to find some very special elements of an image that HDR tends to over-produce and in most cases actually ruin. Shadow areas of an image, for example, are crucial to the depth and feel of an image yet HDR fanatics tend to, what I call rape the shadow areas, lightening them up much more than they appeared to the human eye and it’s so easy to fall into this trap with HDR. Again .. guilty as charged

In the last year I have slowly forced myself back to basics, getting exposures perfect with a single exposure, without filters and without bracketing. It’s not always easy depending on light conditions but actually a lot of the time it is and it all comes down to timing, planning and using all available and natural elements to control the flow of light into the camera.

I’ve enjoyed my journey with HDR and I do know I will still use HDR methods for certain work but with landscape, nature and some other forms of photography I’m finding the step back to basics to be producing very special images like none other and it’s made my photography all that more interesting and challenging again. The mental challenge has always been my driving force and it’s good to have that old friend back at my side.

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Photos Look Better on a Dark Background

If I had a dollar for every time I’ve visited a forum and seen a photographer urging their viewers to view the image against a dark background because it looks better, I’d be a millionaire by now.

Black or dark backgrounds naturally enhance any and all colours, they can even make sub-standard images appear really good but ask yourself this …. are your walls at home painted black or charcoal grey?

I can guarantee that 99.9% of people will answer NO to that and I can also guarantee that 99.9% of your customers who you try and sell images and prints to also do not have dark black or grey walls in their houses.

If you truly want to visualise how an image will look in your house then view it on an appropriate background colour such as white or off-white shades or other neutral tones. As a photographer you should also think a little bit more about this and stop urging people to view it on a dark background, concentrate on making your images look good on lighter backgrounds, that is after all the conditions that 99% of your customers will use to display your print.

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Mistakes Almost Every Photographer Makes

Having been actively involved in photography for a number of years now, I’ve been through many different experiences and behaviors and also taken note of behaviors from other photographers. It seems that at some point in every photographer’s career something shifts inside them and they feel they have to reinvent themselves and their photography. I’ve seen this trait in photographers from all walks of life right up to the top photographers in the world.

Why is it that when you have developed a recognizable style and have found the recipe for your success do you feel the need to change it? Personally I think boredom or a feeling of going stagnant are to blame and that’s just human nature.

Of every photographer I have seen or known who felt the need to reinvent themselves, virtually every single one spent several years “trying” to unsuccessfully reinvent themselves and after a lengthy frustrating journey they realize that what they were doing all along was the right thing and they go right back to doing things the way they have always done it. Sadly some seem to get stuck permanently reinventing themselves and end up getting very lost and even losing their audience or worse giving up photography.

Please don’t misinterpret this topic as me saying you should not improve or advance in your photography, that’s not what I am saying. I advance and improve on a daily basis, I thrive for creating new and interesting images, I learn new techniques all the time but I do not reinvent the way I do things, I perfect them. I have been down this road like everyone else I’ve known but I luckily realized it quite quickly and stumbled back onto the path I was already travelling.

Happy Shooting 😉

Backing Up Your Safari Photos and Memories

Whether you’ve grown your image collection into thousands of images or only have yourself a few hundred prized photographs and memories, just how securely backed up are those images of yours. Do you even have them backed up at all?

Everybody at some point in their life will experience the awful feeling of data loss. This normally happens on a day when you least expect it, when out of the blue your perfectly functioning computer system crashes and dies. You take the system to a technical person who then tells you the bad news, all your data is gone. What do you do other than nearly have a nervous breakdown?

First off there are data recovery labs that in many cases can get your data back, some of them are so good they can even take a hard drive that has been smashed into pieces and get data back bit by bit. This however is an extremely costly scenario, for the most part the charges are by the hour and it can literally run into hundreds of hours and there is no guarantee’s offered whatsoever.

“Oh why didn’t I backup my images” starts to play over and over in your head even haunting you in your dreams.

The answer is to avoid this scenario altogether, it’s not pleasant and I speak from experience. Once you’ve lost data once you spend the rest of your life making sure everything is securely backed up and sadly many people only learn this the hard way.

So what are your options for backing up your images?

