NASA Confirms Asteroid Apophis Will Pass Closer to Earth Than Some Satellites in 2029

On the evening of April 13, 2029 — a Friday the 13th — up to two billion people will be able to watch a point of light drift across the sky, moving fast enough relative to background stars that its motion will be perceptible within minutes [1]. That point of light will be 99942 Apophis, a 370-meter asteroid named after the Egyptian god of chaos, passing closer to Earth than any known object of its size in recorded history [2].

The flyby is confirmed safe. But the story of how Apophis went from a 2.7% impact probability to a guaranteed miss — and the questions its approach raises about humanity's readiness for the asteroid that won't miss — is one of the most consequential science narratives of the decade.

How Close Is Close?

At 21:46 UTC on April 13, 2029, Apophis will pass approximately 31,600 kilometers (19,600 miles) above Earth's surface [3]. To put that distance in context:

• Starlink satellites orbit at roughly 550 km altitude. Apophis will pass far above them.
• GPS satellites operate at about 20,200 km. Apophis will pass above this shell as well.
• Geosynchronous communications satellites sit at approximately 35,786 km (22,236 miles) [4]. Apophis will pass below this ring — closer to Earth than roughly 580 operational satellites that provide television broadcasts, weather data, and military communications [5].

The asteroid will be just one-tenth the distance to the Moon and about five Earth radii from the surface [3]. During its closest approach, Apophis will brighten to magnitude 3.1, comparable to the stars in the Big Dipper, and will sweep an arc of 205 degrees across the sky in approximately 24 hours — from Centaurus through Perseus to Pisces [1].

Despite passing within the geosynchronous belt, Apophis poses no collision risk to satellites. Its trajectory is inclined 40 degrees to the equatorial plane, meaning it crosses the equatorial plane — where geosynchronous satellites cluster — at a distance well outside the geostationary ring [6]. No space agency has issued guidance for satellite operators to maneuver their spacecraft out of the way.

From Panic to All-Clear: The Probability Timeline

Apophis was discovered on June 19, 2004, at the Kitt Peak National Observatory [7]. Within months, initial orbital calculations produced an alarming figure: a 2.7% chance of striking Earth in 2029 [8]. That made Apophis the first asteroid to reach Level 4 on the Torino Impact Hazard Scale, a classification that indicates a "close encounter, meriting attention by astronomers."

Source: NASA JPL / ESA

Data as of May 31, 2026CSV

The alarm was short-lived. Additional observations in early 2005 ruled out a 2029 impact entirely [8]. But the refined trajectory revealed a new concern: during its 2029 pass, Apophis would thread through a narrow gravitational "keyhole" — a small region of space where Earth's gravity could bend the asteroid's orbit just enough to set up a collision on a future return. The 2036 return visit initially carried a 1-in-45,000 chance of impact, later refined downward to 1-in-250,000 [8]. A separate 2068 approach carried residual odds of approximately 1-in-333,000 [8].

In March 2021, radar observations from the Goldstone Deep Space Communications Complex during a distant flyby refined Apophis's orbit with sufficient precision for NASA's Jet Propulsion Laboratory to issue a definitive statement: "A 2068 impact is not in the realm of possibility anymore, and our calculations don't show any impact risk for at least the next 100 years" [9].

What If It Did Hit?

Apophis is roughly 370 meters in diameter and has an estimated mass of about 61 million metric tons [3]. Were it to strike Earth — which it will not — the consequences would depend heavily on where it landed.

The object responsible for the 1908 Tunguska event in Siberia was estimated at 50 to 60 meters wide and produced a blast of roughly 15 megatons of TNT equivalent, flattening 80 million trees over 2,150 square kilometers [10]. Apophis is roughly four to six times the diameter of the Tunguska impactor, but because kinetic energy scales with mass and the cube of diameter, the energy released would be on the order of 1,000 megatons — approximately 100 times the Tunguska event [11].

