Monday, September 3, 2012

What (on Earth) is a Space Elevator?

The number one roadblock on the way to space is access to launch vehicles. The cost of launch is by far the most expensive part of a satellite campaign; You can build a high quality, small, capable satellite for 100,000 dollars if you are creative and thrifty, but a ride to space on a rocket costs at least 2-3 million, and even then smaller payloads have almost no control over when and where the rocket launches.

In addition to being outrageously expensive, rockets are also bad for the environment. The Space Shuttle Main Engines burn about a half-million gallons of fuel during lift-off and acceleration, producing 28 tons of carbon dioxide, and, according to Discover Magazine, "23 tons of harmful particulate matter settle around the launch area each liftoff, and nearly 13 tons of hydrochloric acid kill fish and plants within half a mile of the site."  Furthermore, rockets are not reusable.

Besides the cost and environmental damage, rockets are complicated! Rocket engines and their fuel systems are so complex that only three countries have ever put people in orbit. And once you figure out how to do it, the risk of something going wrong is incredibly high. In the last 45 years, 15 people have died during the take-off or re-entry phases of their mission.

It makes you wonder who said "Hmmm. Clearly the easiest, safest way to get to space is to fill a giant tube with explosives, put some people in the tip, and light it on fire." (For the record, it was Jules Verne who, in 1865, wrote the novel that inspired the movement to send people to space in rockets, although he proposed using a giant cannon to escape Earth.) Why not, say, build a really long ladder reaching from Earth into space, and keep climbing until you have escaped the Earth's gravitational pull, then let go? Ouala! - you are in orbit.
Tsiolkovsky, looking old and wise.
(Source: Wikipedia)

In fact, someone did have this idea. In 1885, 30 years after Verne published his novel, Russian scientist Konstantin Tsiolkovsky was inspired by the Eiffel Tower to propose just such a system. His design included a "celestial castle" at the top of a spindle-shaped cable that reached out 22,238 mi above sea level, which is the altitude required for geo-stationary orbit.

Tsiolkovsky never built his elevator (though he is considered a founding father of rocketry), but the basic principles behind space elevator design have not changed since his original proposal. All space elevator designs include a giant cable attached to Earth's equator that reaches up into space. The centripetal force provided by the Earth's rotation keeps the cable extended and stationary above a point on Earth. (Imagine holding on to a long string and spinning around in place - the string flies around you in your orbital plane, extending out from your hand). Designs also include a counter weight at the space end of the cable - like Tsiolkovsky's celestial castle - that provides enough mass to keep the cable straight. (Tie a tennis ball to the end of your string - it now flies out straight from your arm rather than curving away from the direction of motion). Once the cable is in place, a robot can simply climb the cable, starting from Earth. Traveling at 180 mph - the speed of a fast train - a climber could reach GEO orbit in about 5 days. And by the time it got to the end, it will have achieved orbital velocity (taken from the Earth's rotation). It could toss a satellite out the window and call it a day. No rockets required.

So why don't we have a space elevator yet? 
Diagram of a space elevator. The height relative 
to the diameter of the Earth on the diagram is 
to scale. The height of the counterweight varies 
by design and a typical, workable height is 
shown. Source: Wikipedia.
The major difficulty is in finding a sufficiently strong material with which to construct the cable. Tension on the cable increases with distance from Earth, so the cable must grow exponentially wider as it moves away from Earth in order to sustain the force of the cable below it, and provide a centripetal force to the cable and counter-weight above it. (If you use a flimsy string to swing your tennis ball around, it breaks by the tennis ball, not near your hand, right?) The cable must therefore be made of a material with an extremely high specific strength. Currently, the only materials with the requisite strength are carbon nanotubes, which were developed at MSFC in the 90s, and are difficult to create and connect to form a long, low-mass cable while still preserving their strength, though research continues.

Other challenges include handling space-trash collisions at LEO altitudes without damaging the cable, designing a climber that can scale a cable that varies in thickness (some current designs have rollers that use friction to roll up the cable), and deciding what to use for the counter-weight (maybe material that is ferried up from Earth along the cable, or perhaps a captured asteroid?). There are also more complicated concerns, like managing cable oscillations and vibrational nodes as climbers move up and down, or satellites are launched off of the cable at various altitudes. 

Though it is not necessarily on the general public's radar, the space elevator concept is being actively explored by the space community. NASA has long supported the idea, mostly through financing competitions and prizes to encourage innovation in the area. The US-based group Liftport hopes to use crowd-sourced fundraising (via Kickstarter) to design and build a moon-based space elevator, which would allow astronauts to gently descend to the lunar surface from orbit, and then climb away again. Astronauts or robots would launch from Earth in a rocket and rendezvous with the elevator cable at a base station located in the L1 Lagrange point between Earth and the Moon. (Here is a video of a test the group performed 6 years ago using a prototype robot to climb a cable held aloft by giant helium balloons).  In February the Daily Yomiyuri reported that Japanese construction firm Obayashi Corp, (the same company that is currently refurbishing the Golden Gate Bridge), has announced plans to build a space elevator by 2050 that would shuttle 30 people to space at a time, and in November 2011 the New York Times reported that Google has been secretly working away at a space elevator design in its Google X lab in Mountain View. 

