This is so cool – and impressive, most impressive! A 16mm camera located near the base of the Saturn V rocket captured incredible detail about the ignition and lift off of the Apollo 11 mission to the Moon. The high-quality video slows down 30 second of footage to about 8 minutes, but it’s worth every second to watch! The narrator explains it all in great detail. You’ll see the first moments of ignition where the flames light and expand, then get sucked back into the flame trench; and fire and ice all in one video. It really is awesome!
Damage to the Apollo 13 spacecraft from the oxygen tank explosion. Credit: NASA
Note: To celebrate the 40th anniversary of the Apollo 13 mission, for the next 13 days, Universe Today will feature “13 Things That Saved Apollo 13,” discussing different turning points of the mission with NASA engineer Jerry Woodfill. Click here for our preview article.
Oxygen Tank two in the Apollo 13 Service Module exploded at Mission Elapsed Time (MET) 55 hours and 55 minutes, 321,860 kilometers (199,990 miles) away from Earth. If the tank was going to rupture and the crew was going to survive the ordeal, the explosion couldn’t have happened at a better time. “Not everyone agrees with all the things I’ve come up with in my research,” said NASA engineer Jerry Woodfill who has studied the Apollo 13 mission in intricate detail, “but pretty much everyone agrees on this, including Jim Lovell. The timing of when the explosion happened was key. Much earlier or later in the mission would have prevented a successful rescue.”
If the explosion happened earlier (and assuming it would have occurred after Apollo 13 left Earth orbit), the distance and time to get back to Earth would have been so great that there wouldn’t have been sufficient power, water and oxygen for the crew to survive. Had it happened much later, perhaps after astronauts Jim Lovell and Fred Haise had already descended to the lunar surface, there would not have been the opportunity to use the lunar lander as a lifeboat.
But looking at why the explosion happened when it did shows how fortuitous the timing ended up to be.
The control panel of the Apollo 13 capsule. The module is on display at the Kansas Cosmosphere and Space Center in Hutchinson, KS. Photo courtesy Kansas Cosmosphere and Space Center.
The explosion occurred when Jack Swigert flipped a switch to conduct a “stir” of the O2 tank. The Teflon insulation on the wires to the stirrer motor in O2 tank 2 had unknowingly been damaged because the manufacturer failed to update the heater design for 65 volt operation, and the tank overheated during a pre-flight test, melting the insulation. The damaged wires shorted out and the insulation ignited. The resulting fire rapidly increased pressure beyond its nominal 1,000 psi (7 MPa) limit and either the tank or the tank dome failed.
The O2 tanks were stirred in order to get an accurate reading on the gauging systems, as the cryogenic oxygen tends to solidify in the tanks, and stirring allows for a more accurate reading on the quantity of O2 remaining in the tank.
But this was not the first time the crew had been ordered to stir the tank. It was the fifth time during the mission. And most interestingly, the tanks normally were stirred approximately once every 24 hours. So, why was it stirred that often?
In what Woodfill said was a problem unrelated to what caused the explosion, the quantity sensor or gauge was not working correctly on O2 tank 2. The EECOM (Electrical Environmental and Consumables) flight controller in Houston discovered that the quantity sensor was not reading accurately, and because of that Mission Control asked the astronauts to perform additional actuations of the stirrer to try and troubleshoot why the sensor wasn’t working correctly.
So, it took five actuations until the short circuit and the resulting fire and explosion occurred. If the gauge had been working correctly and the normal stirring of the tank had been done, that would have put the time of the fifth stirring after Lovell and Haise had departed for the lunar surface, and the rescue scenario that ultimately was carried out couldn’t have happened.
“Check the arithmetic,” said Woodfill. “Five actuations at 24 hour periods amounts to a MET of 120 hours. The lunar lander would have departed for the Moon at 103.5 hours into the mission. At 120 hours into the mission, the crew of Lovell and Haise would have been awakened from their sleep period, having completed their first moon walk eight hours before. They would receive an urgent call from Jack Swigert and/or Mission Control that something was amiss with the mother ship orbiting the Moon.”
Apollo 13 crew: Jim Lovell, Jack Swigert and Fred Haise. Credit: NASA
Who knows what would have happened to the crew? The fuel cells required the liquid oxygen tanks. This meant no production of electrical power, water and oxygen. The attached lunar lander had to be available. Likely, the two ships couldn’t even have docked back together. And what if the accident had happened behind the Moon without mission control’s help? Alone in the Command module, Swigert would have had difficulty analyzing the problem. Without a fueled lunar lander descent stage attached, lacking its consumables and engines as well as the needed battery power, water and oxygen, the crippled Command Module could not have returned to Earth with live astronaut(s). Not only would Lovell and Haise have perished but Swigert’s fate would have been the same. Even if the damaged Service Module’s engine had worked, no fuel cells meant the ship would die. The situation that the Apollo 13 crew actually faced was dire, but the alternative scenario would certainly have been fatal.
Woodfill contends that the quantity sensor malfunction assured the lunar lander would be present and fully fueled at the time of the disaster. It was an extremely fortuitous event. Had it not occurred, the timing of the explosion would have been far different and the crew would have perished.
