Rocket possible collision with Moon

  • #1


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Science Advisor
SpaceX launched its first interplanetary mission nearly seven years ago. After the Falcon 9 rocket's second stage completed a long burn to reach a transfer orbit, NOAA's Deep Space Climate Observatory began its journey to a Sun-Earth LaGrange point more than 1 million km from the Earth.

By that point, the Falcon 9 rocket's second stage was high enough that it did not have enough fuel to return to Earth's atmosphere. It also lacked the energy to escape the gravity of the Earth-Moon system, so it has been following a somewhat chaotic orbit since February 2015.

Now, according to sky observers, the spent second stage's orbit is on course to intersect with the Moon. According to Bill Gray, who writes the widely used Project Pluto software to track near-Earth objects, asteroids, minor planets, and comets, such an impact could come in March.

This information is important because it will allow satellites presently orbiting the Moon, including NASA's Lunar Reconnaissance Orbiter and India's Chandrayaan-2 spacecraft , to collect observations about the impact crater. With the LCROSS mission, NASA deliberately impacted a spent rocket upper stage into the Moon in 2009 for this purpose. Although scientists are most keen to understand the presence of ice at the lunar poles, being able to observe the subsurface material ejected by the Falcon 9 rocket's strike could still provide some valuable data.

The dry mass of the Falcon 9's second stage is about 4 metric tons, and it should impact the Moon at a velocity of about 2.58 km/s.
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Answers and Replies

  • #2
I'm curious if an impact would be visible from Earth with a small telescope. Assuming it impacts the near side, that is.
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  • #3
It's probably a Chinese rocket stage.
A Falcon 9 booster was plausible when the object was first discovered and no one spent more time on it because it was just a random rocket booster on an uneventful trajectory. Once it got more attention people studied the origin better, and a Chinese rocket fits much better to the initial trajectory.

The impact will be on the far side.
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  • #4
and a Chinese rocket fits much better to the initial trajectory.
The rocket is now said to be 2014-065B, the booster for the Chang'e 5-T1, launched in 2014 as part of the Chinese space agency's lunar exploration program.

The surprise announcement was made by astronomer Bill Gray, who first identified the future impact, and admitted his mistake last weekend.

"This (honest mistake) just emphasizes the problem with lack of proper tracking of these deep space objects," tweeted astronomer Jonathan McDowell, who advocates for greater regulation of space waste.
So where will SpaceX's booster be going?
  • #6
So where will SpaceX's booster be going?
The better question would be who is responsible for tracking such objects? My guess is nobody.
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  • #7
The better question would be who is responsible for tracking such objects? My guess is nobody.
Somebody is monitoring space debris. I've seen plots of the defunct satellites, boosters and pieces of debris in LEO, and perhaps out to NEO.
More than 27,000 pieces of orbital debris, or “space junk,” are tracked by the Department of Defense’s global Space Surveillance Network (SSN) sensors. Much more debris -- too small to be tracked, but large enough to threaten human spaceflight and robotic missions -- exists in the near-Earth space environment. Since both the debris and spacecraft are traveling at extremely high speeds (approximately 15,700 mph in low Earth orbit), an impact of even a tiny piece of orbital debris with a spacecraft could create big problems.

Tracking Debris

The Department of Defense maintains a highly accurate satellite catalog on objects in Earth orbit. Most of the cataloged objects are larger than a softball (approximately 10 centimeters).

NASA and the DoD cooperate and share responsibilities for characterizing the satellite (including orbital debris) environment. DoD’s Space Surveillance Network tracks discrete objects as small as 2 inches (5 centimeters) in diameter in low-Earth orbit and about 1 yard (1 meter) in geosynchronous orbit. Currently, about 27,000 officially cataloged objects are still in orbit and most of them are 10 cm and larger. Using special ground-based sensors and inspections of returned satellite surfaces, NASA statistically determines the extent of the population for objects less than 4 inches (10 centimeters) in diameter.

Collision risks are divided into three categories depending upon size of threat. For objects 4 inches (10 centimeters) and larger, conjunction assessments and collision avoidance maneuvers are effective in countering objects which can be tracked by the Space Surveillance Network. Objects smaller than this usually are too small to track for conjunction assessments and collision avoidance. Debris shields can be effective in withstanding impacts of particles smaller than half an inch (1 centimeter) for the U.S. modules on the International Space Station.

ESA has its own program -
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  • #8
I know that we track Earth object objects and debris, I meant deep space objects.
  • #9
deep space objects.
How deep? There are limits to ground-based telescopes. One would need a space-based telescope to look say out to Jupiter's orbit and beyond.

Between the sun and the asteroid belt, there is a NASA program to look for asteroids and objects orbiting the sun and crossing Earth's orbit.

The new system improves the capabilities of NASA JPL’s Center for Near Earth Object Studies to assess the impact risk of asteroids that can come close to our planet.