With private companies like SpaceX, Virgin Galactic, and Sierra Nevada Corp (to name just a few) entering the market and competing for contracts at a faster pace than ever before, I think it is probable that we will have cheaper, more reliable rockets years before we have a cheap, reliable space elevator. But that is beside the point. What will happen when a weekend trip entails a casual train ride the edge of outer space? Or when designing satellites to be small, light, and compact is no longer necessary? Or when you can stretch out a net to capture passing space trash, or build a permanent science laboratory at any altitude? A space elevator wouldn't just replace rockets, it would open up outer space to a whole new world of possibilities. 

Saturday, August 25, 2012

Mars Science Laboratory Beams Back Landing Video

The HIRISE spacecraft photographed MSL as it was parachuting down to
the Martian surface. Credit: NASA.
I haven't posted about the Mars Curiosity rover yet, because it has been thoroughly covered by other news sources and I've just been enjoying reading about all of its success so far. However, NASA just released the video of Curiosity's descent, as viewed from the spacecraft itself. It is pretty incredible to see such high quality video of the fantastic landing, which was a feat of creativity, sophisticated software, and brilliant systems integration.

Mike Wall, from, describes what you will see in the video:
The high-definition video chronicles the final 2.5 minutes of Curiosity's 7-minute plunge through the Martian atmosphere in real time, starting just after the rover jettisoned its heat shield. The first few seconds show the heat shield falling away toward the red dirt of Gale Crater far below. 
Other milestones follow, such as parachute deploy and ignition of the engines on Curiosity's "sky crane" descent stage, which lowered the 1-ton rover to the Martian surface on cables. Audio from mission control at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif., plays over the video, describing the nail-biting action
As Curiosity nears the Martian surface, huge dust clouds billow around the $2.5 billion robot, kicked up by the sky crane's rockets. Then the view clears to show a close-up, static shot of scattered pebbles.

If you haven't seen it yet, watch 7 Minutes of Terror, the movie trailer-esqu video simulation of the landing sequence before watching the real thing.

7 Minutes of Terror:

Real video of MSL descent:

Sunday, August 19, 2012

Proba-1 is Back in Business.

ESA's Proba-1 microsat was built and launched by the ESA as a proof-of-concept for semi-autonomous Earth observation - operators can upload coordinates and the satellite will autonomously image that location. The satellite ended up turning into a heavily-used science tool, but it almost shut down in May due to star tracker degradation. 

Proba-1 captured this image of London's Olympic Park
 neighborhood.   Credit: ESA 
Many small satellites use star trackers to orient themselves. The star trackers point behind the satellite (away from the Sun and Earth) and take pictures of star fields, which they can identify and use to calculate the satellite's orientation.  The CCD camera's attached to Proba-1's star trackers had sustained severe radiation (they were 5 years older than the planned lifetime for Proba-1), and the radiation had created permanent damaged or "hot" pixels which  show up in images as white spots. The star trackers were mistaking hot pixels for stars, and sending incorrect coordinates to the main satellite computer, causing it to error out or mispoint. 

Proba-1 was saved by a software patch written specifically for the satellite, which - once loaded - allowed the star trackers to distinguish between hot pixels and real stars. The star trackers are apparently working "as good as new" now, even with degraded CCDs. The proof is in the pudding - at the right is a farewell shot of Olympic Park that the satellite shot last week.

Monday, July 16, 2012

Virgin Galactic Announces LauncherOne System for Small Satellites

The White Knight plane will be used to launch a small rocket
carrying satellites. 
On July 11, Virgin Galactic announced that they were building a new kind of launch system for small satellites. The system, dubbed "LauncherOne", will build upon their existing SpaceShipOne launch system, which launches a suborbital space plane off of their unique White Knight airplane. Richard Branson, Virgin Galactic's hippy-entrepreneur founder, said at the press conference that the company plans to be launching small satellites by 2016. The specs: 500 pounds of payload for under $10 million. This is the first privately-funded launching system specifically designed for small satellites, and Branson says: 
"LauncherOne is bringing the price of satellite launch into the realm of affordability for innovators everywhere, from start-ups and schools to established companies and national space agencies. It will be a critical new tool for the global research community, enabling us all to learn about our home planet more quickly and affordably."
The other benefit of the system, aside from the affordability, is the flexibility allowed by a plane-based launch system.  This reduces infrastructure headaches (and costs) associated with launch vehicle setup and deployment, and allows satellite builders to launch their satellite from a huge selection of sites, thereby releasing their satellites into a wider range of orbital planes than is otherwise possible. For an Earth-Observation constellation the more planes their satellites are in, the better the coverage of Earth at any given time.

Initial information about LauncherOne is that it would use a two-stage rocket powered by liquid oxygen and kerosene. The video below shows what the launch progression will look like.

(I like that they drop the "save the Earth" spiel after the obligatory shots of  deforested plains and fuming smokestacks. "Melting Glaciers? Check. Let's get to the good stuff." Also, the satellites being launched from LauncherOne will likely not be large enough to have deployable Solar Arrays, but that's a nit pick.)