Additional Articles from the “13 Things That Saved Apollo 13” series that have now been posted:
ISS as seen by the departing Endeavour crew on STS-130. Credit: NASA
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How long can the International Space Station really operate – until 2020, or 2028 or beyond? I recently had the chance to talk with Mark Uhran, NASA’s Assistant Associate Administrator of the ISS. We were both attending a conference on water sustainability at Kennedy Space Center, but Uhran took the time to talk with me about the state of our space station, NASA’s new budget and how that might affect ISS operations, and — speaking of water — how is the urine recycling system working these days?
Universe Today: How are things going as far the extension of the ISS? I heard there was recently a meeting with the international partners where they said it could be extended to 2028 if need be. Mark Uhran. Credit: NASA
Mark Uhran: We’ve made the decision in the United States as part of the President’s budget proposal to Congress, so we’re over the hump here in the US. And then we began a series of meetings with the partners starting in Japan last week. Of course each of the partners has been working with us for the past 12-18 months, but they are fully prepared to approach their governments and ask for an extension. There are no technical obstacles to extending to at least 2020, and we’re also going to be doing an evaluation to what the ultimate lifetime of the ISS might be. That evaluation is in process. So we’re looking at whether we can go as long as 2028, but that remains to be seen.
Universe Today: Since we’re here talking about water, how are things going with the recycling system up there on the station. I know there have been some glitches here and there.
Uhran: The station has been a real testbed for developing regenerative water and air technologies. We knew at the time deploying these systems they would be in a testbed mode, and it would probably take about a year to shakedown all the systems and we are making steady progress towards doing just that. All the systems are working today – that’s not to say they will be working tomorrow. We certainly do expect them to go up and down throughout the course of the year as we fine tune them and work out the details. By the end of this year we hope to add a Sabatier (carbon dioxide reduction system) reactor that will allow us produce yet further water on orbit. NASA"s Water Recovery System for the ISS. Credit: NASA
Hauling water is a very expensive proposition for us. Once the Sabatier is up there later this year, we’ll have basically the entire designed system deployed and I’m confident by this time next year we’ll have worked out all the filtration issues, the film formation issues, and precipitant issues and we’ll have this tuned so that it is basically available 90% of the time, which is an outstanding availability rate. So, this has been very worthwhile from our point of view not just because of the cost of hauling water to the space station but for the implications for human exploration beyond low Earth orbit.
Universe Today: The new NASA budget, which eliminates Constellation, how do you see that affecting space station operations?
Uhran: Well, space station is relatively small factor in that new budget. We’ve been extended, which is a major achievement from our point of view. But in terms of financial constraints, we are pretty well prepared now to go ahead and operate until the end of the decade, as well as to ramp up our research program on the station. With the assembly process being completed, the crew time now becomes available for supporting research. So most of our activities this year are geared towards repositioning our utilization program so that when the shuttle stops flying and the commercial cargo resupply services begin we are ready to ramp up that program aggressively, and that’s going very well.
Universe Today: I’ve been here at Kennedy Space Center for about a month and a half and a lot of the people here are talking about a possible extension for the space shuttle program. What are your thoughts on that?
Uhran: Well, the shuttle was certainly required for the assembly phase because we were hauling 20 metric ton elements up to orbit. It literally is the equivalent of a six-wheeler truck. But for the utilization phase, we can continue to maintain and operate the space station at much lower supply rates; typically 3 metric tons on a half a dozen to a dozen times a year. So there are other vehicles both that our international partners bring to the table as well as we’re hoping that the commercial US industry will demonstrate in the next 12-24 months that really will meet our needs once those are available. So although we’d all like to see the shuttles continue to fly forever, we really don’t have a requirement on space station for that kind of relatively heavy lift capability. A close-up look at the Solar Alpha Rotary Joint. Credit: NASA
Universe Today: Another issue that has been sort of looming for the space station is the solar alpha rotary joints (SARJ). Any progress on understanding why they aren’t working as hoped?
Uhran: Well, they are working now. And the failure analysis has been completed. So we know the root causes of the problem. The most challenging mechanisms in any spacecraft system are rotating mechanisms. So the control moment gyros, the solar array rotary joints, the thermal radiator rotary joints – they are all rotating mechanisms. And we’re passing power through those mechanisms, which adds to the complexity. So we think that we have all these under control. It turned out with the SARJ that we have determined the cause of the failure, and we’re doing, really two things. We’re operating the system more gently – we ramp it up more slowly, we stop it more slowly. That doesn’t put as much load on the system. And we find that is applicable to all our systems. The more gently we can operate them the less loads they bear and the longer their lifetime. So we’ll be operating the system more gently and we’ll be lubricating them more regularly. So between those two approaches, we’re pretty confident we won’t have any more problems with the SARJ. We do have a couple of tricks in our pocket in the case that we do see further problems but we think we can get there with the two remedial actions we’ve got now.
Universe Today: To do the lubrication requires a spacewalk?
