Tag Archives: space

Frontiers of Space Flight Technology

Human beings have been launching spacecraft since World War 2. Rocketry, in principle has not changed much from the early days of rocketry in ancient China to Von Braun who invented the worlds first rockets like the V-2 capable of sub-orbital flight and atmospheric reentry. Chemical rockets are rather simple in concept. A generally explosive fuel + oxidizer mixture forms the propellant, which is burnt in a controlled fashion in a reaction chamber. The hot gases exit a nozzle providing a large amount of thrust to the rocket. De Laval Nozzle CFD, Courtesy flowsquare.com

Since then we’ve done several fancy things to a rocket. We’ve put a space capsule on the top, making it possible for man to travel out of earth’s orbit. We’ve attached airplanes to the rocket body which we lovingly knew as a space shuttle. Space shuttles were not a NASA creation alone. The Soviet Union created its own version of the space shuttle called ‘Buran’. Buran completed one unmanned spaceflight in 1988 which was an unmanned test flight. The program ended shortly due to budget cuts arising from the collapse of the Soviet Union. NASA’s space shuttle programme was however the successful and ambitious effort in human spaceflight till date.

NASA’s Space Shuttle Atlantis

Soviet Buran Orbitter

The space shuttle was a a marvelous piece of engineering. Not only it put humans in orbit. It also had a massive payload capacity. Powered by two giant solid booster rockets and cyogenic engines, the shuttle could lift a total payload mass of 27 tonnes to low earth orbit. The shuttle programme also pushed the frontiers of spacecraft reentry technology. The shuttle on atmospheric reentry slams into the atmosphere at a speed in excess of Mach 25. For the new reader thats 25 times the speed of sound or 8.7 Km/s. Normally for small objects, the reentry shield is a carbon-ablative material. Ablative materials were used by early spacecraft like Apollo and Gemini programmes. They are also used in ballistic missile payloads. In simple talk these are shields made out of carbon. As the material heats up, it slowly burns off, keeping the payload relatively cool. However these things are difficult to fabricate for larger objects. Another problem with the ablation system was that once the temperature fell in a zone where shielding was needed but low enough to prevent the ablation, they would cease to function making them somewhat unreliable.

The space shuttle introduced a different type of heat shielding. This strategy is called “thermal soak”, where the shield has an enormous capacity to trap heat. You could heat the substance to over a 1000 degrees in one end, and still hold it with your fingers at the other
Super Insulators like this ceramic cube is red hot inside, but cool enough to be lifted by bare hands
This strategy is wildly popular and used by all space programs. However there have been issues with tiles in how they are integrated onto the spacecraft. The ceramics are usually brittle and many times have caused serious problems. The Columbia space shuttle disaster in 2003 is a typical example where a piece of insulating foam from the main external tank hit the leading edge of the shuttle’s wing, destroying some of the tiles. This was enough to cause the orbiter to burn up during atmospheric reentry and instantly kill the crew. Losing a few tiles had been a common occurrence on previous shuttle missions too, the risk associated with losing this critical thermal protection was well known too. However since then NASA has taken a lot of measures to ensure that such accidents would not happen on future missions.

In recent years, space programs have had to face major budgetary cuts all over the world. NASA’s budget fell from 1% of US GDP to approximately 0.5% of the GDP. For comparison this number was about 4.4% at the peak of the Cold War. The Russian space program has also seen similar cuts for a variety of reasons, both political and economical. In times of financial crisis governments usually trim funding for space programs. For mankind’s space ambition to survive, it could no longer afford to be a drain on large amounts of cash. So a concept of reusable launch vehicles was conceived. Bulk of the spaceflight industry comprises of launch systems that put satellites in orbit. It made sense, if we could find a way to do it cheaper and faster.

RLV technology is not that novel. The US operates unmanned spacecraft routinely. The X-37 is a reusable unmanned spacecraft that is boosted into orbit by chemical rockets, but lands back on the ground like a conventional plane.