Many people with a smaller image collection can get away using CD-roms for their backups. They are one of the most affordable forms of media around and this allows you to make multiple copies to store in different locations. But how safe are CD-roms? Many people mistakenly assume that a CD-rom will last for ever. This is a picture painted into people’s minds in the early days when CD-roms first came onto the market, they were marketed as indestructable. Well quite simply they are not. Simply dropping a CD-rom from a desk can damage the disc badly if it contacts the ground wrong. A CD-rom is nothing more than a plastic disc with a microscopically thin layer of foil material which is the recording surface. If you took a sharp knife and ran it quickly over the recording surface you’d see silver flakes (and data) come flying off. In modern times CD-roms are in mass production and the materials used to manufacture them are cheaper resulting in lower quality products. You can buy CD-rom discs for less than a Rand a disc and you can buyCD-rom discs for a few Rand a disc and there is indeed quite a difference. Cheap no name brand discs will become your worst enemy, they seem fine and seem no different than their more expensive counterparts but there will come a time when you take data written onto a cheap disc, put it into your Cd-rom drive and discover your drive cannot read the disc. You try in a friend’s drive to find the same problem and you eventually discover that disc no longer works ….. what happened …. your data is GONE? “This can’t be happening” you say to yourself. Well uh yes it can. There is major differences in the price of CD-roms due to the quality of the foil recording surface. Cheap CD-roms may only last 1-5 years, more expensive ones may last 5-10 years and then you can get what we call medical grade CD-roms which have a “claimed” lifespan of 100 years. The price between them is remarkably different, the cheap discs can cost R1.00 a disc, the more expensive “name” brands could cost you about R2.50 per disc and medical grade discs could cost you abour R20-R25 each. So depending on just how important that data is, the choice is yours. If you choose to use cheap CD-roms then every year you will need to re-record them and discard the old ones. Trust me this ends up being a tedious process and once your image collection starts requiring several discs at a time it’s time to look at another solution.

The next best solution which works very well is to use external hard drives to back up your image data. Having been personally involved in the high-tech industry for nearly 20 years I have been through just about every brand of hard drive and above all Seagate drives seem to have the longest lifespan and the least chance of failing. I have Seagate external hard drives that are nearly 5 years old and still functioning perfectly so I have standardised on Seagate as a trusted name. Seagate produces a variety of external hard drive solutions called FreeAgent ranging from 250GB drives upwards to 2TB. They also have a range called FreeAgent “Go” which are small enough to fit in your pocket. Using an external hard drive for your backups is quick and easy. You get yourself a program like Super Flexible File Synchroniser and set it up to mirror your images and other data and you can run it daily or once a week. Simply having one external backup is not enough. If you buy yourself one 500Gb external drive you actually need to purchase two and every time you do backups you do it onto both hard drives. One hard drive you can store in your safe (hopefully fire proof) and the other you should store off site at a friend or family member’s house, and preferably in their safe too. Having everything in triplicate stored in 3 different locations guarantees you that should trouble strike you have one totally safe backup. The cost of external hard drives have come down dramatically and they are by far the most cost effective form of storage around but you really need to refrain from saving yourself a few bucks considering cheaper external drives, stick with Seagate (no I do NOT work for them) do your backups in duplicate and store one off site and you’ll be good to go for many years.

When your image collection grows beyond the confines of a 2TB external hard drive it may be time to start looking for a more serious back solution. For this photographers are turning to the Drobo system because of it’s great offerings. Drobo has essentially taken very expensive RAID technologies which were out of the reach of the average Joe for many years and brought out a fully redundant raid product with a more affordable price tag. A basic Drobo which can house 4 hard drives could cost you around R12-14000 or thereabouts. Then you could move onto a Drobo Pro system which is a lot more expensive but can house 8 drives, it all depends on how much cash you wish to part ways with and just how serious you are about your data. Again, having one Drobo storing all your data, even though it has full redundancy, is no guarantee your data is safe. I know of several people whose Drobo’s have crashed on them so essentially like above with external hard drives, if you buy one Drobo, you actually buy two and one gets locked away very safely, preferably off site.

When it comes to data backups you need to have a plan, something you’ve invested some thought into and you need to stick to it religiously. It’s no good storing a backup off site and never updating it. If you formulate a backup plan you will thank yourself one day when things do go wrong, you will rest assured knowing your data and images are securely backed up. I’ll revisit this topic again one day. For now, get backing up.

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Magaliesburg Photographer Trump’s Lunar Eclipse Photos

The Lunar Eclipse Over South Africa on 15 June 2011 captured as never before by South African Photographer Mitchell Krog
South African Photographer Mitchell Krog, based in the beautiful Magaliesburg region has once again pulled something magical out of his photographic hat. Mitchell, a multi award winning photographer, is no stranger to the night skies and has spent much of the last 5 years photographing them. On Wednesday evening the 15th June 2011 a lunar eclipse event occured over much of the Southern Hemisphere and had sky watchers all over the world outside to witness this magical event.