Uhran: It’s an EVA based activity, yes. It is relatively simple. And not even that time consuming. We were lubricating before, we’ll just increase the frequency.
Thanks to Mark Uhran for taking the time to talk with Universe Today. For more information on the International Space station, visit www.nasa.gov/station.
Witnesses give statements to the House Committee on Science and Technology’s Subcommittee on Space and Aeronautics hearing on spaceflight safety yesterday. Image Credit: Subcommittee on Space and Aeronautics
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The U.S. House of Representatives Subcommittee on Space & Aeronautics held a hearing yesterday on the issue of how to ensure the future safety of human flight into space for both commercial and governmental agencies. The hearing was attended by a number of witnesses that represented NASA, one from the Commercial Spaceflight Federation, the CEO of a risk-analysis firm, and a former astronaut. The subcommittee was chaired by Rep. Gabrielle Giffords.
This hearing comes on the tails of the Augustine Commission final report, which examined the future of spaceflight in the U.S. and laid out a “flexible path” plan that includes utilizing private, commercial firms for human transport into Low Earth Orbit (LEO) and the International Space Station.
Yesterday’s hearing was meant to help inform members of Congress about the safety concerns presented to manned flights, and what future regulations will be needed if commercial companies start to have a larger role in human spaceflight. The hearing’s charter states as its purpose:
On December 2, 2009 the Subcommittee on Space and Aeronautics will hold a hearing focused on issues related to ensuring the safety of future human space flight in government and non-government space transportation systems. The hearing will examine (1) the steps needed to establish confidence in a space transportation system’s ability to transport U.S. and partner astronauts to low Earth orbit and return them to Earth in a safe manner, (2) the issues associated with implementing safety standards and establishing processes for certifying that a space transportation vehicle is safe for human transport, and (3) the roles that training and experience play in enhancing the safety of human space missions.
Witnesses at the hearing included Chief of Safety and Mission Assurance for NASA Bryan O’Connor, Constellation Program Manager Jeff Hanley, Aerospace Safety Advisory Panel Council Member John C. Marshall, President of the Commercial Spaceflight Federation Bretton Alexander, Vice President of Valador, Inc. Dr. Joseph R. Fragola, and former astronaut Lt. Gen. Thomas P. Stafford, USAF, who flew in some of the Apollo and Gemini missions.
Each witness gave statements to the panel, all of which is available in .pdf format on the committee’s site. After hearing the testimony of these witnesses, Rep. Giffords said:
“At the end of the day, I am left with the firm conviction that the U.S. government needs to ensure that it always has a safe way to get its astronauts to space and back. As I have said in the past, I welcome the growth of new commercial space capabilities in America and do not see them as competitors with, but rather complementary to the Constellation systems under development. Based on what we’ve heard today, I see no justification for a change in direction on safety-related grounds. Instead, I am very impressed with the steps that have been taken to infuse safety into the Constellation program, and want to encourage their continued efforts to make Ares and Orion as safe as possible.”
Part of the reason for the hearing was to compare the safety of commercial vehicles to the Constellation program for getting astronauts to the International Space Station after the Shuttle program is shut down. Constellation won’t be ready to go until 2015 at the earliest, so the gap of five years could potentially be filled by private contractors.
Of course, you might notice that only one of the members of the witness panel of six represents commercial interests, which has caused some critics – like the Orlando Sentinel – to call the safety hearing a “Pro-Constellation rally.” The Space Politics blog also pointed this lack of representation out.
Though commercial aerospace companies like SpaceX, Masten Space Systems and XCOR weren’t represented directly on the witness panel, they are members of the Commercial Spaceflight Federation. Bretton Alexander stressed the importance of safety in his statement, and also pointed out that private space companies could take over the majority LEO launches here at home to allow NASA and its partners the resources to go to the Moon (and beyond).
Heat shields are an important part of any space vehicle that re-enters the Earth’s atmosphere. The next generation of heat shields to protect astronauts and payloads on their re-entry into the Earth’s atmosphere may use superconducting magnets to deflect the plasma that forms in front of spacecraft as they travel at high speeds in the air. The first test of such a heat shield could happen as early as ten years from now, and the basic technology is already in development.
Traditional heat shields use the process of ablation to disperse heat away from the capsule. Basically, the material that covers the outside of the capsule gets worn away as it is heated up, taking the heat with it. The space shuttle uses tough insulated tiles. A magnetic heat shield would be lighter and much easier to re-use, eliminating the cost of re-covering the outside of a craft after each entry.
A magnetic heat shield would use a superconductive magnetic coil to create a very strong magnetic field near the leading edge of the vehicle. This magnetic field would deflect the superhot plasma that forms at the extreme temperatures cause by friction near the surface of an object entering the Earth’s atmosphere. This would reduce or completely eliminate the need for insulative or ablative materials to cover the craft.
Problems with the heat shield on a spacecraft can be disastrous, even fatal; the Columbia disaster was due largely to the failure of insulative tiles on the shuttle, due to damage incurred during launch. Such a system might be more reliable and less prone to damage than current heat shield technology.