Virgin Atlantic also announced that they already have at least four companies signed up to buy several launches on the new vehicle. One of the companies recognized as an early customer (that is very near and dear to me) was Skybox Imaging, a Silicon-Valley based commercial Earth imagery startup. Speaking at the event, Skybox CEO Tom Ingersoll said, "Skybox's objective is to provide world-class, affordable access to space imagery and information, and in order to do so, we need world-class, affordable access to space. Virgin Galactic is unique in having the right mix of ingredients to support our vision, as well as that of the growing small satellite community. We plan to make full use of LauncherOne."

Other companies signed up to buy rides on LauncherOne include GeoOptics Inc., a U.S.-based company developing a constellation of non-imaging remote sensing satellites; Spaceflight, Inc., a aggregator and integrator of small satellites; and Planetary Resources, Inc., the newly-announced, billionaire-backed company that plans to make millions mining asteroids.

This is a really neat prospect, and can only mean good things for the smallsat community!

Saturday, June 30, 2012

The B612 Foundation

Antoine de Saint-Exupéry's Little prince on the original B612 asteroid.
On June 28th, the B612 foundation announced its plans to build, launch, and operate a deep-space telescope, Sentinel, which will find and map asteroids that could pose a danger to planet Earth. The official press release summarizes the mission:
“The orbits of the inner solar system where Earth lies are populated with a half million asteroids larger than the one that struck Tunguska (June 30, 1908), and yet we’ve identified and mapped only about one percent of these asteroids to date, said Ed Lu, Space Shuttle, Soyuz, and Space Station Astronaut, now Chairman and CEO of the B612 Foundation. “During its 5.5-year mission survey time, Sentinel will discover and track half a million Near Earth Asteroids, creating a dynamic map that will provide the blueprint for future exploration of our Solar System, while protecting the future of humanity on Earth.”
The B612 foundation has actually been around since 2001, working towards its mission of protecting Earth from a potentially disastrous asteroid impact. Prior to yesterday's announcement they had been focusing on technologies that could deflect threatening asteroids away from Earth's orbit, such as gravity tractors, kinetic impactors, and nuclear vaporization. However, they eventually realized that these technologies would be useless if no one knows the asteroid is coming, and that nobody was doing anything to find and track the most threatening asteroids. the organization's website explains: 
"NASA’s Spaceguard survey has succeeded in mapping 90 percent of the largest NEAs (larger than 1 km), yet due to the limitations of searching for asteroids using mostly ground based optical telescopes, only about one percent of these asteroids larger than Tunguska have been discovered and tracked to date. We are essentially flying around the Solar System with our eyes closed." 
The foundation estimates that in 5.5 years, Sentinel will have identified around half a million Near Earth Asteroids, with enough temporal information to project their orbits 100 years into the future. They think there is a 50% chance that the mission will identify at least one asteroid on a collision course with Earth that will need to be deflected in order to prevent a potentially catastrophic Earth impact.
The Sentinel Telescope (preliminary design by Ball Aerospace).
Source: B612

The Sentinel telescope will operate in the infrared, where asteroids stand out against the cold blackness of space, and be built by Ball Aerospace, the same folks that built the Kepler, Spitzer, and Hubble telescopes. It will be placed into an orbit similar to Venus's. This orbit will allow it to scan the side of the Sun opposite from Earth, which it would not be able to do if it were in orbit around Earth. However, it will also make operations and communications tricky because its distance from Earth will vary between 30 - 170 million miles, as opposed to the much more cozy 350 milles between Earth and Hubble. This is difficult but by no means unheard of - we have been operating spacecraft on Mars and beyond for tens of years. Current estimates put launch in 2017-2018, aboard one of SpaceX's Falcon 9 rockets.

Sentinel's orbit, which will allow it to map the side of the Sun opposite from Earth.
Source: B612 foundation. 
The B612 Foundation has signed a Space Act Agreement with NASA in June 2012, under which NASA will provide communications, tracking, and technical support for the Sentinel Mission. However, B612 is a nonprofit 501(c) 3 organization that "intends to raise the money for the Sentinel Mission in a manner similar to philanthropic capital campaigns for civic projects." If they do it right, and take advantage of flashy publicity videos and social media, I bet they could raise the necessary money very quickly - this is a subject that people can easily get excited about. 

Kudos to the B612 foundation for taking on a huge but necessary project. As John Stuart recently put it, "Do you know how rarely the news in 2012 looks and sounds how you thought news would look and sound in 2012?"

Wednesday, June 20, 2012

Intelsat IS-19 Deploys Damaged Solar Array

Intelsat's IS-19 communication satellite, which will provide telecommunications services and broadband coverage in the Pacific Ocean region, finally deployed its south solar array yesterday, after keeping it stowed for 13 days. The solar array sustained severe damage during launch, and was stuck in the stowed position for several days. Once deployed, operators estimated that the damage reduced the array's power-collecting capacity by half. The spacecraft is still operational, but will only be able to reach 75% power capacity.
Credit: Space Systems/Loral

IS-19 was built by Space Systems/Loral, in Palo Alto, CA, and launched by the Swiss company Sea Launch. Both sides continue to deflect blame for the damage, but Sea Launch did report an "unexplained pressure event" 72 seconds into the launch, which mirrors a similar event detected in the Sea Launch rocket in 2004, when launching another Space Systems/Loral satellite (Telstar 14/Estrela do Sul 1) whose solar array never deployed.

