Spartan – A Little Spacecraft That Could
by Philip Chien
The National Air and Space Museum is the most popular museum in the world. Its main building, on the Mall in Washington D.C., gets about six million visitors each year. They marvel over the original Wright Flyer, Spirit of St. Louis, Apollo 11 command module, and other historic airplanes and spacecraft. Long ago it was recognized that the building, while extremely large, didn’t have enough room for the larger vehicles in the Smithsonian’s giant collection.
The decision was made to build an annex at Dulles Airport in the suburban D.C. area. The Udvar-Hazy (pronounced OOD-var HAH-zee) center opened on December 15, 2003. Its collection features Enola Gay - the bomber which dropped the first atomic bomb, a supersonic Concorde, the original Boeing 707 “Dash 80" prototype, a SR-71 Blackbird, and the space shuttle prototype “Enterprise".
One of the more unusual displays, hanging from the ceiling, is Spartan 201. The spacecraft gets very little attention and the sign just says it flew on five space shuttle missions from 1993 to 1998 and studied solar astronomy. What the minimalist display doesn’t tell you is the fascinating history behind this little spacecraft.
Spartan 201 barely looks like a spacecraft. It’s box-shaped with a cylinder sticking through the middle, has white circles with black dots all over, and isn’t that a bicycle reflector mounted on the side?
The Spartan program was an outgrowth of NASA’s sounding rockets. Sounding rockets are relatively small rockets that carry scientific instruments into outer space for a short period - typically around one to fifteen minutes. The sounding rocket doesn’t have enough energy to put the payload into a permanent orbit, but it’s far less expensive than a full-size launch vehicle. Spartan puts sounding rocket instruments on a relatively low cost reusable spacecraft. The Spartan spacecraft flies to and from space within the space shuttle’s cargo bay. The shuttle’s robot arm releases Spartan and then the shuttle backs away and performs other tasks. After two days the shuttle performs a rendezvous with Spartan and puts it back into the cargo bay for return to Earth. A Spartan mission can collect a couple of days of science, 160 times as much as a sounding rocket. It’s far less expensive than a dedicated spacecraft, and more versatile than instruments mounted within the shuttle’s cargo bay.
Spartan first flew on the STS 51-G mission in 1985 and was extremely successful. Spartan-Halley was lost in the space shuttle Challenger accident in 1986. Spartan was also flown in the Spartan 204 configuration (ultraviolet astronomy and sensor tests), as the OAST-Flyer (Office of Aeronautics and Space Technology – the NASA division which sponsored the technology experiments), and an inflatable antenna experiment, but this is Spartan 201’s story.
Spartan 201’s scientific instruments cost about $5.7 million, plus the $6 Million spacecraft, and $1 Million to prepare it for launch for a grand total of about $13 Million. Each reflight cost about $1 Million more. A Million here, a Million there and sooner or later you’re talking real money. But in NASA terms it was a relatively cheap spacecraft that could perform science which wasn’t otherwise possible.
Spartan 201 was a solar astronomy mission. It needed to fly in space for two very important reasons. The atmosphere absorbs most of the Sun’s spectrum, in particular ultraviolet light and normally the Sun’s corona (outer layer) can only be seen during a solar eclipse where the Moon blocks out the Sun, but leaves its corona visible. An artificial eclipse can be created in space by putting a black disk in front of a scientific sensor (a coronagraph). Spectrometers are fancy prisms; spreading out light so individual colors (chemicals) can be studied. Spartan 201 featured two scientific instruments - the Ultraviolet Coronal Spectrometer from the Harvard-Smithsonian Center for Astrophysics and White Light Coronagraph from the National Center for Atmospheric Research’s High Altitude Observatory.
Spartan 201 made its maiden voyage on the STS-56 mission in 1993. This writer was the only reporter who got to go inside the Hanger AO cleanroom at the Kennedy Space Center where Spartan was prepared before launch. I was rather amused that somebody had used plastic tape to draw a smiley face on the protective wrapping over the coronagraph’s cylinder.
The WorldWide Web was just beginning in 1993 and webpages were fairly informal. If a NASA manager wanted to put up a webpage he did it himself without asking for permission from a public affairs person. Spartan 201 manager Craig Tooley is a big Elvis fan and his Spartan 201 webpage included a link to one of the first Elvis Presley tribute websites. When NASA’s public affairs office took over NASA’s public webpages the Elvis link was removed.