At the European air and space conference 2009 in Manchester in October, Detlev Konigorski from the private aerospace firm Astrium EADS said that with the cooperation of German aerospace center DLR and the European Space Agency, Astrium was developing a potential magnetic heat shield for testing within the next few years.
The initial test vehicle would be launched from a submarine aboard a Russian Volna rocket on a suborbital trajectory, and land in the Russian Kamchatka region. A Russian Volan escape capsule will be outfitted with the device, and the re-entry trajectory will take it up to speeds near Mach 21.
Though the scientists are currently testing the capabilities of a superconducting coil to perform this feat, there is the challenge of calculating changes to the trajectory of a test vehicle, because the air will be deflected away much more than with current heat shield technology. The ionized gases surrounding a capsule using a magnetic heat shield would also put a wrench in the current technique of using radio signals for telemetry data. Of course, there are a long list of other technical challenges to overcome before the testing will happen, so don’t expect to see the Orion crew vehicle outfitted with one!
Today was a proud day in the history of New Zealand, marking the first ever home-grown rocket launch from the island. The private space company Rocket Lab, Ltd launched their Atea-1 rocket to a height of over 100 km at 2:28pm (NZST). The launch took place at Great Mercury Island, just off the coast of the North Island, and is a first for the company as well as the country.
Rocket Lab, Ltd was formed three years ago with the hopes of developing a rocket that would make space more accessible. The Atea-1 rocket has a small payload capacity, 2kg (4.4lbs). This first test of the rocket had a payload that recorded how well the engine burned during the 22-second firing, as well as a GPS locator for recovery. As of this writing, the 1st stage booster section was recovered, but the company is still looking for the payload stage.
The target of the launch was 50km (31miles) northeast of Great Mercury Island, and the team hopes to recover the second stage within the next two days so as to analyze the measurements taken on how well the test flight went.
The launch was initially scheduled for 7:10am, but a number of technical issues delayed the flight until the afternoon. A section of aerocoupler, which connects the fuel line to the rocket, froze up, which stuck the rocket in place on its pad. A helicopter was dispatched to Whitianga on the North Island to pick up another coupler from an engineering supplier.
After almost scrubbing the launch three times, emptying the rocket and refueling it, the team was ready to go at 2:30. The 6meter (20 foot) long rocket was launched above the Karman line, 100 km (62 miles) above the Earth, making this an official flight into space.
Atea is the Maori word for space, and this specific rocket was named Manu Karere – meaning ‘bird messenger’ – by the local Thames iwi. Rocket Lab founder, Mark Stevens (who legally changed his name to Mark Rocket about seven years ago) told the Waikato Times, “The last six months have been a terrific amount of work. The tech team has put in a massive effort. It’s not trivial sending something into space. This is a huge technological leap for New Zealand.”
The video interview of Mark Stevens and Peter Beck embedded below is courtesy of the New Zealand Herald.
Rocket Lab has produced a number of products for the aerospace industry, including separation systems, rocket fuel and software. The company is completely privately funded.
This isn’t the first rocket to be launched from the island. That distinction belongs to a rocket that was imported in 1963 by the Cantrbury University physics department to conduct upper atmospheric research in collaboration with the Royal New Zealand Air Force. That rocket only went to 75km (46 miles), making Atea-1 the first ever rocket to be launched into space, and adding New Zealand and Rocket Lab to the ever-lengthening list of space-faring enterprises.
The major shortcoming of current chemical powered rockets lies in the ratio of payload to fuel. The dream of rocketeers would have a spacecraft almost all payload. Leik Myrabo and John Lewis have an idea for this and they present it in the book “Lightcraft – Flight Handbook LTI-20 “. Within the book lies great detail on a special flying craft and some of its essential subsystems.
This book aims to extol the virtues of a large craft that relies upon microwaves to transfer energy from one location to itself. Via this, the craft need not carry any significant power supply, though the book does mention backup batteries. Further, the book describes, with great relish, the use of ionizers that create the thrust and provide the flight control. Though perhaps sounding farfetched, one author, Leik Myrabo, is recognized as being a worldwide expert in this field and he has undertaken trials on laser launched vehicles. From this, the book has an authoritative ring.
Now the book’s subject does sound very futuristic. And the book’s layout acknowledges this by being written as a flight handbook for travellers in the year 2025. That is, if you were to take a ride on the LTI-20 laser powered craft, then you would need to know the contents of the book so as to understand the craft’s functionality. Hence, the result for the reader is a book that smacks whole heartedly of science fiction even though practical research has taken place.
So here’s your dilemma regarding this book. Do you buy it for the fun science fiction or do you buy it because of the novel method of power supply and flight control. If you want both, then you are in luck. If you like science fiction technology, such as headgear for partial liquid ventilation, this book has lots, but it’s very disjointed and most topics are unsubstantiated. If you want to know more about laser power, this book has the details, but at the level of an article for Popular Mechanics. And sadly, the connection between the future described within the book and current research is tenuous at best. Hence, this book, while entertaining, lacks from a practical stand point.
