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PLANETARY DEFENSE

The problemsEarth & SpacePlanetary Defense

Updated · July 2026

How close are we to planetary defense?Could we stop an asteroid hitting Earth?

Could we stop an asteroid hitting Earth?How close are we to planetary defense?

Humanity has demonstrated one asteroid-deflection technique, but the survey needed to find regional-scale threats is only halfway to its statutory goal.We have moved one harmless asteroid. The bigger gap is seeing a dangerous one early enough: more than half of the estimated regional-size population is still unknown.

Current stageEngineeringEngineering a system that works outside the labBuilding a system that works outside the lab
Read the evidence Where we stand
The path so far

Recorded milestones

  1. Largest objects mostly found

  2. Regional-threat survey reaches 45%

Open tests · conceptual branches

TODAY
  1. OPEN TEST02 ↗
    Find almost every regional-size threatNinety-percent regional-threat surveyNASA estimated 45% had been discovered by April 2025. The 90% line is a legal goal, not a forecast.Discover and secure orbits for 90% of estimated near-Earth objects at least 140 metres in diameter.
TODAY
OPEN TEST02 ↗
Find almost every regional-size threatNinety-percent regional-threat surveyNASA estimated 45% had been discovered by April 2025. The 90% line is a legal goal, not a forecast.Discover and secure orbits for 90% of estimated near-Earth objects at least 140 metres in diameter.
Milestones are in recorded order. Open tests are separate questions, not a forecast.Milestones are in date order. Open tests are separate tests, not a promise.
Planetary DefenseWhere we stand

The path shows Regional-threat survey reaches 45%. Open thresholds are separate tests in a conceptual map, not a forecast. No single percentage represents progress.

01 · Where we standWhere we stand

Where we standWhere we stand

The current stage, the evidence recorded, and the single threshold that gates the next stage.The stage reached, the evidence recorded, and the one test still blocking the next step.

What the evidence has shownWhat the evidence has shown

We have moved one harmless asteroid. The bigger gap is seeing a dangerous one early enough: more than half of the estimated regional-size population is still unknown.Humanity has demonstrated one asteroid-deflection technique, but the survey needed to find regional-scale threats is only halfway to its statutory goal.

1 of 2 tests recorded1 of 2 thresholds achieved open
✓Move an asteroid on purposeKinetic-impact demonstrationAchieved
Find almost every regional-size threatNinety-percent regional-threat surveyOpen test

The next testBlocking threshold

Find almost every regional-size threatNinety-percent regional-threat survey

NEO Surveyor launches and begins its five-year infrared survey of bright and dark objects.NEO Surveyor launches and begins its five-year infrared survey of bright and dark objects.

02 · Thresholds & evidenceThresholds & evidence

What would count as proof?What would count as proof?

A clear test, the evidence behind it, and the limits of the claim.A clear test, the evidence behind it, and what it still leaves open.

✓Achieved · Sep 2022

Move an asteroid on purposeKinetic-impact demonstration

DART hit the harmless moonlet Dimorphos and shortened its orbit by about 32 minutes.Deliberately and measurably alter the orbit of a planetary-defense-relevant asteroid target.

Recorded result DART completed the first full-scale demonstration of asteroid deflection.

Next test Hera's post-impact survey must constrain Dimorphos's structure and DART's outcome well enough to improve predictive models.

SOURCE RECORD

NASA - Double Asteroid Redirection Test ↗

Still to demonstrateWhat this does not establishA separate system can still have different conditions and results.The named measurement has no wider implication until the supporting system test is also shown.

View every evidence record

Achieved

Move an asteroid on purposeKinetic-impact demonstration

DART hit the harmless moonlet Dimorphos and shortened its orbit by about 32 minutes.Deliberately and measurably alter the orbit of a planetary-defense-relevant asteroid target.

Recorded result: Sep 2022 · DART completed the first full-scale demonstration of asteroid deflection.

Next test: Hera's post-impact survey must constrain Dimorphos's structure and DART's outcome well enough to improve predictive models.