The X-37B Orbital Test Vehicle waits in the encapsulation cell of the Evolved Expendable Launch vehicle April 5, 2010, at the Astrotech facility in Titusville, Fla. Half of the Atlas V five-meter fairing is visible in the background. (Courtesy photo)
The X-37B Orbital Test Vehicle waits in the encapsulation cell of the Evolved Expendable Launch vehicle April 5, 2010, at the Astrotech facility in Titusville, Fla. Half of the Atlas V five-meter fairing is visible in the background. (Courtesy photo)

One of the biggest pioneers of reusable technology is South African capitalist, Elon Musk’s SpaceX Corporation. SpaceX has been able to make significant strides in space technology in a rather small amount of time. In the man’s own words

“If one can figure out how to effectively reuse rockets just like airplanes, the cost of access to space will be reduced by as much as a factor of a hundred. A fully reusable vehicle has never been done before. That really is the fundamental breakthrough needed to revolutionize access to space”

This is no longer science fiction. In April 2016, the first stage of a Falcon-9 spacecraft landed safely on an offshore barge. This was after one year of hard work and four other failed attempts. I put this video below, and I must admit, it is pretty darn cool. According to SpaceX lot of work still needs to be done to make this technology reliable, but there is no doubt that it is a game changer in the space industry.

Recently India has also been working on a RLV program. Earlier it was code named “AVATAR” which was a RLV concept that used scramjet propulsion. AVATAR stood for “Aerobic Vehicle for Transatmospheric Hypersonic Aerospace TrAnspoRtation”. Since then it has evolved into what is now called the RLV-TD project. ISRO has staged its RLV program in small steps. The first of this was the HEX or Hypersonic Flight Experiment was performed earlier this month in 2016. The experiement was designed to validate flight performance of the spaceplane at Mach 6. The plane itself was boosted into Mach 6 speed by a sounding rocket booster and had no propulsion. In the future flights, it will feature a scramjet engine. The hope is that ISRO’s RLV will be used to deploy small satellites into LEO and return back to earth

isro RLV liftoff
ISRO Reusable Launch Vehicle (HEX-1) Launch
ISRO Reusable Launch Vehicle Closeup

Dramatic Time Lapse Video of International Space Station at Night

Check out this dramatic time lapse footage of earth seen from the int’l space station at night. Pretty darn cool
You can see all the air glow, auroras and thunderstorms. The city lights are not real but an overlay captured using a special IR camera called Visible Infrared Imaging Radiometer Suite (VIIRS)
All in, a pretty spectacular video.. the music is quite dramatic too

Pitfalls of an Eclipse Flight, Lessons learnt

It’s easy to be wise after the event- Some wise man

Ok, recently you may have heard a couple of space-nuts chartered a B737 jet to chase the July 22nd eclipse from a height of 41000 feet. I guess considering the monsoon, it was a good idea that would guarantee that you atleast got to see the eclipse. Passengers paid approximately Rs 80,000 for “sun side” seats and Rs 29,000 for “earth side” seats. Personally I don’t know why would I pay to see the sun’s shadow on earth.

From that point of view it was a good idea, considering places like Taregna, Patna, Shanghai and most parts of India got clouded or washed out!

However people on board with cameras and photography equipment will be kicking themselves because of some things that got overlooked. When you dig deep into your pocket for an experience like this a little more research should have gone into it

It may me useful to remember that while shooting from a plane’s windows, ( yes.. in case you forgot, you’re inside the plane and you have to take photos from inside the aircraft’s double paned window, both of which usually have thousands of microscratches) two results are inevitable

The image of a bright object may have double reflections from both window surfaces. Unfortunately this will always be there and playing with the camera focus cannot get rid of it. The sun will be at infinity and the extended light path due to reflection does not affect it. The result??, see for yourself

Look at this picture of totality taken from the eclipse flight, if you look carefully, there is a double reflection glaring at you at the bottom edge of the image. This was a specimen frame drawn from video taken by the BBC media crew on board the flight. We checked this with other videos taken by AAJ TAK etc, which also had the same issue.

There is also a second problem. As mentioned earlier, the windows are usually scratchy and not very clean. It is pretty easy to get rid of these scratches out of focus in the image. However with a eclipse, especially the diamond ring a big quality issue arrives.

The microscratches on the window scatter light in all directions completely ruining the photo. Both images above were taken aboard the eclipse flight.

One of the reports we heard from the people conducting photographic experiments onboard had another unforeseen issue, Apparently the plane went off charted course to bypass some clouds, sending their automation software “Eclipse Orchestrator” haywire


If you were careful in reading what I wrote, yes there are CLOUDS at 41000 feet. We got wind of this fact a day before the eclipse. A curious me and Vishnu did ask the Captain of our Spicejet flight to Varanasi when we landed at Babatpur for the eclipse

So if you are serious about taking pictures of totality, you might want to keep these details in mind before swiping that credit card.

The views expressed in this article are by the Author only, and may not be shared by the AAAD as a whole