Spartan 201 worked well on its maiden flight and additional flights were planned. One of the key advantages to Spartan is the ability to do co-observations with other spacecraft. While Spartan performs its two days of observations another long duration spacecraft observes the Sun at the same time, increasing the amount of science which can be performed by either spacecraft. In some cases Spartan’s instruments could be used to recalibrate the instruments aboard those spacecraft.
Spartan 201’s second and third missions were primarily co-observations with the Ulysses solar probe. Ulysses was flying a unique orbit where it could observe the Sun’s north and south poles. Those Spartan flights took place on the STS-64 and STS-69 missions.
Solar astronomy took a major leap with the launch of SOHO (Solar and Heliospheric Observatory) in 1995. SOHO (pronounced “so hoe") was positioned at a gravitationally stable location between the Earth and the Sun. It could perform continuous solar observations in colors invisible from the Earth’s surface, and provide advanced warning for major solar storms headed toward the Earth. One of SOHO’s twelve instruments was an advanced version of Spartan 201’s Ultraviolet Coronagraph Spectrometer. NASA scheduled the Spartan 201-4 mission on STS-87 in 1997 to do co-observations with SOHO.
On STS-87 astronaut Kalpana Chawla (K.C.) lifted Spartan with the robot arm and set it free. Spartan was supposed to activate its thrusters and rotate itself to indicate it was functioning properly. But Spartan just sat in space without rotating.
Most of an astronaut's training is for when things go wrong. If there was no indication Spartan was working Chawla was supposed to re-grab the satellite with the robot arm but she unintentionally hit Spartan with the arm and it went into an uncontrolled spin. During the flight K.C. told this reporter, “It all seemed to go real fast. After I moved the arm back [and Spartan was spinning], I thought maybe Spartan was doing the [activation] maneuver it was supposed to do earlier. That was my immediate thought.".
Commander Kevin Kregel flew Columbia around Spartan in an attempt to put it in a position where Chawla could try to re-grab the wayward satellite. But after an hour of trying and using precious propellant, Mission Control told Kregel to stop so he could save enough propellant for a later rendezvous attempt.
The crew quickly determined what had happened. They reviewed their procedures step-by-step and determined that K.C. had missed a step: Spartan was never turned on. And just as important -- nobody else noticed. The way the software was written there was no way of informing the crew that something had been missed. Afterwards Chawla told me, "We had figured out very early on that's probably what happened. We also knew that [with that] software, there's no insight [any indications that the commands had been properly entered into the computer].".
Kregel got his crew together and told them that while it was regrettable, the mistake was made and there was nothing they could do to change that and they had to concentrate on the rest of their mission. Mission Control devised a plan where spacewalkers Winston Scott and Takao Doi would manually capture Spartan. They grabbed the satellite with their spacesuit gloves and Chawla used the robot arm to gently pushed Spartan back into its latches for the trip home. It was a bittersweet recovery. They were happy to rescue Spartan, but it was coming home without any scientific data.
NASA considered relaunching Spartan for an abbreviated mission, but decided not to because there wasn't enough propellant. The disappointed Spartan team on the ground put a slash through the word “Deploy" on their conference board.
The Spartan “Close Call Investigation Board" verified that K.C. had missed a step in the procedures to turn Spartan on. It stated, “The Board’s conclusion based on all the evidence available is the crew inadvertently omitted the Spartan Standby step." Everybody realized that Chawla had made a mistake -- but it was a human mistake anybody could have made.
Just as important was the software's design. The programmers did not include any warnings to the crew that they were about to deploy the satellite without completing its activation sequence, nor did Spartan’s circuits include any feedback mechanism. This was intentional in Spartan's design. Originally Spartan wasn't even controlled by a computer program -- just a set of switches. Astronauts had made mistakes using that switchbox in the past, although not with such embarrassing public results. When the engineers decided to replace the switchbox with a computer program the program duplicated the functions of the switches but did not improve the “user interface". The failure board recommended several changes including more emphasis in crew training for when things go wrong, more training for the astronauts to work together as a team, and improvements to Spartan's computer software and instructions.
Chawla always acknowledged her personal mistakes. Insiders note that it was her honesty and candor that saved her career. K.C. told me, "Something like that you don't forget. Even though people who looked at [the software] said before the next flight you should definitely make those changes [to the software and procedures]. So even though they came up with a lot of recommendations you always feel eternally guilty. I think you can live ten lifetimes after that and still feel the burden of something like that." Some Indian organizations have tried to insist that it wasn't Chawla's fault, and it was sloppy news reporters incorrectly blaming her when unclear instructions were really responsible. The same instructions were used for Spartan on each of its previous flights, and while the instructions were not as clear as they could have been, that didn't excuse Chawla.