NASA - Double Asteroid Redirection Test ↗

Open test

Find almost every regional-size threatNinety-percent regional-threat survey

NASA estimated 45% had been discovered by April 2025. The 90% line is a legal goal, not a forecast.Discover and secure orbits for 90% of estimated near-Earth objects at least 140 metres in diameter.

Next test: NEO Surveyor launches and begins its five-year infrared survey of bright and dark objects.

03 · The recordThe record

The record behind the verdictThe record behind the verdict

Major milestones and smaller context events share one source-linked record. Scheduled targets are marked separately from recorded events.Milestones, smaller events and setbacks share one sourced record. Scheduled targets are marked separately from recorded events.

Event key
TheoryExperimentFundingSetbackPolicyDeployment Future / scheduled
1994-20042 events1 shown

Impacts become a present-day hazard

This record spans “Shoemaker-Levy 9 strikes Jupiter” to “One-kilometre survey goal set”.

1994
Shoemaker-Levy 9 strikes JupiterExperiment
Twenty-one comet fragments hit Jupiter while spacecraft and observatories watched, showing large impacts occurring in the modern Solar System.
Global observatories and NASA
1998
One-kilometre survey goal set
The United States directed NASA to find 90% of near-Earth asteroids at least one kilometre across.
US Congress and NASA
2005-20122 events1 shown

The survey expands to regional threats

This record spans “Survey threshold drops to 140 metres” to “Kilometre survey passes 90%”.

2005
Survey threshold drops to 140 metresPolicy
Congress set a goal for NASA to detect 90% of near-Earth objects at least 140 metres wide by 2020.
US Congress
2011
Kilometre survey passes 90%
NEOWISE estimated that 911 of 981 near-Earth asteroids larger than one kilometre were known, or 93%.
NASA NEOWISE
2013-20202 events1 shown

Chelyabinsk exposes the blind spots

This record spans “Chelyabinsk arrives without warning” to “NASA creates a defense office”.

2013
Chelyabinsk arrives without warningSetback
An approximately 18-metre object exploded over Chelyabinsk, damaging buildings and injuring more than 1,000 people.
Global observing community
2016
NASA creates a defense office
NASA established the Planetary Defense Coordination Office to manage detection, tracking, characterization and mitigation work.
NASA
2021-20253 events1 shown

Humanity moves an asteroid

This record spans “DART launches a deflection test” to “Hera launches to the impact site”.

2021
DART launches a deflection test
NASA launched the first mission built to demonstrate asteroid deflection with a kinetic impactor.
NASA and Johns Hopkins APL
2022
DART changes an asteroid's orbitExperiment
DART struck the harmless moonlet Dimorphos and shortened its orbit around Didymos by about 32 minutes.
NASA DART
2024
Hera launches to the impact site
ESA launched Hera to survey Dimorphos and reduce uncertainties around the DART result.
European Space Agency
2026-20271 event0 shown

Measuring the shove and widening the search

Scheduled target: “Hera targets Didymos rendezvous”.

2026
Hera targets Didymos rendezvousDeploymentTarget
Hera is on course to reach the binary system and begin the close measurements DART could not make from Earth.
European Space Agency
2025-20272 events1 shown

Additional records

This record spans “Regional-size survey reaches only 45%” to “NEO Surveyor launch readiness” and includes scheduled targets.

2025
Regional-size survey reaches only 45%SetbackWe are here
NASA's inspector general reported 45% estimated completeness for near-Earth objects at least 140 metres across, versus the missed 90% goal.
NASA Office of Inspector General
2027
NEO Surveyor launch readinessDeploymentTarget
NASA lists its dedicated infrared asteroid telescope for launch no earlier than September 2027; the date and survey result remain future work.
NASA and JPL
— end of record · 12 events shown —
04 · The dataThe data

The data behind the verdictThe data behind the verdict

Read each measure with its units, conditions, uncertainty and source; targets remain distinct from observations.Read each chart with its conditions, limits and source. Future targets remain distinct from recorded results.

