Parker Solar Probe continues to bring its instruments and secondary systems online — slightly ahead of schedule — as it speeds away from Earth.
On Friday, Aug. 31, flight controllers at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland performed a second planned Trajectory Correction Maneuver (TCM-2), a thruster burn which lasted for 35.2 seconds. This maneuver, which was executed with a high degree of precision, adjusted the direction of the spacecraft to position it for its Venus flyby on Oct. 3, when it will use Venus’ gravity to shed speed and draw its orbit closer to the Sun in preparation for its first solar approach.
On Sept. 2, four two-meter electric field antennas, part of the FIELDS instrument suite, were deployed. These antennas (as well as a fifth, which is mounted on the long boom at the other end of Parker Solar Probe) need to be extended away from the spacecraft to accurately measure the electric fields of the corona. These four antennas are not protected by Parker Solar Probe’s Thermal Protection System, or heat shield, so they are made of niobium C-103, a high-temperature alloy that can withstand the intense solar heat.
An artist’s concept of Parker Solar Probe in space. The FIELDS antennas extend out from behind the heat shield, and the Solar Probe Cup is visible on the right. Credit: NASA/JHUAPL
Just a few hours after the FIELDS antennas were deployed, the Solar Wind Electrons Alphas and Protons (SWEAP) investigation team successfully opened the covers of two instruments, the Solar Probe Analyzer (SPAN) instruments. The SPAN instruments are used to measure the solar wind when it is coming in at an angle relative to the spacecraft.
Before opening the SPAN instrument doors, the team ramped up high voltages on the Solar Probe Cup (SPC) instrument, also part of SWEAP. Solar Probe Cup measures the thermal solar wind plasma flowing radially from the Sun — requiring this instrument to be mounted outside the heat shield and pointed directly at the Sun. Like the FIELDS antennas, Solar Probe Cup’s heat shield is constructed of niobium C-103.
Other systems and instruments have completed checkouts as well. The spacecraft’s high gain antenna — which will be used to send high-rate science data to Earth — has been moved through its full range of motion.
EPI-Lo and EPI-Hi, the two Energetic Particle Instruments that make up the IS☉IS suite (pronounced “ee-sis” and short for Integrated Science Investigation of the Sun), have been turned on and have completed low voltage checks.
The Wide-field Imager for Solar Probe (WISPR) instrument has been turned on and has taken closed-door test images to calibrate the systems and imagers.
“The spacecraft continues to perform as designed, and thanks to the team’s careful planning and execution, we’re commissioning instruments slightly ahead of schedule,” said APL’s Andy Driesman, Parker Solar Probe project manager.
“The science team is excited to begin the investigation phase of the mission,” said Nour Raouafi of APL, Parker Solar Probe project scientist. “We’re looking forward to seeing this initial science data and getting our first look at what we know will be many discoveries that Parker Solar Probe will make.”
As of 12 p.m. EDT on Sept. 4, Parker Solar Probe was more than 15 million miles from Earth, travelling at about 44,700 miles per hour (72,000 kilometers per hour).
Editor’s note: The original version of this post misstated the length of the TCM-2 thruster burn. This version has been updated with the correct figure.
At 6:07 a.m. EDT on Aug. 20, 2018, NASA’s Parker Solar Probe successfully completed its first trajectory correction maneuver (known as TCM-1), achieving a near-perfect firing of its propulsion system and putting the spacecraft on course to “touch” the Sun. This maneuver sets up the orbital geometry that will allow Parker Solar Probe to come within about 3.83 million miles (8.86 solar radii) of the Sun’s surface on its closest approach in 2024.
Following launch at 3:31 a.m. EDT on Aug. 12, the spacecraft control team at the Johns Hopkins Applied Physics Laboratory, or APL, in Laurel, Maryland, analyzed Parker Solar Probe’s position and quickly developed a re-optimized trajectory to place it in the best path for the seven Venus gravity assist maneuvers and 24 solar orbits that the mission will make. Re-assessing a spacecraft’s trajectory after launch is a normal step, as the mission team is then able to accurately track the spacecraft’s actual speed, direction and position to create a more precise trajectory plan.
The United Launch Alliance Delta IV Heavy rocket launches NASA’s Parker Solar Probe to touch the Sun, Sunday, Aug. 12, 2018 from Launch Complex 37 at Cape Canaveral Air Force Station, Florida. Credit: NASA/Bill Ingalls
Spacecraft controllers at the mission operation center initiated the two-part TCM-1 beginning at 6:00 a.m. EDT on Aug. 19 with a 44-second burn of the engines. The majority of the engine firing, which lasted just over seven minutes, began at 6:00 a.m. EDT on Aug. 20.