In South Africa it is currently winter and up on the highveld in the Magaliesburg region it gets especially cold at night. Braving the cold weather, Mitchell headed out to capture his 4th lunar eclipse and decided to try something different. Instead of just focusing on close up images of the moon, Mitchell decided to go much wider and set up one of his camera’s with an extreme wide angle lens.

What came out of his camera was nothing short of amazing and has certainly trumped a plethora of lunar eclipse images all over the web. Mitchell describes this effect, “A combination of heavy dew fall and misting from the very cold weather is probably what caused the camera to capture this, it is an amazing optical effect like I’ve never seen before and I’ve spent hundreds of nights out photographing the night skies. What I find amazing about this image is that, optical effect or not, it clearly shows the moon sitting in shadow surrounded by the blue glow of Earth’s light. It’s easy for people to jump out and say it’s manipulated but it most certainly is not, this is direct from camera to screen but I’m so accustomed to critics and competitors trying any avenue to demoralize or discredit.”
All we can say is we’re amazed with this image and it already seems to be circulating all over the web and being very much WOW’d.

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Bubbling Spacecraft UFO in the South African skies

The strange craft which fleeted across South Africa’s night skies on Sunday the 18th of October 2009 causing UFO reports to flood observatories and Radio 702. Most people in South Africa thought they had seen a UFO but this object turned out to be a Centaur rocket carrying out tests when they passed over South Africa. From Mitchell Krog’s Astrophotography Portfolio. (Copyright Mitchell Krog – All Rights Reserved)

Information from thanks to Claire from the Planetarium for doing so much research into this event.

Hundreds of South Africans saw a star-like point moving across the sky while emitting “haloes” or “bubbles” of light just before 9pm on Sunday evening October 18th. This strange sight turns out to have been a Centaur rocket carrying out tests as it passed over South Africa nearly three hours after launch. The mission (AV-017) is a project of United Launch Alliance – see for a nice video of the launch and a 23-page “mission overview”. The purpose was to launch a US Defence Force weather satellite (DMSP F18) into orbit.

Ground Track

Event timeline (all times are South African time)Atlas Centaur

6:12pm – Atlas V rocket launches from Vandenberg Airforce Base

6:16pm – booster rocket shuts down and is jettisoned over the Pacific

– Centaur main engine starts

– payload fairing jettisoned

6:27pm – Centaur main engine shuts down

6:30pm – satellite released

– Collision and Contamination Avoidance Maneuver

6:46pm – testing begins

8:57pm – testing ends

9:10pm – Centaur main engine fires for 4min to send the rocket away from Earth (into an Earth-escape trajectory)

9:17pm – “blowdown” of the fuel tanks

9:56pm – burn off of residual hydrazine

What caused the bubbles?

Possibly venting of fuel during the tests, or firing of “reaction control” motors used to change the orientation or spin of the vehicle.

Tests carried out on the Centaur

Since the DMSP satellite was relatively light, the Centaur rocket had fuel left over after completing its mission of putting the satellite into orbit.  The collision and contamination avoidance manoeuvre gets the rocket a safe distance from the satellite.

After this, the Centaur is in free-fall – a (almost) zero-gravity state that can be created on Earth for a short time by dropping something from e.g. a tall tower, or in a plane for a few minutes (e.g. NASA’s “Vomit Comet“).  The test phase of the Centaur lasted about two hours.

The tests carried out during this time were described by ULA as:

“zero-g, long-coast propellant management . . . we do zero-g settling by the very reduced motion of the settling thrusters . . . [and then] settle the propellants against the wall of the tank by spinning the stage with no settling thrusters . . . [and] some venting during zero-g.”

Before re-starting the engine, the engineers also planned “a pulsed chill down demo . . . then some experiments related to the depletion of [the engine]“

One interesting use for these tests is to see how feasible orbiting “filling stations” are.  These would be useful for future manned spacecraft missions to the Moon or Mars, that would have to carry large (heavy) amounts of equipment into space.  Some of the experiments that would be useful for the design of these orbiting “propellant depots” include spinning the spacecraft to settle the fuel against the sides of the container, and firing small rockets or venting small amounts of fuel to push the fuel against one end of the container.  A large fuel tanker in zero-gravity has problems that include leakage of the hydrogen fuel (hydrogen molecules are very small and eventually leak through the walls of containers), and keeping the fuel cool.

United Launch Alliance has a great collection of (fairly technical) publications related to the future development of space exploration – see their publications page, especially this one which mentions using the DMSP-18 mission for zero-g propellant tests.

“The mothership is watching us”. What many would love to believe was a UFO turns out to be something actually from this world. A centaur rocket is captured dumping excess propellant into the atmosphere as part of a testing phase of this rocket launch. From Mitchell Krog’s Astrophotography Portfolio.