Sea Launch has released launch telemetry indicating that "all systems performed nominally throughout the launch profile...Boeing engineers did notice an unexpected, isolated event around 72 seconds after launch" . They cheekily point the finger by adding "while it is premature to speculate on its origin…it bears a striking resemblance to a prior Space Systems/Loral mission". 

It is worth noting that Space Systems/Loral has a small history of challenged solar arrays. The company also built Telstar 14R (Estrela so Sul 2), which experienced a problem deploying the solar arrays after launch as well, but was launched on a Russian Proton rocket.

The Sea Launch platform - a converted
oil rig. Credit: Sea Launch
Sea Launch is an interesting company - it launches its Zenith 3SL rockets from a converted oil rig which is towed from Long Beach, California to the middle of the Pacific Ocean right on the equator, an optimal location for launching satellites to geosynchronous transfer orbits. The company was formed in 1999 as a joint venture between companies from Norway, Russia, the Ukraine, and the United States, and is managed by Boeing. It recently emerged from bankruptcy in 2010 and has had two successful launches in as many years.

Saturday, June 16, 2012

China Sends 3 Taikonauts to Space

The Long March II-F rocket being transported to the launch pad. Image released June 11, 2012.
CREDIT: China Manned Space Engineering 
I previously wrote about China's plans to build their own space station to compete with the US and Russia. Today, they began the execution of the next phase of their ambitious space plan by launching 3 astronauts to space atop a Long March 2F rocket. The group of taikonauts, which includes China's first woman in space, will perform a docking maneuver with the Tiangong-1 Space Module, and live aboard the miniature space station for a short time, performing experiments. (In case you were wondering, the first woman in space was Soviet cosmonaut Valentina Tereshkova, in 1963. Sally Ride didn't blast off until 1983.)

Apparently, the successful launch elicited cheers from the Chinese control center, where Chinese State Councilor Liu Yandong read an emotional and enthusiastic congratulatory statement from Chinese President Hu Jintao, who effused "I feel very glad to hear the success of launching the Shenzhou 9 manned spacecraft".

In addition to building a space station by 2020, China has previously announced plans to land on the moon by 2016. The US news coverage of this important milestone is funny to read because nearly every article ends with some sort of reassurance from "analysts" that the US is still far ahead of China in the field of space exploration and technology. This instinctive reassurance is humerous but can only mean good things for NASA. If anything can spur public support for the US space program, it's the threat of communism.

Thursday, June 14, 2012

Repurposing a Spy Satellite

On June 4, NASA announced that they have acquired two spy satellites from the National Reconnaissance Office (NRO). The satellites include extremely high quality telescopes with 2.4 meter collection mirrors - the same size as Hubble, and much better quality. For reference, that kind of light-collection power would allow you to see a dime on top of the Washington Monument (or what Kim Jong-un is eating for dinner). The donation is a windfall to NASA's cash-strapped astronomical research program, which will likely turn the impressive optics towards space in the Wide Field Infrared Survey Telescope (WFIRST) project to hunt for dark energy, IF, that is, they can scrape up enough money to launch and commission one of the telescopes. That kind of money may not be available for several years.
The donated satellites have better quality
optics than the Hubble telescope.

It's nice to see where our national priorities lie - as NASA's Planetary Science department literally holds bake sales to raise money and awareness about budget cuts (Obama's 2013 budget cuts 21% from NASA's planetary-science budget, and 38% from its Mars projects,) the NRO has two Hubbles lying around, collecting dust. Of course, we must remember that the NRO deals with very, very important issues of national security, whereas NASA is just playing around with trivial matters of casual public interest, like investigating the mysterious energy that permeates space and accounts for 73% of all matter in the universe.

Sunday, June 10, 2012

Risky Rescue of an Air Force Satellite

Wired had a great article recently about the risky rescue of a malfunctioning Air Force communications satellite. The series of anomalies that occurred are a great example of some of the things that satellite operations teams should be prepared to confront, and made for a very exciting 2 years for the AEHF-1 operations team! First, a bit of background on the satellite, from Air-Force Magazine:
"The AEHF program, one of the largest space programs of the decade, is designed to augment and eventually replace the legacy Milstar satellite communications network. Lockheed Martin is the prime contractor, Northrop Grumman built the payload, and everything is run by Space and Missile Systems Center at Los Angeles AFB, Calif. The constellation of four cross-linked AEHF satellites is expected to provide a communications capacity exceeding that of Milstar by a factor of 10."
The 7 ton, $2 billion satellite, AEHF-1, was launched aboard an Atlas V rocket back in August 2010, and at first it seemed to be functioning perfectly. It was placed into an elliptical orbit about 220 km above the Earth's surface, and the first step in the mission was to fire the satellite's hydrazine engine to booste it into a circular, geosynchronous orbit where it would become part of the Air Force's comms satellite constellation. 
AEHF-1 in the clean room.
Credit: Lockheed Martin

The first sign that something was not right came when the operators first tried to ignite the engine to boost the satellite into geo. Nothing happened. They tried again; the engine did not fire. (In my opinion, firing the engine again was a huge mistake on the part of the operators. As Albert Einstein said, "Insanity is doing the same thing over and over again and expecting different results". In operations, repeating something that didn't work the first time, without first figuring out why it did not work, can mean the end of the mission.) At this point David Madden, the head of the comms satellites at the Space and Missile Systems Center at Los Angeles Air Force Base, stepped in and rounded up a group of engineers who analyzed the telemetry and detrmined that the anomaly was likely caused by a piece of fabric left in the fuel line during the manufacturing process. They also realized that repeated attempts to fire the engine would flood the fuel line and cause the satellite to explode. (Needless to say, they quickly abandoned the "try, try again" tactic.)