To date, nearly 28,000 near-Earth asteroids (NEAs) have been found by survey telescopes that continually scan the night sky, adding new discoveries at a rate of about 3,000 per year. But as larger and more advanced survey telescopes turbocharge the search over the next few years, a rapid uptick in discoveries is expected. In anticipation of this increase, NASA astronomers have developed a next-generation impact monitoring algorithm called Sentry-II to better evaluate NEA impact probabilities.
Dec. 6, 2021 -

Astronomers spotted one of two new Oort cloud objects in August 2013 using Pan-STARRS1, a telescope on Maui designed to survey the sky for potentially dangerous asteroids.

IfA’s Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) atop Haleakalā currently finds nearly as many NEOs and PHAs as the rest of the world’s observatories combined, and nearly 60% of the largest and most dangerous ones with sizes greater than 140 meters across (459 feet).
5 years ago -
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  • #10
So where will SpaceX's booster be going?
It's likely in a heliocentric orbit now, somewhere among the trillions of similarly-sized asteroids. Even if it's still in some sort of Earth orbit it's not an issue in any way. No one is actively tracking all interplanetary spent rocket stages. The situation is different in lower Earth orbits where you have relevant collision risks.
  • #11
China says moonbound rocket stage was not from 2014 lunar mission: report
"According to China's monitoring, the upper stage of the rocket related to the Chang'e-5 mission entered into Earth's atmosphere and completely burned up,” foreign ministry spokesperson Wang Wenbin said Monday (Feb. 21) on a Chinese government website, first spotted by SpaceNews.

Wang was referring to a test mission known as Chang'e-5-T1, a precursor to the more famous Chang'e 5 mission that brought a sample of the moon back to Earth in December 2020. Adding credence to the Chinese claim is tracking data from the U.S. Space Force's 18th Space Control Squadron showing that the Chinese rocket stage indeed re-entered the atmosphere in October 2015, SpaceNews said.
  • #12
Hi, this is a relevant link, interesting info on junk tracking included.

"U.S. Space Force data suggest a fiery re-entry about 1 year after the 2014 launch, but Daniel Adamo, an astrodynamicist working with McDowell, says this is only an estimate based on the rocket’s initial launch trajectory. The Chinese booster remains the best candidate for the upcoming lunar impactor, he adds."

It does look like some objects of interest are still being tracked. :)
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  • #13
I removed "SpaceX" from the title. Chinese rocket stage or not, the title was simply outdated.
  • #14
Wondering... with "Space Junk" in Low Earth Orbit getting all the attention lately, is anyone looking into salvaging materials?
Self editing for clarity: (sorry) I'm referencing salvaging Lunar Junk, not LEO Junk.
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  • #15
Wondering... with "Space Junk" in Low Earth Orbit getting all the attention lately, is anyone looking into salvaging materials?
Self editing for clarity: (sorry) I'm referencing salvaging Lunar Junk, not LEO Junk.
Somehow I think the transportation costs would exceed the scrap value... unless you can sell the stuff as Historical Artifacts!

Hmm, on second thought maybe not. The only ones that could pay the shipping price are those that put the stuff there in the first place.

Oh Well.

  • #17
Hi Tom,
After reading the Nature article I began wondering about the Lunar debris problem, in particular how long it would take before it was addressed in some form other than as a "talking point".

It seems to me that Humans have a very poor track record when it comes to anticipating certain obvious problems, like space junk etc.
We get: Willy Ley predicted in 1960 that "In time, a number of such accidentally too-lucky shots will accumulate in space and will have to be removed when the era of manned space flight arrives".
That seems fairly prophetic. (I don't put much faith in prophecy but a little extrapolation never hurt anyone)
At least there was an ample "Heads Up" warning, it just took a few decades as well as a few ASAT tests to get people motivated into saving there investments from turning into pretty meteor showers, at least in LEO anyway.

I'll leave the whole "Cascading" point out since we're talking about the Lunar surface and Kessler Syndrome doesn't really apply here on a Lunar scale, not yet anyway.

As far as shipping rates on the salvage materials, I was contemplating something like recycling them for use in situ since as you point out, someone already picked up the Tab. This may drive the value of salvage rights to "out of this world" prices but the per pound price of Titanium etc. on the moon might be pretty steep. :wink:
There probably is a market for Historical Artifacts of this nature, although the shipping on those would drive the price range way out of my neighborhood.

I'm picturing something between "Sanford and son" and "SpaceX" but someone will certainly get in on it as long as there's a buck to be made.

Cheers to ya' Scott
  • #18
It will hit the Moon at at least 2.38 km/sec (the escape velocity).
Hi Keith,
That should be just about right for "URD", recycling the kinetic energy of the crash to breakdown the raw material is another bonus. (The actual recovery of said materials might be problematic but I have faith in Science.)

Cheers, Scott
  • #20
The impact crater has been spotted.
The impact craters, to be more precise - surprisingly it left two overlapping craters, which could tell us something about its mass distribution.
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