A land impact on a densely populated region would obliterate an area the size of a small country's capital and its surrounding metropolitan area. The blast wave, thermal radiation, and seismic effects would cause casualties extending well beyond the immediate crater zone. Estimates for a direct hit on a major city run into the tens of millions of casualties [11].

An ocean impact would generate tsunamis, though recent modeling suggests the risk from ocean strikes has been overstated in earlier studies. The 2019 probabilistic assessment published in Icarus found that airburst effects, not tsunami, dominate the casualty risk for asteroids in this size range [12].

For comparison, the Chicxulub impactor that contributed to the end-Cretaceous mass extinction 66 million years ago was roughly 10 kilometers wide. Apophis is a regional threat, not a civilization-ending one — but "regional" in this context can mean millions of lives.

The Race to Rendezvous

Two spacecraft are scheduled to study Apophis during or shortly after its 2029 encounter, though both face funding uncertainties.

Ramses (ESA/JAXA): The European Space Agency's Rapid Apophis Mission for Space Safety is designed to arrive at Apophis in February 2029, approximately two months before the closest approach [13]. The spacecraft will observe the asteroid before, during, and after Earth's gravitational influence reshapes its spin state, surface features, and orbital parameters. JAXA will provide solar arrays and a thermal infrared imager and launch the mission on an H3 rocket in April 2028 [14]. ESA's Ministerial Council approved the mission in November 2025, though full funding had not been secured at the time of approval [13]. ESA has also announced plans to deploy a small lander on Apophis's surface [15].

OSIRIS-APEX (NASA): An extension of the OSIRIS-REx mission that returned samples from asteroid Bennu in 2023, OSIRIS-APEX will arrive at Apophis shortly after the 2029 flyby to study the asteroid's altered state [16]. The mission has faced repeated threats of cancellation. The White House's fiscal year 2027 budget proposal included no funding for OSIRIS-APEX, but the House Appropriations Committee allocated $20 million to keep the mission alive [17]. This is the second consecutive year that Congress has overridden a proposed cancellation.

NEO Surveyor: Though not an Apophis-specific mission, NASA's Near-Earth Object Surveyor space telescope — the first purpose-built for detecting potentially hazardous asteroids — passed its critical design review in February 2025 and is on track for a late 2027 launch [18]. It will survey from the Sun-Earth L1 Lagrange point, aiming to catalog at least two-thirds of near-Earth objects larger than 140 meters within its five-year baseline mission.

The Budget Question

NASA's planetary defense budget has grown from $5.8 million in fiscal year 2010 to approximately $200 million in fiscal year 2024 — a 34-fold increase driven largely by the addition of the DART (Double Asteroid Redirection Test) mission and expanded near-Earth object observation programs [19].

Source: The Planetary Society

Data as of May 31, 2026CSV

DART, which successfully deflected the moonlet Dimorphos in September 2022, cost $324.5 million in total — $308 million for spacecraft development, $68.8 million for launch, and $16.5 million for operations and analysis [20]. Data published in Nature confirmed that the kinetic impactor technique works: DART altered Dimorphos's orbital period by 33 minutes, far exceeding the minimum benchmark of 73 seconds [21].

But critics of planetary defense spending raise a straightforward question about resource allocation. The annual probability of a Tunguska-class impact (objects 50 meters and above) is roughly 1 in 1,000. For Apophis-sized objects (300+ meters), it drops to approximately 1 in 70,000 per year [12]. Meanwhile, approximately 1.35 million people die annually in road traffic crashes, and preventable medical errors kill an estimated 250,000 people per year in the United States alone.

Proponents counter with a standard expected-value argument: the probability is low, but the potential casualty count from a single large impact dwarfs any single terrestrial disaster. A Chicxulub-class event — roughly 1-in-100-million per year — could end civilization. When the stakes include extinction, even small probabilities justify meaningful investment [22].

The Planetary Society has argued that current spending remains modest relative to the risk: $200 million per year is less than the cost of a single F-35 fighter jet [19]. And unlike earthquakes, volcanic eruptions, or hurricanes, asteroid impacts are the only large-scale natural disaster that can, in principle, be entirely prevented with sufficient warning and technology [22].