Nevertheless, there is no mistaking the potential of microwaves to transfer energy to flying craft as described within. As well, ionizers should provide effective flight control, at least while a sufficient quantity of atoms exist (i.e. this won’t work in space). So, for the pleasure of reading about cutting edge technology then Leik Myrabo and John Lewis’ book “Lightcraft – Flight Handbook LTI-20 ” is for you.
When it comes to exploring the hostile environment of space, robots have done a lot (if not most) of the exploring. The only other planet besides Earth that humans have set foot on is the Moon. Robotic explorers, however, have set down on the Moon, Mars, Venus, Titan and Jupiter, as well as a few comets and asteroids. Robotic missions can travel further and faster, and can return more scientific data than missions that include humans. There is much debate on whether the future of space exploration should rely solely on robots, or whether humans should have a role.
As contentious as this issue is, there is no doubt that robots have and will continue to contribute to our understanding of the Universe. Here’s a short list of past, current, and future robotic missions that have done or will do much in the way of exploration of our cosmos.
The most famous robots in space have to be the series of orbiters, rovers and landers that have been sent to Mars. The first orbiter was Mariner 4, which flew past Mars on July 14, 1965 and took the first close up photos of another planet. The first landers were the Viking landers. Viking 1 landed July 20, 1976, and Viking 2 on September 3, 1976. Both landers were accompanied by orbiters that took photos and scientific data from above the planet. The landers included instruments to detect for life on the surface of Mars, but the data they returned is somewhat ambiguous, and the question of whether there is life on Mars still requires an answer. Currently, Spirit and Opportunity are roving away on the Martian surface, well past their expected mission lifetime, and the Phoenix lander returned a wealth of information about our neighbor. For more about the entire series of Mars missions, go to NASA’s Mars Exploration Program website. Of course, NASA isn’t the only space organization represented at Mars – the European Space Agency currently has Mars Express orbiting the planet, and has the first webcam of another planet available!
Mars isn’t the only place to go in the Solar System, though. Both the U.S. and the Russians sent numerous missions to Venus, with a lot of successes and failures. For a complete list of the many missions to Venus visit the Planetary Society. The most notable firsts are: Mariner 2 was the first successful Venus flyby on December 14, 1962, and the Russian lander Venera 7 was the first human-made vehicle to successfully land on another planet and transmit data back to Earth on December 14, 1962.
Sputnik 1, of course, was the first robot in space, and was launched October 4th, 1957 by the USSR.
The Voyager missions are notable for the milestone of having a robot leave the Solar System. Voyager 1 and 2 were launched in 1977 are still making their way out of the Solar System, and have entered the heliopause, where the solar wind starts to drop off, and the interstellar wind picks up. To keep up with their status, visit the weekly status page.
Dextre, a robotic arm developed by the Canadian Space Association, is a very cool robot aboard the International Space Station. Dexter allows for delicate manipulation of objects outside the station, reducing the number of space walks and increasing the ability of the ISS crew to maintain and upgrade the station.
This is by no means an exhaustive list of the enormous number of robotic space missions. To learn a lot, lot more check out the Astronomy Cast episode on Robots in Space, the ESA robotics page, NASA missions page, and the Planetary Society missions page.
An artist's representation of a rotating space station.
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Have you ever noticed that astronauts float around in the space shuttle and in the International Space Station, while space travelers on television and in the movies keep their feet firmly on the ground. That’s because it would be very difficult (and expensive) to have your actors floating around in every scene. So science fiction writers invent some kind of artificial gravity technology, to keep everyone standing on the ground.
Of course, there’s no technology that will actually generate gravity in a spaceship. Gravity only comes from massive object, and there’s no way to cancel the acceleration of gravity. And so if you wanted to have a spacecraft that could generate enough artificial gravity to keep someone’s feet on the ground, the spaceship would need to have the mass of the Earth.
Floating in space is actually very hard on astronauts’ bodies. The lack of gravity softens their bones and causes their muscles to weaken. After any long trip into space, astronauts need several days and even weeks to recover from traveling in microgravity.
But there a couple of ways you could create artificial gravity in a spaceship. The force we feel from gravity is actually our acceleration towards a massive body. We’d keep falling, but the ground is pushing against us, so we stand on the ground. If you can provide an alternative form of acceleration, it would feel like gravity, and provide the same benefits of standing on the surface of a planet.
The first way would be through accelerating your spaceship. Imagine you wanted to fly your spaceship from Earth to Alpha Centauri. You could fire your rockets behind the spacecraft, accelerating at a smooth rate of 9.8 meters/second2. As long as the rocket continued accelerating, it would feel like you were standing on Earth. Once the rocket reached the halfway point of its journey, it would turn around and decelerate at the same rate, and once again, you would feel the force of gravity. Of course, it takes an enormous amount of fuel to accelerate and decelerate like this, so we can consider that pretty much impossible.
A second way to create acceleration is to fake it through with some kind of rotation. Imagine if your spaceship was built like a big donut, and you set it spinning. People standing on the inside hull would feel the force of gravity. That’s because the spinning causes a centrifugal force that wants to throw the astronauts out into space. But the spaceship’s hull is keeping them from flying away. This is another way to create artificial gravity.
