diff --git a/apps/api/src/hyp3_api/validation.py b/apps/api/src/hyp3_api/validation.py
index 6d9ff9646..4355f71f6 100644
--- a/apps/api/src/hyp3_api/validation.py
+++ b/apps/api/src/hyp3_api/validation.py
@@ -179,6 +179,23 @@ def check_granules_intersecting_bounds(job, granule_metadata):
         )
 
 
+def check_same_relative_orbits(job, granule_metadata):
+    previous_relative_orbit = None
+    for granule in granule_metadata:
+        name_split = granule['name'].split('_')
+        absolute_orbit = name_split[7]
+        # "Relationship between relative and absolute orbit numbers": https://sentiwiki.copernicus.eu/web/s1-products
+        offset = 73 if name_split[0] == 'S1A' else 27
+        relative_orbit = ((int(absolute_orbit) - offset) % 175) + 1
+        if not previous_relative_orbit:
+            previous_relative_orbit = relative_orbit
+        if relative_orbit != previous_relative_orbit:
+            raise GranuleValidationError(
+                f'Relative orbit number for {granule["name"]} does not match that of the previous granules: '
+                f'{relative_orbit} is not {previous_relative_orbit}.'
+            )
+
+
 def convert_single_burst_jobs(jobs: list[dict]) -> list[dict]:
     jobs = deepcopy(jobs)
     for job in jobs:
diff --git a/job_spec/SRG_GSLC.yml b/job_spec/SRG_GSLC.yml
index 26609f537..ccff7c84e 100644
--- a/job_spec/SRG_GSLC.yml
+++ b/job_spec/SRG_GSLC.yml
@@ -38,7 +38,8 @@ SRG_GSLC:
           example: -116.583
   validators: [
     check_bounds_formatting,
-    check_granules_intersecting_bounds
+    check_granules_intersecting_bounds,
+    check_same_relative_orbits
   ]
   cost_profiles:
     DEFAULT:
diff --git a/job_spec/SRG_TIME_SERIES.yml b/job_spec/SRG_TIME_SERIES.yml
index 2cfe31af0..c081bf8c4 100644
--- a/job_spec/SRG_TIME_SERIES.yml
+++ b/job_spec/SRG_TIME_SERIES.yml
@@ -38,7 +38,8 @@ SRG_TIME_SERIES:
           example: -116.583
   validators: [
     check_bounds_formatting,
-    check_granules_intersecting_bounds
+    check_granules_intersecting_bounds,
+    check_same_relative_orbits
   ]
   cost_profiles:
     DEFAULT:
diff --git a/tests/test_api/test_validation.py b/tests/test_api/test_validation.py
index 410d01d77..6a32aefc4 100644
--- a/tests/test_api/test_validation.py
+++ b/tests/test_api/test_validation.py
@@ -536,3 +536,20 @@ def test_check_granules_intersecting_bounds():
         validation.check_granules_intersecting_bounds(job_with_specified_bounds, invalid_granule_metadata)
     with raises(validation.GranuleValidationError, match=error_pattern):
         validation.check_granules_intersecting_bounds(job_with_default_bounds, invalid_granule_metadata)
+
+
+def check_same_relative_orbits():
+    valid_granule_metadata = [
+        {'name': 'S1A_IW_RAW__0SDV_20201015T161622_20201015T161654_034809_040E95_AF3C'},
+        {'name': 'S1A_IW_RAW__0SDV_20200816T161620_20200816T161652_033934_03EFCE_5730'},
+        {'name': 'S1B_IW_RAW__0SDV_20200810T161537_20200810T161610_022863_02B66A_F7D7'},
+        {'name': 'S1B_IW_RAW__0SDV_20200623T161535_20200623T161607_022163_02A10F_7FD6'}
+    ]
+    invalid_granule_metadata = valid_granule_metadata
+    invalid_granule_metadata.append(
+        {'name': 'S1B_IW_RAW__0SDV_20200623T161535_20200623T161607_012345_02A10F_7FD6'}
+    )
+    validation.check_same_relative_orbits({}, valid_granule_metadata)
+    error_pattern = r'.*23 is not 87.*'
+    with raises(validation.GranuleValidationError, match=error_pattern):
+        validation.check_same_relative_orbits({}, invalid_granule_metadata)