Many in our Boundary County / Pacific Northwest region are aware that space experts are closely monitoring a spent rocket booster stage that is wobbling out of its current orbit and will soon be falling back to earth in an uncontrolled reentry.

This rocket stage is huge.  With its height about the same as a 16-story building, and weight of about 25 tons, it is the sixth largest space equipment object to ever reenter.

When will it reenter the atmosphere and crash back to earth?  The experts’ latest calculations say:  Tomorrow.  That would be tomorrow, Saturday, July 30.  And they even have a time for you:  the current projection is for reentry to occur at 11:05 am Boundary County time, plus or minus five hours.

All of this information is provided by the experts at the Center for Orbital and Reentry Debris Studies (CORDS), which is a division of The Aerospace Corporation, a federally-funded nonprofit research and development center that focuses exclusively on the enterprises of space, and spans all disciplines of space-related science and engineering.

Keep in mind that because of the uncontrolled nature of this reentry, the estimates of the time, and location, of reentry are continuously changing—but gradually becoming more refined—over time.  This uncontrolled reentry does not have a defined and clearly predictable reentry path.  However, using the data available, the experts at CORDS are able to make some very useful predictions, and some pathway calculations, which they are constantly fine tuning with new data and observations.

Getting to the questions that are foremost in everyone’s thinking:

• Where will reentry occur?

• Will there be dangerous space debris crashing to earth with this reentry?

• How did this happen?

ANSWERING THE FIRST QUESTION:  Where will reentry occur?

To answer the first question, thanks to the experts at CORDS and The Aerospace Corporation, we can safely say that reentry will most likely not occur over Boundary County, nor over the Pacific Northwest, for that matter.

CORDS has calculated an entry window for this rocket stage.  The window as it is currently calculated is in the shape of a belt that wraps around the central and southern surfaces of the earth.  This is a wavy belt shape.  The following chart gives a visual idea of where the reentry point could occur.  See the text below the picture for more of an explanation.

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At this time, according to the most recent data provided by CORDS, the falling rocket stage could reenter at any point along the yellow or blue waving lines drawn on this map of the world.  The orange circle with the yellow text attached to it simply marks the center spot of this predicted reentry pathway.  Note that the dark / light areas of the map with the white line border show what parts of the earth will be in daylight or nighttime at the projected time of reentry.

CORDS says that reentry is NOT expected to occur at a point outside of the marked blue or yellow paths.  Thus, as one can observe on the map graphic, our area and the rest of the Pacific Northwest is not expected to be endangered directly by this uncontrolled reentry.  Unfortunately, many populated land areas of the world are directly within the projected reentry pathway.

As mentioned above, as the time of reentry draws closer, the expected pathway of reentry can gradually be more clearly defined.  This can be illustrated by comparing (below) the chart released yesterday with yesterday’s predictions for the projected reentry pathway, with the more highly refined and precise projected pathway that was released today, showing the projections honed to a more specific path.

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One can see that over time, since yesterday, the potential path for reentry of this renegade rocket stage has been been trimmed substantially.  As hours pass, CORDS will be able to increasingly pinpoint the most likely reentry areas.

ANSWERING THE SECOND QUESTION:  Will there be dangerous space debris crashing to earth with this reentry?

The short answer is:  Most likely, yes.  We all know that when objects enter earth’s atmosphere, most of the time those objects burn up.  However, with very large objects, like this 25-ton rocket stage, its massive size is too large for the object to completely burn up on passing through the atmosphere.

According to Space Debris expert Marlon Sorge, a technical fellow for the Space Innovation Directorate of The Aerospace Corporation, “The general rule of thumb is that 20–40% of the mass of a large object will reach the ground, but the exact number depends on the design of the object. In this case, we would expect about five to nine metric tons.”

We will do the math for you.  Five to nine metric tons is equal to about 5.5 to 9.9 regular tons.

Where will these tons of debris strike?  They can’t exactly say.  According to the CORDS experts:  “The spread of debris, referred to as the “debris footprint,” is not something experts can speculate on at this time, given the degree of uncertainty remaining for the reentry point. However, any spot away from the lines [on the chart above] are very unlikely to be at risk from debris.”

Calling your attention to the last sentence of that quotation just given, our area is also very unlikely, based upon these calculations, to see any of the debris from the breaking and burning of the rocket stage on its uncontrolled reentry.  However, again many populated areas of the world are within the area at higher risk for those 5.5 to 9.9 tons of debris to fall, according to the chart above.

ANSWERING THE FINAL, THIRD QUESTION:  How did this happen?

The rocket stage that is now in uncontrolled reentry to earth is a stage from a Chinese launch that occurred less than a week ago, last Sunday, July 24.  China is currently working on a longterm process of assembling an orbiting space station, the Tiangong Space Station.

Last Sunday, as part of their space station program, China launched one of their Long March 5B rockets to deliver the Wentian experiment module to their space station.  “The Long March 5B reentry is unusual,” according to the experts at CORDS, “because during launch, the first stage of the rocket reached orbital velocity instead of falling downrange as is common practice. The empty rocket body is now in an elliptical orbit around Earth where it is being dragged toward an uncontrolled reentry.”

This is not the first time an uncontrolled reentry crash has resulted from China’s space station assembly program.  On April 29, 2021, when China launched the first module of their Tiangong space station, again using a Long March 5B rocket, that rocket body also traveled into orbit instead of falling downrange into the sea, a situation almost exactly like we have today.  That rocket stage back in April 2021 also ended up in an uncontrolled reentry.  According to CORDS, “[The uncontrolled 2021] rocket’s path crossed several populated areas and captured the world’s attention before eventually landing in the Indian Ocean near the Maldives on May 8.”

Today, we now deal with the crashing reentry of China’s booster rocket for the second module of its under-construction space station.

We are fortunate that our region appears at this point to be safe from the reentry of the falling rocket stage, and from tons of crashing debris.  However other areas of the world remain in potential danger.  According to The Aerospace Corporation and their CORDS division, we should know the results of this uncontrolled large rocket stage reentry within the next 24 hours or so.