Could We Stop One in Time?

DART answered the question of whether a kinetic impactor works. The harder question is whether one could be deployed fast enough if a threat were confirmed with limited warning.

The DART mission took roughly five years from formal project start to impact. A dedicated deflection mission for an Apophis-sized object would require even more energy — and thus a larger spacecraft, heavier launch vehicle, or longer lead time to accumulate the necessary velocity change [21].

If Apophis had been confirmed as an impactor in, say, 2027, the realistic timeline for a deflection mission would likely be inadequate. Two years is insufficient to design, build, launch, and deliver a kinetic impactor to an asteroid 370 meters across with enough momentum transfer to meaningfully alter its trajectory. Planetary defense experts generally cite a minimum of 5 to 10 years of lead time as necessary for a credible deflection campaign against an object of this size [22].

The institutional architecture for responding to such a threat exists in outline form. NASA's Planetary Defense Coordination Office (PDCO) coordinates detection and characterization efforts [23]. The United Nations Committee on the Peaceful Uses of Outer Space (COPUOS) has established two working groups: the International Asteroid Warning Network (IAWN), which coordinates observations and warning notifications, and the Space Mission Planning Advisory Group (SMPAG), which develops deflection mission options [24].

What does not exist is a binding international treaty that authorizes any nation or body to launch a deflection mission. The 1967 Outer Space Treaty prohibits placing nuclear weapons in space, which complicates one class of deflection strategies — nuclear standoff detonation — that may be the only viable option for large objects detected with short warning times [24]. No current treaty framework establishes who decides, who pays, or who bears liability if a deflection attempt goes wrong and redirects an asteroid toward a different country.

In 2013, the United States and Russia signed an agreement expressing intent to cooperate on asteroid defense, but it remains a statement of principle rather than an operational framework [24].

A Once-in-a-Millennium Laboratory

For scientists, the 2029 flyby is less about risk and more about opportunity. Apophis's close approach will allow ground-based radar, optical telescopes, and two dedicated spacecraft to observe how Earth's gravity alters an asteroid in real time — a natural experiment that cannot be replicated in any laboratory [13].

Researchers expect the encounter to change Apophis's spin rate and possibly trigger surface landslides or expose fresh subsurface material. These observations will directly inform future deflection strategies: understanding how an asteroid's internal structure responds to external forces is essential for predicting how it would respond to a kinetic impactor or other intervention [13].

The Ramses mission, in particular, is designed to obtain a complete "before and after" portrait. Arriving two months early, it will map Apophis's shape, composition, spin state, and surface features before Earth's gravity acts on the asteroid, then document the changes during and after closest approach [14].

What Apophis Teaches Us

Apophis is not going to hit Earth. The science on this point is settled for at least the next century [9]. But the asteroid's story — from initial alarm to confirmed safety to ambitious scientific exploitation — illustrates both the strengths and gaps in humanity's planetary defense posture.

The strengths are real: ground-based detection networks identified Apophis, subsequent observations refined its orbit, and the DART mission demonstrated that deflection technology works. The gaps are equally real: funding for Apophis-related missions faces annual cancellation threats, no international legal framework governs deflection decisions, and the minimum response time for a credible deflection campaign exceeds the warning time that many potential impactors would provide.

The next three years offer a window to address some of these gaps. NEO Surveyor's 2027 launch will dramatically expand the catalog of known near-Earth objects [18]. The Ramses and OSIRIS-APEX missions, if fully funded, will provide unprecedented data on asteroid response to gravitational perturbation [13][16]. And the sheer spectacle of a 370-meter asteroid visible to the naked eye may generate the public attention that planetary defense advocates have long sought.

On April 13, 2029, roughly two billion people will have a chance to look up and watch Apophis cross the sky [1]. The rock will pass harmlessly. The question is whether humanity will be ready the next time the answer is different.