January 22, 2022


Through Education Matters

Wind: Discoveries and Impacts of a Venerable Spacecraft


The Wind spacecraft, introduced on 1 November 1994, is a vital ingredient in NASA’s Heliophysics Procedure Observatory (HSO) – a fleet of spacecrafts developed to understand the dynamics of the Sun‐Earth process. The mix of its longevity, its varied enhance of instrumentation, and high resolution and accurate measurements has led to it getting the “standard candle” of photo voltaic wind measurements. A modern report released in Assessments of Geophysics describes the contributions of Wind to heliophysics and astrophysics. We asked the direct author what Wind has been accomplishing for the past 25 many years and what the upcoming may keep.

What was the initial drive at the rear of launching the Wind spacecraft in November 1994?

A poster celebrating Wind‘s 1994 launch. Credit: NASA (Community Domain)

Wind was intended and launched as aspect of the stand-by itself World wide Geospace Science (GGS) plan, a subset of the Global Solar Terrestrial Physics (ISTP) software.

The ISTP system was an intercontinental collaboration that included the Japanese Geotail spacecraft, the European four-spacecraft Cluster mission and SoHO spacecraft, the 4 Russian Interball spacecraft, and the two GGS spacecraft, Wind and Polar.

The targets for Wind had been to look into primary plasma procedures in the around-Earth solar wind and magnetosphere and to deliver baseline, in the vicinity of-Earth solar wind observations for internal and outer heliospheric missions.

This mission was 1 of the initial, coordinated attempts to greater understand the Sun-Earth connection and the close to-Earth room ecosystem.  This all has been lumped into the broader time period “space temperature.”

Wind is also a single of the very first missions (if not the initially) that flew a Russian instrument, which came at the close of the Chilly War. The scientific scientific studies enabled by Wind have progressed above time owing to its longevity and range of instruments and range of space environments explored.

How is Wind distinct from other heliophysics missions?

There are various matters that make Wind exceptional to almost all NASA missions, not just heliophysics missions. For instance, the diversity of environments explored in the around-Earth room has nonetheless to be recurring by any solitary mission. Wind created at minimum 11 lunar flybys such as via the lunar wake. Wind built massive, east-west prograde orbital loops to a number of hundred Earth radii from Earth. Wind explored the second Earth-Sun Lagrange position, close to 235 Earth radii powering Earth together the Earth-Solar line. Wind manufactured about 67 petal-shaped (i.e., very elliptical) orbits as a result of Earth’s magnetosphere. All of these ended up executed prior to June 2004, immediately after which Wind was positioned in its remaining orbital site at the first Earth-Sunlight Lagrange place. Wind also has an unusually wide and redundant established of instrument suites. Wind is also the 2nd oldest NASA Heliophysics mission in procedure, but contrary to lots of other missions effectively earlier their layout life time, Wind is even now thoroughly operational.

What instruments are on board and what forms of information have they been gathering?

Wind has an unusually wide array of instrumentation compared to most other NASA missions still functioning. Numerous devices measure the lower energy, thermal particles permitting for redundancy to cross-calibrate each and every instrument. Wind also actions electrical and magnetic fields from quasi-static all the way up to radio frequencies. Wind can evaluate energetic particles up to close to 50 megaelectron volts for each nucleon and distinguish ion species from hydrogen to uranium which include carbon, nitrogen, oxygen, neon, silicon, sulfur, iron, argon, and so on. Wind also had two gamma ray instruments, one particular however working that was delivered by Russia. So, Wind can measure particles from a several electron volts to tens of megaelectron volts, electromagnetic fields from about Hz to 13 MHz, and gamma rays with energies up to about 15 megaelectron volts. (For context, a regular blue photon would have an electrical power of about 3 electron volts, which is about 5 million situations much less power for each photon.) Note that 1 electron volt is the energy attained by an electron remaining accelerated by a 1 volt electrical prospective.

A 2D histogram representation of 25+ years of Wind observations.
A 2D histogram representation of 25+ several years of Wind observations. Credit: Wilson et al. [2021], Figure 2

How have the contributions of Wind superior the fields of heliophysics and astrophysics?

Wind data have led to paradigm shifting outcomes in studies of statistical solar wind developments, magnetic reconnection, huge-scale solar wind structures, kinetic physics, electromagnetic turbulence, the Van Allen radiation belts, coronal mass ejection topology, interplanetary and interstellar dust, the lunar wake, solar radio bursts, solar energetic particles, and intense astrophysical phenomena this kind of as gamma-ray bursts and magnetars.

The effects of Wind’s info on science is mirrored in the a lot more than 5,810 refereed publications from start to the conclusion of 2020, which have been given a lot more than 156,880 citations. So, whilst Wind is now 26 a long time old, it is nevertheless producing new discoveries, even now applied as a calibration baseline for other missions, and is still advancing the industry of heliophysics.

What is the Wind mission very best recognized for?

This would rely upon with whom you communicate. The magnetospheric neighborhood regard Wind as the upstream monitor, i.e., the spacecraft that informs them of what the photo voltaic wind is undertaking. A solar wind researcher may perhaps glance at Wind as a terrific mission to look into huge-scale, transient magnetic structures like interplanetary coronal mass ejections or as 1 of the ideal missions for investigating compact-scale, kinetic phenomena like plasma instabilities. A photo voltaic physicist will look to Wind for its very correct and trusted distant-sensing radio instrumentation to examine photo voltaic radio bursts or to its gamma ray instruments to investigate solar flares. Planetary and photo voltaic system researchers may perhaps look to Wind for its big statistical dataset of micron-sized dust impact measurements. This dataset contains the two interplanetary and interstellar dust. Astrophysicists rely upon Wind for detecting gamma ray bursts and smooth gamma ray repeaters (magnetars). Wind is really exclusive for a wide array of factors to several fields of examine.

After a quarter of century in flight, how a lot for a longer period is the Wind mission expected to proceed? What is the foreseeable future probable of Wind?

Just after 25 yrs, Wind is by no suggests done. The spacecraft nevertheless has adequate gas for more than 50 extra yrs of flight and all instruments continue to be nominal. Wind‘s solar arrays can supply adequate electric power for at minimum 20 more many years with the latest intake costs. There are numerous mitigation strategies to increase this even more, if required. Thus, it is totally envisioned that Wind will dwell to at the very least 40 years of age barring any unpredicted mechanical failure of issues like thrusters or magnetic tape drives.

Wind is now a significant collaborator with the more recent missions these types of as the Magnetospheric Multiscale (MMS), Parker Solar Probe, and the European Solar Orbiter missions. It continues to make novel discoveries, the team is doing the job to release new details goods for community usage and publish scientific results. In truth, Wind had 11 publications in Character journals in 2020 on your own, and there are at minimum four more Character and two Science papers presently in 2021 as of March.

A picture of Wind being cleaned.
Wind staying cleaned in advance of start. Credit history: NASA  (General public Area)

―Lynn B. Wilson III ([email protected], ORCID logo 0000-0002-4313-1970) Heliophysics Science Division, NASA Goddard Place Flight Center, United states of america