There are no spacecraft that use any form of artificial gravity today, but if humans do more space exploration, we will likely see the rotational method used in the future.
Navigating a spacecraft through the heavens has been compared to sailing a ship on the open seas or driving a vehicle on a long, cross country journey. Analogies are necessary, since spacecraft navigation is performed by a relatively small sampling of the human race, and the job usually involves doing things that have never been done before. Those of us who have trouble making sense of a road map here on Earth stand in awe of what these celestial navigators can accomplish.
Literally, this is rocket science.
In simplest terms, spacecraft navigation entails determining where the spacecraft is and keeping it on course to the desired destination. But it’s not as easy as just getting from Point A (Earth) to Point B (a planet or other body in our solar system.) These are not fixed positions in space. Navigators must meet the challenges of calculating the exact speeds and orientations of a rotating Earth, a rotating target destination, as well as a moving spacecraft, while all are simultaneously traveling in their own orbits around the Sun. Chris Potts points to Gusev Crater on Mars on January 4, 2004, after the MER navigation team landed the Spirit rover on Mars with unprecedented accuracy. Photo courtesy of Chris Potts
Chris Potts, who helped lead the navigation teams for the Mars Exploration Rovers (MER), compared the target requirements of landing the Spirit rover inside a specific crater on Mars to being able to shoot a basketball through a hoop 9000 miles away. “Not only do you have to make the shot perfectly without the ball touching the rim, but the timing has to be perfect, so you make the shot exactly as the buzzer sounds,” he said.
Ken Williams was the Navigation Team Chief for the Stardust mission’s return of pristine samples of a comet back to Earth. For a successful re-entry and landing at a precise location in Utah, the navigation team had to target the return capsule’s entry to a specific point in the Earth’s atmosphere to within eight 100ths of a degree, a feat that’s been compared to hitting the eye of a sewing needle with a piece of thread from across a room.
Navigation is essential to every robotic mission, and while mission success hinges on how well the navigation team performs, navigators aren’t usually found in the limelight, sitting up on stage for a press conference. Typically that’s reserved for the mission scientists and designers. The navigators, seemingly, work behind the scenes, manning the trenches in relative anonymity.
But I had the opportunity to talk to a few spacecraft navigators, learning more about their job and discovering the innate qualities of those who guide our spacecraft to places beyond. Neil Mottinger. Image courtesy Neil Mottinger.
Neil Mottinger has been part of numerous missions since he started working at the Jet Propulsion Laboratory in 1967. He assisted with some of the early lunar and planetary missions, and developed some of the software that navigators still use today.
There are several different sub-disciplines to spacecraft navigation, and one of Mottinger’s specialties is orbit determination. “Orbit determination is knowing where the spacecraft is and where it’s going,” said Mottinger, who currently works with the Mars Reconnaissance Orbiter (MRO) mission and the upcoming LCROSS (Lunar Crater Observation and Sensing Satellite) mission to the moon. “It starts with predicting the trajectory where the spacecraft will be immediately after launch so that the Deep Space Network (DSN) knows where to point their antenna and on what frequency to expect the signal.” The DSN consists of a network of extremely sensitive deep space communications antennas at three locations: Goldstone, California; Madrid, Spain; and Canberra, Australia. The strategic placement approximately 120 degrees apart on Earth’s surface allows constant observation of spacecraft as the Earth rotates.
Since there’s no GPS in outer space, navigators process the radiometric tracking data received from the DSN to determine the spacecraft’s position and velocity. They also use optical data, where the spacecraft takes a picture of the star background to help refine the spacecraft’s trajectory.
For many years, Mottinger worked with a group that provided navigation support for the launch of over 100 spacecraft. “I never got attached to any one mission since right after a launch we moved on the next mission,” Mottinger said. But now he stays with missions longer and has been with the MRO mission for the better part of three years. Mottinger is thrilled with the scientific data this mission has returned. “We have to provide accurate predictions of where the spacecraft is going to be. Then the engineers know how to orient spacecraft so that the scientists can make their observations,” he said. “If we do our job, the scientists can see a landslide on Mars or look at specific areas on the planet. If our predictions are wrong, the cameras are pointed in the wrong direction. Navigation is integral to the whole process of ensuring mission success.” An active volcano on Io, taken by the New Horizons spacecraft. Credit: NASA
Mottinger said that typically one doesn’t think of navigators as scientists, only as a means to an end for the scientists to get results. However, sometimes scientific by-products come from navigation. The most famous instance involved the Voyager mission when navigator Linda Morabito discovered a volcano on Jupiter’s moon Io from looking at optical navigation images. In the Lunar Orbiter missions, navigators realized there were large concentrations of mass, (now called mascons) underneath the moon’s surface that were accelerating spacecraft in orbit.
Additionally, the science used in navigation has improved dramatically over the years. “When you look at the types of things we didn’t understand when I first started versus what we know now, it’s overwhelming,” said Mottinger. For example navigators can now create very accurate models of solar pressure – how particles of sunlight push against a spacecraft and alter its trajectory — which includes not only how sunlight is reflected from different surfaces of the spacecraft, but also the re-radiation of energy absorbed by the solar panels and radiated out the back side.