With the oxidizer tanks sealed off, rendering the main engine useless, AEHF-1 was stranded in an ineffective and slowly decaying orbit, losing 3 miles of altitude each day.  Compounding the problem was the fact that at its altitude AEHF-1 was sharing an orbit with huge amounts of space junk. Operators were having to fire the small thrusters  in small maneuvers to avoid debris, wasting valuable fuel. 

The operations team was barricaded in a conference room for a week - pizzas were literally slipped to them under the door - and they emerged with a plan to salvage the mission: They would fire the satellite's small thrusters, hydrazine-fueled reaction engine assemblies (REAs) and tiny xenon-fueled Hall Current Thrusters (HCTs). These were originally intended for small orbit adjustments and momentum dumps, but would now be used in a series of more than 450 maneuvers over 14 months to get the satellite into GEO. This would require painstaking planning and precision.

The boosting maneuvers commenced with phase 1 of the recovery procedure: a big orbit-boosting burn to get the satellite out of the danger zone. Very quickly, the second anomaly popped up: The small thrusters required burns that were several hours long in order to be effective, and during these burns the satellite was left with the same side facing the sun, causing components on the sun-facing side to overheat. Overheating can at best diminish mechanism performance, and at worst quickly destroy crucial satellite components. The operations team quickly devised a set of maneuvers to flip the satellite periodically. These maneuvers were inserted during the boosting maneuvers so that no part of the satellite was facing the sun for too long. Flipping the spacecraft, while continuing to keep the thrusters pointed in the right direction and the spacecraft on-target, required an entirely new operations strategy.

Once the schedule of mission-saving maneuvers was in place, operators soon realized that the fuel supply on board was not sufficient to complete the rescue. Every ounce of fuel means another ounce of mass to launch into space (and find space to store onboard the satellite), so the fuel supply is budgeted very carefully based on the minimum mission requirements. Even if AEHF-1 had enough fuel to get to geo, it would still need propellant for station-keeping and momentum management maneuvers once in place, and thus each firing of the minor thrusters meant a shortened mission life. To solve this problem, the software engineers buckled down and re-wrote a chunk of the flight software. The new software allowed operators to position the satellite using the reaction wheels rather than the thrusters, saving fuel. It also optimized fuel consumption in the REA thrusters. The new software was uplinked and implemented successfully.

Engineers calculated the amount of fuel necessary to execute the mission once the satellite was in GEO, and allotted the rest of the fuel to the REA thrusters for the duration of phase 2. When this fuel ran out, the REA thrusters could no longer be used for the rescue effort. At this point AEHF-1  was in the Van Allen radiation belt, a high radiation zone where energetic charged particles are held in place by the Earth’s magnetic field. These particles can damage a satellite's electrical system very quickly, especially the solar panels. This presented a catch-22 for the ops team, because escaping the Van Allen Belt without the REA thrusters would require using the HCT thrusters, which run on electric current. Generating electric current, of course, would require deploying the solar arrays and exposing them to the dangerous radiation of the Van Allen Belt. After much deliberation, the team came up with a strategy to deploy the arrays and fire the thrusters quickly to escape the danger zone with minimal damage.

Once out of the Van Allen Belt, Stage 3 of the rescue continued, with the ops team relying solely on the HCTs to perform the necessary boosting maneuvers. HCTs are generally used for station-keeping maneuvers, and they use electricity and Xenon fuel to emit short, relatively weak puffs of power. However, they can burn for thousands of hours. They had never been used for extended amounts of time in zero G. 
Source: Air-Force Magazine

The HCT motors were optimized to fire at the apogee (the point in the orbit farthest from the Earth) of the AEHF satellite’s orbit, in order to increase the orbit's perigee (the point in the orbit closest to the Earth). (Think of it like a lever - the farther out you push, the more thrust you get).  From late October 2010 to June 2011, the HCTs burned for 10 to 12 hours per day. This required frequent analysis and tuning. Madden described the tedious process: "They’re like a finicky old car, one that you’ve got to constantly adjust to get it to optimize. There’s no instruction manual for how to do that. It’s basically an art."

Once the satellite reached its target altitude of 17,000 miles, the orbit had to be circularized at the correct inclination, which required additional burns to increase the perigree to 22,000 miles, decrease the apogee by 10,000 miles, and drive the inclination down closer to the equator to allow the satellite to see more of the Earth. The ops team timed the burns to take advantage of the beneficial effects of Earth’s gravitational pull, thereby conserving valuable fuel.