Chawla’s next flight was STS-107, Columbia’s last mission. Because of her death many people want to ignore K.C.'s mistakes on STS-87 or pretend they never happened. Spartan only showed that K.C. was human and wasn’t infallible. After her death, many in Mission Control said their main regret was personal resentment they held against K.C. because of Spartan, and that they were sorry they didn't treat her better.
NASA decided to fly Spartan 201 on the STS-95 flight in 1998. There was an unplanned bonus because of the one year change. In 1997 the sunspot index was 40. A year later it had grown to 99, with solar activity 2 to 3 times more frequent as the Sun approached the highest activity in its eleven year cycle. Astronomer Dick Fisher noted they anticipated three to five giant mass ejections each day, where the Sun spits out the equivalent of 100 supertankers of material so fast it could travel from the Earth to the Moon in just 20 minutes.
Unfortunately very few people even realized Spartan was on STS-95. All of the activities during the mission and the rest of the crew were overshadowed by the presence of legendary Mercury astronaut John Glenn. STS-95 had 85 different experiments, but all NASA’s public affairs office, most of the media, and the public seemed to be interested in was John Glenn. Glenn was praised for doing everything on the mission (even though he was only actively involved with a few experiments). According to some of Glenn’s more enthusiastic supporters he apparently ran the mission single-handed!.
What few people know is STS-95 was a unique mission for astronomy. It is the ONLY space mission to ever combine solar astronomy, astronomy within the solar system, astronomy within the Milky Way galaxy, extra-galactic astronomy, and test hardware for another astronomical spacecraft. It’s extremely difficult to design an instrument that can look at the super bright Sun and also super dim extra-galactic objects. STS-95 accomplished so many different astronomical tasks by including three separate astronomy payloads. Spartan 201 observed the Sun. The International Extreme ultraviolet Hitchhiker (IEH-3) set of payloads handled solar system, galactic, and extra-galactic astronomy. Finally HOST, the Hubble Orbital Systems Test, checked out hardware scheduled for installation aboard the Hubble Space Telescope on future servicing missions.
Spartan worked like a champ on STS-95. Astronauts Curt Brown, Steve Lindsey, Scott Parazynski, and Steve Robinson were responsible for its proper operation. The other members of the crew, Perdo Duque, Chiaki Mukai, and John Glenn, worked on their own tasks during Spartan's activities.
A year after STS-95 NASA put out a press release “HISTORIC GLENN MISSION HELPS EXPLAIN SOLAR MYSTERY." The scientists talked about how wonderful John Glenn was, mentioning his name twelve separate times during the press conference. Not mentioned was the other six members of the crew or any of the hundreds of scientists, engineers, and technicians who made the mission possible. I asked, “What did John Glenn do on the mission?" and one of the scientists responded, “He took the photos." I followed up, “Then why didn’t you mention Curt Brown, Steve Lindsey, Steve Robinson, or Scott Parazynski – the members of the crew who were responsible for operating Spartan?" – the response, “Oh, we love all of our astronauts." I was incredibly tempted to retort, “Name them." but didn’t.
After STS-95 Spartan 201 was donated to the Smithsonian. The shuttle program was concentrating all of its efforts on building and maintaining the International Space Station and there just wasn’t any space for any other payloads. A more advanced version of Spartan never made it off the drawing board. Eventually almost all of the Spartan webpages disappeared from NASA’s servers when they were declared ‘obsolete’.
Oh, and the black dots all over the spacecraft? They were part of a test to evaluate the Canadian Space Vision System (SVS). A computer would analyze video views of a spacecraft and calculate its orientation and position based on which calibration dots it could see. The SVS is a critical tool used by astronauts to assemble the International Space Station when they have to use the robot arms to manipulate space station modules into precise positions. And the bicycle reflectors are off-the-shelf bicycle reflectors so the astronauts can spot Spartan in the distance during their rendezvous.
Because the Udvar-Hazy annex is in a suburban area instead it gets about one sixth as many visitors as the main museum on the Washington Mall surrounded by other museums and tourist attractions. But it’s worth a visit.
Links
An official Spartan 201 web page as part of the SOHO project.
Author Philip Chien’s page on Kalpana Chawla including her comments on the Spartan 201-4 incident.
The Udvar-Hazy annex to the National Air and Space Museum.
An introduction to the UVCS instrument (primarily describing the version on the SOHO spacecraft).
A technical paper on UVCS monitoring of solar wind.
A fact sheet on plans for future versions of Spartan which never flew.
About the author
Author Philip Chien followed the space program for over two decades, including all five of Spartan 201’s missions.
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