Open figure in archive: This is a size-threshold comparison, not a time trend: the scarcer kilometre-scale population is much more completely surveyed than the larger 140-metre-plus population.Open figure in archive: One precisely observed deflection of one harmless rubble-pile moonlet-not a universal result for every asteroid type.
Estimated NEOs at least 140 m discoveredEstimated NEOs at least 140 m discovered
Scale

NASA OIG baseline · 24 % · 2014 · verification unspecified

Estimated NEOs at least 140 m discovered over time, with measured values, projected values, and a goal at 90 %.2030405060708090Estimated NEOs at least 140 m discovered · %Year20142025GOAL 90 · US statutory survey goal - not a…NASA OIG baselineNASA estimate, April 2025~45 % to goal
NOTE - These percentages are estimates derived from population models, not a direct census. The 90% mark is the still-unmet US survey goal for objects at least 140 metres across; it is not a completion forecast.
View data table
All metric observations
DateValueStatusCondition / labelVerificationCICensoringSource
201424 %observedNASA OIG baselineunspecified—noneNASA OIG - planetary-defense strategy audit (2025)
202545 %observedNASA estimate, April 2025unspecified—noneNASA OIG - planetary-defense strategy audit (2025)
AS OF July 2026
View every data figure
Estimated NEOs at least 140 m discoveredEstimated NEOs at least 140 m discovered
Scale

NASA OIG baseline · 24 % · 2014 · verification unspecified

Estimated NEOs at least 140 m discovered over time, with measured values, projected values, and a goal at 90 %.2030405060708090Estimated NEOs at least 140 m discovered · %Year20142025GOAL 90 · US statutory survey goal - not a…NASA OIG baselineNASA estimate, April 2025~45 % to goal
NOTE - These percentages are estimates derived from population models, not a direct census. The 90% mark is the still-unmet US survey goal for objects at least 140 metres across; it is not a completion forecast.
View data table
All metric observations
DateValueStatusCondition / labelVerificationCICensoringSource
201424 %observedNASA OIG baselineunspecified—noneNASA OIG - planetary-defense strategy audit (2025)
202545 %observedNASA estimate, April 2025unspecified—noneNASA OIG - planetary-defense strategy audit (2025)
AS OF July 2026
This is a size-threshold comparison, not a time trend: the scarcer kilometre-scale population is much more completely surveyed than the larger 140-metre-plus population.This is a size-threshold comparison, not a time trend: the scarcer kilometre-scale population is much more completely surveyed than the larger 140-metre-plus population.

Independent records

Discovery completeness by size threshold linear scale · %

linear scale · %
Larger than 1 km201193 %
At least 140 m202545 %
observed self-reported target / pathway right-censored lower bound
View data table
All plotted observations
SeriesDateValueStatusCondition / labelVerificationCICensoringSource
Discovery completeness by size threshold201193 %observedLarger than 1 kmunspecified—noneNASA - NEOWISE survey result
Discovery completeness by size threshold202545 %observedAt least 140 munspecified—noneNASA OIG - planetary-defense strategy audit (2025)
AS OF July 2026
One precisely observed deflection of one harmless rubble-pile moonlet-not a universal result for every asteroid type.One precisely observed deflection of one harmless rubble-pile moonlet-not a universal result for every asteroid type.

linear scale · minutes by year

Observed after impact · -32 minutes · Jan 2022 · verification unspecified

One precisely observed deflection of one harmless rubble-pile moonlet-not a universal result for every asteroid type.-32 minutes · Jan 2022Observed after impact: -32 minutes · Jan 2022Year
Log-scale line joins each new longest record; all observations remain individual dots.

Latest record

Observed after impact

-32 minutes · Jan 2022

observed · Verification unspecified

View data table
All plotted observations
SeriesDateValueStatusCondition / labelVerificationCICensoringSource
DART Dimorphos orbital-period change2022-32 minutesobservedObserved after impactunspecified—noneNASA - Double Asteroid Redirection Test
AS OF July 2026
05 · What it unlocksWhat it unlocks

If the remaining tests pass.If the remaining tests pass.