Additionally ephemerides, the tables navigators use to obtain the positions of astronomical objects, have also improved in accuracy over the years. “The devil is in the details,” said Mottinger. “Navigation is getting to be an incredibly precise game.”
Like many who work at JPL, Mottinger enjoys talking to schools or community groups to share the excitement and recent discoveries of space exploration. “It’s important to be out there telling our message to get people excited about what we’re doing,” he said. “And the public is entitled to be excited, because they’re paying the bill.”
Several years ago Mottinger returned to his hometown of Oswego, Illinois to talk to students about his job as a navigator. Sitting in the classroom was a young Chris Potts, who decided spacecraft navigation was the career he wanted to pursue. Potts, who has been at JPL since 1984, was the Deputy Navigation Team Chief for MER and now works with the Dawn Mission that is en route to orbit two asteroids, Ceres and Vesta. Chris Potts and Neil Mottinger with a model of the Mars Exploration Rover at JPL. Photo courtesy of Chris Potts
Potts’ specialty is flight path control. This involves firing the propulsion system to alter the spacecraft’s velocity or trajectory, known as Trajectory Correction Maneuvers (TCM). “That includes understanding the spacecraft’s control capabilities and determining any limitations,” said Potts. “You determine when you’re going to fire the propulsion system, how often and the objective of each maneuver. You also have to evaluate the delivery requirements, to make sure you can land within a crater on Mars, for example, and minimize risk along the way.”
The design aspect is Potts’ favorite part of the job. “You try to develop a strategy that puts all the pieces together,” he said. “You have to talk with the mission scientists and understand what their requirements are, and then know what the spacecraft can do. It’s like people who have an old car and they’ve been around it so long, they know how to get the most out of that vehicle. Taking advantage of what the spacecraft does well and working around its limitations feeds into the design of a strategy that pulls it all together to make it work.”
Much of Potts’ work involves simulations and testing. “We see how the spacecraft behaves, and try out different strategies to improve it for our situation,” he said. “The navigation section has a whole ‘toolbox’ of software that we’re able to use.” Artist concept of the Dawn spacecraft. Credit: NASA
The Dawn spacecraft uses an ion engine, and this is the first time Potts has worked with a low thrust propulsion system. “It’s quite a different mission,” he said. “The concerns are little bit different than other missions because the thrust is so efficient. One of the things you worry about is not having enough time to make any corrections that are needed. Although the thrust is low, over time it builds up quite a velocity change and you’re always designing trajectories and changing commands to make sure the ion engine is firing in the right direction. If there’s any kind of spacecraft fault or hiccup along the way, you have to scramble, and some future events might have to be moved around.” Dawn will arrive at Vesta in 2011.
Potts enjoys being part of the excitement of all the different missions at JPL. “I really enjoy working with some extremely intelligent and talented people here and you can definitely sense the passion for the work that they do,” he said. “Sometimes that can be intimidating, but you realize that everyone has their own talent to offer, and everyone helps drive you to do your best here. We get to do a variety of interesting work, and it’s very challenging. No two days are the same.”
One of the rewards of his job, Potts said, is seeing the fruition of his work come to light in scientific discoveries. “With the Stardust sample return, to watch the capsule land right where it was supposed to in Utah was very rewarding,” he said. “And to see the scientists get their hands on that data and start to perform their investigations, you sense how thrilled and excited they are to finally get to work on their lifelong ambition.”
Potts and Mottinger both worked on the Stardust mission under the leadership of Ken Williams. Williams worked at JPL for several years, but currently is employed by KinetX, a private engineering firm specializing in aerospace technology and software development. At present, KinetX provides navigation support for the New Horizons mission to Pluto, as well as the MESSENGER (Mercury Surface Space Environment Geochemistry and Ranging) mission to Mercury, and Williams is MESSENGER’s navigation team chief. Unlike Mottinger and Potts, Williams hasn’t always been involved in space missions and his career in navigation evolved from a background in physics. He worked at the Applied Physics Lab at Johns Hopkins University before coming to work at JPL in 1994. Ken Williams of KinetX.
Williams’ favorite part of being a navigator is finding and solving interesting technical problems. “That’s what gets my interest,” he said. “MESSENGER certainly has a number of those. We flew by Earth once, Venus twice and Mercury twice. We’ll have to fly by Mercury one more time before we finally go into orbit on the fourth encounter. Finding a trajectory that does all those things successfully is a very interesting technical problem that I’m very glad to be involved with. We have to consider all sorts of constraints, too, such as keeping the spacecraft pointed away from the sun so that the components don’t get too warm.”
As a Navigation Team Chief, Williams coordinates all the sub-disciplines of orbit determination, flight path control, and optical navigation along with the needs of mission scientists in terms of observations when they encounter a planet or comet.
Williams, too, enjoys the exhilaration of being in the thick of the action in important space missions. “I suppose it’s like being in a battle, or in a basketball or football game,” he said. “You feel the excitement of seeing events unfold, and responding to any anomalies or surprises that come up. And when it’s all done you have a tremendous sense of satisfaction.”
