SpaceAtlas Space Object Data
NASA JPL SBDB · 2021 HS1

2021 HS1

2021 HS1 belongs to the Apollo group of near-Earth asteroids, whose orbits cross the path of Earth; with a semi-major axis of 1.122 AU it takes 1.19 yr to circle the Sun.

Apollo Observations: 31
Orbital Period · P
1.19 yr
v(q)
31.5 km/s
v(Q)
25.1 km/s
Diameter · ≈
0.02 km
TJ
5.55
Eccentricity · e
0.1145

Orbit and dynamics

The path is an ellipse reaching 0.994 AU from the Sun at perihelion and 1.25 AU at aphelion, a radial span of 0.256 AU.

Applying Kepler's third law to a = 1.122 AU gives an orbital period of 1.19 yr, or about 434 days.

An eccentricity of 0.115 makes the orbit moderately elongated.

The orbital plane is tilted 6.63° relative to the ecliptic.

By the vis-viva equation its orbital speed rises to 31.5 km/s at perihelion and falls to 25.1 km/s at aphelion.

Because q < 1 AU and Q > 1 AU, this orbit geometrically intersects the region of Earth's orbit.

Size and surface

No direct size measurement is available; from an absolute magnitude of H = 26.26 and an assumed geometric albedo of 0.14, the diameter works out to roughly 0.02 km.

Observation record and orbit quality

The current orbit solution is based on 31 observations and has a weighted RMS residual of 0.4881 arcseconds.

Condition code U = 6 indicates a moderately constrained orbit; predictions decades ahead still carry noticeable uncertainty.

About these computed values

Orbital periods, perihelion and aphelion speeds, and diameter estimates on this page are computed by SpaceAtlas from the JPL SBDB orbital elements. They are derived quantities, not values copied from the source catalogue.

Orbital Parameters

Semi-Major Axis
1.122 AU
Eccentricity
0.1145
Perihelion
0.994 AU
Aphelion
1.250469 AU
Inclination
6.63°
Orbital Period
— yr
Epoch
2461200.5
Mean Anomaly
164.37°

Orbit diagram

The Sun sits at the focus (orange). Earth's orbit is the grey circle at 1 AU. The red dot marks the object's position at the catalog epoch.

3D orbit (interactive)

Drag to rotate; scroll or pinch to zoom. The Sun is at the focus (orange), Earth's orbit is the grey ring at 1 AU, and the red dot marks the object's current position.

Close approaches

Predicted close approaches to Earth, from NASA's Center for Near-Earth Object Studies (CNEOS).

Date (UTC)Miss distanceVelocity
2027-Jan-10 19:29 0.330068 AU
49377416 km
11.49 km/s
2027-Jul-19 21:38 0.246401 AU
36861028 km
3.85 km/s
2033-Sep-17 21:28 0.234342 AU
35057060 km
5.19 km/s
2034-Apr-28 23:22 0.423582 AU
63366941 km
15.85 km/s
2040-Apr-09 04:37 0.053949 AU
8070609 km
6.12 km/s
2052-Aug-20 16:09 0.259460 AU
38814653 km
4.86 km/s
2058-Oct-11 11:24 0.211148 AU
31587231 km
5.01 km/s
2059-Apr-21 05:25 0.312607 AU
46765290 km
11.61 km/s
2065-Apr-02 02:14 0.021555 AU
3224513 km
3.81 km/s
2071-Jan-07 15:19 0.314235 AU
47008919 km
13.57 km/s

Distances in astronomical units (AU) and kilometres. Source: NASA/JPL CNEOS Close Approach Data API.

Physical Parameters

Diameter
— km
Albedo
—
Density
— g/cm³
Rotation Period
— h
Absolute Magnitude
26.26

Orbit Quality

RMS
0.48809
Condition
6
Orbit ID
—
Data source: NASA JPL Small-Body Database · NASA CNEOS. Orbital periods, perihelion and aphelion speeds, and diameter estimates on this page are computed by SpaceAtlas from the JPL SBDB orbital elements. They are derived quantities, not values copied from the source catalogue.

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