Finally, after almost two years, the satellite reached it's target location, and the payload was successfully deployed. Madden says that it still has enough remaining fuel to continue operating for it's full planned lifetime of 14 years. (Of course, this is likely due to the habit of aerospace companies to grossly and purposefully under-predict lifetimes to ensure mission success; with a full tank of gas I'm sure the team was hoping the satellite would last much, much longer.) Nevertheless, it was a remarkable and complex recovery effort. I am sure it was a giant relief to finally deploy the payload, which had been stored inside the satellite in order to fit in the Atlas V launch cone, and see that it worked. Next up: the team will launch and deploy AEHF-2. Best of luck to them, although I bet the operations team is pretty sick of the entire AEHF family at this point.

Summary of Anomalies:

Anomaly 1: Clogged fuel line
Solution: Use REA thrusters to boost orbit

Anomaly 2: Potential Collisions with Space Debris
Solution: Small maneuvers with REA thrusters, and rapid exit from LEO

Anomaly 3: Overheating during orbit-boosting maneuvers
Solution: Periodic spacecraft flips during maneuvers

Anomaly 4: Fuel Shortage
Solution: Re-write/load of the flight software to optimize fuel consumption for new operations plan; Strategic scheduling of burns to take advantage of orbital and gravitational affects.

Anomaly 5: High radiation from Van Allen Belt
Solution: Rapid Solar Array deployment and use of Hall Current Thrusters to quickly boost altitude.

Monday, May 28, 2012

Made in China

Here's something I didn't know: China has launched a prototype space station, and plans to send three astronauts up for an extended stay sometime between June and August of this year.

The Tiangong 1 Space Laboratory Module has been in LEO since September 2011, and has already been visited by the unmanned Shenzhou 8 spacecraft in November 2011, which demonstrated docking ability and other maneuvers. The Tiangong 1 will be de-orbited in 2013 and replaced with Tiangong 2 and 3 in preparation for deployment of the more permanent Chinese Space Station (CSS) in 2020.

The purpose of the space station is to act as a zero-G laboratory for science experiments, and as an eventual refueling station for manned deep space exploration missions.

Here is a hilarious Chinese propaganda-y animation depicting the mission:

I especially like the shot at the 1:00 minute mark of two astronauts hanging out in their space suits inside an empty module while a third seems to be skipping joyfully around on a casual, untethered space walk. Even more funny than the video is the fact that the Chinese Space Agency originally released a similar animation with "America the Beautiful" mysteriously playing in the background. No explanation was given for what can only be assumed to be an unfortunate gaffe - or an ingenious prank by some pro-American CCTV intern who may or may not still have his job - but the video remains up on the CCTV website, with the soundtrack removed.

Saturday, May 26, 2012

Can Constellation Rise from the Ashes?

Back in 2010 the Obama administration canceled Constellation, Bush's space program that would have sent US astronauts back to the moon, and eventually to Mars and beyond. I do not agree with President Bush on very much, but his ambition and vision for NASA was laudable, and I was sad when they cancelled Constellation. Despite being “over budget, behind schedule, and lacking in innovation due to a failure to invest in critical new technologies” according to the White House's budget plan, Constellation did provide an exciting and inspiring goal: Mars. The same cannot be said of Obama's replacement plan to focus on "building block technologies" and eventually send US astronauts to an asteroid. The goal is not nearly as romantic, and half the US population thinks it has already been accomplished. Moreover, with the recent explosion of Planetary Resources onto the public stage, we now see that there are market forces sufficient to propel private sector missions to asteroids; the same cannot be said of missions to Mars. In this new age of privatized space, NASA's main goal should be to fund innovative research and missions that would not otherwise be funded due to a lack of immediate profitabilityBut I digress. 

The Liberty launch vehicle combines the proven systems from NASA's space shuttle fleet and 
Europe's Ariane 5 expendable rocket. This graphic shows how they combine into the new 
ATK-Astrium Liberty rocket. CREDIT: ATK
It now seems that Constellation might just make like a Phoenix and rise from the congressional ashes. Development of the Orion Crew Module, which would have carried astronauts to Mars, has continued under the new title of "Multi-Purpose Crew Vehicle" (MPCV) since program cancellation. And now it looks like the heavy-lift vehicle, (née Ares 1), which would have propelled Orion into space, is not completely dead either. On May 9th, Alliant Techystems (better known as ATK) announced plans to combine the first stage of the Ares 1, a five-stage solid rocket booster, with the second stage of the European Space Agency's Ariane V rocket, which has been in use since '96, to make the "Liberty Rocket". These rocket stages would be topped with ATK's own Orion spinoff, with a composite structure and less robust heat shield than the metal Orion system since ATK's version would only be reentering the atmosphere from LEO instead of deep space and thus have half the energy to dissipate upon reentry. ATK plans to develop the Liberty Rocket system into a full-fledged commercial enterprise, carrying crew and cargo into low earth orbit for both NASA and other commercial space venture companies. ATK thinks it can move quickly through development and testing since the first two rocket stages have already been tested thoroughly. They hope to launch their first test flight by 2015.