His experiences with Stardust’s return to Earth stand out as a highlight. “Getting all that effort coordinated and getting the spacecraft down successfully was probably the single most rewarding experience in all the time I was at JPL,” he said. “On nearly every mission I’ve worked on there has been a time where you have a sense of euphoria about having the spacecraft be in the right place at the right time. That’s a good feeling to have.” The Stardust Mission Navigation Team was presented with Popular Mechanics’ Breakthrough Award. Said Team Chief Ken Williams: “The day we took this picture, I felt a strong sense of camaraderie with all these folks after everything had worked so well. They’re a very talented group of people who did a tremendous job.” FRONT ROW – left to right:Tung-Han You, Ken Williams, Prem Menon. 2nd Row: Roby Wilson, Katherine Nakazono, Julie Kangas. 3RD Row: Daniel Lyons, Ram Ramachand, Bhat Shyam Bhaskaran, Cliff Helfrich, Jeff Tooley, David Jefferson, Dimitri Gerasimatos, Paul Thompson, Neil Mottinger. Last row: Darren Baird, Jae Lee, Chris Potts, Tim McElrath, Brian Kennedy
Although leaving JPL was a difficult decision, Williams enjoys his experiences at a private company. “It would have been easy to stay at JPL and be what they call a ‘greybeard’ in terms of having experience, but after Stardust, I liked the challenge of leading a navigation team and growing in technical areas,” he said. “I thought there would be a better opportunity to do that with a small team in a small company, and I thought KinetX was a good place to accomplish that.“
Quite the opposite of a ‘greybeard’ is navigator Emily Gist. She has been at JPL for 4 years and is part of the navigation team for the Cassini mission at Saturn. Like Potts, she works in flight path control, helping to plan the trajectory and estimate the future position of the spacecraft, and to control the corrections required to achieve the mission objectives. Artist concept of the Cassini spacecraft at Saturn. Credit: NASA
She takes great satisfaction knowing she is helping to facilitate exploration. “The Saturnian system is more beautiful than most would have imagined and more diverse than previously known,” she said. “The information Cassini has provided has enlightened us all. More specifically I love how much I learn each and every day at JPL and working on the Cassini Mission.”
As part of the ‘next generation’ of navigators, Gist enjoys the challenging environment that JPL provides. “We had an Operations Readiness Test on Cassini where the team was tested to see how we would react to a failure or fault on the spacecraft in an operational environment,” she said. “The senior engineers weren’t in play so the newer generation had to figure it out on our own and we did an excellent job. It made me proud of all the folks I work with. They are truly talented people.”
Gist said gender has never been an issue in her job as a navigator. “JPL has a wonderfully diverse staff and while there are not very many female navigators we are not treated differently,” she said. “I am pretty biased, but I think what we lack in quantity we make up for in quality. I work with some amazing women.”
“Additionally, I feel fortunate to live in a time and society where regardless of gender one can find the thing they want to do and do it to the best of their ability. I love being an engineer and what I try to convey to young women is that they can love anything they want, even if it’s math and science, without fear that it’s a less feminine job.”
The hardest question for all the navigators to answer was if they had a least favorite part of the job. They cited the usual problems with any job: not enough time and too much paperwork. And stress comes with the job. “Deadlines, especially working at JPL, are very real,” said Potts. “If you’re not prepared for a critical event in the mission, you usually don’t get a second chance. There’s a lot riding on getting your job done properly.”
But all the navigators emphasized the importance of the team aspect in their job. “You look for the inherent quality of the team,” said Mottinger. “I had a project manager who said that a team catches each other’s mistakes and the whole is greater than the sum of the parts. Everything is done in a spirit of camaraderie, and there’s no such thing as a stupid question.” Galileo at Jupiter. Credit: NASA
But seeking individual limelight just doesn’t seem to be in a navigator’s makeup.
“I’m more comfortable working behind the scenes than doing an interview,” said Potts. “When I know I’ve done my job, and contributed to the mission success, that’s enough for me.”
“I am fine with my work being behind the scenes,” added Gist. “However when I consider the work the engineers before me and around me have done I sometimes feel they should get more recognition.”
Williams feels, in general, the field of navigation itself should get more recognition. “I think scientists and people who do purely hardware systems underestimate the difficulty of what navigators have to do,” he said. “It would be nice if we got more recognition from our peers just from the standpoint of being able to influence how missions are planned and designed to begin with so that navigation issues can be addressed before launch and not only left for us to deal with after launch. I feel more strongly about that than any recognition of my own accomplishments.”
Williams said that what navigators do is more of an art form. “It’s not reducible to a set of algorithms that can be stored on board a flight system like power or propulsion, for example. It’s constant refining.”
And are navigators bothered by the sometimes long and odd hours their job requires? “No,” said Mottinger, “I wouldn’t trade it for anything. There’s nothing else like it.”
Venus, with a lot of successes and failures. For a complete list of the many missions to Venus visit the 