Downstream capabilities remain conditional on results that are not yet in.These are possible next capabilities, conditional on results that are not yet in.

TODAY
  1. PASSED · Sep 202201 ↗
    Move an asteroid on purposeKinetic-impact demonstrationDART hit the harmless moonlet Dimorphos and shortened its orbit by about 32 minutes.Deliberately and measurably alter the orbit of a planetary-defense-relevant asteroid target.
  2. OPEN TEST02 ↗
    Find almost every regional-size threatNinety-percent regional-threat surveyNASA estimated 45% had been discovered by April 2025. The 90% line is a legal goal, not a forecast.Discover and secure orbits for 90% of estimated near-Earth objects at least 140 metres in diameter.
PASSED · Sep 202201 ↗
Move an asteroid on purposeKinetic-impact demonstrationDART hit the harmless moonlet Dimorphos and shortened its orbit by about 32 minutes.Deliberately and measurably alter the orbit of a planetary-defense-relevant asteroid target.
TODAY
OPEN TEST02 ↗
Find almost every regional-size threatNinety-percent regional-threat surveyNASA estimated 45% had been discovered by April 2025. The 90% line is a legal goal, not a forecast.Discover and secure orbits for 90% of estimated near-Earth objects at least 140 metres in diameter.

Possible, if the open tests pass.

  1. Preventable impact disasters

    This is a possible benefit only if preventable impact disasters works safely, reliably and at useful scale.Potential benefit only if the stated use (Preventable impact disasters) is demonstrated with evidence for safety, reliability, affordability and scale.

  2. Rapid small-body reconnaissance

    This is a possible benefit only if rapid small-body reconnaissance works safely, reliably and at useful scale.Potential benefit only if the stated use (Rapid small-body reconnaissance) is demonstrated with evidence for safety, reliability, affordability and scale.

  3. International hazard coordination

    This is a possible benefit only if international hazard coordination works safely, reliably and at useful scale.Potential benefit only if the stated use (International hazard coordination) is demonstrated with evidence for safety, reliability, affordability and scale.

These are possible outcomes, if the open tests pass. They are conditional, not promises.
06 · SourcesSources

Follow the evidence.Follow the evidence.

10 sources — every figure on this page traces to one.10 sources — every figure on this page traces to one.

Source · what this page citesScope and limits
  1. 01

    NASA OIG - planetary-defense strategy audit (2025)

    Read source ↗assets.science.nasa.gov
    Used on this page
    All 12 uses across 10 destinations

    Scope: Not recorded. Limit: Not recorded.

  2. 02

    Scope: Not recorded. Limit: Not recorded.

  3. 03

    Scope: Not recorded. Limit: Not recorded.

  4. 04

    ESA - Hera mission

    Read source ↗esa.int

    Scope: Not recorded. Limit: Not recorded.

  5. 05

    Scope: Not recorded. Limit: Not recorded.

  6. 06

    NASA - Chelyabinsk impact retrospective

    Read source ↗science.nasa.gov

    Scope: Not recorded. Limit: Not recorded.

  7. 07

    Timeline · Shoemaker-Levy 9 strikes Jupiter

    Read source ↗science.nasa.gov
    Used on this page
    All 2 uses across 1 destination

    Scope: Not recorded. Limit: Not recorded.

  8. 08

    Timeline · One-kilometre survey goal set

    Read source ↗science.nasa.gov
    Used on this page
    All 2 uses across 2 destinations

    Scope: Not recorded. Limit: Not recorded.

  9. 09

    Timeline · Hera launches to the impact site

    Read source ↗esa.int
    Used on this page
    All 2 uses across 2 destinations

    Scope: Not recorded. Limit: Not recorded.

  10. 10

    Scope: Not recorded. Limit: Not recorded.

Sources describe evidence. Inclusion is not endorsement.