I'm glad to see that the billions of dollars and thousands of hours of hard work already poured into Orion and Ares may not have been for naught, but I have reservations about the frankenstein nature of Liberty. Rand Simberg, in a great summary of the program, pointed out that using the Ariane V as a second stage (rather than as a first stage, as it has been used by the ESA) will mean coordinating in-flight ignition of the very complex combustion engine. The difficulty of pulling this off is one of the reasons that the Space Shuttle's SSME was abandoned by NASA's Constellation team for the J2-X. 

I also can't imagine that integrating 3 different rocket stages, built by three different companies, will yield an elegant, cost-effective, or scalable result. The Ariane 5 brings 15 years of ESA heritage technology with it, the Ares rocket undoubtedly possesses the marks of 60+ years of NASA history, and the Orion capsule is being developed by Lockheed Martin, which has its own hefty share of heritage. The plan greatly undervalues the benefits of in-house design. SpaceX, for example, built their entire system (rocket and capsule) from scratch in-house. The mechanical engineers building the Falcon engines eat lunch with the electrical engineers designing the Dragon capsule and the systems engineers building the operational plans (I saw this with my own eyes when I visited SpaceX headquarters in 2010). While an ATK systems engineer will have three sets of clumsy and likely incomplete documentation to sift through, and none of the original designers to help with the task, a SpaceX engineer who wants to know why something was built a certain way merely has to find the person who designed it and ask. ATK's kludged-together rocket might be cheap and fast now, but I doubt that it will be scalable or easily updated in the long-term. 

In any case, it is likely that Liberty - which will require support from the Ares team - will receive support from members of Congress who championed Constellation and would like to see those jobs return to their districts. It will be interesting to see how Liberty changes course once it enters the political sphere.

Friday, May 25, 2012

The New Space Race

The AP had a great article by Seth Borenstein recently about the New Space Race, highlighting all of the companies currently working on programs to shuttle cargo and/or people to space. This, of course, is old news, but it's great to see the industry finally getting some serious attention from the press now that SpaceX is doing things for NASA that are useful (and least eventually). A couple eye-opening excerpts:

"There are now more companies looking to make money in orbit — at least eight — than major U.S. airlines still flying."

"There are already eight different licensed spaceports in the U.S. where companies can launch from and most of them have no connection to NASA."

Of the companies mentioned by Borenstein, five (SpaceX, Orbital Sciences, Boeing, Sierra Nevada, and Blue Origin) have received money from NASA and are aiming to reach the ISS within the next 5 years. Orbital is the closest behind SpaceX, with a trip to the ISS scheduled for November.

XCor's "Rocket Racer" Looks surprisingly lightweight and
simple. It will carry space tourists on suborbital flights.
In addition to the companies looking to make money from NASA by building ISS shuttles, there are several companies looking to make money the old-fashioned way - by finding people who have too much money and offering a service they can spend it on. I previously wrote about SpaceX and Bigelow's deal to shuttle space tourists to a space hotel. Space Tourism is also being pursued by Virgin Galactic (Richard Branson's company), and XCor Aerospace, who hope to send tourists on day-trips to space. Their reusable spaceships will take off from an airplane runway and reach sub-orbital altitudes, giving passengers several minutes of zero G, and some fantastic views of the Earth, before landing again.

So how much will a space vacation set you back? XCor and Virgin are not publishing prices, but Space Adventures, which has been helping rich people get to space since 2010, charges $20 million for a trip to the ISS, but has accepted $5 million down-payments for sub-orbital flights. I'm guessing that XCor and Virgin are hoping to undercut this price point significantly. Still, it will likely only be affordable to the 1%. But who knows, with the current pace of innovation in the space industry, maybe in 2040 the middle classes will be complaining about leg room in their space shuttle.

Wednesday, May 23, 2012

SpaceX Launches Dragon Capsule

After a two day delay due to an anomaly in one of the rocket engines, SpaceX's falcon 9 rocket blasted off early this morning, launching a Dragon capsule filled with cargo for the ISS.
There was plenty of news coverage of the event, but there were three little tidbits that I especially enjoyed.
  1. The description of the humorous juxtaposition of the young, casual, SpaceX mission controllers with the suited NASA old guard in the control room: "Many of the SpaceX controllers wore untucked T-shirts and jeans or even shorts, a stark contrast to NASA’s old suit-and-tie shuttle team."
  2. View from Spacex's Dragon spacecraft looking outward
    at one of two solar array panels in the process of deploying.
    Source: SpaceX
  3. The picture that @SpaceX tweeted of the Dragon capsule solar arrays after they deployed. News reports say the cheering in the control room after the successful deployment of the solar arrays was almost louder than the cheering following the successful launch. In many ways, deploying the solar arrays is the most stressful, high stakes activity of commissioning. It takes less force, and different mechanics, to deploy arrays in a zero G environment than it does on Earth. In fact, many spacecraft (like the James Webb Telescope) are never able to fully test solar array deployment on Earth; gravity makes the solar arrays too heavy to operate with the motors that will be used in space. Operators must trust in the capability of the mechanical engineers and software simulations without ever testing the full deployment procedure. I have a friend who was working on a satellite at Space Systems Loral when one of the solar arrays failed to deploy during commissioning. In a last ditch effort to save the spacecraft they fired a spacecraft thruster at the array to try to push it out, and ended up losing whatever capability they had from the partially deployed array by blowing a hole through it. The satellite is now a very expensive piece of space junk, floating around in GEO with 100 million dollars worth of expensive, cutting edge technology and equipment, and no power. 
  4. The smaller, public interest news articles about Celestis, the for-profit company that sent the ashes of 300 people to orbit aboard the Falcon 9. The "special payload" included the remains of James Doohan (Scotty, from Star Trek) and Gordon Cooper (one of the famous Mercury 7 astronauts). The ashes were in the second stage of the Falcon 9 rocket, which was jettisoned about 10 minutes after launch and will remain in orbit for about a year before its orbit decays and it burns up in Earth's atmosphere. This was actually the backup flight for Celestis - the first round of ashes failed to make it to orbit on the botched 2008 SpaceX launch that crashed into the Pacific Ocean.
Congrats to SpaceX! I am excited to follow the mission over the next two weeks as the Dragon performs several maneuvers and is eventually grabbed by ISS astronauts using the station's robotic arm. The SpaceX Ops team has a lot on their plate - It must be an incredibly exciting experience, but I don't envy the pressure on them or their likely sleep schedule for the next two weeks!