“TCM-1 is one of the critical events of the mission and a major mission milestone,” said Parker Solar Probe mission design and navigation manager Yanping Guo, from APL. “In the future, we only need to fine-tune the trajectory periodically, and no major adjustments or large maneuvers will be required unless something unusual happens. In short: We are on our way to touch the Sun!”
“The team completely nailed this maneuver,” said APL’s Andy Driesman, Parker Solar Probe project manager. “Execution of the burn was exceptional, measuring at less than 0.2 percent magnitude error—which translates to a 0.3 standard deviation, or sigma, from optimal. We had defined success for TCM-1 as up to 3 sigma, which really illustrates how phenomenally this was executed.”
As of 12:00 p.m. EDT on August 20, Parker Solar Probe was 5.5 million miles from Earth, travelling at 39,500 miles per hour.
NASA and its mission partners have analyzed and approved an extended launch window for Parker Solar Probe until Aug. 23, 2018 (previously Aug. 19). The spacecraft is scheduled to launch no earlier than Aug. 11, 2018, at 3:48 a.m. with a window of 45 minutes.
Parker Solar Probe will launch from Space Launch Complex 37 on Cape Canaveral Air Force Station in Florida aboard on a United Launch Alliance Delta IV Heavy rocket.
NASA’s Parker Solar Probe has cleared the final procedures in the clean room before its move to the launch pad, where it will be integrated onto its launch vehicle, a United Launch Alliance Delta IV Heavy.
Parker Solar Probe was encapsulated within its fairing on July 16, 2018, in preparation for its move to Space Launch Complex 37. Credit: NASA/Johns Hopkins APL/Ed Whitman
On July 11, 2018, the spacecraft was lifted and mated to the third stage rocket motor, a Star 48BV from Northrop Grumman. In addition to using the largest operational launch vehicle, the Delta IV Heavy, Parker Solar Probe will use a third stage rocket to gain the speed needed to reach the Sun, which takes 55 times more energy than reaching Mars.
Parker Solar Probe is lifted and lowered toward the third-stage rocket motor. Credit: NASA/Johns Hopkins APL/Ed Whitman
On July 16, the spacecraft was encapsulated within its 62.7-foot fairing in preparation for the move from Astrotech Space Operations in Titusville, Florida, to Space Launch Complex 37 on Cape Canaveral Air Force Station, where it will be integrated onto the Delta IV Heavy. Parker Solar Probe’s launch is targeted for Aug. 11, 2018.
Parker Solar Probe sits inside half of its fairing. Credit: NASA/Johns Hopkins APL/Ed Whitman
Members of the Parker Solar Probe team examine and align one of the spacecraft’s two solar arrays on May 31, 2018. Credit: NASA/Johns Hopkins APL/Ed Whitman
NASA’s Parker Solar Probe depends on the Sun, not just as an object of scientific investigation, but also for the power that drives its instruments and systems. On Thursday, May 31, 2018, the spacecraft’s solar arrays were installed and tested. These arrays will power all of the spacecraft’s systems, including the suites of scientific instruments studying the solar wind and the Sun’s corona as well as the Solar Array Cooling System (SACS) that will protect the arrays from the extreme heat at the Sun.
After installation of the solar arrays on May 31, 2018, Parker Solar Probe team members use a laser to illuminate the solar cells and verify that they can create electricity and transfer it to the spacecraft. Credit: NASA/Johns Hopkins APL/Ed Whitman
“Unlike solar-powered missions that operate far from the Sun and are focused only on generating power from it, we need to manage the power generated along with the substantial heat that comes from being so close to the Sun,” said Andy Driesman, project manager from the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland. “When we’re out around the orbit of Venus, we fully extend the arrays to get the power we need. But when we’re near the Sun, we tuck the arrays back until only a small wing is exposed, and that portion is enough to provide needed electrical power.”
Parker Solar Probe’s two solar arrays – one of which is shown here on the spacecraft – were installed on the spacecraft on May 31, 2018. Credit: NASA/Johns Hopkins APL/Ed Whitman
The solar arrays are cooled by a gallon of water that circulates through tubes in the arrays and into large radiators at the top of the spacecraft. They are just over three and a half feet (1.12 meters) long and nearly two and a half feet (0.69 meters) wide. Mounted on motorized arms, the arrays will retract almost all of their surface behind the Thermal Protection System – the heat shield – when the spacecraft is close to the Sun. The solar array installation marks some of the final preparation and testing of Parker Solar Probe leading up to the mission’s July 31 launch date.
