A Day Late ... NASA's TRACERS mission is getting started

You might have heard about the strange issue near Vandenberg Space Force Base on Tuesday, that caused the delay not just the SpaceX rideshare mission carrying the TRACERS mission, but the complete shutdown of air traffic off the coast of southern California.  Afterwards, the FAA issued the following statement.

“A regional power outage in the Santa Barbara area disrupted telecommunications at the Los Angeles Air Route Traffic Control Center, which manages air traffic over the Pacific Ocean,” an FAA spokesperson said in a statement. “As a result, the FAA postponed the SpaceX Falcon 9 TRACERS launch on Tuesday, July 22. The FAA took this action to ensure the safety of the traveling public.”  

Since the launch window was closed for the day, everyone agreed to try again on Wednesday, July 23.  The launch was by the book, including recovering the booster and deploying the payloads.  

The $170 million mission TRACERS mission is to better study a phenomenon of space weather that has eluded researchers since the dawn of the Space Age. 

The twin spacecraft are part of the NASA-funded TRACERS mission, which will spend at least a year measuring plasma conditions in narrow regions of Earth's magnetic field known as polar cusps. As the name suggests, these regions are located over the poles. They play an important but poorly understood role in creating colorful auroras as plasma streaming out from the Sun interacts with the magnetic field surrounding Earth.

The same process drives geomagnetic storms capable of disrupting GPS navigation, radio communications, electrical grids, and satellite operations. These outbursts are usually triggered by solar flares or coronal mass ejections that send blobs of plasma out into the Solar System. If one of these flows happens to be aimed at Earth, we are treated with auroras but vulnerable to the storm's harmful effects.  

The Solar Storms of May 2024 were the strongest Geomagnetic storms of not just Cycle 25, but the strongest since 1989.  Storms like this may offer beautiful aurora displays or cause radio conditions entertaining to those of us who play in the VHF ham bands, but they also can cause damages that cost real money.  Lots of money.  The May storms degraded GPS navigation signals, resulting in more than $500 million in economic losses in the agriculture sector as farms temporarily suspended spring planting.  That isn't even scratching the surface of the damages and costs.  Remember that this has been going on for as long as the Earth and Sun have been here. 

TRACERS, short for Tandem Reconnection and Cusp Electrodynamics Reconnaissance Satellites, will study a process known as magnetic reconnection. As particles in the solar wind head out into the Solar System at up to 1 million mph, they bring along pieces of the Sun's magnetic field. When the solar wind reaches our neighborhood, it begins interacting with Earth's magnetic field.

The high-energy collision breaks and reconnects magnetic field lines, flinging solar wind particles across Earth's magnetosphere at speeds that can approach the speed of light. Earth's field draws some of these particles into the polar cusps, down toward the upper atmosphere. This is what creates dazzling auroral light shows and potentially damaging geomagnetic storms.

The problem is that nobody understands how these storms work.  That's a big part of why there are two satellites that are precisely spaced with respect to each other.  

That's because magnetic reconnection is a dynamic process, and a single satellite would provide just a snapshot of conditions over the polar cusps every 90 minutes. By the time the satellite comes back around on another orbit, conditions will have changed, but scientists wouldn't know how or why, according to David Miles, principal investigator for the TRACERS mission at the University of Iowa.

"You can't tell, is that because the system itself is changing?" Miles said. "Is that because this magnetic reconnection, the coupling process, is moving around? Is it turning on and off, and if it's turning on and off, how quickly can it do it? Those are fundamental things that we need to understand... how the solar wind arriving at the Earth does or doesn't transfer energy to the Earth system, which has this downstream effect of space weather." 

This is why the tandem part of the TRACERS name is important.  The novel part of this mission is that it features two identical spacecraft, each about the size of a washing machine flying at an altitude of 367 miles (590 kilometers). Over the next few weeks, the TRACERS satellites will drift into a formation with one trailing the other by about two minutes as they zip around the world at nearly five miles per second. This positioning will allow the satellites to sample the polar cusps one right after the other, instead of forcing scientists to wait another 90 minutes for a data refresh.

With TRACERS, scientists hope to pick apart smaller, fast-moving changes with each satellite pass. Within a year, TRACERS should collect 3,000 measurements of magnetic reconnections, a sample size large enough to start identifying why some space weather events evolve differently than others.

One of the two TRACERS satellites undergoes launch preparations at Millennium Space Systems, the spacecraft's manufacturer.  Image Credit: Millennium Space Systems

There is broader knowledge to be gained with TRACERS.  Magnetic reconnection is ubiquitous throughout the Universe, and the same physical processes produce solar flares and coronal mass ejections from the Sun.