Monday, May 14, 2012


The Soyuz blasts off from Kazakhstan
AP Photo/Mikhail Metzel
A hearty Поздравляю! to NASA Astronaut Joe Acaba and the two Russian cosmonauts who blasted off last night in a Soyuz capsule headed for the ISS. If all goes well, they will get to witness the docking of SpaceX's Dragon Capsule on May 19 - the first by a private sector company. The capsule will contain cargo and supplies for the ISS, and will be the first of 12 planned supply missions to the ISS by SpaceX. If all goes well with the Dragon capsule missions (and the prerequisite Falcon 9 launches), SpaceX will eventually be shuttling astronauts to the ISS, eliminating the need for NASA to rely on Russia to taxi US astronauts back and forth.

Last night's launch is a good example of why we badly need the private sector to reinvigorate the space industry: After 50 years of NASA's monopoly on manned space flight, we are sending one astronaut at a time to the ISS in a Russian capsule designed in the 1960s. May 19 cannot come soon enough.

Sunday, May 13, 2012

Gas Station of the Future

Here's an interesting idea: MDA is working on a Space Infrastructure Servicing (SIS) vehicle, which would essentially act as a travelling gas station for aging satellites. Comms satellites usually die once they run out of fuel for delta V maneuvers that keep them in geosynchronous orbit. The SIS would extend the life of a satellite by sidling up it and transferring fuel directly into its tank.

MDA announced a contract with Intelsat about a year ago to service several of its aging communications satellites, but Intelsat has since withdrawn after MDA failed to secure any more customers. In February, MDA said it was waiting on a contract decision by DARPA before deciding whether to shelve the project.

I think the idea is pretty neat, if not exactly revolutionary. Satellites are incredibly expensive to build, and a life extension of even a few years could have a big payoff, especially because the most expensive part of launching a satellite is paying for the launch vehicle. Plus, longer satellite lives means slower turnover and fewer dead satellites contributing to the growing amount of debris in space.

That said, I think ViviSat might have the better idea - they propose a Mission Extension Vehicle that would dock with a satellite, then use its own fuel to boost the satellite's orbit. This approach has two benefits:
1. Less risk - no need to actually open up the gas tank of the satellite being serviced.
2. Wider market - ViviSat claims the MEV would be able to dock with 90% of the 450 or so geostationary satellites in orbit, whereas the SIS can dock to only 75% that have a certain kind of gas tank. Plus, the MEV would be able to do orbit boosting for nanosats with no propellant system, which would make it possible to keep small satellites with no thrusters going at low orbits (<600 km) for more than a few years. If the service was available at a reasonable price point, THAT could be pretty revolutionary.

Saturday, May 12, 2012

Envisat Redlines

Yesterday operators called off the resuscitation effort on Envisat, the European Space Agency's massive Earth-imaging satellite, after a month of unresponsiveness from the 10 year old satellite. There are several possible causes of the loss of communication. According to, "The failure of a power regulator may be blocking the satellite's telemetry and telecommand systems, ESA officials said. There may have also been a short circuit on board that plunged Envisat into a protective "safe mode," then a second malfunction that left the satellite in an unknown state, incapable of receiving commands from Earth. As a fellow operator, my heart goes out to the Envisat Ops team. I can't imagine anything more frustrating than troubleshooting an unknown anomaly in the blind, with the whole space world watching. 

Despite having no comms, the ESA was able to verify that the solar arrays were still deployed thanks to a neat photo from the CNES Earth-observing Pleiades satellite:
Envisat, as images by Pleiades. Source: CNES 
The ESA says that operators will continue to command in the blind and consider failure scenarios for the next couple months. (I imagine they will also be job hunting!) Assuming they cannot raise Envisat from the dead, the satellite will be the latest casualty in the shrinking fleet of Earth-observation satellites. 
Looks like there's going to be a vacuum in the industry pretty soon. Hmmmmm. Maybe an innovative startup could find a way to take advantage?

Though Envisat's death is sad, we should remember that it had a meaningful and long life, (it's initial lifetime projection was only 5 years) and it died doing what it loved.