A memory card containing 1,137,202 names submitted by the public to travel to the Sun was installed on Parker Solar Probe on May 18, 2018. Credit: NASA/Johns Hopkins APL/Ed Whitman
Throughout its seven-year mission, NASA’s Parker Solar Probe will swoop through the Sun’s atmosphere 24 times, getting closer to our star than any spacecraft has gone before. The spacecraft will carry more than scientific instruments on this historic journey — it will also hold more than 1.1 million names submitted by the public to go to the Sun.
“Parker Solar Probe is going to revolutionize our understanding of the Sun, the only star we can study up close,” said Nicola Fox, project scientist for Parker Solar Probe at the Johns Hopkins Applied Physics Lab in Laurel, Maryland. “It’s fitting that as the mission undertakes one of the most extreme journeys of exploration ever tackled by a human-made object, the spacecraft will also carry along the names of so many people who are cheering it on its way.”
NASA’s Parker Solar Probe gets its power from the Sun, so the solar arrays that collect energy from our star need to be in perfect working order. This month, members of the mission team tested the arrays at Astrotech Space Operations in Titusville, Florida, to ensure the system performs as designed and provides power to the spacecraft during its historic mission to the Sun.
Andrew Gerger of the Johns Hopkins Applied Physics Laboratory inspects one of NASA’s Parker Solar Probe’s two solar panels by passing current through the array, which causes it to glow red and allows him to examine each individual solar cell. The testing occurred on May 2, 2018, at Astrotech Space Operations in Titusville, Florida. Credit: NASA/Johns Hopkins APL/Ed WhitmanAndrew Gerger of the Johns Hopkins Applied Physics Laboratory and Rick Stall of Newforge Technologies check and adjust a purple laser using a replica of a solar array wing on May 3, 2018. Later, when the solar arrays are attached to the spacecraft, the laser will be used to illuminate each string of cells on the array to confirm the string is connected and will provide power to the spacecraft. Credit: NASA/Johns Hopkins APL/Ed Whitman
Parker Solar Probe is powered by two solar arrays, totaling just under 17 square feet (1.55 square meters) in area. They are mounted to motorized arms that will retract almost all of their surface behind the Thermal Protection System – the heat shield – when the spacecraft is close to the Sun.
Andrew Gerger, an engineer from the Johns Hopkins Applied Physics Laboratory, prepares to conduct an inspection of one of the solar arrays from NASA’s Parker Solar Probe on May 2, 2018, at Astrotech Space Operations in Titusville, Florida. Credit: NASA/Johns Hopkins APL/Ed WhitmanNASA’s Parker Solar Probe is powered by two solar arrays, shown here on May 2, 2018, at Astrotech Space Operations in Titusville, Florida. Credit: NASA/Johns Hopkins APL/Ed Whitman
You don’t get to swim in the Sun’s atmosphere unless you can prove you belong there. And Parker Solar Probe’s Faraday cup, a key sensor on the spacecraft, earned its stripes on April 19 by enduring testing in a homemade contraption designed to simulate the Sun.
The cup will scoop up and examine the solar wind as the probe passes closer to the Sun than any previous human-made object. In order to confirm the cup will survive the extreme heat and light of the Sun’s corona, researchers previously tortured a model of the Faraday cup at temperatures exceeding 3,000 degrees Fahrenheit, courtesy of the Oak Ridge National Laboratory’s Plasma Arc Lamp. The cup, built from refractory metals and sapphire crystal insulators, exceeded expectations.
But the final test took place on April 19, in a homemade contraption Kasper and his research team call the Solar Environment Simulator. While being blasted with roughly 10 kilowatts of light on its surface—enough to heat a sheet of metal to 1,800 degrees Fahrenheit in seconds—the Faraday cup model ran through its paces, successfully scanning a simulated stream of solar wind.
Justin Kasper, University of Michigan associate professor of climate and space sciences and engineering, is principal investigator for Parker Solar Probe’s Solar Wind Electrons Alphas and Protons (SWEAP) investigation.
NASA’s Parker Solar Probe will carry 1,137,202 submitted and confirmed names on its journey to the Sun. Submissions opened on March 6, 2018, and closed on April 27 at 11:59 p.m. EDT. A chip containing the names will be installed onto the spacecraft before launch.
Participants received a certificate after they confirmed their submission.